Amperometric glucose biosensor based on electrodeposition of platinum nanoparticles onto covalently immobilized carbon nanotube electrode

A new amperometric biosensor for glucose was developed based on adsorption of glucose oxidase (GOx) at the gold and platinum nanoparticles-modified carbon nanotube (CNT) electrode. CNTs were covalently immobilized on gold electrode via carbodiimide chemistry by forming amide linkages between carboxylic acid groups on the CNTs and amine residues of cysteamine self-assembled monolayer (SAM). The fabricated GOx/Au_nano/Pt_nano/CNT electrode was covered with a thin layer of Nafion to avoid the loss of GOx in determination and to improve the anti-interferent ability. The immobilization of CNTs on the gold electrode was characterized by quartz crystal microbalance technique. The morphologies of the CNT/gold and Pt_nano/CNT/gold electrodes have been investigated by scanning electron microscopy (SEM), and the electrochemical performance of the gold, CNT/gold, Pt_nano/gold and Pt_nano/CNT/gold electrodes has also been studied by amperometric method. In addition, effects of electrodeposition time of Pt nanoparticles, pH value, applied potential and electroactive interferents on the amperometric response of the sensor were discussed.

The enzyme electrode exhibited excellent electrocatalytic activity and rapid response for glucose in the absence of a mediator. The linear range was from 0.5 to 17.5 mM with correction coefficient of 0.996. The biosensor had good reproducibility and stability for the determination of glucose.     

An Amperometric Glucose Biosensor Based on Poly (Pyrrole‐2‐Carboxylic Acid)/Glucose Oxidase Biocomposite

A newly developed amperometric glucose biosensor based on graphite rod (GR) working electrode modified with biocomposite consisting of poly (pyrrole‐2‐carboxylic acid) (PCPy) particles and enzyme glucose oxidase (GOx) was investigated. The PCPy particles were synthesized by chemical oxidative polymerization technique using H₂O₂ as initiator of polymerization reaction and modified covalently with the GOx (PCPy‐GOx) after activation of carboxyl groups located on the particles surface with a mixture of N‐(3‐dimethylaminopropyl)‐N′‐ethylcarbodiimide hydrochloride (EDC) and N‐hydroxysuccinimide (NHS). Then the PCPy‐GOx biocomposite was dispersed in a buffer solution containing a certain amount of bovine serum albumin (BSA). The resulting biocomposite suspension was adsorbed the on GR electrode surface with subsequent solvent airing and chemical cross‐linking of the proteins with glutaraldehyde vapour (GR/PCPy‐GOx). It was determined that the current response of the GR/PCPy‐GOx electrodes to glucose measured at +300 mV vs Cl reference electrode was influenced by the duration of the PCPy particles synthesis, pH of the GOx solution used for the PCPy particles modification and the amount of immobilized PCPy‐GOx biocomposite. An optimal pH of buffer solution for operation of the biosensor was found to be 8.0. Detection limit was determined as 0.039 mmol L⁻¹ according signal to noise ratio (S/N: 3). The proposed glucose biosensor was tested in human serum samples.     

纳米金-还原氧化石墨烯修饰葡萄糖氧化酶传感器的制备及其电流法检测饮料中的葡萄糖

利用纳米金(Au NPs)与还原氧化石墨烯(rGO)复合纳米材料制备了葡萄糖氧化酶生物传感器并用于饮料中葡萄糖含量的检测。将壳聚糖作为还原剂及稳定剂,通过一步法合成了Au NPs-rGO复合材料,并通过物理吸附固定葡萄糖氧化酶(GOx)来制作GOx生物传感器。该传感器在磷酸盐缓冲溶液(0.1 mol/L,p H6.0)中,-0.45 V(vs.Ag/Ag Cl)电位下电流法检测葡萄糖含量,线性检测范围为0.01~0.88 mmol/L,灵敏度为22.54μA·mmol-1·L·cm-2,检出限为1.01μmol/L,且表观米氏常数为0.497 mmol/L。该传感器用于多种饮料中葡萄糖含量的直接检测,结果满意。     

Glucose biosensing based on the highly efficient immobilization of glucose oxidase on a Prussian blue modified nanostructured Au surface

We report on a novel glucose biosensor based on the immobilization of glucose oxidase (GOx) on a Prussian blue modified nanoporous gold surface. The amperometric glucose biosensor fabricated in this study exhibits a fast response and the very low detection limit of 2.5 μM glucose. The sensitivity of the biosensor was found to be very high, 177 μA/mM; the apparent Michaelis–Menten constant is calculated to be 2.1 mM. In addition, the biosensor has good reproducibility and remains stable over 60 days. The anti-interference ability of the biosensor was also assessed, showing little interference from possible interferents such as ascorbic acid (AA), acetaminophen (AP) and uric acid (UA).     

Development of Amperometric Glucose Biosensor Based on Reconstitution of Glucose Oxidase on Polymeric 3‐Aminophenyl Boronic Acid Monolayer

An amperometric biosensor for determining glucose based on deflavination of the enzyme glucose oxidase and subsequent reconstitution of the apo‐protein with a complexed flavin adenine dinucleotide (FAD) monolayer is described. The GOx‐reconstituted electrode exhibited excellent electrocatalytic activities towards the reduction and oxidation of hydrogen peroxide as well. The prepared biosensor showed an excellent performance for glucose at +0.5 V with a high sensitivity (5.94 μA/mM) and relatively good response time (～12 s) in a wide concentration range of 1–17 mM (correlation coefficient of 0.9998). The applicability to blood analysis was also evaluated.     

Construction of glucose biosensor based on sorption of glucose oxidase onto multilayers of polyelectrolyte/nanoparticles

A new approach to constructing an enzyme-containing film on the surface of a gold electrode for use as a biosensor is described. A basic multilayer film (BMF) of (PDDA/GNPs) _n /PDDA was first constructed on the gold electrode by electrostatic layer-by-layer self-assembly of poly(diallyldimethylammonium chloride) (PDDA) and gold nanoparticles (GNPs). Glucose oxidase (GOx) was then sorbed into this BMF by dipping the BMF-modified electrode into a GOx solution. The assembly of the BMF was monitored and tested via UV-vis spectroscopy and cyclic voltammetry (CV). The ferrocenemethanol-mediated cyclic voltammograms obtained from the gold electrode modified with the (PDDA/GNPs) _n /PDDA/GOx indicated that the assembled GOx remained electrocatalytically active for the oxidation of glucose. Analysis of the voltammetric signals showed that the surface coverage of active enzyme was a linear function of the number of PDDA/GNPs bilayers. This result confirmed the penetration of GOx into the BMF and suggests that the BMF-based enzyme film forms in a uniform manner. Electrochemical impedance measurements revealed that the biosensor had a lower electron transfer resistance (R _et) than that of a sensor prepared by layer-by-layer assembly of PDDA and GOx, due to the presence of gold nanoparticles. The sensitivity of the biosensor for the determination of glucose, which could be controlled by adjusting the number of PDDA/GNPs bilayers, was investigated.     

Pt nanoparticles modified Au nanowire array for amperometric and potentiometric detection of glucose

A new glucose biosensor, based on the modification of highly ordered Au nanowire arrays (ANs) with Pt nanoparticles (PtNPs) and subsequent surface adsorption of glucose oxidase (GOx), is described. Morphologies of ANs and ANs/PtNPs were observed by scanning electron microscope. The electrochemical properties of ANs, ANs/GOx, ANs/PtNPs, and ANs/PtNPs/GOx electrodes were compared by cyclic voltammetry. Results obtained from comparison of the cyclic voltammograms show that PtNPs modification enhances electrochemical catalytic activity of ANs to H₂O₂. Hence, ANs/PtNPs/GOx biosensor exhibits much better sensing to glucose than ANs/GOx. Optimum deposition time of ANs/PtNPs/GOx biosensor for both amperometric and potentiometric detection of glucose was achieved to be 150 s at deposition current of 1?×?10^?6 A. A sensitivity of 0.365 μA/mM with a linear range from 0.1 to 7 mM was achieved for amperometric detection; while for potentiometric detection the sensitivity is 33.4 mV/decade with a linear range from 0.1 to 7 mM.     

High stability amperometric biosensor based on enzyme entrapment in microgels

The preparation and characterization of an amperometric glucose biosensor based on the entrapment of glucose oxidase (GOx) in a polyacrylamide microgel is described. This study proves that polyacrylamide microgels provide an excellent matrix for GOx immobilization that can be used as a biological material in amperometric biosensors. The interference produced by ascorbic and uric acid has been eliminated by including acrylic acid in the polymeric matrix. With this modification, we obtain an adequate device for glucose determination in complex samples such as blood and serum. The study of the temperature effect in the response of biosensors indicates that swelling of the microgels directly influences the enzymatic activity. Thus, the behaviour of the enzyme in the swollen microgels is similar to the enzyme in solution, but the enzyme's activation energy increases when the water content in the microgels decreases. One important property of these biosensors is their remarkable stability. After 4 months of its manufacture, there is no loss in the initial response. Furthermore, the enzymatic activity of freeze-dried microgels containing enzyme remains unaltered for at least 18 months.     

An integrated bienzyme glucose oxidase-fructose dehydrogenase-tetrathiafulvalene-3-mercaptopropionic acid-gold electrode for the simultaneous determination of glucose and fructose

A bienzyme biosensor for the simultaneous determination of glucose and fructose was developed by coimmobilising glucose oxidase (GOD), fructose dehydrogenase (FDH), and the mediator, tetrathiafulvalene (TTF), by cross-linking with glutaraldehyde atop a 3-mercaptopropionic acid (MPA) self-assembled monolayer (SAM) on a gold disk electrode (AuE). The performance of this bienzyme electrode under batch and flow injection (FI) conditions, as well as an amperometric detection in high-performance liquid chromatography (HPLC), are reported. The order of enzyme immobilisation atop the MPA-SAM affected the biosensor amperometric response in terms of sensitivity, with the immobilisation order GOD, FDH, TTF being selected. Similar analytical characteristics to those obtained with single GOD or FDH SAM-based biosensors for glucose and fructose were achieved with the bienzyme electrode, indicating that no noticeable changes in the biosensor responses to the analytes occurred as a consequence of the coimmobilisation of both enzymes on the same MPA-AuE. The suitability of the bienzyme biosensor for the analysis of real samples under flow injection conditions was tested by determining glucose in two certified serum samples. The simultaneous determination of glucose and fructose in the same sample cannot be performed without a separation step because at the detection potential used (+0.10 V), both sugars show amperometric response. Consequently, HPLC with amperometric detection at the TTF-FDH-GOD-MPA-AuE was accomplished. Glucose and fructose were simultaneously determined in honey, cola softdrink, and commercial apple juice, and the results were compared with those obtained by using other reference methods.     

Anti‐Interferent Properties of Oxidized Nickel Based on Layered Double Hydroxide in Glucose Amperometric Biosensors

An amperometric biosensor based on Pt electrodes modified with a thin film of a Ni, Al layered double hydroxide (LDH), submitted to a preliminary oxidative treatment in order to have the nickel centers at the oxidation state +4, and glucose oxidase (GOx) is presented. The oxidized LDH acts both as a system to support the enzyme and as a barrier to anions since it acquires an overall negative charge, as demonstrated by electrochemical impedance spectroscopy. Even if the biosensor response is due to the detection of H₂O₂ at anodic potentials, glucose can be accurately determined in the presence of ascorbic acid or other interferences, commonly present in real matrices in anionic form, since they can not reach the electrode surface. The effectiveness of the developed biosensor has been demonstrated by measuring glucose in samples of fruit juices containing ascorbic acid at high levels.     

Encapsulation of glucose oxidase within poly(ethylene glycol) methyl ether methacrylate microparticles for developing an amperometric glucose biosensor

Poly(ethylene glycol) methyl ether methacrylate (PEGMEM) microparticles were synthesized and glucose oxidase (GOx) was immobilized within the microparticles. An amperometric biosensor was fabricated using the microparticles with GOx as biological component. The enzyme immobilization method was optimized by investigating the influence of monomer concentration and cross-linker content used in the preparation of the microparticles in the response of the biosensor. The best analytical results were obtained with the microparticles prepared with 0.21 M PEGMEM and 0.74% cross-linking. Furthermore, we have investigated the influence on the biosensor behaviour of parameters such as working potential, pH, temperature and enzymatic load. In addition, analytical properties such as sensitivity, linear range, response time and detection limit were determined. The biosensor was used to determine glucose in human serum samples and to avoid common interferents present in human serum such as uric and ascorbic acids. A Nafion layer was deposited on the electrode surface with satisfactory results. The useful lifetime of the biosensor was at least 520 days.     

Reduced Graphene Oxide/Pt Nanoparticles/Zn‐MOF‐74 Nanomaterial for a Glucose Biosensor Construction

In this study, a new glucose biosensor was fabricated by immobilizing glucose oxidase (GOx) on platinum nanoparticles (Pt NPs) decorated reduced graphene oxide (rGO)/Zn‐MOF‐74 hybrid nanomaterial. Herein, the biosensor fused the advantages of rGO with those of porous Zn‐MOF and conductive Pt NPs. This has not only enlarged the surface area and porosity for the efficient GOx immobilization and faster mass transport, but also provided favorable electrochemical features such as high current density, remarkable electron mobility through metal nanoparticles, and improved electron transfer between the components. The GOx‐rGO/Pt NPs@Zn‐MOF‐74 coated electrode displayed a linear measurement range for glucose from 0.006 to 6 mM, with a detection limit of 1.8 μM (S/N: 3) and sensitivity of 64.51 μA mM^?1 cm^?2. The amperometric response of the enzyme biosensor demonstrated the typical behavior of Michaelis‐Menten kinetics. The obtained satisfying sensitivity and measurement range enabled fast and accurate glucose measurement in cherry juice using the fabricated biosensor. The water‐stable Zn‐MOF‐74 demonstrated higher enzyme loading capacity and can be potent supporting material for biosensor construction.     

Direct electrochemical sensing of glucose using glucose oxidase immobilized on functionalized carbon nanotubes via a novel metal chelate-based affinity method

We report on a novel amperometric glassy carbon biosensing electrode for glucose. It is based on the immobilization of a highly sensitive glucose oxidase (GOx) by affinity interaction on carbon nanotubes (CNTs) functionalized with iminodiacetic acid and metal chelates. The new technique for immobilization is exploiting the affinity of Co(II) ions to the histidine and cysteine moieties on the surface of GOx. The direct electrochemistry of immobilized GOx revealed that the functionalized CNTs greatly improve the direct electron transfer between GOx and the surface of the electrode to give a pair of well-defined and almost reversible redox peaks and undergoes fast heterogeneous electron transfer with a rate constant (k _s) of 0.59?s^?1. The GOx immobilized in this way fully retained its activity for the oxidation of glucose. The resulting biosensor is capable of detecting glucose at levels as low as 0.01?mM, and has excellent operational stability (with no decrease in the activity of enzyme over a 10?days period). The method of immobilizing GOx is easy and also provides a model technique for potential use with other redox enzymes and proteins.

Fabrication of Bienzymatic Glucose Biosensor Based on Novel Gold Nanoparticles‐Bacteria Cellulose Nanofibers Nanocomposite

An exploration of gold nanoparticles–bacterial cellulose nanofibers (Au‐BC) nanocomposite as a platform for amperometric determination of glucose is presented. Two enzymes, glucose oxidase (GOx) and horseradish peroxidase (HRP) were immobilized in Au‐BC nanocomposite modified glassy carbon electrode at the same time. A sensitive and fast amperometric response to glucose was observed in the presence of electron mediator (HQ). Both of GOx and HRP kept their biocatalytic activities very well in Au‐BC nanocomposite. The detection limit for glucose in optimized conditions was as low as 2.3 µM with a linear range from 10 µM to 400 µM. The biosensor was successfully applied to the determination of glucose in human blood samples.     

Inclusion of metal micro-particles into poly(pyrrolylalkylammonium) films containing an enzyme for bioelectrocatalysis: a preliminary study

The electrocatalytic detection of products issued from enzymatic reactions occuring at biosensor interfaces can be improved owing to metal microparticle dispersions. This contribution describes the faesability of this concept for the modification poly(pyrrolylalkylammonium) films containing an enzyme through the inclusion of platinum. A model enzyme, glucose oxidase (GOx) was employed to demonstrate the reliability of this approach through the design of an amperometric glucose biosensors. The obtained composite assemblies were characterised regarding their sensing capabilities toward glucose. Platinum particles incorporation was operated within the biofilms to obtain a suitable sensitivity of the biosensor to glucose at a lower operational oxidation potential (eg 0.5 V/SCE) than the oxidation potential generally observed for hydrogen peroxide detection onto carbon electrodes. The incorporation procedure of platinum aggregates has been optimised to design biosensors exhibiting a sensitivity of about 8 mA. M(-1) cm(-2).     

Amperometric Glucose Biosensor Based on Electrochemically Deposited Gold Nanoparticles Covered by Polypyrrole

Graphite rod (GR) modified with electrochemicaly deposited gold nanoparticles (AuNPs) and adsorbed glucose oxidase (GOx) was used in amperometric glucose biosensor design. Enzymatic formation of polypyrrole (Ppy) on the surface of GOx/AuNPs/GR electrode was applied in order to improve analytical characteristics and stability of developed biosensor. The linear glucose detection range for Ppy/GOx/AuNPs/GR electrode was dependent on the duration of Ppy‐layer formation and the linear interval was extended up to 19.9 mmol L⁻¹ after 21 h lasting synthesis of Ppy. The sensitivity of the developed biosensor was determined as 21.7 μA mM⁻¹ cm⁻², the limit of detection – 0.20 mmol L⁻¹. Ppy/GOx/AuNPs/GR electrodes demonstrated advanced good stability (the t _1/2 was 9.8 days), quick detection of glucose (within 5 s) in the wide linear interval. Additionally, formed Ppy layer decreased the influence of electroactive species on the analytical signal. Developed biosensor is suitable for the determination of glucose in human serum samples.     

Sulfonated polyaniline network grafted multi-wall carbon nanotubes for enzyme immobilization, direct electrochemistry and biosensing of glucose

A new nanomaterial was prepared by grafting a layer of sulfonated polyaniline network (SPAN-NW) on to the surface of multi-walled carbon nanotube (MWNT) and effectively utilized for immobilization of an enzyme and for the fabrication of a biosensor. SPAN-NW was formed on the surface of MWNT by polymerizing a mixture of diphenyl amine 4-sulfonic acid (DPASA), 4-vinyl aniline (VA) and 2-acrylamido-2-methyl-1-propane sulfonic acid (APASA) in the presence of amine functionalized MWNT (MWNT-NH₂). The MWNT-g-SPAN-NW was immobilized with glucose oxidase (GOx) to fabricate the SPAN-NW/GOx biosensor. MWNT-g-SPAN-NW/GOx electrode showed direct electron transfer (DET) for GOx with a fast heterogeneous electron transfer rate constant (k_s) of 4.11 s^− 1. The amperometric current response of MWNT-g-SPAN-NW/GOx biosensor shows linearity up to 9 mM of glucose, with a correlation coefficient of 0.99 and a detection limit of 0.11 μM (S/N = 3). At a low applied potential of − 0.1 V, MWNT-g-SPAN-NW/GOx electrode possesses high sensitivity (4.34 μA mM^− 1) and reproducibility towards glucose.     

Amperometric glucose biosensor based on a gold nanorods/cellulose acetate composite film as immobilization matrix

We report on the utilization of gold nanorods to create a highly responsive glucose biosensor. The feasibility of an amperometric glucose biosensor based on immobilization of glucose oxidase (GOx) in gold nanorod is investigated. GOx is simply mixed with gold nanorods and cross-linked with a cellulose acetate (CA) medium by glutaraldehyde. The adsorption of GOx on the gold nanorods is confirmed by X-ray photoelectron spectroscopy (XPS) measurements. Circular dichroism (CD) and UV-spectrum results show that the activity of GOx was preserved after conjugating with gold nanorods. The current response of modified electrode is 10 times higher than that of without gold nanorods. Under optimal conditions, the biosensor shows high sensitivity (8.4 μA cm⁻² mM⁻¹), low detection limit (2 × 10⁻⁵ M), good storage stability and high affinity to glucose (). A linear calibration plot is obtained in the wide concentration range from 3 × 10⁻⁵ to 2.2 × 10⁻³ M.     

Synergistic contributions of multiwall carbon nanotubes and gold nanoparticles in a chitosan–ionic liquid matrix towards improved performance for a glucose sensor

We report an ingenious approach for the fabrication of a promising glucose sensor, GOx/Au/CS–IL–MWNT(SH), that exploits the synergistic beneficial characteristics of multiwalled-carbon nanotubes (MWNTs), gold nanoparticles (AuNPs), chitosan (CS) and room temperature ionic liquid (RTIL). Direct electron transfer between glucose oxidase (GOx) and electrode was achieved. Scanning electron microscopy and atomic force microscopy images of GOx/Au/CS–IL–MWNT(SH) reveal that MWNTs and AuNPs are dispersed in CS–IL matrix. Cyclic voltammetry, impedance spectroscopy and chronoamperometry were used to evaluate the performance of biosensor. The GOx/Au/CS–IL–MWNT(SH) biosensor exhibits a linear current response to glucose concentration (1–10 mM) at a low potential of 0.10 V and precludes interferences from uric acid and ascorbic acid. The GOx/Au/CS–IL–MWNT(SH) biosensor has superior performances over GOx/CS–IL–MWNT(SH).     

Glucosinolate Amperometric Bienzyme Biosensor Based on Carbon Nanotubes‐Gold Nanoparticles Composite Electrodes

A novel electrochemical biosensor design for glucosinolate determination involving bulk‐incorporation of the enzymes glucose oxidase and myrosinase into a colloidal gold ‐ multiwalled carbon nanotubes composite electrode using Teflon as binder is reported. Myrosinase catalyzes the hydrolysis of glucosinolate forming glucose, which is enzymatically oxidized. The generated hydrogen peroxide was electrochemically detected without mediator at the nanostructured composite electrode at E=+0.5 V vs. Ag/AgCl. Under the optimized conditions, the bienzyme MYR/GOx‐Au_coll‐MWCNT‐Teflon exhibited improved analytical characteristics for the glucosinolate sinigrin with respect to a biosensor constructed without gold nanoparticles, i.e. a MYR/GOx‐MWCNT‐Teflon electrode, as well as with respect to other glucosinolate biosensor designs reported in the literature. The biosensor exhibits good repeatability of the amperometric measurements and good interassay reproducibility. Furthermore, the biosensor exhibited a high selectivity with respect to various potential interferents. The usefulness of the biosensor was evaluated by the determination of glucosinolate in Brussel sprout seeds.