1335-57-5Relevant articles and documents
Copper Complexes as Bioinspired Models for Lytic Polysaccharide Monooxygenases
Concia, Alda Lisa,Beccia, Maria Rosa,Orio, Maylis,Ferre, Francine Terra,Scarpellini, Marciela,Biaso, Frédéric,Guigliarelli, Bruno,Réglier, Marius,Simaan, A. Jalila
, p. 1023 - 1026 (2017)
We report here two copper complexes as first functional models for lytic polysaccharide monooxygenases, mononuclear copper-containing enzymes involved in recalcitrant polysaccharide breakdown. These complexes feature structural and spectroscopic properties similar to those of the enzyme. In addition, they catalyze oxidative cleavage of the model substrate p-nitrophenyl-β-d-glucopyranoside. More importantly, a particularly stable copper(II) hydroperoxide intermediate is detected in the reaction conditions.
Three dimensional porous graphene-chitosan composites from ice-induced assembly for direct electron transfer and electrocatalysis of glucose oxidase
Qian, Lei,Lu, Lu
, p. 38273 - 38280 (2014)
Three dimensional porous graphene-chitosan (GR-CS) composites via ice-induced assembly for glucose oxidase (GOD) immobilization were reported for the first time. By adjusting the GR amount, the porous GR-CS composites containing different GR content could be produced. It was found that the GR amount played an important role in their morphologies. Higher GR amount resulted in more pores appearing in the GR-CS composites. When the GR amount was 70 wt%, the GR-CS composites (GR70-CS) had good flexibility and interpenetrating porous structures. The GR70-CS composite showed good stability, and still kept a porous structure even after dispersing and coating on the substrates. Current response from the GR70-CS composite modified glassy carbon electrode (GR70-CS/GCE) was about two times that from the bare GCE with Fe(CN) 63-/4- as a probe. The direct electrochemical behavior was observed when GOD was immobilized onto the GR70-CS/GCE. The GOD modified GCE also showed good electrocatalytic activity for glucose. Using ferrocenecarboxylic acid as a mediator, a linear relationship from 0.14 to 7.0 mM (R = 0.995) between currents and the glucose concentration with a detection limit of 17.5 μM was obtained. the Partner Organisations 2014.
Redox Polymer Films Containing Enzymes. 2. Glucose Oxidase Containing Enzyme Electrodes
Gregg, Brian A.,Heller, Adam
, p. 5976 - 5980 (1991)
Glucose oxidase is covalently bound in a film of cross-linked, redox-conducting epoxy cement on the surface of electrodes.The binding simultaneously immobilizes the enzyme and connects it electrically with the electrode.The effects of cross-linker concentration, film thickness, enzyme concentration, temperature, and oxygen concentration on the steady-state electrocatalytic oxidation of glucose at the redox-epoxy enzyme electrodes are described.The catalytic "reaction layer" extends through the entire film, even for films as thick as ca. 5 μm.The limiting catalytic current density is a function of the enzyme concentration, reaching a maximum near 35 wtpercent enzyme for films about 1 μm thick.In such films, the activation energy for the electrocatalytic reaction at high glucose concentration is 63 kJ/mol, and the apparent Michaelis constant monotonically decreases with increasing enzyme concentration and increases with increasing oxygen concentration.These results are explained by postulating that in such ca. 1 μm thick redox-epoxy enzyme films that the rate-limiting kinetic step at high substrate concentration is related to electron transfer away from the enzyme active site, a process involving flexing of the cross-linked redox chain segments.This bottleneck may be attributed to the high activity of the enzyme and the small contact area between the redox polymer and the enzyme-active site that is recessed inside the insulating protein shell of the enzyme.
Direct electrochemistry of glucose oxidase and sensing of glucose at a glassy carbon electrode modified with a reduced graphene oxide/fullerene-C60 composite
Thirumalraj, Balamurugan,Palanisamy, Selvakumar,Chen, Shen-Ming,Yang, Cheng-Yu,Periakaruppan, Prakash,Lou, Bih-Show
, p. 77651 - 77657 (2015)
In the present work, a glucose biosensor was fabricated based on the direct electrochemistry of glucose oxidase at glassy carbon modified with a reduced graphene oxide (RGO) and fullerene-C60 (C60) composite. The reduced graphene oxide/fullerene (RGO-C60) composite was prepared by electrochemical reduction of a graphene oxide (GO) and C60 composite at -1.4 V for 200 s in pH 5 solution; while the GO-C60 composite was prepared by a simple sonication of C60 in GO solution for 6 hours at 45°C. A well-defined and enhanced reversible redox peak of GOx was observed at RGO-C60 composite compared with other modified electrodes. The heterogeneous electron transfer rate constant (Ks) and the surface coverage concentration of GOx at RGO-C60/GOx modified electrode were calculated to be 2.92 s-1 and 1.19 × 10-10 mol cm-2, respectively. Under optimum conditions, the amperometry response of the biosensor was linear against the concentration of glucose from 0.1 to 12.5 mM with a response time of 3 s. The limit of detection was estimated to be 35 μM based on S/N = 3 with a high sensitivity of 55.97 μA mM-1 cm-2. In addition, the fabricated biosensor showed a good practical ability for the detection of glucose in human blood serum samples.
Design and development of Co3O4/NiO composite nanofibers for the application of highly sensitive and selective non-enzymatic glucose sensors
Ramasamy, Ramachandran,Ramachandran,Philip, Geo George,Ramachandran, Rasu,Therese, Helen Annal,Gnana Kumar
, p. 76538 - 76547 (2015)
Cobaltosic oxide/nickel oxide (Co3O4/NiO) composite nanofibers were synthesized via an electrospinning technique and their electrocatalytic activities toward non-enzymatic glucose sensors were evaluated in detail. The Co3O4/NiO composite exhibited the homogeneously distributed nanofibers with high porosity, effective inter connectivity and an extended number of conducting channels with an average diameter of 160 nm. The diffraction patterns depicted the face centred cubic crystalline structure of Co3O4/NiO nanofibers and the purity of the composite nanofibers was further ensured by using FT-IR and UV-vis spectroscopic analyses. The electrocatalytic performances of prepared nanofibers toward the oxidation of glucose was determined by cyclic voltammetry and amperometry techniques and the experimental results showed that the Co3O4/NiO composite nanofibers exhibited a maximum electrooxidation toward glucose, owing to the synergistic effect of Co3O4 and NiO. The electrospun Co3O4/NiO nanofibers exhibited a detection limit of 0.17 μM, a wide linear range of 1 μM to 9.055 mM and a high sensitivity of 2477 μA mM-1 cm-2. The nanofibers have also exhibited favorable properties such as good selectivity, reproducibility, durability and real sample analysis, which ensured its potential applications in the clinical diagnosis of diabetes.
Preparation of Ni(OH)2 nanoplatelet/electrospun carbon nanofiber hybrids for highly sensitive nonenzymatic glucose sensors
Chen, Linlin,Liu, Lijuan,Guo, Qiaohui,Wang, Zhonghui,Liu, Guiling,Chen, Shuiliang,Hou, Haoqing
, p. 19345 - 19352 (2017)
Ni(OH)2 nanoplatelet/electrospun carbon nanofiber (ECF) hybrids have been simply prepared for the construction of nonenzymatic glucose biosensors. The resulting Ni(OH)2/ECF hybrids were carefully examined using SEM, TEM, HRTEM, XRD, and XPS. For all hybrids, two-dimensional Ni(OH)2 nanoplatelets were uniformly anchored on the one-dimensional ECFs, forming a hierarchical nanostructure, and the thickness of Ni(OH)2 nanoplatelets could be readily tailored by controlling the content of Ni(OH)2 precursor. Cyclic voltammetric studies showed enhanced redox properties for Ni(OH)2/ECF-based electrodes relative to pure Ni(OH)2 nanoplatelet electrode and significantly improved the electrocatalytic activity for glucose oxidation. The application of Ni(OH)2/ECF-based electrodes to glucose detection was explored. A low limit of detection (0.1 μM), wide detection linear range (0.005-13.05 mM), and excellent signal stability and reproducibility were demonstrated by this novel Ni(OH)2/ECF-0.06 hybrid. The sensor was also applied in real serum samples, giving satisfactory results. The simple preparation, low cost, and enhanced electrocatalytic performance of these hybrids could pave the way for highly sensitive glucose sensors.
Enhanced glucose sensing based on a novel composite CoII-MOF/Acb modified electrode
Wen, Yuanyuan,Meng, Wei,Li, Chen,Dai, Lei,He, Zhangxing,Wang, Ling,Li, Ming,Zhu, Jing
, p. 3872 - 3879 (2018)
In this work, we demonstrate the synthesis and application of a novel CoII-based metal-organic framework {[Co2(Dcpp)(Bpe)0.5 (H2O)(μ2-H2O)]·(Bpe)0.5}n (CoII-MOF, H4Dcpp = 4,5-bis(4′-carboxylphenyl)-phthalic acid, Bpe = 1,2-bis(4-pyridyl)ethane) as an electrochemical sensor for glucose detection. Single-crystal X-ray diffraction analysis shows that the CoII-MOF has a two-dimensional (2D) bilayer structure composed of Co2 units and Dcpp4- ligands. There are two kinds of Bpe in the structure: one serves as a bidentate ligand linking two Co1 atoms in each 2D layer; the other is just free in the lattice. The CoII-MOF modified glassy carbon electrode (GCE) shows good electrocatalytic activity towards glucose oxidation. To further improve the catalytic activity of the electrode, a new composite of CoII-MOF/acetylene black (CoII-MOF/Acb) was constructed. The CoII-MOF/Acb modified electrode exhibits enhanced sensing behavior for glucose detection. The sensing performance of CoII-MOF/Acb/GCE with different Acb loadings was investigated in detail. The results demonstrate that CoII-MOF/GCE with 2% Acb (CoII-MOF/Acb-2%/GCE) exhibits the best sensing behavior, including a high sensitivity of 0.255 μA μM-1 cm-2 and a wide linear range of 5-1000 μM, as well as a low detection limit of 1.7 μM (S/N = 3). It's worth noting that the linear range of CoII-MOF/Acb-2%/GCE was extended by more than ten times when compared to that of CoII-MOF/GCE without Acb addition. In addition, CoII-MOF/Acb-2%/GCE shows good selectivity and stability in the sensing process.
Self-powered sensor for Hg2+ detection based on hollow-channel paper analytical devices
Zhang, Lina,Wang, Yanhu,Ma, Chao,Wang, Panpan,Yan, Mei
, p. 24479 - 24485 (2015)
In this work, a novel and effective self-powered device was introduced in a microfluidic paper-based analytical device (μ-PAD) with hollow channels to transport fluids for mercury ion (Hg2+) detection. In this device, a mediator-less and compartment-less glucose/O2 biofuel cell (BFC) device served as the core component, using gold nanoparticle (AuNP) and platinum nanoparticle functionalized carbon nanotube (Pt/CNT) modified paper electrodes as the anodic and cathodic substrates, respectively. To construct the self-powered Hg2+ sensor, an Hg2+-specific oligonucleotide capture aptamer was first immobilized on an AuNP modified anode. In the presence of Hg2+, a AuNP@glucose dehydrogenase (GDH) labeled signal aptamer was hybridized with the immobilized capture probe through a thymine (T)-Hg2+-T interaction. Nicotinamide adenine dinucleotide (NAD+/NADH) was used as a cofactor in the proposed BFC device, and GDH in the anode could catalyze the oxidation of glucose used as fuel to generate gluconolactone, protons and electrons. Meanwhile the Pt/CNT in the cathode showed direct bioelectrocatalytic activity towards the oxygen reduction reaction (ORR). At the optimal conditions, this self-powered sensor could detect Hg2+ at the picomolar level, providing a simple approach to fabricate low-cost and portable powered devices on small-size paper for point-of-care testing. In addition, this self-powered sensor could be also used as a powerful tool for a wide range of potential applications in biotechnology and medicine.
Hierarchical Cu/Cu(OH)2 nanorod arrays grown on Cu foam as a high-performance 3D self-supported electrode for enzyme-free glucose sensing
Bie, Lili,Luo, Xue,He, Qingqing,He, Daiping,Liu, Yan,Jiang, Ping
, p. 95740 - 95746 (2016)
Hierarchical Cu/Cu(OH)2 nanorod arrays grown on commercially available Cu foam (Cu/Cu(OH)2 NRA/CF) was prepared via a three-step strategy involving the wet chemical synthesis of Cu(OH)2 NRA/CF, a chemical reduction reaction for conversion from Cu(OH)2 NRA/CF to Cu NRA/CF, and finally galvanostatic anodization to grow Cu(OH)2 nanoparticles on Cu NRA/CF. Hierarchical Cu/Cu(OH)2 NRA/CF shows high catalytic activity towards glucose oxidation in an alkaline solution and can serve as a promising electrode material for enzyme-free glucose sensing. At an applied potential of +0.5 V, the sensor showed a broad detection range of 0.001-1.0 mM, a high sensitivity of 9.18 mA mM-1 cm-2, and a low detection limit of 0.45 μM (S/N = 3). Furthermore, the sensor exhibits excellent selectivity against common interferents and good reliability for glucose detection in human serum samples.
Highly selective non-enzymatic electrochemical sensor based on a titanium dioxide nanowire-poly(3-aminophenyl boronic acid)-gold nanoparticle ternary nanocomposite
Muthuchamy,Gopalan,Lee, Kwang-Pill
, p. 2138 - 2147 (2018)
A novel three component (titanium dioxide nanowire (TiO2 NW), poly(3-aminophenyl boronic acid) (PAPBA) and gold nanoparticles (Au NPs)) based ternary nanocomposite (TNC) (designated as TiO2 NW/PAPBA-Au TNC) was prepared by a simple two-stage synthetic approach and utilized for the fabrication of a non-enzymatic (enzyme-free) glucose (NEG) sensor. In stage 2, the PAPBA-Au NC was formed by oxidative polymerization of 3-APBA using HAuCl4 as oxidant on the surface of pre-synthesized TiO2 NW via electrospinning (stage 1). The formation of PAPBA-Au NC as the shell on the surface of the TiO2 NW (core) was confirmed by field emission scanning electron microscopy (FE-SEM). Notably, we obtained a good peak to peak separation, and a high peak current for the redox Fe(CN)63-/4- process indicating excellent electron transfer capability at the glassy carbon electrode (GCE)/TiO2 NW/PAPBA-Au TNC interface. Also, the fabricated TiO2 NW/PAPBA-Au TNC provides excellent electrocatalytic activity towards glucose detection in neutral (pH = 7.0) phosphate buffer solution. The detection of glucose was monitored using differential pulse voltammetry. The obtained sensitivity and detection limits are superior to many of the TiO2 based enzymatic and non-enzymatic glucose sensors reported in the literature. Furthermore, the TiO2 NW/PAPBA-Au TNC sensor is preferred because of its high selectivity to glucose in the presence of co-existing interfering substances and practical application for monitoring glucose in human blood serum samples.
Cascade reactions in an all-enzyme nanoreactor
Delaittre, Guillaume,Reynhout, Irene C.,Cornelissen, Jeroen J. L. M.,Nolte, Roeland J. M.
, p. 12600 - 12603 (2009)
The composed of horseradish peroxidase-polystyrene (HRP-PS) and horseradish peroxidase-poly (methyl methacrylate) (HRP-PMMA) giant amphiphiles, which contain a guest enzyme (glucose oxidase, GOx) inside the self- assembled structures has been reported. The polymer can be attached to the cofactor, the protoporphyrin IX (PPIX), either by the use of an initiator-modified derivative followed by polymerization or by the coupling of an acetylene end-capped polymer to an azido-derived cofactor by click chemistry. The heme-PMMA-based giant amphiphile gave spherical aggregates with diameters of 50-100 nm. Enzymatic activities were measured by using an ABTS/H2O2 assay. The cofactor reconstitution appears to be the technique of choice, since the same cofactor can serve for the reconstitution of several different apoproteins and thus different combinations inside the shell can also be envisioned.
Quaternized chitosan as support for the assembly of gold nanoparticles and glucose oxidase: Physicochemical characterization of the platform and evaluation of its biocatalytic activity
Bracamonte, Maria V.,Bollo, Soledad,Labbé, Pierre,Rivas, Gustavo A.,Ferreyra, Nancy F.
, p. 1316 - 1322 (2011)
We report for the first time the use of quaternized chitosan (QCHI) for the immobilization of gold nanoparticles (NP) and glucose oxidase (GOD), the characterization of the resulting platform and its biocatalytic activity using glucose as substrate. The c
Nonenzymatic Glucose Sensing and Magnetic Property Based on the Composite Formed by Encapsulating Ag Nanoparticles in Cluster-Based Co-MOF
Liu, Yang,Shi, Wen-Juan,Lu, Yu-Ke,Liu, Ge,Hou, Lei,Wang, Yao-Yu
, p. 16743 - 16751 (2019)
Utilizing the oxygen-bridged 5,5′-oxidiisophthalic acid (H4L) linker, one Co(II)-based 3D porous MOF {[Co5(L)2(OH)2(OH2)2(H2O)4]·2DMF·H2O}n (1) with pentanuclear [Co5(μ3-OH)2(μ2-OH2)2]8+ cluster was prepared. The glassy carbon electrode was modified by 1, and the obtained electrode revealed electrocatalytic performance for glucose oxidation. The porous MOF matrix is beneficial for dispersing Ag nanoparticles evenly in the interior cages or channels, so Ag?1 composite composed of both Ag nanoparticles and MOF was further prepared through deposition-reduction method to enhance electrocatalytic activity. The result demonstrates that the glucose oxidation by Ag?1 was greatly increased with low detection limit (1.32 μM) and good selectivity and sensitivity (0.135 μA μM-1), which promote the application of MOF-template porous composites as advanced electrochemical sensor materials. Furthermore, 1 shows an interesting magnetic spin-glass slow dynamics for the existing of peculiar pentanuclear Co(II) clusters.
Photopatterning enzymes on polymer monoliths in microfluidic devices for steady-state kinetic analysis and spatially separated multi-enzyme reactions
Logan, Timothy C.,Clark, Douglas S.,Stachowiak, Timothy B.,Svec, Frantisek,Frechet College Of Chemistry, Jean M. J.
, p. 6592 - 6598 (2007)
A method for photopatterning multiple enzymes on porous polymer monoliths within microfluidic devices has been developed and used to perform spatially separated multienzymatic reactions. To reduce nonspecific adsorption of enzymes on the monolith, its pore surface was modified by grafting poly(ethylene glycol), followed by surface photoactivation and enzyme immobilization in the presence of a nonionic surfactant. Characterization of bound horseradish peroxidase (HRP) was carried out using a reaction in which the steady-state profiles of the fluorescent reaction product could be measured in situ and then analyzed using a plug-flow bioreactor model to determine the observed maximum reaction rate and Michaelis constant. The Michaelis constant of 1.9 μmol/L agrees with previously published values. Mass-transfer limitations were evident at relatively low flow rates but were absent at higher flow rates. Sequential multienzymatic reactions were demonstrated using the patternwise assembly of two- and three-enzyme systems. Glucose oxidase (GOX) and HRP were patterned in separate regions of a single channel, and product formation was analyzed as a function of flow direction. Significant product formation occurred only in the GOX to HRP direction. A three-enzyme sequential reaction was performed using invertase, GOX, and HRP. All possible arrangements of the three enzymes were tested, but significant product formation was only observed when the enzymes were in the correct sequential order. Photopatterning enzymes on polymer monoliths provides a simple technique for preparing spatially localized multiple-enzyme microreactors capable of directional synthesis.
Enzyme immobilization in biosensor constructions: Self-assembled monolayers of calixarenes containing thiols
Demirkol, Dilek Odaci,Yildiz, Huseyin Bekir,Sayin, Serkan,Yilmaz, Mustafa
, p. 19900 - 19907 (2014)
Herein, an amperometric glucose oxidase (GOx) biosensor is presented using calixarenes as an immobilization matrix of the biomolecule. Firstly, thiol-containing calixarenes (Calix-SH) were synthesized, then self-assembled monolayers (SAMs) of Calix-SH on a gold surface were formed and hydroxyl groups of Calix-SH were activated using 1,1′-carbonyldiimidazole (CDI) chemistry. To test the usability of Calix-SH modified surfaces as a biosensor, glucose oxidase was used as a model biological component. After optimization of preparation and working conditions, our results indicate that the Calix-SH/GOx biosensor has a linear range in the range 0.1-1.0 mM (LOD: 0.015 mM) for glucose with a 25 s response time. Finally, the application of the biosensor was examined to detect glucose in real samples. The glucose amounts were calculated as 19.460 ± 0.521 and 31.647 ± 2.125 mM in coke and fizzy drink (with orange), respectively. To confirm the reliability of the Calix-SH/GOx biosensor, the calculated glucose concentrations which were analyzed by the Calix-SH/GOx biosensor were compared to conventional spectrophotometric glucose kits. The glucose amounts in coke and fizzy drink were calculated as 18.509 ± 0.732 mM and 31.579 ± 4.466 mM, respectively.
Electrochemical growth of Au architectures on glassy carbon and their evaluation toward glucose oxidation reaction
Arjona,Guerra-Balcázar,Trejo,Ledesma-García,Arriaga
, p. 2555 - 2561 (2012)
Arrow-like, flower, splintery flower-like and pin wheel Au architectures were obtained using cyclic voltammetry (I), differential pulse amperometry (II), square wave voltammetry (III) and second harmonic AC voltammetry (IV) as electrochemical methods of synthesis, named systems I, II, III and IV respectively. Architecture sizes were 610, 380, 590 and 480 nm, meanwhile crystal sizes were 48, 76, 120 and 210 nm, respectively. XRD patterns showed that systems I, III and IV preferentially exhibited the (111) plane and system II preferentially exhibited the (200) plane. The catalytic properties of the architectures were tested employing D-(+)-glucose at 10, 50 and 100 mM, where the results showed that two processes occur in the glucose electrooxidation: at ～-0.2 V vs. NHE, glucose is oxidized to gluconolactone, and after at ～0.3 V vs. NHE the successive oxidation of the gluconolactone by-product were carried out. Systems with the (111) preferential plane favor gluconolactone oxidation; while system II with the (200) plane enhanced glucose oxidation toward the gluconolactone by-product. Also, system II showed a higher current density with 26.4 mA cm-2 at 100 mM glucose. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2012.
Regulatory role of surfactants in the kinetics of glucose oxidase-catalyzed oxidation of D-glucose by ferrocenium and n-butylferrocenium ions
Firsova,Ryabov
, p. 1700 - 1706 (1997)
The effect of micelles of different surfactants (cationic, anionic, and neutral) on the kinetics of the glucose oxidase-catalyzed reduction of ferrocenium cations RFc+ (R = H, Bun) by D-glucose was studied by spectrophotometry. In micellar media of Triton X-100 and sodium dodecyl sulfate (SDS), the Michaelis dependence of the reaction rate on the HFc+ concentration is observed, while this dependence has an extreme character in cationic micelles of cetyltrimethylammonium bromide (CTAB). The nature and concentration of surfactants of all types have a slight effect on the rate of reduction of HFc+. The level of enzymatic activity is approximately equal in the case of Triton X-100 and CTAB and is considerably lower in the SDS micelles. On going from HFc+ to BunFc+, the reaction rate is maximum in the cationic CTAB micelles, the anionic SDS micelles exhibit almost no activity, and the activity has an intermediate value in neutral micelles of Triton X-100. The conditions are presented under which the micellar medium controls the catalytic activity of glucose oxidase with respect to ferrocenium cations.
Micellar effect on quinquivalent vanadium ion oxidation of D-glucose in aqueous acid media: A kinetic study
Saha, Bidyut,Sarkar, Sucharita,Chowdhury, Kiran M.
, p. 282 - 286 (2008)
Vanadium(V) oxidation of D-glucose shows first-order dependence on D-glucose, vanadium(V), H+, and HSO4-. These observations remain unaltered in the presence of externally added surfactants. The effect of the cationic surfactant (i.e., N-cetylpyridinium chloride [CPC]), anionic surfactant (i.e., sodium dodecyl sulfate [SDS]), and neutral surfactant (i.e., Trion X-100 [TX-100]) has been studied. CPC inhibits the reactions, whereas SDS and TX-100 accelerate the reaction to different extents. Observed effects have been explained by considering the hydrophobic and electrostatic interaction between the surfactants and reactants.
Fabrication of a non-enzymatic Ni(ii) loaded ZSM-5 nanozeolite and multi-walled carbon nanotubes paste electrode as a glucose electrochemical sensor
Hassaninejad-Darzi, Seyed Karim
, p. 105707 - 105718 (2015)
Effective electro-oxidation of glucose is critically important in developing analytical sensors and carbohydrate-based fuel cells. In this study, a template-free ZSM-5 nanozeolite was synthesized hydrothermally with spherical particle diameters of 40-60 nm, as characterized by scanning electron microscopy. Then, a carbon paste electrode (CPE) was modified by multi-walled carbon nanotubes (MWCNTs), ZSM-5 nanozeolite and Ni2+ ions (Ni-MW-ZSM-5/CPE). Electrochemical studies of this electrode were performed using cyclic voltammetry which exhibits the redox behavior of the Ni(iii)/Ni(ii) couple in alkaline medium. This modified electrode was used as an anode for the electrocatalytic oxidation of glucose in 0.1 mol L-1 NaOH solution. The results confirmed that ZSM-5 nanozeolite at the surface of the CPE improved the catalytic efficiency of the dispersed nickel ions toward glucose oxidation. The values of electron transfer coefficient, electrode surface coverage and charge-transfer rate constant for Ni(iii)/Ni(ii) redox couple were found to be 0.65, 4.04 × 10-8 mol cm-2 and 0.184 s-1, respectively. Also, the diffusion coefficient and the mean value of the catalytic rate constant for glucose and redox sites of the electrode were found to be 1.66 × 10-4 cm2 s-1 and 1.136 × 108 cm3 mol-1 s-1, respectively. The sensor showed an acceptable linear range of 0.5-6.1 mM with a detection limit of 0.14 mM (S/N = 3) by cyclic voltammetry technique. Moreover, differential pulsed voltammetry method revealed a linear range of 0.0001-0.01 mM with a detection limit of 3.5 × 10-5 mM. Based on the results, the fabricated electrode (Ni-MW-ZSM-5/CPE) showed good catalytic activity, good stability, high sensitivity and reproducibility.
Characterization and electrochemical properties of a nickel film/carbon paper electrode prepared by a filtered cathodic vacuum arc technique
Fu, Yingyi,Su, Wen,Wang, Tong,Hu, Jingbo
, p. 54777 - 54782 (2015)
A nickel film was prepared through plasma deposition of a metal onto a carbon paper (CP) substrate with the filtered cathodic vacuum arc technique. Nickel metal plasma was generated at a current of 90 A and deposited on the CP substrate for 3 seconds, forming the nickel film modified electrode. The morphology image of the nickel film on the substrate surface was characterized by scanning electron microscopy (SEM). The existence of the nickel film was verified by energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The results of the water contact angle measurement (WCA) showed that the existence of the nickel film improved the hydrophilicity of the CP. Cyclic voltammetry (CV) was carried out to investigate the electrochemical properties of the Ni/CP electrode. The nickel film provided a good electron conduction pathway and it improved the electron transfer ability of the substrate. It was found that the Ni/CP electrode exhibited good electrocatalytic oxidation behaviour towards glucose. Amperometric responses showed a good linear relationship with glucose concentration in the range from 2 μM to 500 μM with a detection limit of 0.6 μM. Thus this material is expected to have wide potential applications in glucose biosensors.
Synthesis and self-assembly of organoclay-wrapped biomolecules
Patil, Avinash J.,Muthusamy, Eswaramoorthy,Mann, Stephen
, p. 4928 - 4933 (2004)
Gift wrapped: Biomolecules can be enveloped within an ultrathin shell of an aminopropyl-functionalized magnesium (organo)phyllosilicate to produce aqueous dispersions of discrete protein-inorganic nanoparticles. Similar procedures but with organoclay oligomers that have pendent long-chain hydrophobic moieties result in self-assembly of the protein-inorganic nanoparticles into higher-order superstructures (see picture).
Enzyme-free glucose sensor based on au nanobouquet fabricated indium tin oxide electrode
Lee, Jin-Ho,El-Said, Waleed Ahmed,Oh, Byung-Keun,Choi, Jeong-Woo
, p. 8432 - 8438 (2014)
In this study, we demonstrated a simple, rapid and inexpensive fabrication method to develop a novel gold nanobouquet structure fabricated indium tin oxide (GNB/ITO) electrode based on electrochemical deposition of gold ions onto ITO substrate. The morphology of the fabricated electrode surface was characterized by scanning electron microscopy (SEM) to confirm the GNB formation. Enzyme-free detection of glucose using a GNB/ITO electrode was described with high sensitivity and selectivity based on cyclic voltammetry assay. The results demonstrate a linear relation within wide concentration range (500 nM to 10 mM) of glucose, with a correlation coefficient of 0.988.The interference effect of uric acid was effectively avoided for the detection of glucose (1 μM to10 mM). Moreover, the developed sensor was applied to determine the concentration of glucose in the presence of human serum to indicate the ability of GNB/ITO electrodes in real samples. Hence, newly developed GNB/ITO electrode has potential application in enzyme-free glucose sensor with highly sensitivity and selectivity.
Permanganate transfer and reduction by D-glucose in benzene-cetyltrimethyl- ammoniumbromide aqueous solution: A kinetic study
Malik, Maqsood Ahmad,Khan, Zaheer
, p. 496 - 503 (2008)
The addition of cationic surfactant, cetlytrimethylammoniumbromide (CTAB), in benzene and aqueous potassium permanganate solution brought the MnO 4- from the aqueous phase to the organic phase. At 525 nm, the absorbance of the organic phase increased until it reached a maximum, and then decreased with [CTAB). The effect of (CTAB] on the reduction of permanganate by D-glucose in a benzene-CTAB system has been studied spectrophotmet-rically. The observed effect on the rate constant is catalytic up to a certain concentration of CTAB; thereafter, a saturation phenomenon is observed with an increased concentration of CTAB. The oxidation reaction obeyed the first-order kinetics with respect to the D-glucose. On addition of H 2SO4, there was a decrease in the rate constants. There is evidence for the existence of manganese as a water-soluble colloidal MnC 2 A detailed mechanism with the associated reaction kinetics is presented and discussed.
Enzyme Kinetics via Open Circuit Potentiometry
Smith, Lettie A.,Glasscott, Matthew W.,Vannoy, Kathryn J.,Dick, Jeffrey E.
, p. 2266 - 2273 (2020)
We demonstrate the application of open circuit potentiometry (OCP) to measure enzyme turnover kinetics, kturn. The electrode surface will become poised by the addition of a well-behaved redox pair, such as ferrocenemethanol/ferrocenium methanol (FcMeOH/FcMeOH+), which acts as the cosubstrate for the enzymatic process. A measurable change in potential results when an enzyme consumes the one-electron transfer mediator. Glucose oxidase was studied as a test-case, but the method is generalizable across oxidoreductase enzymes that rely on electron transfer mediators. In the presence of glucose and FcMeOH+, glucose oxidase delivers electrons to FcMeOH+, and the potential changes with respect to the Nernst equation. A theoretical model incorporating enzymatic rate expressions into the Nernst equation was derived to explain the observed potential transients, and experimental data fit theory well. A similar experiment was performed using amperometry on ultramicroelectrodes (UMEs). Here, the same enzymatic rate expression may be incorporated into the equation for steady-state flux to an UME to obtain kturn. While similar kinetic information was obtained from the potentiometric and amperometric responses, potentiometry is independent of electrode size and mass transfer effects. Finally, we show how kturn changes as a function of one-electron mediator. Our results may eventually find applications to biosensors, where electrode fouling plagues long-term sensor performance.
Amino acid intercalated montmorillonite: Electrochemical biosensing applications
Demir, Filiz,Demir, Bilal,Yalcinkaya, Esra E.,Cevik, Serdar,Demirkol, Dilek Odaci,Anik, Ulku,Timur, Suna
, p. 50107 - 50113 (2014)
The present work is the first that includes the use of glycine (Gly), lysine (Lys) and glutamic acid (Glu) modified clay mineral matrices in the biosensors. For this purpose, initially, Gly, Lys and Glu were intercalated with montmorillonite (Mt), thus, various modified Mts were obtained. These modified materials were then characterized via X-ray diffraction, Fourier transform infrared spectroscopy, zeta potential and thermal gravimetric analysis (TGA/DTG) and scanning electron microscopy (SEM). In order to investigate the applicability of amino acid modified clay minerals in biosensor areas, glucose oxidase (GOx) was selected as the model enzyme and a GOx based biosensor was prepared. After immobilizing the enzyme with amino acid modified Mt onto a glassy carbon electrode, working conditions like pH and modifier type were optimized. Among the modified Mts, Gly-Mt was the optimum clay mineral type and pH 4.0 was the optimum pH value. Then analytical characteristics were examined under optimum experimental conditions. The linear range of optimum sensor design was 0.1-1.0 mM within the kinetic parameters of an immobilized enzyme Kmapp = 0.7 mM, Imax = 107.8 nA. Finally, the developed biosensor was applied to real samples where the results were compared with a spectrophotometric reference method.
Anticancer and antileishmanial in vitro activity of gold(I) complexes with 1,3,4-oxadiazole-2(3H)-thione ligands derived from δ-D-gluconolactone
Espinosa, Andrés Villase?or,Costa, Danilo de Souza,Tunes, Luiza Guimar?es,Monte-Neto, Rubens L. do,Grazul, Richard Michael,de Almeida, Mauro Vieira,Silva, Heveline
, p. 41 - 50 (2020/07/28)
Four gold(I) complexes conceived as anticancer agents were synthesized by reacting [Au(PEt3)Cl] and [Au(PPh3)Cl] with ligands derived from δ-d-gluconolactone. The ligands’ structure was designed to combine desired biological properti
Synthesis of Cu(OH)F microspheres using atmospheric dielectric barrier discharge microplasma: a high-performance non-enzymatic electrochemical sensor
Hu, Zhangmei,Huang, Ke,Jiang, Xue,Wang, Qiang,Yu, Huimin,Zhao, Li,Zhou, Jiaxin
supporting information, p. 18277 - 18281 (2021/10/19)
In this study, Cu(OH)F microspheres suppported on a carbon cloth (Cu(OH)F MS/CC) were rapidly synthesized (at 90 V with 20 min) using an atmospheric dielectric barrier discharge microplasma (DBD). As a multifunctional electrochemical sensor for the detection of glucose (Glu), formaldehyde and hydrogen peroxide, it can accurately detect blood glucose levels in actual serum samples and can determine the contents of formaldehyde and hydrogen peroxide in water samples. Furthermore, it shows good sensitivity and selectivity, which confirmed the feasibility of the Cu(OH)F microsphere electrode for electrochemical sensing. This method was not only rapid and mild (at room temperature and atmospheric pressure) but also provided a promising route for the preparation of nanomaterials for electrochemical sensors.
Detection of subtle extracellular glucose changes by artificial organelles in protocells
Appelhans, Dietmar,Boye, Susanne,Moreno, Silvia,Voit, Brigitte,Wang, Dishi
supporting information, p. 8019 - 8022 (2021/08/20)
Feedback-controlled detection of subtle changes of extracellular biomolecules as known from cells is also needed in protocells. Artificial organelles, located in protocells, detect the small variation in pH which is triggered by different amounts of invad
