- The reduction of Cr(VI) to Cr(III) by the α and β anomers of D-glucose in dimethyl sulfoxide. A comparative kinetic and mechanistic study
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The reduction of Cr(VI) by α-D-glucose and β-D-glucose was studied in dimethyl sulfoxide in the presence of pyridinium p-toluensulfonate, a medium where mutarotation is slower than the redox reaction. The two anomers reduce Cr(VI) by formation of an intermediate Cr(VI) ester precursor of the slow redox step. The equilibrium constant for the formation of the intermediate chromic ester and the rate of the redox steps are different for each anomer. α-D-Glucose forms the Cr(VI)-Glc ester with a higher equilibrium constant than β-D-glucose, but the electron transfer within this complex is slower than for the β anomer. The difference is attributed to the better chelating ability of the 1,2-cis-diolate moiety of the α anomer. The Cr(V) species, generated in the reaction mixture, reacts with the two anomers at a rate comparable with that of Cr(VI). The EPR spectra show that the α anomer forms several linkage isomers of the five-coordinate Cr(V) bis-chelate, while β-D- glucose affords a mixture of six-coordinate Cr(V) mono-chelate and five- coordinate Cr(V) bis-chelate. The conversion of the Cr(V) mono- to bis- chelate is discussed in terms of the ability of the 1,2-cis- versus 1,2- trans-diolate moieties of the glucose anomers to bind Cr(V). (C) 2000 Elsevier Science Ltd.
- Signorella, Sandra,Lafarga, Rubén,Daier, Verónica,Sala, Luis F.
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- Au/Pt-Egg-in-Nest Nanomotor for Glucose-Powered Catalytic Motion and Enhanced Molecular Transport to Living Cells
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Nanostructures converting chemical energy to mechanical work by using benign metabolic fuels, have huge implications in biomedical science. Here, we introduce Au/Pt-based Janus nanostructures, resembling to “egg-in-nest” morphology (Au/Pt-ENs), showing enhanced motion as a result of dual enzyme-relay-like catalytic cascade in physiological biomedia, and in turn showing molecular-laden transport to living cells. We developed dynamic-casting approach using silica yolk-shell nanoreactors: first, to install a large Au-seed fixing the silica-yolk aside while providing the anisotropically confined concave hollow nanospace to grow curved Pt-dendritic networks. Owing to the intimately interfaced Au and Pt catalytic sites integrated in a unique anisotropic nest-like morphology, Au/Pt-ENs exhibited high diffusion rates and displacements as the result of glucose-converted oxygen concentration gradient. High diffusiophoresis in cell culture media increased the nanomotor-membrane interaction events, in turn facilitated the cell internalization. In addition, the porous network of Au/Pt-ENs facilitated the drug-molecule cargo loading and delivery to the living cells.
- Kumar, Amit,Kumari, Nitee,Kwon, Taewan,Lee, In Su,Lim, Jongwon,Son, Chang Yun
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- Glucose biosensor based on new carbon nanotube-gold-titania nano-composites modified glassy carbon electrode
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In this paper, a novel biosensor was prepared by immobilizing glucose oxidase (GOx) on carbon nanotube-gold-titania nanocomposites (CNT/Au/TiO 2) modified glassy carbon electrode (GCE). SEM was initially used to investigate the surface morphology of CNT/Au/TiO2 nanocomposites modified GCE, indicating the formation of the nano-porous structure which could readily facilitate the attachment of GOx on the electrode surface. Cyclic voltammogram (CV) and electrochemical impedance spectrum (EIS) were further utilized to explore relevant electrochemical activity on CNT/Au/TiO2 nanocomposites modified GCE. The observations demonstrated that the immobilized GOx could efficiently execute its bioelectrocatalytic activity for the oxidation of glucose. The biosensor exhibited a wider linearity range from 0.1 mmol L-1 to 8 mmol L-1 glucose with a detection limit of 0.077 mmol L-1.
- Wu, Yue-Li,Li, Qi-Wei,Zhang, Xiao-Lu,Chen, Xiao,Wang, Xue-Mei
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- Sol-gel encapsulated glucose oxidase arrays based on a pH sensitive fluorescent dye
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Optical glucose oxidase (GOx) arrays based on pH sensitive fluorescent dye (2-(4-tolyl)-4-[4-(1,4,7,10-tetraoxa-13-azacyclopentadecyl)benzylidene] -5-oxazolone) (CPO) has been constructed. The arrays were prepared by spotting of CPO and GOx together with tetraethoxysilane (TEOS)/Chitosan (CHIT) mixture via a microarrayer. After optimization studies, analytical characterization of enzyme arrays were carried out. The fluorescence intensity of the system was linearly correlated to glucose concentration in the range of 1.0-30.0 mM (in potassium phosphate buffer; 2.5 mM at pH 7.0). Furthermore, the developed arrays were used to analyze glucose in some beverages and HPLC was used as a reference method for independent glucose analysis.
- Yildirim, Nimet,Odaci, Dilek,Ozturk, Gulsiye,Alp, Serap,Ergun, Yavuz,Dornbusch, Kay,Feller, Karl-Heinz,Timur, Suna
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- Oxidation of d-Glucose to Glucaric Acid Using Au/C Catalysts
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The reactivity of Au and AuBi nanoparticles supported on activated carbon AC was investigated in the direct oxidation of glucose to glucaric acid. The catalysts were very active, regardless of the Au nanoparticles size, but the catalyst with the smallest average particle diameter was the least selective to glucaric acid because of the enhanced consecutive oxidative degradation of the intermediately formed gluconic acid. The reaction network included the fast oxidation of glucose to gluconic acid, which was the only primary product, and its consecutive oxidation into either glucaric acid or lighter mono and dicarboxylic acids. The best glucaric acid yield obtained with a AuBi/AC catalyst (Au/Bi 3:1) was 31 %, with 18 % residual gluconic acid. The control of reaction parameters was essential to achieving the best selectivity. Specifically, the glucose concentration turned out to be a critical parameter in relation to O2 pressure and to glucose/metal ratio.
- Solmi, Stefania,Morreale, Calogero,Ospitali, Francesca,Agnoli, Stefano,Cavani, Fabrizio
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- Label-free Si quantum dots as photoluminescence probes for glucose detection
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Si quantum dots have been demonstrated to be environmentally friendly photoluminescence probes and their fluorescence was quenched by H 2O2 that was produced from the glucose oxidase-catalyzed oxidation of glucose. This strategy could be used to detect glucose with high sensitivity and selectivity.
- Yi, Yinhui,Deng, Jianhui,Zhang, Youyu,Li, Haitao,Yao, Shouzhuo
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- Diverse applications of TMB-based sensing probes
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Extending the research on 3,3′,5,5′-tetramethylbenzidine (TMB) and its derivatives in analytical chemistry is important, considering that TMB is widely used as an enzyme catalytic substrate. In this work, two TMB derivatives, TMBS and TMBB, were synthesized via a facile and one-step condensation reaction between the -NH2 group of TMB and the -CHO group of salicylaldehyde or benzaldehyde. Because at low pH the two Schiff base compounds can release TMB which can emit strong fluorescence, the probes could show dual-modal signal responses, fluorescence and UV-vis absorption, towards the pH. Practical applications of pH sensing in Chinese rice vinegar and lemon juice samples were successfully demonstrated. On the basis of these findings, a catalytic chromogenic reaction was developed to monitor the pH with the naked eye, too. Furthermore, considering the chemical equilibrium reaction between CO2 and H2O and that glucose oxidase (GOD) can catalyse the dehydrogenation and oxidation reaction of β-d-glucose to produce gluconic acid, both of which can result in lowering the pH values of the two Schiff base systems, highly sensitive and selective dual-modal sensing systems for detecting CO2 and β-d-glucose have also been successfully established. Therefore, the two synthesized TMB derivatives can demonstrate their robust application potential.
- Huang, Li,Cao, Ying-Juan,Sun, Xiang-Ying,Liu, Bin,Shen, Jiang-Shan
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- Structure sensitivity and kinetics of D-glucose oxidation to D-gluconic acid over carbon-supported gold catalysts
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The heterogeneously catalyzed oxidation of D-glucose to D-gluconic acid over Au/C catalysts has been studied. A series of Au/C catalysts were prepared by the gold sol method with different reducing agents and different kinds of carbon support providing Au mean particle diameters in the range 3-6 nm. The activities of these catalysts with respect to D-glucose oxidation were compared, and several aspects influencing activity, especially Au particle size, were discussed. The influence of reaction conditions (T=30-90°C, pH 7.0-9.5) on the kinetics of the D-glucose oxidation has been examined using the most active Au/C catalyst. By a detailed analysis of all reaction products under different reaction conditions, a reaction network of the D-glucose oxidation is presented, and a reaction mechanism for D-glucose oxidation that explains the influence of pH on reaction rate is proposed. Ensuring that D-glucose oxidation takes place in the kinetic regime (sufficient stirring rate and airflow rate), a semiempirical model based on a Langmuir-Hinshelwood-type reaction pathway is assumed. At 50°C and pH 9.5 kinetic parameters were calculated by an optimization routine. The resulting concentration courses of D-glucose and D-gluconic acid were in good agreement with the experimental data. All experiments were carried out in a semibatch reactor under pH control at atmospheric pressure.
- Oenal,Schimpf,Claus
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- Behavior of IrCl3 as a Homogeneous Catalyst on the Oxidation of N-Acetylglucosamine in Acid Medium and Uncatalyzed Reaction in Alkaline Medium with Bromamine-B: Exploration of Kinetic, Mechanistic and Catalytic Chemistry
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Abstract: The experimental rate laws for the oxidation of N-acetylglucosamine with bromamine- B are: ? d[BAB]/dt = k/ [BAB]1 [GlcNAc]0.69 [HClO4]?0.76 [IrCl3]0.48 [BSA]?0.33 in acid medium and –d[BAB]/dt = k/?[BAB]1 [GlcNAc]1 [NaOH]0.79 in alkaline medium. The IrCl3 catalyzed reaction is thirteen fold faster than uncatalyzed reaction. Appropriate mechanisms and rate laws were deduced. Graphical Abstract: The reaction of N-acetylglucosamine with Bromamine-B in acid and alkaline medium is [Figure not available: see fulltext.].
- Shankarlingaiah, Dakshayani,Puttaswamy
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- Efficient Oxidation of Glucose into Gluconic Acid Catalyzed by Oxygen-Rich Carbon Supported Pd Under Room Temperature and Atmospheric Pressure
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Abstract: A new method has been developed for the oxidation of glucose into gluconic acid over Pd/C catalysts under the room temperature and atmospheric pressure. The carbon support was prepared by the hydrothermal treatment of renewable glucose, thus contained abundant active oxygen species. The Pd/C catalyst showed high catalytic activity towards the oxidation of glucose into gluconic acid. A 100% glucose conversion and a 98% gluconic acid yield were attained within 2?h at 0.1?MPa and room temperature. Structural analysis showed that the Pd paricle sizes of the catalysts were in the range of 10.1–16.2?nm influenced by the loading of Pd. The structure/size study showed that the catalyst with optimal particle size of 10.9?nm exhibited the highest TOF (0.2388?molglucose?molPd/s). The catalyst showed no significant loss of activity after recycled for four times. Graphical Abstract: [Figure not available: see fulltext.].
- Liu, Anqiu,Huang, Zhong,Wang, Xiaochen
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- A falling-film microreactor for enzymatic oxidation of glucose
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Many oxidation processes require the presence of molecular oxygen in the reaction media. Reactors are needed that provide favorable conditions for the mass transfer between the gas and the liquid phase. In this study, two recent key technologies, microreactor technology and biotechnology, were combined to present an interesting alternative to conventional methods and open up excellent possibilities to intensify chemical processes in the field of fine chemicals. An enzyme-catalyzed gas/liquid phase reaction in a falling-film microreactor (FFMR) was examined for the first time. The test reaction was the oxidation of β-D-glucose to gluconic acid catalyzed by glucose oxidase (GOx). Various factors influencing the biotransformation, such as oxygen supply, temperature, enzyme concentration, and reaction time were investigated and compared to those in conventional batch systems. The most critical factor, the volumetric mass-transfer coefficient for the efficient use of oxygen-dependent enzymes, was determined by using the integrated online detection of dissolved oxygen in all systems. The extremely large surface-to-volume ratio of the FFMR facilitated the contact between the enzyme solution and the gaseous substrate. Hence, in a continuous bubble-free FFMR system with a residence time of 25 seconds, a final conversion of up to 50 % in enzymatic oxidation was reached, whereas conversion in a conventional bubble column resulted in only 27 %. Finally, an option for scale-up was shown through an enlarged version of the FFMR. Oxygen intake: An enzyme-catalyzed gas/liquid phase reaction in a falling film microreactor (FFMR) was examined for the first time. The test reaction was the oxidation of β-D-glucose to gluconic acid catalyzed by glucose oxidase. As a result of to the large surface-to-volume ratio, extremely high oxygen transfer rates are achieved.
- Illner, Sabine,Hofmann, Christian,Loeb, Patrick,Kragl, Udo
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- A sandwich-like electrochemiluminescent biosensor for the detection of concanavalin A based on a C60-reduced graphene oxide nanocomposite and glucose oxidase functionalized hollow gold nanospheres
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A sensitive sandwich-like electrochemiluminescent (ECL) biosensor was designed for the detection of concanavalin A (ConA) using a C60-reduced graphene oxide (C60-rGO) nanocomposite as a platform and glucose oxidase (GOX) decorated hollow gold nanospheres (HGNSs) as a label. First, C60-rGO with a large surface area was prepared for combining with phenoxy-derivatized dextran, which served as the recognition element for interacting with ConA by biospecific carbohydrate-protein (lectin) interactions. Then, GOX decorated HGNSs (GOX-HGNSs) were linked to the electrode surface through the biospecific interaction between the intrinsic carbohydrate residues of GOX and ConA. These localized GOX and HGNSs amplified the ECL signal of luminol intensely, which was achieved by the efficient catalysis of the GOX towards the oxidation of glucose to in situ generate an improved amount of hydrogen peroxide (H2O2) as a coreactant, and the excellent catalysis of HGNSs towards the ECL reaction of luminol-H2O2. The prepared biosensor exhibited a sensitive response for the determination of ConA, ranging from 0.10 to 100 ng mL-1 with a detection limit down to 30 pg mL-1 (signal to noise = 3). With excellent stability, sensitivity, selectivity and simplicity, the prepared biosensor showed great prospects in lectin sensing or carbohydrate sensing. This journal is
- Zhang, Juanjuan,Ruo, Yuan,Chen, Shihong,Zhong, Xia,Wu, Xiaoping
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- Direct monitoring of enzyme-catalyzed reactions via laser-based polarimetry
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A new method is described in which a laser-based polarimetric detection system is used to monitor enzyme-catalyzed reactions. This method provides direct detection of the reaction progress based on the inherent chirality of either the substrate or product. The technique is tested on the glucose oxidase catalyzed conversion of β-D-glucose to D-gluconic acid. The ability of this system to negate the large background signals produced by optically active substrates is examined, and a mass limit-of-detection for glucose oxidase of 34 fmol is demonstrated. Results obtained with the polarimetric technique are compared to those from an accepted spectrophotometric method, and the technique is shown to be as accurate with an LOD 15 times lower. The theoretical relationship between the polarimetric response and various experimental parameters will be developed and verified.
- Rice, Patrick D.,Bobbitt, Donald R.
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- Electrical contacting of flavoenzymes and NAD(P)+-dependent enzymes by reconstitution and affinity interactions on phenylboronic acid monolayers associated with Au-electrodes
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The preparation of integrated, electrically contacted, flavoenzyme and NAD(P)+-dependent enzyme-electrodes is described. The reconstitution of apo-glucose oxidase, apo-GOx, on a FAD cofactor linked to a pyrroloquinoline quinone (PQQ) phenylboronic acid monolayer yields an electrically contacted enzyme monolayer (surface coverage 2.1 × 10-12 mol cm-2) exhibiting a turnover rate of 700 s-1 (at 22 ± 2 °C). The system is characterized by microgravimetric quartz-crystal microbalance analyses, Faradaic impedance spectroscopy, rotating disk electrode experiments, and cyclic voltammetry. The performance of the enzyme-electrode for glucose sensing is described. Similarly, the electrically contacted enzyme-electrodes of NAD(P)+-dependent enzymes malate dehydrogenase, MaID, and lactate dehydrogenase, LDH, are prepared by the cross-linking of affinity complexes generated between the enzymes and the NADP+ and NAD+ cofactors linked to a pyrroloquinoline quinone phenylboronic acid monolayer, respectively. The MaID enzyme-electrode (surface coverage 1.2 × 10-12 mol cm2) exhibits a turnover rate of 190 s-1, whereas the LDH enzyme-electrode (surface coverage 7.0 × 10-12 mol cm2) reveals a turnover rate of 2.5 s-1. Chronoamperometric experiments reveal that the NAD+ cofactor is linked to the PQQ-phenylboronic acid by two different binding modes. The integration of the LDH with the two NAD+ cofactor configurations yields enzyme assemblies differing by 1 order of magnitude in their bioelectrocatalytic activities.
- Zayats, Maya,Katz, Eugenii,Willner, Itamar
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- Reinforcing the Induction of Immunogenic Cell Death Via Artificial Engineered Cascade Bioreactor-Enhanced Chemo-Immunotherapy for Optimizing Cancer Immunotherapy
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Traditional chemo-immunotherapy can elicit T cell immune response by inducing immunogenic cell death (ICD), however, insufficient ICD limits the lasting antitumor immunotherapeutic efficacy. Herein, tadpole–ovoid manganese-doped hollow mesoporous silica coated gold nanoparticles (Au@HMnMSNs) as biodegradable catalytic cascade nanoreactors are constructed to generate intratumoral high-toxic hydroxyl radicals combined with DOX and Aspirin (ASA) for enhancing the induction of ICD and maturation of dendritic cells (DCs). The released Mn2+ can catalyze endogenous H2O2 to hydroxyl radicals, while internal gold nanoparticles mimetic glucose oxidase (GOx) converted glucose into H2O2 to accelerate the generation of hydroxyl radicals. On the other hand, tadpole oval-structured Au@HMnMSNs can avoid the inactivation of gold nanoparticles due to strong protein adsorption. The introduction of ASA is to recruit DCs and cytotoxic T lymphocytes (CTLs) to tumor sites and restrain the intratumoral infiltration of immunosuppressive cells by decreasing the expression of prostaglandin E2 (PGE2). Accordingly, this work presents a novel insight to introduce GOx-like catalytic cascade ICD nano-inducer into antitumor immunotherapy for synergistic tumor therapy.
- Sun, Kai,Hu, Jinzhong,Meng, Xiangyu,Lei, Yunfeng,Zhang, Xuezhong,Lu, Zhuoxuan,Zhang, Liming,Wang, Zhifei
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- Low temperature synthesis of Cu2O crystals: Shape evolution and growth mechanism
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An interesting shape evolution of Cu2O crystals, that is, from cubes, truncated octahedra, octahedra, and finally to nanospheres was first realized in high yield by reducing the copper-citrate complex solution with glucose. X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (H RTEM) techniques were employed to characterize the samples. We elucidate the important parameters (including poly (vinyl pyrrolidone) (PVP) concentration, reaction time, and reaction temperature) responsible for the shape-controlled synthesis of Cu2O crystals. The possible formation mechanism for the products with various architectures is presented, which is mainly based on the variation of the ratio (R) of the growth rates along the ( 100) and (111) direction. In addition, the effect of the low supersaturation on the formation of star-shaped samples with six symmetric branches is also taken into account. This polymer-mediated method should be readily extended to the controlled synthesis of other metal oxides and the proposed growth model could also be used to explain and direct the growth of crystals with a cubic structure
- Sui, Yongming,Fu, Wuyou,Yang, Haibin,Zeng, Yi,Zhang, Yanyan,Zhao, Qiang,Li, Yangen,Zhou, Xiaoming,Leng, Yan,Li, Minghui,Zou, Guangtian
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- Crystal structure of human senescence marker protein 30: Insights linking structural, enzymatic, and physiological functions
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Human senescence marker protein 30 (SMP30), which functions enzymatically as a lactonase, hydrolyzes various carbohydrate lactones. The penultimate step in vitamin-C biosynthesis is catalyzed by this enzyme in nonprimate mammals. It has also been implicated as an organophosphate hydrolase, with the ability to hydrolyze diisopropyl phosphofluoridate and other nerve agents. SMP30 was originally identified as an aging marker protein, whose expression decreased androgen independently in aging cells. SMP30 is also referred to as regucalcin and has been suggested to have functions in calcium homeostasis. The crystal structure of the human enzyme has been solved from X-ray diffraction data collected to a resolution of 1.4 .... The protein has a 6-bladed I-propeller fold, and it contains a single metal ion. Crystal structures have been solved with the metal site bound with either a Ca2+ or a Zn 2+ atom. The catalytic role of the metal ion has been confirmed by mutagenesis of the metal coordinating residues. Kinetic studies using the substrate gluconolactone showed a kcat preference of divalent cations in the order Zn2+ > Mn2+ > Ca2+ > Mg2+. Notably, the Ca2+ had a significantly higher value of Kd compared to those of the other metal ions tested (566, 82, 7, and 0.6 μm for Ca2+, Mg2+, Zn2+, and Mn 2+, respectively), suggesting that the Ca2+-bound form may be physiologically relevant for stressed cells with an elevated free calcium level.
- Chakraborti, Subhendu,Bahnson, Brian J.
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- Preparation and catalytic activity of poly(N-vinyl-2-pyrrolidone)-protected Au nanoparticles for the aerobic oxidation of glucose
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PVP-protected Au nanoparticles (NPs) for the aerobic oxidation of glucose were prepared by using NaBH4 reduction method. The effects of processing parameters such as Au3+ ion concentration, reaction temperature, ratio of NaBH4 or PVP to Au3+, and solvent composition on their particle sizes and catalytic activities were studied in detail and the synthesis conditions optimized. As-prepared Au NPs possessed a FCC structure, with an average size varying from about 100 to 2.6 nm depending on their preparation conditions. The size changes affected their catalytic activities in the aerobic oxidation of glucose. The Au NPs with the average size of 2.6 nm prepared under the optimal conditions showed a high instantaneous catalytic activity as well as a high long-time stability. Based on the kinetic study on the glucose oxidation over the PVP-protected Au NPs, the corresponding apparent activation energy was determined as 82 kJ mol-1. Copyright
- Zhang, Haijun,Li, Wenqi,Gu, Yajun,Zhang, Shaowei
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- Fabrication of autofluorescent protein coated mesoporous silica nanoparticles for biological application
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Glucose sensitive and autofluorescent protein coated mesoporous silica nanoparticles are synthesized through a layer-by-layer technique. The resulting nano-composites can be adhered to the surface of a cell and embedded into the cell membrane. These unique features make this nanocomposite a good candidate as cell marker or drug carrier. The Royal Society of Chemistry 2011.
- Yang, Yang,Jia, Yi,Gao, Liang,Fei, Jinbo,Dai, Luru,Zhao, Jie,Li, Junbai
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- Base-free glucose oxidation using air with supported gold catalysts
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We report the selective oxidation of glucose to gluconic acid under mild conditions and show that if a basic support is used then the reaction can be carried out without the addition of sacrificial base or pH control. The use of sol-immobilisation prepared catalysts supported on magnesium oxide facilitates the use of ambient air as an oxidant source. These mild conditions resulted in an excellent selectivity towards gluconic acid. Different heat treatments result in an improvement in the activity of the catalyst, these improvements are discussed in terms of XRD, DRIFTD and TEM analysis of the catalysts, despite significant particle growth and phase segregation occurring during the thermal treatments. This journal is the Partner Organisations 2014.
- Miedziak, Peter J.,Alshammari, Hamed,Kondrat, Simon A.,Clarke, Tomos J.,Davies, Thomas E.,Morad, Moataz,Morgan, David J.,Willock, David J.,Knight, David W.,Taylor, Stuart H.,Hutchings, Graham J.
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- A kinetic study of d-glucose oxidation by bromine in aqueous solutions
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The kinetics of the oxidation of d-glucose to d-gluconic acid by bromine in aqueous solution were studied using potentiometric techniques and theoretical considerations of complex bromine-bromide-pH equilibria. The pH has a strong influence on reaction rate. At pH 9.5, the reaction is further accelerated due to the formation of hypobromite. The proposed kinetics expression for gluconic acid formation, based on the determined kinetic parameters at pH 9.24, is of the form. dc(GA)/dt = 160c2(G)c0(HOBr)c0(H+)c0(Br-).
- Grgur, Branimir N.,Zugic, Dragana L.,Gvozdenovic, Milica M.,Trisovic, Tomislav Lj.
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- DNA-Directed Assembly of Gold Nanohalo for Quantitative Plasmonic Imaging of Single-Particle Catalysis
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Plasmonic imaging under a dark-field microscope (DFM) holds great promise for single-particle analysis in bioimaging, nanophotonics, and nanocatalysis. Here, we designed a DNA-directed programmable assembly strategy to fabricate a halo-like Au nanostructure (nanohalo) that couples plasmonic large gold nanoparticles (L-AuNPs) with catalytically active small AuNPs (S-AuNPs) in a single nanoarchitecture. Catalytic reaction occurring on S-AuNPs changes its permittivity, which results in a significant variation of the plasmonic resonance of the nanohalo. Hence, we can indirectly monitor catalytic reactions on a single nanohalo under DFM, on the basis of which we have obtained quantitative information on both nanocatalysis and catalyst poisoning. Our study thus provides a cost-effective means to quantitatively study metal NP-based catalysis at single-particle level.
- Li, Kun,Wang, Kun,Qin, Weiwei,Deng, Suhui,Li, Di,Shi, Jiye,Huang, Qing,Fan, Chunhai
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- Insights into the "free state" enzyme reaction kinetics in nanoconfinement
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The investigation of enzyme reaction kinetics in nanoconfined spaces mimicking the conditions in living systems is of great significance. Here, a nanofluidics chip integrated with an electrochemical detector has been designed for studying "free state" enzyme reaction kinetics in nanoconfinement. The nanofluidics chip is fabricated using the UV-ablation technique developed in our group. The enzyme and substrate solutions are simultaneously supplied from two single streams into a nanochannel through a Y-shaped junction. The laminar flow forms in the front of the nanochannel, then the two liquids fully mix at their downstream where a homogeneous enzyme reaction occurs. The "free state" enzyme reaction kinetics in nanoconfinement can thus be investigated in this laminar flow based nanofluidics device. For demonstration, glucose oxidase (GOx) is chosen as the model enzyme, which catalyzes the oxidation of beta-d-glucose. The reaction product hydrogen peroxide (H 2O2) can be electrochemically detected by a microelectrode aligning to the end of nanochannel. The steady-state electrochemical current responding to various glucose concentrations is used to evaluate the activity of the "free state" GOx under nanoconfinement conditions. The effect of liquid flow rate, enzyme concentration, and nanoconfinement on reaction kinetics has been studied in detail. Results show that the "free state" GOx activity increases significantly compared to the immobilized enzyme and bath system, and the GOx reaction rate in the nanochannel is two-fold faster than that in bulk solution, demonstrating the importance of "free state" and spatial confinement for the enzyme reaction kinetics. The present approach provides an effective method for exploiting the "free state" enzyme activity in nanospatial confinement.
- Wang, Chen,Ye, De-Kai,Wang, Yun-Yi,Lu, Tao,Xia, Xing-Hua
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- A comparative evaluation of the activity modulation of flavo and non-flavo enzymes induced by graphene oxide
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Graphene, and its water soluble derivative graphene oxide, has shown great promise in various biomedical applications, such as cancer therapeutics, drug delivery, etc. and in industrial applications such as enzyme immobilization, etc. Thus, modulation of the activities of different classes of enzymes by graphene materials is an important aspect in the formulation of different biological applications. We have demonstrated here how flavin adenine dinucleotide (FAD) moieties protect the binding site from conformational change in the presence of an inhibitor, graphene oxide, and also explore differences in the mode of interactions between flavo and non-flavo enzymes. It was shown that there was a much greater loss of activity with the non-flavo enzyme, l-lactate dehydrogenase (LDH), of ～74% compared to that with the flavo-enzyme, glucose oxidase (GOX), of ～45%, in the presence of equal concentrations of GO. Furthermore, GO acts as an enzyme inhibitor and the mode of inhibition is uncompetitive for GOX and competitive for LDH. Circular dichromism measurements showed a 21% decrease in the α helix of GOX and a 31% decrease in the α helix of LDH in the presence of a given concentration of GO (0.5 mg mL-1). There was a slight change in the average emission lifetime of tryptophan in GOX in the presence of GO from 3.2 to 2.6 ns. In contrast, there was no change in the average emission lifetime of tryptophan in LDH in the presence of GO. The extents of fluorescence quenching for GOX and LDH were 39% and 70% upon addition of a certain amount of GO. The present study provides insight into the development of sensors through the immobilization of enzymes and the possible formulation of a multifunctional protein and graphene composite system for various biomedical applications such as bio-sensing, gene and drug delivery, etc.
- Maiti, Susmita,Kundu, Somashree,Roy, Chandra Nath,Ghosh, Debasmita,Das, Tushar Kanti,Saha, Abhijit
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- KINETICS OF OXIDATION OF D-GLUCOSE BY HEXACHLOROIRIDATE(IV) AND TETRACHLOROAURATE(III)
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Kinetic data for the oxidation of D-glucose by hexachloroiridate(IV) and tetrachloroaurate(III) are reported.The reactions have been studied spectrophotometrically over a vide range of experimental conditions.Theactivation parameters have been calculated and mechanims are suggested.
- Gupta, Kalyan Kali Sen,Gupta, Shipra Sen,Chatterejee, Uma,Tarafdar, Archana,Samanta, Tapashi,Shamra, Umashankar
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- Aerobic oxidation of glucose with gold catalyst: Hydrogen peroxide as intermediate and reagent
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Careful analytical determinations show that the gold-catalysed aerobic oxidation of glucose occurs through a two-electrons mechanism leading to gluconate and hydrogen peroxide. This latter decomposes before reaching the critical concentration for competing with O2 in glucose oxidation. A mechanism of glucose oxidation on gold nanoparticles is presented.
- Comotti, Massimiliano,Della Pina, Cristina,Falletta, Ermelinda,Rossi, Michele
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- Studies on the co-immobilized GOD/CAT on cross-linked chitosan microsphere modified by lysine
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Glucose oxidase (GOD) and catalase (CAT) were co-immobilized on a novel crosslinked chitosan resin modified by l-lysine. The immobilized system exhibited the best performance when the immobilization process was conducted at 4 C for 3 h with GOD/CAT activity ratio of 1:18 and pH 7.0. Under the optimum pH 4.0 and temperature 40 C, the enzyme system could achieve to the maximum conversion of glucose, which was 68.9%. Acidoresistance and thermotolerance of the enzymes were both strengthened. The Km of the co-immobilized enzyme system obtained in this study was 31.02 mM. The GOD enzyme immobilized in this system could maintain 94% of initial activity after the 12th operational cycle. 95.8% of initial activity was left after 50 weeks' storage at 4 C. GOD achieved better performance in this new immobilized enzyme system due to its effective elimination of H2O2, which showed potential applications for various commercial uses.
- Zhang, Jie,Zhou, Xiaohua,Wang, Dan,Wang, Yingli,Zhou, Xing,Wang, Honghui,Li, Qiang,Tan, Shiyu
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- Preparation of sulfonated poly(ether-ether-ketone) functionalized ternary graphene/AuNPs/chitosan nanocomposite for efficient glucose biosensor
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A facile method of preparing water-dispersible sulfonated graphene (SPG) using sulfonated poly(ether-ether-ketone) organic polymer as a modifier was realized. A glucose biosensor was fabricated by immobilizing glucose oxidase (GOx) on the surface of AuNPs used to modify SPG and chitosan (CH) deposited on an indium tin-oxide (ITO) glass electrode by a solution casting method. Morphological and structural characterizations confirm that the AuNPs can be efficiently applied to the SPG-CH matrix. The amperometric response of the GOx/SPG-AuNPs-CH/ITO bioelectrode shows a broad linear range of 0.5 to 22.2 mM, with a limit of detection of 0.13 mM and a high sensitivity of 6.51 μA/(mM cm2). The excellent performance of the constructed biosensor is attributed to the large surface-to-volume ratio and electron transfer ability of SPG, the high catalytic activity of the AuNPs, and the good biocompatibility of CH. In addition, the sensor has important advantages, such as its simple preparation, fast response time (10 s), good stability (70 days), and high reproducibility. Favorable results upon examining the electrochemical response for the determination of glucose in human blood serum were obtained, without the assistance of a negligible effect of interfering bio-analytes. The results of studies show that the ternary SPG-AuNPs-CH nanocomposite may offer a new approach for developing novel types of highly sensitive and stable electrochemical biosensors.
- Singh, Jay,Khanra, Partha,Kuila, Tapas,Srivastava, Manish,Das, Ashok K.,Kim, Nam Hoon,Jung, Bong Joo,Kim, Da Yeong,Lee, Seung Hee,Lee, Dong Won,Kim, Dae-Ghon,Lee, Joong Hee
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- Glucose-specific sensing with boronic acid utilizing enzymatic oxidation
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A novel sensing system for glucose-specific detection has been established based on a combination of a boronic acid and enzymes. To overcome the inherently low biding affinity of glucose toward boronic acids, glucose is converted into gluconic acid by the enzymatic reaction using glucose oxidase (GOx), and then complexed with a fluorescent boronic acid through the α-hydroxycarboxylate moiety. According to the present strategy, glucose concentration is exclusively determined among other saccharides in aqueous solutions. Copyright
- Kanekiyo, Yasumasa,Tao, Hiroaki
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- One-pot biocatalytic conversion of lactose to gluconic acid and galacto-oligosaccharides using immobilized β-galactosidase and glucose oxidase
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One-pot cascade reaction systems offer several process and technological benefits, completed by the opportunity of the second enzyme to act on a convenient concentration of its substrate. Most of the reported cascade reactions involve immobilization of both biocatalysts on a single support, but in this case the catalytic performance of the whole system is affected if the activity of either enzyme drops. In this work, tailor-made immobilization of two β-galactosidases (from Kluyveromyces lactis and Aspergillus oryzae) and a glucose oxidase (from Aspergillus niger) was investigated, to subsequent utilization of the best performing immobilized biocatalyst of each type for the one-pot conversion of lactose to gluconic acid and galacto-oligosaccharides. The immobilization was performed by covalent binding onto amino-terminated Ni0.4Co0.2Zn0.4Fe2O4 and Ni0,5Zn0,5Fe2O4 magnetic particles and commercial amino- and epoxy-functionalized methacrylate supports. The highest activity for β-galactosidases was achieved on Ni0.5Zn0.5-Fe2O4 magnetic particles, meanwhile the glucose oxidase showed higher affinity for the supports with epoxy active groups. The immobilized biocatalysts have been characterized in detail, demonstrating enhanced storage, pH, and thermal stability as well as better operational stability compared to the soluble enzymes.
- Todea, Anamaria,Benea, Ioana Cristina,B?tcan, Ioan,Péter, Francisc,Klébert, Szilvia,Feczkó, Tivadar,Károly, Zoltán,Biró, Emese
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- Pd(ii) nanoparticles in porous polystyrene: Factors influencing the nanoparticle size and catalytic properties
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In this paper for the first time we present a systematic study of the influence of hydrophobicity of Pd(ii) compounds, (CH3CN) 2PdCl2, (PhCN)2PdCl2, (Sty)(CH 3CN)PdCl2, and (StyPdCl2)2, on nanoparticle (NP) formation in the pores of hydrophobic micro/mesoporous hypercrosslinked polystyrene (HPS). The morphology and composition of HPS-Pd nanocomposites were studied using transmission electron microscopy, X-ray fluorescence measurements, X-ray photoelectron spectroscopy, and liquid nitrogen physisorption. The size and location of Pd compound NPs were found to depend on hydrophobicity of the Pd(ii) environment. Catalytic testing of these nanocomposites in d-glucose oxidation was carried out to illustrate the influence of nanoparticle size and environment on catalytic activity. The highest catalytic activity was achieved for (Sty)(CH3CN)PdCl 2, forming smallest NPs and allowing an optimal hydrophobicity- hydrophilicity balance with HPS. The Royal Society of Chemistry 2012.
- Tsvetkova, Irina B.,Matveeva, Valentina G.,Doluda, Valentin Y.,Bykov, Alexei V.,Sidorov, Alexander I.,Schennikov, Sergey V.,Sulman, Michael G.,Valetsky, Pyotr M.,Stein, Barry D.,Chen, Chun-Hsing,Sulman, Esther M.,Bronstein, Lyudmila M.
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- Preparation of Au-Pd/C catalysts by adsorption of metallic species in aqueous phase for selective oxidation
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Au/C and Au-Pd/C catalysts were prepared on SX PLUS activated carbon using an adsorption method in which the precursor(s)-support interactions in aqueous solution were sought to be optimized. pH windows where maximum adsorption occurs were identified for four bimetallic cases, varying the incorporation order of the adsorbed metallic precursors and the oxidation state of the first metal introduced. All samples were characterized by XPS and SEM/EDXS, and the above-mentioned parameters were found to have an influence on the surface microstructure of the samples and on the activity of the bimetallic catalysts obtained. This preparation method leads to highly active catalysts for the selective oxidation of glucose, with the activity correlated with high surface Pd/C ratios.
- Hermans, Sophie,Deffernez, Aurore,Devillers, Michel
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- Nanocomposite incorporating V2O5 nanowires and gold nanoparticles for mimicking an enzyme cascade reaction and its application in the detection of biomolecules
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Artificial enzyme mimics are a current research interest, and many nanomaterials have been found to display enzyme-mimicking activity. However, to the best of our knowledge, there have not hitherto been any reports on the use of pure nanomaterials to construct a system capable of mimicking an enzyme cascade reaction. Herein, we describe the construction of a novel nanocomposite consisting of V2O5 nanowires and gold nanoparticles (AuNPs) through a simple and facile chemical method, in which V 2O5 and AuNPs possess intrinsic peroxidase and glucose oxidase (GOx)-like activity, respectively. Results suggest that this material can mimic the enzyme cascade reaction of horseradish peroxidase (HRP) and GOx. Based on this mechanism, a direct and selective colorimetric method for the detection of glucose has been successfully designed. Because single-strand and double-strand DNA (ssDNA and dsDNA) have different deactivating effects on the GOx-like activity of AuNPs, the sensing of target complementary DNA can also be realized and disease-associated single-nucleotide polymorphism of DNA can be easily distinguished. Our study opens a new avenue for the use of nanomaterials in enzyme mimetics, and holds promise for the further exploration of nanomaterials in creating alternative catalytic systems to natural enzymes.
- Qu, Konggang,Shi, Peng,Ren, Jinsong,Qu, Xiaogang
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- Localized Supramolecular Peptide Self-Assembly Directed by Enzyme-Induced Proton Gradients
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Electrodes are ideal substrates for surface localized self-assembly processes. Spatiotemporal control over such processes is generally directed through the release of ions generated by redox reactions occurring specifically at the electrode. The so-used gradients of ions proved their effectiveness over the last decade but are in essence limited to material-based electrodes, considerably reducing the scope of applications. Herein is described a strategy to enzymatically generate proton gradients from non-conductive surfaces. In the presence of oxygen, immobilization of glucose oxidase (GOx) on a multilayer film provides a flow of protons through enzymatic oxidation of glucose by GOx. The confined acidic environment located at the solid–liquid interface allows the self-assembly of Fmoc-AA-OH (Fmoc=fluorenylmethyloxycarbonyl and A=alanine) dipeptides into β-sheet nanofibers exclusively from and near the surface. In the absence of oxygen, a multilayer nanoreactor containing GOx and horseradish peroxidase (HRP) similarly induces Fmoc-AA-OH self-assembly.
- Rodon Fores, Jennifer,Martinez Mendez, Miguel Leonardo,Mao, Xiyu,Wagner, Déborah,Schmutz, Marc,Rabineau, Morgane,Lavalle, Philippe,Schaaf, Pierre,Boulmedais, Fouzia,Jierry, Lo?c
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- Influence of the support and the size of gold clusters on catalytic activity for glucose oxidation
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Not all that glitters... The activity of supported gold nanoparticles depends on the method used for their preparation. Gold clusters of about 2 nm in diameter were deposited on nonreducible metal oxides and carbon materials by solid grinding of a volatile organogold complex in a ball mill and subsequent calcination (see scheme). Au/ZrO2 and Au/Al2O3 prepared in this way were extremely efficient catalysts for the aerobic oxidation of glucose. (Chemical Equation Presented).
- Ishida, Tamao,Kinoshita, Naoto,Okatsu, Hiroko,Akita, Tomoki,Takei, Takashi,Haruta, Masatake
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- Catalytic deep eutectic solvents for highly efficient conversion of cellulose to gluconic acid with gluconic acid self-precipitation separation
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A family of FeCl3·6H2O based catalytic deep eutectic solvents (CDESs) were formed and used for the conversion of cellulose to gluconic acid with high efficiency. More importantly, gluconic acid could be separated from the reaction system by self-precipitation.
- Liu, Feijie,Xue, Zhimin,Zhao, Xinhui,Mou, Hongyu,He, Jing,Mu, Tiancheng
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- Enhanced photocatalytic performance for oxidation of glucose to value-added organic acids in water using iron thioporphyrazine modified SnO2
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The selective conversion of glucose into value-added chemicals in the presence of only water is a challenging topic. In this work, selective photocatalytic oxidation of glucose in water was studied using iron thioporphyrazine modified SnO2 (SnO2/FePz(SBu)8) as the catalyst and atmospheric air as the oxidant under simulated sunlight irradiation. It was found that value-added organic acids including glucaric acid, gluconic acid and formic acid could be obtained from the oxidation of glucose under such conditions. The effects of the FePz(SBu)8 content, glucose concentration and additional addition on the conversion of glucose and the selectivity of the organic acids were further explored. Under the optimized conditions, the total selectivity for the organic acids on the SnO2/FePz(SBu)8 photocatalyst reached up to 52.2% at 34.2% glucose conversion. More importantly, it has been demonstrated that the presence of FePz(SBu)8 on the surface of SnO2 can keep the selectivity of the organic acids unchanged under conditions of increasing the glucose conversion. To illustrate the synergistic effect for the enhanced photocatalytic activity between FePz(SBu)8 and SnO2, surface photocurrent, electron spin resonance (ESR) spectra and adsorption behavior experiments were carried out on pure SnO2 and SnO2/FePz(SBu)8. It was found that the introduction of FePz(SBu)8 could enhance the separation of photogenerated charge, promote the generation of active species for photocatalysis and improve the adsorption capacity of glucose, which are beneficial to the enhancement of photocatalytic activity. Additionally, a possible pathway of glucose oxidation was proposed through both detailed analysis of the oxidation intermediate of glucose and comparative experiments with different organic acids as the substrates, indicating that the formation of organic acids were fulfilled by two parallel and subsequent reactions at the beginning of the reaction.
- Zhang, Quanquan,Ge, Yanchun,Yang, Changjun,Zhang, Bingguang,Deng, Kejian
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- Enzyme-immobilized hydrogels to create hypoxia for in vitro cancer cell culture
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Hypoxia is a critical condition governing many aspects of cellular fate processes. The most common practice in hypoxic cell culture is to maintain cells in an incubator with controlled gas inlet (i.e., hypoxic chamber). Here, we describe the design and characterization of enzyme-immobilized hydrogels to create solution hypoxia under ambient conditions for in vitro cancer cell culture. Specifically, glucose oxidase (GOX) was acrylated and co-polymerized with poly(ethylene glycol)-diacrylate (PEGDA) through photopolymerization to form GOX-immobilized PEG-based hydrogels. We first evaluated the effect of soluble GOX on inducing solution hypoxia (O2??5%) and found that both unmodified and acrylated GOX could sustain hypoxia for at least 24?h even under ambient air condition with constant oxygen diffusion from the air-liquid interface. However, soluble GOX gradually lost its ability to sustain hypoxia after 24?h due to the loss of enzyme activity over time. On the other hand, GOX-immobilized hydrogels were able to create hypoxia within the hydrogel for at least 120?h, potentially due to enhanced protein stabilization by enzyme ‘PEGylation’ and immobilization. As a proof-of-concept, this GOX-immobilized hydrogel system was used to create hypoxia for in vitro culture of Molm14 (acute myeloid leukemia (AML) cell line) and Huh7 (hepatocellular carcinoma (HCC) cell line). Cells cultured in the presence of GOX-immobilized hydrogels remained viable for at least 24?h. The expression of hypoxia associated genes, including carbonic anhydrase 9 (CA9) and lysyl oxidase (LOX), were significantly upregulated in cells cultured with GOX-immobilized hydrogels. These results have demonstrated the potential of using enzyme-immobilized hydrogels to create hypoxic environment for in vitro cancer cell culture.
- Dawes, Camron S.,Konig, Heiko,Lin, Chien-Chi
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- Influence of the ionic liquid presence on the selective oxidation of glucose over molybdenum based catalysts
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Two different approaches are proposed in this work in order to study the influence of the ionic liquid presence in the reaction of glucose oxidation by H2O2 in mild conditions. The ionic liquids are applied either as a solvent by using homogeneous Mo based catalyst, [Mo(O)(O2)2(H2O)n] complex, or by using it as an integral part of a heterogeneous catalyst, organic inorganic hybrids based on Mo Keggin structure. Both catalytic strategies resulted in acceptable glucose transformation degrees but lead to different oxidation products depending on the role of the ionic liquid. The hybrid approach restrains the number of the received products being the most selective one. A detailed study of the effect of the hybrid nature and reaction conditions is proposed in the second part of this study.
- Megías-Sayago,Carrasco,Ivanova,Montilla,Galindo,Odriozola
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- Ruthenium(III) catalyzed oxidation of sugar alcohols by dichloroisocyanuric acid - A kinetic study
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Kinetics of ruthenium(III) catalyzed oxidation of biologically important sugar alcohols (myo-inositol, D-sorbitol, and D-mannitol) by dichloroisocyanuric acid was carried out in aqueous acetic acid - perchloric medium. The reactions were found to be first order in case of oxidant and ruthenium(III). Zero order was observed with the concentrations of sorbitol and mannitol whereas, a positive fractional order was found in the case of inositol concentration. An inverse fractional order was observed with perchloric acid in oxidation of three substrates. Arrhenius parameters were calculated and a plausible mechanism was proposed.
- Lakshman Kumar,Venkata Nadh,Radhakrishnamurti
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- Oxidation of D-glucose to D-gluconic and D-glucaric acids catalyzed by sodium nitrite
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Kinetics of catalytic oxidation of D-glucose in the HClO4-H2O-sulfolane system containing NaNO2 was studied. Kinetic equations of the process were derived. A scheme for oxidation of D-glucose with oxygen in the presence of NaNO2 was proposed.
- Grigor'eva,Chernaya,Trusov
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- A new route to the considerable enhancement of glucose oxidase (GOx) activity: The simple assembly of a complex from CdTe quantum dots and GOx, and its glucose sensing
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A new complex consisting of CdTe quantum dots (QDs) and glucose oxidase (GOx) has been facilely assembled to achieve considerably enhanced enzymatic activity and a wide active temperature range of GOx; these characteristics are attributed to the conformational changes of GOx during assembly. The obtained complex can be simultaneously used as a nanosensor for the detection of glucose with high sensitivity. A mechanism is put forward based on the fluorescence quenching of CdTe QDs, which is caused by the hydrogen peroxide (H 2O2) that is produced from the GOx-catalyzed oxidation of glucose. When H2O2 gets to the surface of the CdTe QDs, the electrontransfer reaction happens immediately and H2O2 is reduced to O2, which lies in electron hole traps on CdTe QDs and can be used as a good acceptor, thus forming the nonfluorescent CdTe QDs anion. The produced O2 can further participate in the catalyzed reaction of GOx, forming a cyclic electrontransfer mechanism of glucose oxidation, which is favorable for the whole reaction system. The value of the Michaelis-Menton constant of GOx is estimated to be 0.45 mML-1, which shows the considerably enhanced enzymatic activity measured by far. In addition, the GOx enzyme conjugated on the CdTe QDs possesses better thermal stability at 20-80°C and keeps the maximum activity in the wide range of 40-50°C. Moreover, the simply assembled complex as a nanosensor can sensitively determine glucose in the wide concentration range from micro- to millimolar with the detection limit of 0.10 μM, which could be used for the direct detection of low levels of glucose in biological systems. Therefore, the established method could provide an approach for the assembly of CdTe QDs with other redox enzymes, to realize enhanced enzymatic activity, and to further the design of novel nanosensors applied in biological systems in the future.
- Cao, Lihua,Ye, Jian,Tong, Lili,Tang, Bo
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- Mesoporous carbon-confined Au catalysts with superior activity for selective oxidation of glucose to gluconic acid
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A series of ordered mesoporous carbon (OMC)-supported Au catalysts were successfully prepared by nano-replication, followed by colloidal gold deposition method. Structural analysis showed that the mesopore sizes of the catalysts can be tuned controllably in the range of 3.2-7.6 nm by adjusting the dosage of boric acid used to prepare the carbon supports. TEM observations revealed that the Au nanoparticles were dispersed uniformly in the mesopore channels of the carbon supports. These Au/OMC catalysts were tested for the aerobic oxidation of glucose to produce gluconic acid at 40°C and pH 9. As demonstrated by the structural analysis and reaction results, the activities of these catalysts were closely related to their mesopore sizes. The catalyst with a mesopore size of 5.4 nm exhibited a superior catalytic activity with a TOF of 4.308 mol glucose molAu-1 s-1 to the catalysts reported previously by other researchers. This high activity was mainly ascribed to its unique structure, consisting of 5.4 nm mesopore channels incorporated with 3.3 nm Au nanoparticles, which facilitates contact between glucose molecules and Au nanoparticles. Besides, the abundant active oxygen species existing on this catalyst surface also promote glucose oxidation.
- Ma, Chunyan,Xue, Wenjuan,Li, Jinjun,Xing, Wei,Hao, Zhengping
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- Real-time monitoring of mass-transport-related enzymatic reaction kinetics in a nanochannel-array reactor
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To understand the fundamentals of enzymatic reactions confined in micro-/nanosystems, the construction of a small enzyme reactor coupled with an integrated real-time detection system for monitoring the kinetic information is a significant challenge. Nano-enzyme array reactors were fabricated by covalently linking enzymes to the inner channels of a porous anodic alumina (PAA) membrane. The mechanical stability of this nanodevice enables us to integrate an electrochemical detector for the real-time monitoring of the formation of the enzyme reaction product by sputtering a thin Pt film on one side of the PAA membrane. Because the enzymatic reaction is confined in a limited nanospace, the mass transport of the substrate would influence the reaction kinetics considerably. Therefore, the oxidation of glucose by dissolved oxygen catalyzed by immobilized glucose oxidase was used as a model to investigate the mass-transport-related enzymatic reaction kinetics in confined nanospaces. The activity and stability of the enzyme immobilized in the nanochannels was enhanced. In this nano-enzyme reactor, the enzymatic reaction was controlled by mass transport if the flux was low. With an increase in the flux (e.g., >50 μLmin-1), the enzymatic reaction kinetics became the rate-determining step. This change resulted in the decrease in the conversion efficiency of the nano-enzyme reactor and the apparent Michaelis-Menten constant with an increase in substrate flux. This nanodevice integrated with an electrochemical detector could help to understand the fundamentals of enzymatic reactions confined in nanospaces and provide a platform for the design of highly efficient enzyme reactors. In addition, we believe that such nanodevices will find widespread applications in biosensing, drug screening, and biochemical synthesis.
- Li, Su-Juan,Wang, Chen,Wu, Zeng-Qiang,Xu, Jing-Juan,Xia, Xing-Hua,Chen, Hong-Yuan
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- carba Nicotinamide Adenine Dinucleotide Phosphate: Robust Cofactor for Redox Biocatalysis
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Here we report a new robust nicotinamide dinucleotide phosphate cofactor analog (carba-NADP+) and its acceptance by many enzymes in the class of oxidoreductases. Replacing one ribose oxygen with a methylene group of the natural NADP+ was found to enhance stability dramatically. Decomposition experiments at moderate and high temperatures with the cofactors showed a drastic increase in half-life time at elevated temperatures since it significantly disfavors hydrolysis of the pyridinium-N?glycoside bond. Overall, more than 27 different oxidoreductases were successfully tested, and a thorough analytical characterization and comparison is given. The cofactor carba-NADP+ opens up the field of redox-biocatalysis under harsh conditions.
- D?ring, Manuel,Sieber, Volker,Simon, Robert C.,Tafertshofer, Georg,Zachos, Ioannis
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supporting information
p. 14701 - 14706
(2021/05/13)
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- Enzyme aggregation and fragmentation induced by catalysis relevant species
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It is usually assumed that enzymes retain their native structure during catalysis. However, the aggregation and fragmentation of proteins can be difficult to detect and sometimes conclusions are drawn based on the assumption that the protein is in its native form. We have examined three model enzymes, alkaline phosphatase (AkP), hexokinase (HK) and glucose oxidase (GOx). We find that these enzymes aggregate or fragment after addition of chemical species directly related to their catalysis. We used several independent techniques to study this behavior. Specifically, we found that glucose oxidase and hexokinase fragment in the presence ofd-glucose but notl-glucose, while hexokinase aggregates in the presence of Mg2+ion and either ATP or ADP at low pH. Alkaline phosphatase aggregates in the presence of Zn2+ion and inorganic phosphate. The aggregation of hexokinase and alkaline phosphatase does not appear to attenuate their catalytic activity. Our study indicates that specific multimeric structures of native enzymes may not be retained during catalysis and suggests pathways for different enzymes to associate or separate over the course of substrate turnover.
- Adair, James,Bhide, Ashlesha,Gentile, Kayla,Ghosh, Subhadip,Kauffman, Joshua,Lee, Tae-Hee,Maiti, Subhabrata,Sen, Ayusman
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p. 20709 - 20717
(2021/10/02)
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- A Sweet H2S/H2O2Dual Release System and Specific Protein S-Persulfidation Mediated by Thioglucose/Glucose Oxidase
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H2S and H2O2 are two redox regulating molecules that play important roles in many physiological and pathological processes. While each of them has distinct biosynthetic pathways and signaling mechanisms, the crosstalk between these two species is also known to cause critical biological responses such as protein S-persulfidation. So far, many chemical tools for the studies of H2S and H2O2 have been developed, such as the donors and sensors for H2S and H2O2. However, these tools are normally targeting single species (e.g., only H2S or only H2O2). As such, the crosstalk and synergetic effects between H2S and H2O2 have hardly been studied with those tools. In this work, we report a unique H2S/H2O2 dual donor system by employing 1-thio-β-d-glucose and glucose oxidase (GOx) as the substrates. This enzymatic system can simultaneously produce H2S and H2O2 in a slow and controllable fashion, without generating any bio-unfriendly byproducts. This system was demonstrated to cause efficient S-persulfidation on proteins. In addition, we expanded the system to thiolactose and thioglucose-disulfide; therefore, additional factors (β-galactosidase and cellular reductants) could be introduced to further control the release of H2S/H2O2. This dual release system should be useful for future research on H2S and H2O2.
- Li, Xiaolu,Ni, Xiang,Qian, Wei-Jun,Shen, Tun-Li,Xian, Ming
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p. 13325 - 13332
(2021/09/03)
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- Efficient Catalysts for the Green Synthesis of Adipic Acid from Biomass
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Green synthesis of adipic acid from renewable biomass is a very attractive goal of sustainable chemistry. Herein, we report efficient catalysts for a two-step transformation of cellulose-derived glucose into adipic acid via glucaric acid. Carbon nanotube-supported platinum nanoparticles are found to work efficiently for the oxidation of glucose to glucaric acid. An activated carbon-supported bifunctional catalyst composed of rhenium oxide and palladium is discovered to be powerful for the removal of four hydroxyl groups in glucaric acid, affording adipic acid with a 99 % yield. Rhenium oxide functions for the deoxygenation but is less efficient for four hydroxyl group removal. The co-presence of palladium not only catalyzes the hydrogenation of olefin intermediates but also synergistically facilitates the deoxygenation. This work presents a green route for adipic acid synthesis and offers a bifunctional-catalysis strategy for efficient deoxygenation.
- Deng, Weiping,Yan, Longfei,Wang, Binju,Zhang, Qihui,Song, Haiyan,Wang, Shanshan,Zhang, Qinghong,Wang, Ye
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supporting information
p. 4712 - 4719
(2021/01/20)
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- Symplocosins C-P: Fourteen triterpene saponins from the leaves of symplocos cochinchinensis var. philippinensis
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Extensive phytochemical work on the 1-BuOH-soluble fraction of a MeOH extract of the leaves of Symplocos cochinchinensis var. philippinensis resulted in the isolation of 14 new triterpenene saponins, along with four known ones. Their structures were elucidated by comparison of NMR spectroscopic data with related compounds reported in the literature. Three oleanane-type saponins, symplocosins K, M, and P, possessed glucuronic acid as a sugar component, and their carboxyl groups appeared as methyl esters. These are probably formed during extraction and isolation procedures. Symplocosin K (9) showed moderate cytotoxicity toward A549 cells. In addition, all isolated compounds did not show α-glucosidase inhibitory activity.
- Ohyama, Nobuhiro,Cai, Wen-Hu,Kawakami, Susumu,Sugimoto, Sachiko,Matsunami, Katsuyoshi,Otsuka, Hideaki
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p. 1090 - 1099
(2020/11/26)
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- A catalytic glucose oxidation method (by machine translation)
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A catalytic glucose oxidation method, air or oxygen as the oxidizing agent, in order to TEMPO (2, 2, 6, 6 - tetramethyl piperidine - 1 - oxy free radical) and its derivatives with the metal compound is a composite catalytic system, water as the solvent. The simple reaction operation, mild condition, glucose conversion is high, good selectivity product of gluconic acid, has potential application prospect. (by machine translation)
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Paragraph 0025-0066
(2019/06/13)
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- Au-based bimetallic catalysts: How the synergy between two metals affects their catalytic activity
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Supported bimetallic nanoparticles are particularly attractive catalysts due to increased activity and stability compared to their monometallic counterparts. In this work, gold-based catalysts have been studied as catalysts for the selective base-free oxidation of glucose. TiO2-supported Au-Pd and Au-Cu series prepared by the sol-immobilization and precipitation-reduction methods, respectively, showed a significant synergistic effect, particularly when the theoretical weight ratio of the two metals was close to 11 (with an actual experimental bulk Au/Pd molar ratio of ca. 0.8 and ca. 0.4 for Au/Cu) in both cases. XPS analysis showed that the presence of Auδ+, Pd2+ and CuOH species played an important role in the base-free glucose oxidation.
- Sha, Jin,Paul, Sébastien,Dumeignil, Franck,Wojcieszak, Robert
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p. 29888 - 29901
(2019/10/01)
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- Antimicrobial hybrid materials combined with titanium dioxide and glucose oxidase and method for fabricating the same
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The present invention relates to a composite antimicrobial material combined with titanium dioxide and glucose oxidase, and a preparation method thereof. In view of the fact that glucose generates hydrogen peroxide (H_2O_2) when decomposed by glucose oxidase, the present invention induces not only an antimicrobial effect by a photocatalytic reaction of titanium dioxide but also the degradation of glucose by glucose oxidase and the production of hydrogen peroxide by coating the surfaces of titanium dioxide particles with glucose oxidase. Therefore, it is possible to effectively decompose microorganisms through active oxygen (O_2^-, andmiddot;OH) and hydrogen peroxide (H_2O_2) and to reduce glucose, an organic carbon source of microorganisms. According to the present invention, the composite antimicrobial material combined with titanium dioxide and glucose oxidase is provided with glucose oxidase on the surface of titanium dioxide particles. The titanium dioxide particles generate active oxygen through the photocatalytic reaction in an environment where ultraviolet light is irradiated. The glucose oxidase decomposes glucose in the presence of glucose and generates hydrogen peroxide.COPYRIGHT KIPO 2019
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Paragraph 0029; 0030
(2019/09/14)
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- Preparation method of gluconic acid
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The invention discloses a method for preparing gluconic acid from glucose as a raw material with a catalytic oxidation means. Gluconic acid is prepared through oxidation of glucose by an aqueous phasewith air or oxygen as an oxidizing agent and a transition metal compound and nitrous acid or nitrite as a composite catalyst. The reaction is simple in operation and mild in condition, the glucose conversion rate is high, the selectivity of the gluconic acid product is good, and the method has important application prospects.
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Paragraph 0009; 0021; 0024-0059
(2019/06/05)
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- Visible-light-driven selective oxidation of glucose in water with H-ZSM-5 zeolite supported biomimetic photocatalyst
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A new iron tetra(2,3-bis(butylthio)maleonitrile)porphyrazine (FePz(SBu)8)has been synthesized, then it was loaded on H-ZSM-5 zeolite to obtain a supported biomimetic photocatalyst H-ZSM-5/FePz(SBu)8. Using H2O2 as oxidant, the photocatalytic selective oxidation of glucose in water under visible light (λ ≥ 420 nm)irradiation was carried out in presence of H-ZSM-5/FePz(SBu)8. Under such conditions, the glucose can be efficiently converted into value-added chemicals such as glucaric acid, gluconic acid, arabinose, glycerol and formic acid. More importantly, in comparison with pure FePz(SBu)8 and pure H-ZSM-5 zeolite, the H-ZSM-5/FePz(SBu)8 exhibited a higher photocatalytic activity for glucose oxidation and the formation of glucaric acid was observed only when H-ZSM-5/FePz(SBu)8 was used, deriving from the synergistic effect between FePz(SBu)8 and H-ZSM-5 zeolite. Some reaction parameters of glucose oxidation catalyzed by the H-ZSM-5/FePz(SBu)8 were discussed, such as loading amount of FePz(SBu)8, H2O2:glucose ratio, glucose concentration, and so on. It was demonstrated that the Soret-band of FePz(SBu)8 contributed more to the visible light photocatalytic activity than the Q-band during the photocatalytic process. The stability of H-ZSM-5/FePz(SBu)8 during the photocatalytic process was further evaluated by the reusability test. In addition, the generation of reactive oxygen species was determined by electron spin resonance (ESR)technology and scavenger experiments. A possible reaction pathway of glucose oxidation was also discussed.
- Chen, Rui,Yang, Changjun,Zhang, Quanquan,Zhang, Bingguang,Deng, Kejian
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p. 297 - 305
(2019/05/24)
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- Quantitative Determination of Pt- Catalyzed d -Glucose Oxidation Products Using 2D NMR
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Quantitative correlative 1H-13C NMR has long been discussed as a potential method for quantifying the components of complex reaction mixtures. Here, we show that quantitative HMBC NMR can be applied to understand the complexity of the catalytic oxidation of glucose to glucaric acid, which is a promising bio-derived precursor to adipic acid, under aqueous aerobic conditions. It is shown through 2D NMR analysis that the product streams of this increasingly studied reaction contain lactone and dilactone derivatives of acid products, including glucaric acid, which are not observable/quantifiable using traditional chromatographic techniques. At 98% glucose conversion, total C6 lactone yield reaches 44%. Furthermore, a study of catalyst stability shows that all Pt catalysts undergo product-mediated chemical leaching. Through catalyst development studies, it is shown that sequestration of leached Pt can be achieved through use of carbon supports.
- Armstrong,Hirayama,Knight,Hutchings
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p. 325 - 335
(2019/01/04)
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- A novel colorimetric immunoassay of ultrasensitive alpha-fetoprotein sensing in magnetic bead-based mimic enzyme-chromogenic substrate system
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This work described a simple and feasible colorimetric immunoassay. Using hemin (a horseradish peroxidase (HRP) mimic enzyme) and the mimic enzyme-chromogenic substrate system, it can qualitatively and quantitatively detect α-fetoprotein (AFP) at an ultralow concentration. The glucose oxidase (GOx) catalyzed oxidation of glucose leads to the formation of gluconic acid and hydrogen peroxide (H2O2). The latter can oxidize 4-aminoatipyrine (4-AAP) to chromogenic products, and the reaction was catalyzed by hemin. With the increase of H2O2, the absorbance increased, and the color of the solution changed from colorless to pink. On the basis of the system, monitored by recording the color or absorbance (λ = 505 nm), a new immunoassay protocol with GOx-labeled anti-AFP detection antibody was designed. A wide linear dependence was obtained in the range from 0.075 to 280 ng mL?1 with a low detection limit (LOD) of 0.0247 ng mL?1 (S/N = 3).
- Su, Dan,Zeng, Qiang,Feng, Bingwei,Xu, Pengfei,Shan, Baixi,Song, Yonggui
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p. 859 - 866
(2019/08/26)
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- Method for preparing gluconic acid by catalytic oxidation
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The invention provides a method for preparing gluconic acid by catalytic oxidation and relates to the technical field of biomass efficient transformation and utilization. The gluconic acid is preparedby taking glucose as a raw material and carrying out the catalytic oxidation on Pd/C, wherein a carbon source in a Pd/C catalyst is prepared by carrying out hydrothermal synthesis on the glucose. Onthe basis of a traditional Pd/C catalyst, a traditional activated carbon carrier is replaced with a carbon carrier prepared by taking the glucose as the raw material and carrying out the hydrothermalmethod. A carbon material prepared from a biomass through a hydrothermal method contains more oxygen-containing groups including hydroxyl, carboxyl and the like and has stable metal and capability ofimproving reaction activity, so that the stability and activity of the catalyst are greatly improved; 100 percent conversion rate and 98 percent yield can be reached after the catalyst reacts under normal pressure and room temperature, so that the aim of efficiently preparing the gluconic acid from the glucose under a moderate condition is realized.
- -
-
Paragraph 0029; 0033; 0038; 0043
(2018/07/28)
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- Efficient production of sugar-derived aldonic acids by Pseudomonas fragi TCCC11892
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Aldonic acids are receiving increased interest due to their applications in nanotechnology, food, pharmaceutical and chemical industries. Microbes with aldose-oxidizing activity, rather than purified enzymes, are used for commercial production with limited success. Thus it is still very important to develop new processes using strains with more efficient and novel biocatalytic activities for the production of adonic acids. In the present study, Pseudomonas fragi TCCC11892 was found to be an efficient producer of aldonic acids, with the production of galactonic and l-rhamnonic acid by P. fragi reported for the first time. The semi-continuous production of maltobionic acid and lactobionic acid was developed for P. fragi TCCC11892, achieving a yield of over 90 g L?1 for the first 7 cycles. The excellent performance of P. fragi in the production of lactobionic acid (119 g L?1) was also observed when using waste cheese whey as an inexpensive fermentation medium. Scaling up of the above process for production of aldonic acids with P. fragi TCCC11892 cells should facilitate their commercial applications.
- Mao, Shuhong,Liu, Yanna,Hou, Yali,Ma, Xiaoyu,Yang, Juanjuan,Han, Haichao,Wu, Jianlin,Jia, Longgang,Qin, Huimin,Lu, Fuping
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p. 39897 - 39901
(2019/01/03)
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- Synthesis of Furans from Sugars Via Keto Intermediates
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The present invention provides a method of preparing a furan derivative comprising the steps of (a) converting a monosaccharide to provide a keto-intermediate product; and (b) dehydrating the keto-intermediate product to provide a furan derivative; wherein the keto-intermediate product is pre-disposed to forming keto-furanose tautomers in solution. The method may further comprising a step of oxidizing the furan derivative to provide a furandicarboxylic acid or a furandicarboxylic acid derivative.
- -
-
Paragraph 0052
(2018/03/25)
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- Enzyme-immobilized metal-organic framework nanosheets as tandem catalysts for the generation of nitric oxide
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An enzyme-immobilized metal-organic framework (MOF) nanosheet system was developed as a tandem catalyst, which converted glucose into gluconic acid and H2O2, and sequentially the latter could be used to catalyze the oxidation of l-arginine to generate nitric oxide in the presence of porphyrinic MOFs as artificial enzymes under physiological pH, showing great potential in cancer depleting glucose for starving-like/gas therapy.
- Gao, Feng,Lei, Jianping,Ling, Pinghua,Qian, Caihua
-
supporting information
p. 11176 - 11179
(2020/04/23)
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- Highly selective photocatalytic oxidation of biomass-derived chemicals to carboxyl compounds over Au/TiO2
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Highly selective transformation of biomass-derived chemicals into value-added chemicals is of great importance. In this work, selective photooxidation of various biomass-derived chemicals, including ethanol, glucose, xylose, 2-furaldehyde, 5-hydroxymethyl-2-furfural, and furfuralcohol to the corresponding carboxyl compounds was studied using atmospheric air as the oxidant at ambient temperature. It was found that the reactions could be carried out efficiently over Au nanoparticles (AuNPs) supported on TiO2 (AuNPs/TiO2) under both ultraviolet (UV) and visible light in Na2CO3 aqueous solution. Under the optimized conditions, the selectivities for desired products were higher than 95% for all the reactions. Detailed studies indicated that the surface plasmon resonance of AuNPs and the band-gap photoexcitation of TiO2 were responsible for visible-light-responding and UV-light-responding activities, respectively. Na2CO3 acted as the promoter for the visible-light-induced oxidation and the inhibitor of reactive oxygen species with strong oxidation power under UV light.
- Zhou, Baowen,Song, Jinliang,Zhang, Zhanrong,Jiang, Zhiwei,Zhang, Pei,Han, Buxing
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p. 1075 - 1081
(2017/03/17)
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- CTAB-assisted sol-microwave method for fast synthesis of mesoporous TiO2 photocatalysts for photocatalytic conversion of glucose to value-added sugars
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Fabrication technique is an important factor for development of catalysts. Titanium dioxide (TiO2) is one of efficient photocatalysts. In this work, we firstly report the fabrication of TiO2 nanoparticles by sol-microwave method with cetyltrimethylammonium bromide (CTAB) surfactant. Absence of surfactant, microwave treatment significantly reduced the cluster sizes of TiO2, but high aggregations of TiO2 particles were observed. CTAB has great impact on morphology, cluster size and mesoporous structure of TiO2. Therefore, surface area of TiO2 synthesized by sol-microwave method with 0.108 M CTAB increased from 15.97 to 37.60 m2/g. Photocatalytic activity of TiO2 was tested via the glucose conversion to produce value-added chemicals (gluconic acid, xylitol, arabinose and formic acid). It was found that surface area, mesoporous structure and pore size of TiO2 are crucial properties for glucose conversion and product distribution. From the reaction test, 0.108 M CTAB/MW-TiO2 achieved the highest glucose conversion (62.28%).
- Payormhorm, Jiraporn,Chuangchote, Surawut,Laosiripojana, Navadol
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p. 546 - 555
(2017/09/01)
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- SELF-POWERED ENZYME MICROPUMPS
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Drug delivery devices, sensors, and micropumps provided herein can utilize a reaction of an analyte triggered by an enzyme to drive fluid flow. In some cases, a drug delivery device can include a reservoir including a drug (e.g., insulin) and have an enzyme (e.g., glucose oxidase) positioned adjacent to said reservoir. The enzyme can catalyze a reaction of said analyte to drive a fluid flow adjacent to said reservoir to increase a release of the drug from said reservoir. A sensor for an analyte can include an enzyme bound to a surface and a flow meter to detect a flow of fluids adjacent to said surface. A self-powered enzyme micropump provided herein can provide precise control over flow rate in response to specific signals.
- -
-
Paragraph 0066
(2017/04/12)
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- Gold catalysts screening in base-free aerobic oxidation of glucose to gluconic acid
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Base-free aerobic oxidation of glucose in presence of Au/Al2O3, Au/CeO2, Au/CeO2(20?wt%)/Al2O3, Au/CeO2(25?wt%)/ZrO2 and Au/CeO2(50?wt%)/ZrO2 catalysts using molecular oxygen at atmospheric pressure is studied. Within the whole series high conversion and selectivity to gluconic acid are observed after 18?h of reaction at 120?°C. The activity and especially the selectivity changes are related to the support nature in a way that the higher the Lewis acidity of the support the lower the selectivity to gluconic acid and the higher the production of lactic acid. The highest yield to gluconic acid is obtained over Au/Al2O3 for which the influence of the reaction time, temperature and stirring rate are further evaluated and discussed.
- Megías-Sayago,Ivanova,López-Cartes,Centeno,Odriozola
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p. 148 - 154
(2016/11/22)
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- Electrodeposition of platinum-iridium nanoparticles on carbon nanotubes and their electrocatalytic oxidation of glucose
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Platinum-iridium (PtIr) nanoparticles (NPs) have been anchored on the surface of carbon nanotubes by potentiostatic electrodeposition in 0.5 M H2SO4+0.5 M glycerol aqueous solution. The surface and composition of the PtIr NPs/CNTs nanohybrids have been characterized by transmission electron microscopy and energy dispersive spectroscopy, respectively. The electrocatalytic properties of the PtIr NPs/CNTs catalysts for glucose oxidation have been investigated by cyclic voltammetry and chronoamperometry. The size of the PtIr NPs can be controlled from 3.0–7.0 nm by controlling the amount of Ir. In particular, the PtIr NPs has been optimized at 1:1 Pt/Ir atomic ratio. The as-prepared PtIr (1:1) NPs/CNTs catalysts possess unique properties including small size of PtIr NPs, excellent dispersion, high electrochemical active surface area and exhibit high activity towards glucose oxidation. For comparison, Pt NPs/CNTs catalysts have also been prepared under the same controlled procedure. In the absence of Ir, Pt NPs are also uniformly dispersed on the CNTs, and their average diameter is 4.0±0.5 nm, close to that of PtIr NPs. Further, addition of Ir makes PtIr (1:1) NPs/CNTs catalysts superior to Pt NPs/CNTs catalysts in term of better long-term stability and higher catalytic efficiency of glucose oxidation. The PtIr (1:1) NPs/CNTs catalysts are proved to be promising anode catalysts for direct glucose fuel cells.
- Wu, Bohua,Zhu, Jiajin,Li, Xue,Zhou, Ting,Mao, Liqiu,Xiong, Shanxin
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p. 1007 - 1013
(2017/11/03)
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- Method for preparing gluconic acid from glucose in FeCl3 solutions of different concentrations
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The invention provides a method for preparing gluconic acid from glucose in ferric chloride (FeCl3) solutions of different concentrations. The method comprises the steps of mixing commercially available glucose with FeCl3 solutions so as to prepare gluconic acid solutions of different yields by controlling the concentrations of the FeCl3 solutions and the reaction time, and separating the solutions by virtue of a preparation chromatograph provided with a silica gel column so as to separately obtain solutions rich in gluconic acid, formic acid, acetic acid and FeCl3. According to the method, high value-added chemical products are prepared, and meanwhile, the FeCl3 solutions are recycled. Compared with a traditional biological fermentation method for preparing gluconic acid, the method has the advantages that the process is simple, the cost is low, and the production period is relatively short; and the method is more applicable to the large-scale industrial production.
- -
-
Paragraph 0025; 0026; 0027; 0050
(2016/12/01)
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- Phase transformation-controlled synthesis of CuO nanostructures and their application as an improved material in a carbon-based modified electrode
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Column-shaped CuO nanorods have been synthesized by a two-step "precursor formation-crystallization" process using a hydrothermal method with advantages of being template- and surfactant-free. The regular particle morphology of the as-prepared material was explored to be produced through a good transformation process coupled with a series of phase changes from CuCl, to Cu2(OH)3Cl, to Cu(OH)2, which rely on heat by using NaOH and n-butylamine solution in a sealed vessel, and finally to CuO. Scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDX), X-ray diffraction (XRD), and Raman spectroscopy were employed to characterize the morphology and structures of our samples. The as-prepared CuO nanostructures have been employed to modify a glassy carbon electrode for nonenzymatic glucose oxidation. Compared with the bare glassy carbon electrode, the CuO modified electrode exhibits satisfactory performance with an apparent rate constant of κ as high as 231.0 M-1 s-1 due to its high specific surface area and especially good electron delivery capability of the CuO nanorods.
- Xue, Zhonghua,Li, Mengqian,Rao, Honghong,Yin, Bo,Zhou, Xibin,Liu, Xiuhui,Lu, Xiaoquan
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p. 12829 - 12836
(2016/02/18)
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- Microwave-assisted base-free oxidation of glucose on gold nanoparticle catalysts
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Base-free oxidation of glucose to gluconic acid with supported gold catalysts was studied using microwave heating. High conversion and selectivity were obtained in a remarkably shortened reaction time; in 10 min gluconic acid was obtained with up to 76% yields with 0.09 mol% Au/Al2O3 and hydrogen peroxide as oxidant. Very high turn-over frequencies over 10,000 h-1 were measured for the microwave assisted oxidation. Moreover, the catalyst activity remained constant in four consecutive runs, even though minor particle growth was observed.
- Rautiainen, Sari,Lehtinen, Petra,Vehkam?ki, Marko,Niemel?, Klaus,Kemell, Marianna,Heikkil?, Mikko,Repo, Timo
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p. 115 - 118
(2015/12/08)
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- Aqueous oxidation of sugars into sugar acids using hydrotalcite-supported gold nanoparticle catalyst under atmospheric molecular oxygen
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Hydrotalcite-supported gold nanoparticles show good activity as a heterogeneous catalyst for the oxidation of monosaccharides (xylose, ribose, galactose and mannose) and disaccharides (lactose and cellobiose) into the corresponding sugar acids under external base-free conditions in water solvent using atmospheric pressure of molecular oxygen. The produced sugar acids were thoroughly identified by 1H-, 13C-, and HMQC-NMR and ESI-FT-ICR MS spectroscopic techniques.
- Tomar, Ravi,Sharma, Jatin,Nishimura, Shun,Ebitani, Kohki
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supporting information
p. 843 - 845
(2016/07/16)
-
- Oxidation of Glycerol to Dicarboxylic Acids Using Cobalt Catalysts
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In this paper, the performance of cobalt-based catalysts was reported for oxidation of glycerol to dicarboxylic acids such as tartronic and oxalic acids. Cobalt catalysts supported on Mg3Al(OH)y(CO3)z structures prepared by a two-step modified sol-gel method showed 100% glycerol conversion with 64% and 24% selectivity toward tartronic and oxalic acids under mild conditions (55-70 °C and 0.1 MPa O2). Surface and bulk characterization by N2 adsorption/desorption, X-ray diffraction, and temperature-programmed reduction reveals that the cobalt sites interacting with surface hydroxides are catalytically more active than those incorporated into a framework leading to selective glycerol oxidation to dicarboxylic acids in one pot. On the basis of the experiments at different cobalt contents, temperatures, and concentration-time profiles, possible reaction pathways are discussed to explain the selectivity profile. Deactivation of the catalyst under certain conditions has been discussed as a result of loss of surface area due to structural changes.
- Jin, Xin,Zhao, Meng,Zeng, Chun,Yan, Wenjuan,Song, Ziwei,Thapa, Prem S.,Subramaniam, Bala,Chaudhari, Raghunath V.
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p. 4576 - 4583
(2016/07/12)
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- Pt catalysts for efficient aerobic oxidation of glucose to glucaric acid in water
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Glucaric acid, a promising bio-based chemical for the production of adipic acid, is produced on a commercial Pt/C catalyst via aerobic oxidation of glucose in water. Facile oxidation of gluconic acid, an intermediate oxidation product of glucose, under optimal conditions of an initial pH of 7.2, 80 °C, 13.8 bar O2 and a glucose/Pt molar ratio of 54, enabled a maximum glucaric acid yield of 74%, the highest yield reported to date. It is found that in an acidic solution, gluconic acid is the major product while in a highly basic solution, selectivity to glucaric acid is poor due to its C-C bond cleavage to low carbon chain carboxylic acids. High temperatures and high Pt loadings result in lower selectivity to glucaric acid. Recyclability and characterization studies reveal that the catalyst is stable after five cycles with no sign of Pt leaching into the solution.
- Lee, Jechan,Saha, Basudeb,Vlachos, Dionisios G.
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p. 3815 - 3822
(2016/07/07)
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- Method for preparing gluconic acid by taking glucose as raw material under different working conditions
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The invention provides a method for preparing gluconic acid by taking glucose as a raw material under different working conditions. The method comprises the following steps: mixing commercially available glucose with a 40%(w/w) ferric chloride solution, controlling the reaction temperature and time to obtain gluconic acid solutions with different yields, and separating the gluconic acid solutions through preparative chromatography with silica gel columns, so as to obtain solutions rich in gluconic acid, formic acid, acetic acid and FeCl3 (Ferric Chloride) respectively; FeCl3 solutions are further reused while high value-added chemicals are prepared. Compared with the traditional biological fermentation method for preparing the gluconic acid, the method provided by invention has the advantages of being simple process, low in cost, short in production period, and relatively suitable for large-scale industrial production.
- -
-
Paragraph 0040-0041; 0050
(2017/04/03)
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- Oxidative conversion of glucose to gluconic acid by iron(iii) chloride in water under mild conditions
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A simple method was demonstrated to oxidize glucose into gluconic acid in a concentrated FeCl3 solution. The maximum gluconic acid yield (52.3%) was achieved in the 40% FeCl3 solution at 110°C in 4 hours. Formic and acetic acids were the main coproducts with an yield of 10-20%.
- Zhang, Hongdan,Li, Ning,Pan, Xuejun,Wu, Shubin,Xie, Jun
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supporting information
p. 2308 - 2312
(2016/05/19)
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- Highly Selective Oxidation of Carbohydrates in an Efficient Electrochemical Energy Converter: Cogenerating Organic Electrosynthesis
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The selective electrochemical conversion of highly functionalized organic molecules into electricity, heat, and added-value chemicals for fine chemistry requires the development of highly selective, durable, and low-cost catalysts. Here, we propose an approach to make catalysts that can convert carbohydrates into chemicals selectively and produce electrical power and recoverable heat. A 100 % Faradaic yield was achieved for the selective oxidation of the anomeric carbon of glucose and its related carbohydrates (C1-position) without any function protection. Furthermore, the direct glucose fuel cell (DGFC) enables an open-circuit voltage of 1.1V in 0.5 m NaOH to be reached, a record. The optimized DGFC delivers an outstanding output power Pmax=2mW cm-2 with the selective conversion of 0.3 m glucose, which is of great interest for cogeneration. The purified reaction product will serve as a raw material in various industries, which thereby reduces the cost of the whole sustainable process.
- Holade, Yaovi,Servat, Karine,Napporn, Teko W.,Morais, Cláudia,Berjeaud, Jean-Marc,Kokoh, Kouakou B.
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p. 252 - 263
(2016/02/27)
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- Catalysis and Reactivation of Ordered Mesoporous Carbon-Supported Gold Nanoparticles for the Base-Free Oxidation of Glucose to Gluconic Acid
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An ordered mesoporous carbon (CMK-3)-supported gold catalyst was prepared and used in the aerobic oxidation of glucose to gluconic acid under base-free conditions with molecular oxygen. XRD and TEM results revealed that gold nanoparticles were uniformly dispersed on the surface and in the channels of CMK-3. Catalytic tests showed that conversion remarkably increased with decreased selectivity when oxygen pressure and reaction temperature were increased. Glucose conversion to gluconic acid reached over 92% with 85% selectivity under the conditions of 383 K reaction temperature, 0.3 MPa oxygen pressure, and 2 h reaction time. Hydrogen peroxide was generated during reaction, and the relationship between hydrogen peroxide and the byproduct fructose was discussed. Low glucose/Au molar ratio minimized fructose formation. A 92% gluconic acid yield was obtained after reaction for 15 min when the molar ratio of glucose/Au was set to 100. The spent catalyst treated with an aqueous solution of NaOH at 363 K could produce glucose conversion up to 87%, which was close to the result of as-prepared catalyst and excluded the effect of alkaline residues. (Chemical Equation Presented).
- Qi, Puyu,Chen, Shasha,Chen, Jin,Zheng, Jianwei,Zheng, Xinlei,Yuan, Youzhu
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p. 2659 - 2670
(2015/04/14)
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- Hydroxyl radical-induced etching of glutathione-capped gold nanoparticles to oligomeric AuI-thiolate complexes
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Thiol-induced core etching of gold nanoparticles is a general method for the production of gold nanoclusters (AuNCs) of various sizes. This paper is the first report on the efficient reaction of glutathione-capped gold nanoparticles (GSH-AuNPs) with hydroxyl radicals to produce oligomeric AuI-thiolate complexes at ambient temperature. Also, hydroxyl radicals can etch commercially available gold nanoparticles (100 nm); this strategy can be applied for the removal of gold from scrap electronics. Additionally, proteins can trigger the aggregation of oligomeric AuI-thiolate complexes under neutral conditions resulting in the formation of fluorescent AuNCs. For example, the reaction of trypsin, lysozyme, and glucose oxidase with oligomeric AuI-thiolate complexes produces Au5, Au8, and Au13 clusters with emission maxima at 415, 460, and 535 nm, respectively. Interestingly, trypsin- and glucose oxidase-stabilized AuNCs could sense GSH and glucose via GSH-induced etching of AuNCs and H2O2-mediated oxidation of AuNCs, respectively. This journal is
- Chen, Tzu-Heng,Nieh, Chih-Chun,Shih, Ya-Chen,Ke, Chen-Yi,Tseng, Wei-Lung
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p. 45158 - 45164
(2015/06/02)
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- Selective oxidation of uronic acids into aldaric acids over gold catalyst
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Herein, uronic acids available from hemicelluloses and pectin were used as raw material for the synthesis of aldaric acids. Au/Al2O3 catalyst oxidized glucuronic and galacturonic acids quantitatively to the corresponding glucaric and galactaric acids at pH 8-10 and 40-60 °C with oxygen as oxidant. The pH has a significant effect on the initial reaction rate as well as desorption of acid from the catalyst surface. At pH 10, a TOF value close to 8000 h-1 was measured for glucuronic acid oxidation. The apparent activation energy Ea for glucuronic acid oxidation is dependent on the pH which can be attributed to the higher energy barrier for desorption of acids at lower pH. This journal is
- Rautiainen, Sari,Lehtinen, Petra,Chen, Jingjing,Vehkam?ki, Marko,Niemel?, Klaus,Leskel?, Markku,Repo, Timo
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p. 19502 - 19507
(2015/04/28)
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- Photocatalytic conversion of glucose in aqueous suspensions of heteropolyacid-TiO2 composites
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Commercial and home prepared TiO2 samples were functionalized with a commercial Keggin heteropolyacid (HPA) H 3PW12O 40 (PW12) or with a hydrothermally home prepared K 7PW11O 39 salt (PW11). All the materials were characterized by specific surface area measurements (BET), XRD analyses, Raman, DRS along with SEM observations and they have been used for glucose photocatalytic conversion in an aqueous suspension. Different reaction extents and distribution of intermediate oxidation products were observed depending on the photocatalyst. Gluconic acid, arabinose, erythrose and formic acid were observed as oxidation products when bare TiO2 or HPA/TiO2 composite materials were used. Glucose isomerization to form fructose was also observed and in some runs traces of glucaric acid and glyceraldehyde were also found. The carbon mass balance was accomplished in the presence of the commercial Evonik P25 TiO2 powder and the composites where TiO2 was present, whereas the presence of the solvothermically prepared TiO2 gave rise to a carbon unbalance, due to strong adsorption of the products on the photocatalyst surface. No reactivity was observed in the presence of PW12 alone while PW11 induced only isomerization of the glucose.
- Bellardita,García-López,Marcì,Megna,Pomilla,Palmisano
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p. 59037 - 59047
(2016/06/09)
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- A new caffeoylgluconic acid derivative from the nearly ripe fruits of Evodia rutaecarpa
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A new caffeoylgluconic acid derivative, trans-caffeoyl-6-O-d-gluconic acid methyl ester (1), together with two known compounds named trans-caffeoyl-6-O-d-glucono-γ-lactone (2) and trans-caffeoyl-6-O-d-gluconic acid (3), was isolated from the nearly ripe fruits of Evodia rutaecarpa (Juss.) Benth. These compounds were isolated by various separation methods associated with the UPLC-Q-TOF-MS technique. Their structures were elucidated on the basis of extensive spectroscopic methods.
- He, Ying,Li, Jie,Wu, Hong-Hua,Chai, Xin,Yang, Jing,Wang, Yue-Fei,Zhang, Peng,Zhu, Yan,Gao, Xiu-Mei
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p. 1243 - 1248
(2015/03/31)
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- Catalytic oxidation of cellobiose over TiO2 supported gold-based bimetallic nanoparticles
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A series of Au-M (M = Cu, Co, Ru and Pd) bimetallic catalysts were supported on TiO2via a deposition-precipitation (DP) method, using urea as a precipitating agent. The resulting catalysts were employed in the catalytic oxidation of cellobiose to gluconic acid and the properties of these catalysts were carefully examined using various characterization techniques. Cu-Au/TiO2 and Ru-Au/TiO2 catalysts demonstrated excellent catalytic activities in the oxidation of cellobiose to gluconic acid, though with contrasting reaction mechanisms. Complete conversion of cellobiose (100%) with a gluconic acid selectivity of 88.5% at 145 °C within 3 h was observed for reactions performed over Cu-Au/TiO2; whereas, a conversion of 98.3% with a gluconic acid selectivity of 86. 9% at 145°C within 9 h was observed for reactions performed over Ru-Au/TiO2. A reaction pathway was proposed based on the distribution of reaction products and kinetic data. It is suggested that cellobiose is converted to cellobionic acid (4-O-beta-d-glucopyranosyl-d-gluconic acid) and then gluconic acid is formed through the cleavage of the β-1,4 glycosidic bond in cellobionic acid over Cu-Au/TiO2 catalysts. On the other hand, for reactions over the Ru-Au/TiO2 catalyst, glucose was observed as the reaction intermediate and gluconic acid was formed as a result of glucose oxidation. For reactions over Co-Au/TiO2 and Pd-Au/TiO2 catalysts, fructose was observed as the reaction intermediate, along with small amounts of glucose. Co and Pd remarkably promoted the successive retro-aldol condensation reactions of fructose to glycolic acid, instead of the selective oxidation to gluconic acid. This journal is
- Amaniampong, Prince Nana,Jia, Xinli,Wang, Bo,Mushrif, Samir H.,Borgna, Armando,Yang, Yanhui
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p. 2393 - 2405
(2015/04/14)
-
