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Anticancer and antileishmanial in vitro activity of gold(I) complexes with 1,3,4-oxadiazole-2(3H)-thione ligands derived from δ-D-gluconolactone
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
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)

The non-enzymatic electrochemical detection of glucose and ammonia using ternary biopolymer based-nanocomposites
The non-enzymatic electrochemical detection of glucose and aqueous ammonia was carried out using ternary bio-nanocomposites. A co-precipitation method was employed to synthesize cadmium stannate nanoparticles, while bio-nanocomposites of polyaniline-cadmium stannate-chitosan were synthesized via the chemical oxidative polymerization technique. Functional group analysis, structural and morphological studies were further carried out via Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning and transmission electron microscopy techniques. The electrode kinetics and electrochemical properties were validated via cyclic voltammetry, electrochemical impedance spectroscopy (EIS), and chronoamperometric techniques. The sensing properties of the electrocatalysts were explored using cyclic voltammetry and amperometry for the detection of glucose and ammonia solution of varying concentrations using NaOH electrolyte. The electrochemical activity of the electrocatalysts were optimized using different weight percentages of chitosan, and bio-nanocomposites of polyaniline/cadmium stannate/chitosan (10%) showed excellent electrocatalytic and electrochemical activities. Moreover, the bio-nanocomposites have a low detection limit and short response time toward different concentrations of glucose and ammonia solution. Apart from these studies, the sensors have also been evaluated for an anti-interference study. The developed novel sensors present significant potential to be efficiently utilized on a large scale, as they also show effective stability and reproducibility, along with a high level of sensitivity for the given target analytes. This journal is
Bano, Sayfa,Ganie, Adil Shafi,Sultana, Saima,Khan, Mohammad Zain,Sabir, Suhail
p. 8008 - 8021
(2021/05/21)

Synthesis of Cu(OH)F microspheres using atmospheric dielectric barrier discharge microplasma: a high-performance non-enzymatic electrochemical sensor
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.
Hu, Zhangmei,Huang, Ke,Jiang, Xue,Wang, Qiang,Yu, Huimin,Zhao, Li,Zhou, Jiaxin
supporting information
p. 18277 - 18281
(2021/10/19)

Efficient improvement in non-enzymatic glucose detection induced by the hollow prism-like NiCo2S4electrocatalyst
Hollow prism-like NiCo2S4 materials (NiCo2S4 HNPs) were successfully fabricated by a two-step method. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and powder X-ray diffraction (XRD) confirmed the morphology and structure of the as-prepared NiCo2S4 nanoprisms. A non-enzymatic sensor based on NiCo2S4 HNPs was constructed with outstanding electrochemical activity towards glucose oxidation in alkaline medium. The sensor showed a rapid response time (～0.1 s), a high sensitivity of 82.9 μA mM-1 cm-2, a wide linear range (0.005-20.2 mM) and a detection limit of 0.8 μM (S/N = 3) with a good selectivity and reproducibility. Additionally, the proposed electrode also confirmed the feasibility in practical blood serum. These results indicate that NiCo2S4/ITO has great potential in the development of non-enzymatic glucose sensor applications.
Chen, Qiwen,Chen, Xiaojun,Chu, Dandan,Chu, Xue-Qiang,Ge, Danhua,Yan, Li
p. 15162 - 15169
(2021/11/17)

carba Nicotinamide Adenine Dinucleotide Phosphate: Robust Cofactor for Redox Biocatalysis
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
supporting information
p. 14701 - 14706
(2021/05/13)

Enzyme Kinetics via Open Circuit Potentiometry
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.
Smith, Lettie A.,Glasscott, Matthew W.,Vannoy, Kathryn J.,Dick, Jeffrey E.
p. 2266 - 2273
(2020/02/04)

Engineering the valence state of ZIF-67 by Cu2O for efficient nonenzymatic glucose detection
The valence state regulation of Co-based electrocatalysts is extremely important and greatly challenging to enhance the electrochemical performance toward glucose oxidation. Herein, Cu2O?ZIF-67 composites with fine-tuned valence states were rationally constructed for boosting glucose oxidation. X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV) analysis confirm that the content of the high valence state Co (Co3+) in Cu2O?ZIF-67 is much higher than that in the individual ZIF-67 due to the synergistic effects between ZIF-67 and Cu2O. As a result, Co3+-rich Cu2O?ZIF-67 composite exhibits remarkable activity toward glucose electro-oxidation with two linear response ranges of glucose concentration, from 0.01 to 10 mM and 10 to 16.3 mM, high sensitivities of the linear ranges (307.02 and 181.34 μA mM-1 cm-2) as well as a low detection limit (6.5 μM). This research provides a novel avenue for the progress of highly efficient electrocatalysts for nonenzymatic glucose oxidation.
Guo, Kailu,Xu, Cailing,Yang, Nian,Zhang, Yanwen
p. 2856 - 2861
(2020/04/17)

Protein Spherical Nucleic Acids for Live-Cell Chemical Analysis
We report the development of a new strategy for the chemical analysis of live cells based on protein spherical nucleic acids (ProSNAs). The ProSNA architecture enables analyte detection via the highly programmable nucleic acid shell or a functional protein core. As a proof-of-concept, we use an i-motif as the nucleic acid recognition element to probe pH in living cells. By interfacing the i-motif with a forced-intercalation readout, we introduce a quencher-free approach that is resistant to false-positive signals, overcoming limitations associated with conventional fluorophore/quencher-based gold NanoFlares. Using glucose oxidase as a functional protein core, we show activity-based, amplified sensing of glucose. This enzymatic system affords greater than 100-fold fluorescence turn on in buffer, is selective for glucose in the presence of close analogs (i.e., glucose-6-phosphate), and can detect glucose above a threshold concentration of ～5 μM, which enables the study of relative changes in intracellular glucose concentrations.
Samanta, Devleena,Ebrahimi, Sasha B.,Kusmierz, Caroline D.,Cheng, Ho Fung,Mirkin, Chad A.
p. 13350 - 13355
(2020/09/09)

Synthesis of Co0.5Mn0.1Ni0.4C2O4?n H2O Micropolyhedrons: Multimetal Synergy for High-Performance Glucose Oxidation Catalysis
Owing to the synergy between metals, trimetal oxalate micropolyhedrons have been synthesized by means of a room-temperature coprecipitation strategy. The effect of their nanoscale size on their electrochemical performance toward glucose oxidation was investigated. In particular, the Co0.5Mn0.1Ni0.4C2O4?n H2O micropolyhedrons illustrated prominent electrocatalytic activity for the glucose oxidation reaction. Additionally, the Co0.5Mn0.1Ni0.4C2O4?n H2O micropolyhedrons, when used as an electrode material, illustrated an excellent lower limit of detection (1.5 μm), a wide detection concentration range (0.5–5065.5 μm), and a high sensitivity (493.5 μA mm?1 cm?2). Further analysis indicated that the effectively improved conductivity may have been due to the small size of the materials, and it was easier to form a flat film when Nafion was coated onto the glassy carbon electrode.
Li, Nan,Li, Qing,Yuan, Meijuan,Guo, Xiaotian,Zheng, Shasha,Pang, Huan
supporting information
p. 2259 - 2265
(2019/07/10)

High-performance supercapacitors and non-enzymatic electrochemical glucose sensor based on tremella-like NiS/CoS/NiCo2S4 hierarchical structure
NiS/CoS/NiCo2S4 microflower with hierarchical structure is successfully prepared via facile hydrothermal method. The supercapacitive performance displays that the specific capacitance is up to 513 F g?1 at a scan rate of 1 mV s?1. The obvious redox peaks on the cyclic voltammetry curves reveal pseudocapacitive performance of NiS/CoS/NiCo2S4. Furthermore, the glucose detection behavior of NiS/CoS/NiCo2S4 modified electrode (NiS/CoS/NiCo2S4/GCE) has also been performed. Amperometric study indicates that this non-enzymatic sensor displays excellent electrocatalytic performance to glucose. The glucose diffusion from the solution to the electrode surface is the kinetic control process. These results indicate a potential application of NiS/CoS/NiCo2S4 for using as an electrode material in supercapacitors and glucose sensor.
Li, Danqing,Zhang, Xia,Pei, Lei,Dong, Chaoyang,Shi, Jianguo,Xu, Yuandong
(2019/10/22)

Cobalt sulfides/carbon nanohybrids: A novel biocatalyst for nonenzymatic glucose biofuel cells and biosensors
Exploring high-performance electrocatalysts is of great importance in developing nonenzymatic biofuel cells. Hybrid nanostructures with transition metal compounds and carbon nanomaterials exhibit excellent electrocatalytic activity and have emerged as promising low-cost alternatives for various electrochemical reactions. Herein, we report cobalt sulfide/carbon nanohybrids via a facile synthesis, which have excellent electrocatalytic activity for glucose oxidation and oxygen reduction reaction. The nonenzymatic glucose biofuel cells equipped with cobalt sulfide/carbon nanohybrids deliver a high open circuit voltage of 0.72 V with a maximum open power density of 88 μW cm-2, indicating that cobalt sulfide/carbon nanohybrids are high performance biocatalysts for bioenergy conversion.
Li, Zihan,Li, Gangyong,Wu, Zhongdong,Jiao, Shuqiang,Hu, Zongqian
p. 32898 - 32905
(2019/10/23)

Nickel oxide decorated MoS2 nanosheet-based non-enzymatic sensor for the selective detection of glucose
Understanding blood glucose levels in our body can be a key part in identifying and diagnosing prediabetes. Herein, nickel oxide (NiO) decorated molybdenum disulfide (MoS2) nanosheets have been synthesized via a hydrothermal process to develop a non-enzymatic sensor for the detection of glucose. The surface morphology of the NiO/MoS2 nanocomposite was comprehensively investigated by field-emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET) analysis. The electro-catalytic activity of the as-prepared NiO/MoS2 nanocomposite towards glucose oxidation was investigated by cyclic voltammetry, electrochemical impedance spectroscopy (EIS) and amperometry in 0.1 M NaOH. The NiO/MoS2 nanocomposite-based sensor showed outstanding electrocatalytic activity for the direct electro-oxidation of glucose due to it having more catalytic active sites, good conductivity, excellent electron transport and high specific surface area. Meanwhile, the NiO/MoS2 modified glassy carbon electrode (GCE) showed a linear range of glucose detection from 0.01 to 10 mM by amperometry at 0.55 V. The effect of other common interferent molecules on the electrode response was also tested using alanine, l-cysteine, fructose, hydrogen peroxide, lactose, uric acid, dopamine and ascorbic acid. These molecules did not interfere in the detection of glucose. Moreover, this NiO/MoS2/GCE sensor offered rapid response (2 s) and a wide linear range with a detection limit of 1.62 μM for glucose. The reproducibility, repeatability and stability of the sensor were also evaluated. The real application of the sensor was tested in a blood serum sample in the absence and presence of spiked glucose and its recovery values (96.1 to 99.8%) indicated that this method can be successfully applied to detect glucose in real samples.
Jeevanandham, Gayathri,Jerome,Murugan,Preethika,Vediappan, Kumaran,Sundramoorthy, Ashok K.
p. 643 - 654
(2020/01/23)

Effect of Cu addition to carbon-supported Ru catalysts on hydrogenation of alginic acid into sugar alcohols
The objective of this study was to investigate the effect of Cu addition to carbon supported Ru catalysts on the hydrogenation of macroalgae-derived alginic acid into sugar alcohols, mainly sorbitol and mannitol. Both geometric and electronic effects were determined based on results of H2-TPR, H2- or CO-chemisorption, and XPS analyses after Cu was added to Ru. The addition of Cu to Ru caused blocking of active Ru surface and electron transfer between Ru and Cu. The intimate interaction between Ru and Cu formed RuCu bimetallic clusters which expedited hydrogen spillover from Ru to Cu. The highest yield of target sugar alcohols of 47.4% was obtained when 5 wt% of Ru and 1 wt% of Cu supported on nitric acid-treated activated carbon reacted at 180 °C for 2 h. The RuCu bimetallic catalyst exhibited deactivation upon repeated reactions due to the carbon deposition on the catalyst.
Ban, Chunghyeon,Yang, Seungdo,Kim, Hyungjoo,Kim, Do Heui
p. 98 - 104
(2019/04/17)

Conductive Leaflike Cobalt Metal-Organic Framework Nanoarray on Carbon Cloth as a Flexible and Versatile Anode toward Both Electrocatalytic Glucose and Water Oxidation
Transition metal-organic frameworks (MOFs), on account of their unique inherent properties of large pore volume, high specific surface area, tunable pores, and good catalytic activity, have been highly regarded as superior catalysts recently for water electrolysis, supercapacitors, batteries, sensors, and so on. Herein, we report on a cobalt MOF phase with 3D well-aligned nanosheets array architecture on carbon cloth (Co-MOF NS/CC), fabricated by a facile ambient liquid-phase deposition, could serve as a self-standing Janus catalytic electrode toward both glucose and water oxidation. It shows good glucose-sensing performance with low determination limit and large detection range. Also, it exhibits high water-oxidation efficiency with low overpotential and good durability. This work demonstrates the potential of utilizing transition-metal based well-aligned MOF nanoarrays for electrocatalytic oxidation.
Wei, Ziyi,Zhu, Wenxin,Li, Yinge,Ma, Yiyue,Wang, Jing,Hu, Na,Suo, Yourui,Wang, Jianlong
supporting information
p. 8422 - 8428
(2018/07/25)

Mesoporous Co3O4 Nanobundle Electrocatalysts
Tailoring metal oxide nanostructures with mesoporous architectures is vital to improve their electrocatalytic performance. Herein, we demonstrate the synthesis of 2D mesoporous Co3O4 (meso-Co3O4) nanobundles with uniform shape and size by employing a hard-template method. In this study, the incipient wetness impregnation technique has been chosen for loading metal precursor into the silica hard template (SBA-15). The results reveal that the concentration of a saturated precursor solution plays a vital role in mesostructured ordering, as well as the size and shape of the final meso-Co3O4 product. The optimized precursor concentration allows us to synthesize ordered meso-Co3O4 with four to seven nanowires in each particle. The meso-Co3O4 structure exhibits excellent electrocatalytic activity for both glucose and water oxidation reactions.
Narendra Kumar, Alam Venugopal,Li, Yinghao,Yin, Shuli,Li, Chunjie,Xue, Hairong,Xu, You,Li, Xiaonian,Wang, Hongjing,Wang, Liang
p. 2093 - 2100
(2018/08/03)

Highly selective non-enzymatic electrochemical sensor based on a titanium dioxide nanowire-poly(3-aminophenyl boronic acid)-gold nanoparticle ternary nanocomposite
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.
Muthuchamy,Gopalan,Lee, Kwang-Pill
p. 2138 - 2147
(2018/02/06)

Nanoisozymes: Crystal-Facet-Dependent Enzyme-Mimetic Activity of V2O5 Nanomaterials
Nanomaterials with enzyme-like activity (nanozymes) attract significant interest owing to their applications in biomedical research. Particularly, redox nanozymes that exhibit glutathione peroxidase (GPx)-like activity play important roles in cellular signaling by controlling the hydrogen peroxide (H2O2) level. Herein we report, for the first time, that the redox properties and GPx-like activity of V2O5 nanozyme depends not only on the size and morphology, but also on the crystal facets exposed on the surface within the same crystal system of the nanomaterials. These results suggest that the surface of the nanomaterials can be engineered to fine-tune their redox properties to act as “nanoisozymes” for specific biological applications.
Ghosh, Sourav,Roy, Punarbasu,Karmodak, Naiwrit,Jemmis, Eluvathingal D.,Mugesh, Govindasamy
supporting information
p. 4510 - 4515
(2018/03/05)

Asymmetric Synthesis of 1-Phenylethylamine from Styrene via Combined Wacker Oxidation and Enzymatic Reductive Amination
An enantioselective chemoenzymatic two-step one-pot transformation of styrene to 1-phenylethylamine has been developed based on combining an initial Pd/Cu-catalyzed Wacker oxidation of styrene with a subsequent reductive amination of the in situ formed acetophenone. As a nitrogen source only ammonia is needed. The incompatible catalysts were separated by means of a polydimethylsiloxane membrane, thus leading to quantitative conversion and an excellent enantiomeric excess of the corresponding amine. The overall one-pot process formally corresponds to an asymmetric hydroamination of styrene with ammonia.
Uthoff, Florian,Gr?ger, Harald
p. 9517 - 9521
(2018/08/01)

Extracellular hydrogen peroxide measurements using a flow injection system in combination with microdialysis probes – Potential and challenges
There is a strong need for techniques that can quantify the important reactive oxygen species hydrogen peroxide (H2O2) in complex media and in vivo. We combined chemiluminescence-based H2O2 measurements on a commercially available flow injection analysis (FIA) system with sampling of the analyte using microdialysis probes (MDPs), typically used for measurements in tissue. This allows minimally invasive, quantitative measurements of extracellular H2O2 concentration and dynamics utilizing the chemiluminescent reaction of H2O2 with acridinium ester. By coupling MDPs to the FIA system, measurements are no longer limited to filtered, liquid samples with low viscosity, as sampling via a MDP is based on a dynamic exchange through a permeable membrane with a specific cut-off. This allows continuous monitoring of dynamic changes in H2O2 concentrations, alleviates potential pH effects on the measurements, and allows for flexible application in different media and systems. We give a detailed description of the novel experimental setup and its measuring characteristics along with examples of application in different media and organisms to highlight its broad applicability, but also to discuss current limitations and challenges. The combined FIA-MDP approach for H2O2 quantification was used in different biological systems ranging from marine biology, using the model organism Exaiptasia pallida (light stress induced H2O2 release up to ~ 2.7 μM), over biomedical applications quantifying enzyme dynamics (glucose oxidase in a glucose solution producing up to ~ 60 μM H2O2 and the subsequent addition of catalase to monitor the H2O2 degradation process) and the ability of bacteria to modify their direct environment by regulating H2O2 concentrations in their surrounding media. This was shown by the bacteria Pseudomonas aeruginosa degrading ~ 18 μM background H2O2 in LB-broth. We also discuss advantages and current limitations of the FIA-MDP system, including a discussion of potential cross-sensitivity and interfering chemical species.
Mo?hammer, Maria,Schrameyer, Verena,Jensen, Peter ?.,Koren, Klaus,Kühl, Michael
p. 111 - 123
(2018/06/12)

A Breathing Atom-Transfer Radical Polymerization: Fully Oxygen-Tolerant Polymerization Inspired by Aerobic Respiration of Cells
The first well-controlled aqueous atom-transfer radical polymerization (ATRP) conducted in the open air is reported. This air-tolerant ATRP was enabled by the continuous conversion of oxygen to carbon dioxide catalyzed by glucose oxidase (GOx), in the presence of glucose and sodium pyruvate as sequential sacrificial substrates. Controlled polymerization using initiators for continuous activator regeneration (ICAR) ATRP of oligo(ethylene oxide) methyl ether methacrylate (OEOMA, Mn=500) yielded polymers with low dispersity (1.09≤?≤1.29) and molecular weights (MWs) close to theoretical values in the presence of pyruvate. Without added pyruvates, lower MWs were observed due to generation of new chains by H2O2 formed by reaction of O2 with GOx. Successful chain extension of POEOMA500 macroinitiator with OEOMA300 (?≤1.3) and Bovine Serum Albumin bioconjugates (?≤1.22) confirmed a well-controlled polymerization. The reactions in the open air in larger scale (25 mL) were also successful.
Enciso, Alan E.,Fu, Liye,Russell, Alan J.,Matyjaszewski, Krzysztof
supporting information
p. 933 - 936
(2018/01/05)

Versatile Three-Dimensional Porous Cu@Cu2O Aerogel Networks as Electrocatalysts and Mimicking Peroxidases
A facile strategy is presented to form 3D porous Cu@Cu2O aerogel networks by self-assembling Cu@Cu2O nanoparticles with the diameters of ca. 40 nm for constructing catalytic interfaces. Unexpectedly, the prepared Cu@Cu2O aerogel networks display excellent electrocatalytic activity to glucose oxidation at a low onset potential of ca. 0.25 V. Moreover, the Cu@Cu2O aerogels also can act as mimicking-enzymes including horseradish peroxidase and NADH peroxidase, and show obvious enzymatic catalytic activities to the oxidation of dopamine (DA), o-phenyldiamine (OPD), 3,3,5,5-tetramethylbenzidine (TMB), and dihydronicotinamide adenine dinucleotide (NADH) in the presence of H2O2. These 3D Cu@Cu2O aerogel networks are a new class of porous catalytic materials as mimic peroxidases and electrocatalysts and offer a novel platform to construct catalytic interfaces for promising applications in electrochemical sensors and artificial enzymatic catalytic systems.
Ling, Pinghua,Zhang, Qiang,Cao, Tingting,Gao, Feng
supporting information
p. 6819 - 6824
(2018/05/08)

Preparation of Ni(OH)2 nanoplatelet/electrospun carbon nanofiber hybrids for highly sensitive nonenzymatic glucose sensors
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.
Chen, Linlin,Liu, Lijuan,Guo, Qiaohui,Wang, Zhonghui,Liu, Guiling,Chen, Shuiliang,Hou, Haoqing
p. 19345 - 19352
(2017/04/10)

Enzymatic Cascade Catalysis for the Synthesis of Multiblock and Ultrahigh-Molecular-Weight Polymers with Oxygen Tolerance
Synthesis of well-defined multiblock and ultrahigh-molecular-weight (UHMW) polymers has been a perceived challenge for reversible-deactivation radical polymerization (RDRP). An even more formidable task is to synthesize these extreme polymers in the presence of oxygen. A novel methodology involving enzymatic cascade catalysis is developed for the unprecedented synthesis of multiblock polymers in open vessels with direct exposure to air and UHMW polymers in closed vessels without prior degassing. The success of this methodology relies on the extraordinary deoxygenation capability of pyranose oxidase (P2Ox) and the mild yet efficient radical generation by horseradish peroxidase (HRP). The facile and green synthesis of multiblock and UHMW polymers using biorenewable enzymes under environmentally benign and scalable conditions provides a new pathway for developing advanced polymer materials.
Liu, Zhifen,Lv, Yue,An, Zesheng
supporting information
p. 13852 - 13856
(2017/10/09)

GOx@ZIF-8(NiPd) Nanoflower: An Artificial Enzyme System for Tandem Catalysis
We report a facile approach to prepare an artificial enzyme system for tandem catalysis. NiPd hollow nanoparticles and glucose oxidase (GOx) were simultaneously immobilized on the zeolitic imidazolate framework 8 (ZIF-8) via a co-precipitation method. The as-prepared GOx@ZIF-8(NiPd) nanoflower not only exhibited the peroxidase-like activity of NiPd hollow nanoparticles but also maintained the enzymatic activity of GOx. A colorimetric sensor for rapid detection of glucose was realized through the GOx@ZIF-8(NiPd) based multi-enzyme system. Moreover, the GOx@ZIF-8(NiPd) modified electrode showed good bioactivity of GOx and high electrocatalytic activity for the oxygen reduction reaction (ORR), which could also be used for electrochemical detection of glucose.
Wang, Qingqing,Zhang, Xueping,Huang, Liang,Zhang, Zhiquan,Dong, Shaojun
p. 16082 - 16085
(2017/11/27)

Eco-friendly synthesis and morphology-dependent superior electrocatalytic properties of CuS nanostructures
Copper sulfide with desired structure is of special interest for electrocatalytical application due to their unique physicochemical properties, simple synthesis and less toxic in nature. In this study, simple and eco-friendly (without using any template or surfactant) route for the fabrication of copper sulfide nanostructure morphologies were tuned from cauliflower, microflower to nanoparticles inter-connected network-like structures by changing the polarity of solvent medium during solvothermal synthesis. However, to the best of our knowledge, no such kinds of special three types of CuS nanostructure with excellent electro-catalytic properties using only H2O and C2H5OH as the solvents have been reported in the literature. The as-prepared different CuS nanostructure was characterized using FE-SEM, HR-TEM, XRD, XPS and cyclic voltammetry. This morphological alteration able to produce several precise nanostructures with improved electrocatalytic properties that led to an excellent performance towards enzymeless glucose oxidation. The CuS inter-connected nanoparticles modified electrode displayed a synergistic effect towards the oxidation of glucose (ipa: 103?±?5?μA) when compared to that of cauliflower (ipa: 68?±?3.7?μA) and microflower (ipa: 60?±?2.4?μA) modified electrode surfaces. Further, the CuS inter-connected nanoparticles modified electrode showed a wide linear range (2.0?×?10?5?2.5?×?10?3?M), high sensitivity (1085?μA?mM?1?cm?2), low detection limit (2?μM), rapid response time (?3s), good stability, selectivity and reproducibility. The obtained sensing parameters based on CuS inter-connected nanoparticles modified electrode were superior with many reports and also comparable with few reports in the available literatures.
Venkadesh,Radhakrishnan,Mathiyarasu
p. 544 - 552
(2017/06/23)

PROTEIN CONDENSATE GEL AND PRODUCTION METHOD THEREOF
PROBLEM TO BE SOLVED: To provide a protein condensate gel obtained by gathering complexes composed of proteins and other materials, and to provide a production method of the same. SOLUTION: According to the present invention, a protein condensate gel 100 comprises complexes 3 each containing a protein 10, a surfactant 12, and water 11, and a three-dimensional polymer network structure 2 holding the complexes 3. An assembly of the complexes 3 is separated from an aqueous phase and encloses the protein 10 and the water 11. The surfactant 12 comprises a hydrophobic part 21, a parent protein part 23 interacting with the protein 10, and a hydrophilic part 23 interacting with the water 11. SELECTED DRAWING: Figure 2 COPYRIGHT: (C)2017,JPOandINPIT
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(2018/02/23)

Copper Complexes as Bioinspired Models for Lytic Polysaccharide Monooxygenases
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.
Concia, Alda Lisa,Beccia, Maria Rosa,Orio, Maylis,Ferre, Francine Terra,Scarpellini, Marciela,Biaso, Frédéric,Guigliarelli, Bruno,Réglier, Marius,Simaan, A. Jalila
supporting information
p. 1023 - 1026
(2017/02/15)

Electrodeposition of platinum-iridium nanoparticles on carbon nanotubes and their electrocatalytic oxidation of glucose
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
p. 1007 - 1013
(2017/11/03)

Non-enzymatic electrochemical sensing of glucose and hydrogen peroxide using a bis(acetylacetonato)oxovanadium(iv) complex modified gold electrode
A non-enzymatic electrochemical sensor, bis(acetylacetonato)oxovanadium(iv) complex, [VO(acac)2], fabricated on a self-assembled 4-(pyridine-4'-amido)thiophenol (PATP) monolayer modified gold electrode, was developed for the detection of glucose and hydrogen peroxide (H2O2) at neutral pH. The modified electrode was characterized by electrochemical and microscopic techniques. The non-enzymatic sensor exhibited a remarkable catalytic performance for glucose oxidation and H2O2 reduction. Chronoamperometry was used for the electrochemical determination of glucose and H2O2. The non-enzymatic sensing of glucose was realized with a linear response range from 0.001 to 0.5 mM with a detection limit of 0.1 μM (S/N = 3). The sensor also has a good performance for the electrocatalytic reduction of H2O2 with a linear response range from 0.02 to 0.9 mM with a detection limit of 0.03 μM (S/N = 3). In addition, [VO(acac)2]-PATP-Au showed a good selectivity for glucose and H2O2 detection in the presence of potential interfering agents such as ascorbic acid, uric acid, l-dopa, l-cysteine and different ions like Na+, K+, Cl-etc. The kinetic parameters such as the electron transfer coefficient and the catalytic reaction rate constant were also determined for glucose and H2O2. Finally, the modified electrode was used to achieve quantitative detection of glucose and H2O2 in blood and milk, respectively for practical applications.
Barman, Koushik,Jasimuddin, Sk
p. 20800 - 20806
(2016/03/04)

Electrodeposition of nickel nanoflowers on screen-printed electrodes and their application to non-enzymatic determination of sugars
In this work, the electrodeposition of nickel on screen-printed carbon electrodes was carried out. As the main novelty, a galvanostatic electrodeposition methodology (application of a constant current for a specific time) was chosen to perform the electrodeposition from a Ni(ii) solution. Interestingly, these conditions were able to generate nickel nanoflowers of 160 nm all over the surface. The nickel nanoflowers showed a great electrocatalytic effect towards the oxidation of reducing sugars. After the characterization of the electrode surface and the optimization of the experimental conditions, the non-enzymatic electrochemical device was employed for the determination of reducing sugars. A linear range of 25-1000 μM was obtained, showing good performance for the determination of sugars at low concentrations. The reproducibility was 5.5% (intraelectrode) and 6.9% (interelectrode), indicating a high precision using the same or different devices. After fabrication, the electrode is stable at least for 35 days, even using the same device to carry out measurements on different days. Real food samples such as honey and orange juice were also evaluated with the nickel nanoflower electrochemical device.
Pérez-Fernández, Beatriz,Martín-Yerga, Daniel,Costa-García, Agustín
p. 83748 - 83757
(2016/11/05)

Hierarchical Cu/Cu(OH)2 nanorod arrays grown on Cu foam as a high-performance 3D self-supported electrode for enzyme-free glucose sensing
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.
Bie, Lili,Luo, Xue,He, Qingqing,He, Daiping,Liu, Yan,Jiang, Ping
p. 95740 - 95746
(2016/10/25)

NAD-dependent dehydrogenase bioelectrocatalysis: The ability of a naphthoquinone redox polymer to regenerate NAD
Electron mediation between NAD-dependent enzymes using quinone moieties typically requires the use of a diaphorase as an intermediary enzyme. The ability for a naphthoquinone redox polymer to independently oxidize enzymatically-generated NADH is demonstrated for application to glucose/O2 enzymatic fuel cells.
Abdellaoui, Sofiene,Milton, Ross D.,Quah, Timothy,Minteer, Shelley D.
supporting information
p. 1147 - 1150
(2016/01/15)

Role of cationic gemini surfactants (m-s-m type) on the oxidation of d-glucose by permanganate
Cationic gemini (m-s-m type; m = 16, s = 4,5,6) surfactants were used to determine the micelles assisted kinetics parameters, mechanism of permanganate-D-glucose redox system in an aqueous solution by means of UV-visible spectroscopy at 40 °C. Effects of different [gemini surfactant], [permanganate], [D-glucose] and temperature on the reaction rate were investigated. Various activation parameters such as activation energy (Ea), enthalpy of activation (ΔH#), free energy of activation (ΔG#), and entropy of activation (ΔS#) have been evaluated. Menger-Portony pseudo-phase model modified by Bunton was used to analyze the role of gemini surfactant on the rate constant. Spacer chain length of surfactants has significant impact on the oxidation -reduction kinetics. A suitable mechanism reliable with the experimental results has been proposed and discussed. The cationic gemini surfactant micellar media are relatively more efficient than conventional monomeric surfactant i.e. cetyltrimethylammonium bromide (CTAB).
Al-Thabaiti, Shaeel Ahmed,Obaid,Khan, Zaheer,Al-Thubaiti, Khloud Saeed,Nabi, Arshid,Malik, Maqsood Ahmad
p. 538 - 544
(2016/02/18)

Beer-Brewing Method
The present invention relates to a method for beer-brewing comprising adding an enzyme composition comprising catalase without, or essentially without, glucose oxidase so as to improve the flavor and/or flavor stability of the finished beer.
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Paragraph [0022]

(2016/03/22)

Highly Selective Oxidation of Carbohydrates in an Efficient Electrochemical Energy Converter: Cogenerating Organic Electrosynthesis
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.
p. 252 - 263
(2016/02/27)

Subcompartmentalized Nanoreactors as Artificial Organelle with Intracellular Activity
Cell mimicry is an approach which aims at substituting missing or lost activity. In this context, the goal of artificial organelles is to provide intracellularly active nanoreactors to affect the cellular performance. So far, only a handful of reports discuss concepts addressing this challenge based on single-component reactors. Here, the assembly of nanoreactors equipped with glucose oxidase (GOx)-loaded liposomal subunits coated with a poly(dopamine) polymer layer and RGD targeting units is reported. When comparing different surface modifications, the uptake of the nanoreactors by endothelial cells and macrophages with applied shear stress is confirmed without inherent cytotoxicity. Furthermore, the encapsulation and preserved activity of GOx within the nanoreactors is shown. The intracellular activity is demonstrated by exposing macrophages with internalized nanoreactors to glucose and assessment of the cell viability after 6 and 24 h. The macrophage viability is found to be reduced due to the intracellularly produced hydrogen peroxide by GOx. This report on the first intracellular active subcompartmentalized nanoreactors is a considerable step in therapeutic cell mimicry.
Thingholm, Bo,Schattling, Philipp,Zhang, Yan,St?dler, Brigitte
p. 1806 - 1814
(2016/04/19)

Study of direct electron transfer and enzyme activity of glucose oxidase on graphene surface
In recent years, graphene has been widely used as a high performance two-dimensional material in the development of biosensors and biofuel cells for facilitating direct electron transfer (DET) of glucose oxidase (GOx). However, almost all of these reports perform experiments in the presence of oxygen (a natural mediator of oxidase) and whether the GOx with DET property retained their catalytic activity in the absence of mediators has not been studied in detail so far. In this paper, we investigated the DET property and enzyme activity of GOx on graphene surface without and with mediators. Experimental results showed that the biosensor had no response to glucose in mediator-free solutions, even though the DET of GOx was observed, indicating that the GOx with DET property lacked enzymatically catalytic activity. However, in the presence of mediators, the biosensor showed sensitive response to glucose, illustrating that the mediated enzymatic oxidation of glucose occurred, which can be attributed to the catalytically active GOx without DET capability. These results suggest that DET property and enzyme catalytic activity cannot occur on the same GOx simultaneously. Therefore, keeping enzyme activity and DET of GOx at the same time is still a major challenge for biosensor and biofuel cell researches.
Liang, Bo,Guo, Xishan,Fang, Lu,Hu, Yichuan,Yang, Guang,Zhu, Qin,Wei, Jinwei,Ye, Xuesong
p. 1 - 5
(2015/01/09)

Palladium copper nanosponges for electrocatalytic reduction of oxygen and glucose detection
A facile and one-pot wet chemical approach has been applied for the preparation of palladium copper (PdCu) nanosponges (NSs) through the reduction of Pd2+ and Cu2+ ions with l-ascorbic acid in the presence of sodium dodecyl sulfate (SDS) at 95 °C. The PdCu NSs prepared in the presence of 12.5, 25, and 37.5 mM SDS have sizes of 46.0 ± 4.3, 36.8 ± 4.5, and 37.2 ± 2.6 nm, respectively. Relative to a Pd NP electrode (0.33 mA cm-2), Cu NP electrode (0.31 mA cm-2), commercial Pd/C electrode (0.34 mA cm-2) and Pt/C electrode (0.66 mA cm-2), PdCu NS-modified electrodes provide a high current density for the oxygen reduction reaction (1.93 mA cm-2) under alkaline conditions. In addition, the PdCu NS-modified electrodes provide high catalytic activity for glucose oxidation at -0.01 V vs. Ag/AgCl and are stable even after sweeping for 43200 s in 0.1 M NaOH containing 0.1 M glucose. The higher catalytic activity of the PdCu NSs is mainly due to their greater electroactive surface area (EASA) and the synergistic effect caused by the intimate contact between Pd and Cu. The PdCu NS-modified electrodes exhibit high sensitivity (1560 μA mM-1 cm-2), good selectivity, and fast response to glucose over a linear range of 0-30 μM (R2 = 0.997), with a limit of detection (LOD) of 4.1 μM. With the advantages of good stability, excellent electrocatalytic activity, and cost effectiveness, PdCu NSs hold great potential for use in fuel cells using methanol or ethanol as fuel and for the fabrication of electrochemical sensors for the detection of glucose in blood samples.
Wu, Wen-Ping,Periasamy, Arun Prakash,Lin, Guan-Lin,Shih, Zih-Yu,Chang, Huan-Tsung
supporting information
p. 9675 - 9681
(2015/07/15)

Facile fabrication of NiS and a reduced graphene oxide hybrid film for nonenzymatic detection of glucose
In the present study, nickel sulfide (NiS) decorated reduced graphene oxide was synthesized by a facile one-step hydrothermal approach. Characterization of the as-made nanohybrid using a Field emission scanning electron microscope (FE-SEM) and powder X-ray diffraction (XRD) clearly demonstrate the successful attachment of NiS onto the rGO nanosheets. Further, the prepared NiS-rGO nanohybrid has been examined for the electrochemical nonenzymatic detection of glucose using cyclic voltammetry, linear sweep voltammetry and amperometry. The electrochemical studies demonstrated that the NiS-rGO nanohybrid modified electrode detects glucose linearly over a concentration range of 5.0 × 10-5 to 1.7 × 10-3 M with a detection limit of 1.0 × 10-5 M. The obtained detection limit for the NiS-rGO nanohybrid is very much comparable to the recent literature values. Further, the NiS-rGO nanohybrid modified electrode showed an excellent anti-interference ability against electroactive species and showed good reproducibility and stability.
Radhakrishnan, Sivaprakasam,Kim, Sang Jae
p. 44346 - 44352
(2015/06/02)

In situ growth of metallic silver on glucose oxidase for a highly sensitive glucose sensor
This work presents a new idea to fabricate an enzyme glucose sensor. A bio-composite was assembled by in situ reducing Ag+ to Ag in glucose oxidase (GOD) solution. In this way, metallic silver can directly deposit onto the GOD surface and induce tight contact between Ag and GOD. The obtained composites were characterized by FESEM, EDS mapping, FTIR, CD, and electrochemical measurements. The Ag-GOD composite formed by an in situ reducing process exhibits facile, direct electrochemistry and good electrocatalytic performance without any electron mediator. The designed glucose biosensor shows high sensitivity, high selectivity, long life and accurate measurement in real serum samples, which is contributed to by a fast, direct electron transfer due to close proximity between Ag and GOD.
Sun, Qiang-Qiang,Yu, Ya-Nan,Li, Jin-Jin,Bao, Shu-Juan
p. 34486 - 34490
(2015/04/27)

Characterization and electrochemical properties of a nickel film/carbon paper electrode prepared by a filtered cathodic vacuum arc technique
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.
Fu, Yingyi,Su, Wen,Wang, Tong,Hu, Jingbo
p. 54777 - 54782
(2015/06/30)

Design and development of Co3O4/NiO composite nanofibers for the application of highly sensitive and selective non-enzymatic glucose sensors
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.
Ramasamy, Ramachandran,Ramachandran,Philip, Geo George,Ramachandran, Rasu,Therese, Helen Annal,Gnana Kumar
p. 76538 - 76547
(2015/09/28)

Fast electrodeposition, influencing factors and catalytic properties of dendritic Cu-M (M = Ni, Fe, Co) microstructures
The rapid electrochemical deposition of dendritic Cu-M (M = Ni, Fe, Co) microstructures with excellent catalytic activity is reported here. Simple Cu2+ and M2+ salts were employed as the initial metal sources and boric acid was used as the buffer solution. The electrodeposition process was carried out at a deposition current of 10 mA for 5 min in air at room temperature. The phase and morphology of the as-prepared products were characterized by field emission scanning electron microscopy (FESEM), powder X-ray diffraction (XRD), energy dispersive spectrometry (EDS) and transmission electron microscopy (TEM). It was found that the formation of dendritic Cu-M microstructures could be affected by some factors including the amounts of M2+ salts and boric acid, and the deposition current and time. Cu-Ni dendrites were used as a model and their performance was studied. The investigations showed that the as-deposited Cu-Ni dendrites exhibited good electrochemical responses in 0.1 M KOH solution and could be used as an electrochemical catalyst for the reduction of nitrate and the oxidation of glucose. Also, the as-deposited Cu-M dendrites exhibited excellent catalytic activities for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in excess NaBH4 solution.
Zhang, Huying,Ni, Yonghong,Zhong, Yiman,Wu, Hao,Zhai, Muheng
p. 96639 - 96648
(2015/11/24)

Fabrication of a non-enzymatic Ni(ii) loaded ZSM-5 nanozeolite and multi-walled carbon nanotubes paste electrode as a glucose electrochemical sensor
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.
Hassaninejad-Darzi, Seyed Karim
p. 105707 - 105718
(2015/12/30)

A new methodology for optical biosensing with drop-casting fabrication of sensor chips and irradiation/detection of a single laser beam
We propose a new methodology for optical biosensing with drop-casting fabrication of sensor chips and irradiation/detection of a single laser beam. Glucose sensor chips were fabricated by simply depositing a solution, including o-phenylenediamine (oPD), glucose oxidase (GOD), and horseradish peroxidase (HRP), on a glass substrate. A sample solution was dropped on the sensor chip and the concentration was detected by measuring the reflection intensity of the laser beam focused on the chip. A surface deformation induced by the laser irradiation on the chip was observed by electron microscopy, demonstrating that this sensor chip converts the enzyme reactions into morphological changes using the assistance of the laser beam. The mechanism of the laser-induced surface deformation was investigated by testing the effect of sodium azide and fluorescence spectroscopy.
Yoshikawa,Imura,Tamiya
p. 56423 - 56429
(2015/07/15)

Electrodeposition of ZnCo2O4 nanoparticles for biosensing applications
We report the growth of ZnCo2O4 nanoparticles on indium tin oxide (ITO) coated glass substrates by a simple and highly reproducible electrodeposition method. The as-deposited ZnCo2O4 nanoparticles are characterized by various structural and microscopical tools for assessing their crystalline and morphological features. Electrochemical sensing properties of the as-prepared ZnCo2O4 nanoparticles towards glucose and dopamine are studied. ZnCo2O4 nanoparticles show linear response with respect to change in glucose concentration varying from 10 to 290 μM and possess an LOD value of 36.9 μM and a sensitivity of 0.92 μA μM-1 cm-2. In a similar way, ZnCo2O4 exhibits a linear response with respect to change in dopamine concentration varying from 5-100 μM with an LOD value of 15.4 μM and a sensitivity of 0.55 μA μM-1 cm-2 respectively.
Naik, Kusha Kumar,Rout, Chandra Sekhar
p. 79397 - 79404
(2015/10/05)

Electrodeposited spinel NiCo2O4 nanosheet arrays for glucose sensing application
We report the growth of NiCo2O4 nanosheet arrays on a conducting substrate by a simple and highly reproducible electrodeposition method. Non-enzymatic glucose sensing properties of the as-prepared nanosheets are studied. NiCo2O4 nanosheets show a linear response with respect to the change in glucose concentration varying from 5 to 65 μM and exhibit a sensitivity value of 6.69 μA μM-1 cm-2 with a LOD value of 0.38 μM. It is proposed that nanosheets are advantageous for glucose sensing applications because of their large surface area with enormous active edges and superior electrochemical properties providing efficient transport pathways for both electrons and ions.
Naik, Kusha Kumar,Kumar, Suresh,Rout, Chandra Sekhar
p. 74585 - 74591
(2015/09/21)

ELECTROCHEMICAL METHODS AND COMPOUNDS FOR THE DETECTION OF ENZYMES
Disclosed are compositions and methods for the electrochemical detection of enzymes, such as enzymes that are indicative of disease, disorders, or pathogens, such as viruses, bacteria, and fungi, or other disorders. These methods can be used in point-of- care diagnostic assays for the detection of disease, disorder, or pathogen (e.g., to identify the strain of pathogen infecting a patient in a healthcare setting). The electrochemical methods described herein can also be used to assess the susceptibility of a pathogen to an antipathogen drug. Also provided are probes suitable for use in conjunction with the methods described herein.
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(2016/04/26)

Direct electrochemistry of glucose oxidase and sensing of glucose at a glassy carbon electrode modified with a reduced graphene oxide/fullerene-C60 composite
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.
Thirumalraj, Balamurugan,Palanisamy, Selvakumar,Chen, Shen-Ming,Yang, Cheng-Yu,Periakaruppan, Prakash,Lou, Bih-Show
p. 77651 - 77657
(2015/09/28)

Self-powered sensor for Hg2+ detection based on hollow-channel paper analytical devices
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.
Zhang, Lina,Wang, Yanhu,Ma, Chao,Wang, Panpan,Yan, Mei
p. 24479 - 24485
(2015/03/18)