Study of an amperometric glucose sensor based on Pd-Ni/SiNW electrode

An amperometric glucose sensor based on Pd-Ni/SiNW electrode has been investigated. The silicon nanowire (SiNW) electrodes were first fabricated by chemical etching, and then nickel and palladium particles were deposited onto the surfaces of SiNWs via electroless co-plating technique followed by annealing in nitrogen atmosphere at 350 °C for 300 s. The morphology of Pd-Ni/SiNW electrode was characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD). The sensor performance was characterized by cyclic voltammetry (CV) and fixed potential amperometry techniques. In 0.1 M KOH alkaline medium with different glucose concentrations, the sensor shows an excellent sensitivity of 190.72 μA mM⁻¹ cm⁻² with the detection limit (S/N ratio = 3) of 2.88 μM. And it also exhibits superior anti-interference properties to the species including ascorbic acid (AA), uric acid (UA) and 4-acetamidophenol (AP). All results demonstrate that this Pd-Ni/SiNW electrode is a candidate with great potential for glucose detection.     

A new glucose sensor based on encapsulated glucose oxidase within organically modified sol–gel glass

A non-mediated glucose biosensor is reported based on encapsulated glucose oxidase (GOD) within the composite sol–gel glass, which is prepared using optimum concentrations of 3-aminopropyltriethoxy silane, 2-(3, 4-epoxycyclohexyl)-ethyltrimethoxy silane, GOD dissolved in double distilled water and HCl. A white, smooth film of sol–gel glass with controlled thickness is also prepared at the surface of a Pt disk electrode without GOD to study the electrochemistry of ferrocene monocarboxylic acid at the surface of the modified electrode. The electrochemistry of ferrocene monocarboxylic acid at composite sol–gel glass electrode with varying thickness is reported. The GOD-immobilized film over the Pt disk surface shows a yellow colour. The new sol–gel glass in the absence and the presence of GOD is characterized by scanning electron microscopy (SEM). The enzyme-immobilized film of different thickness is made using varying concentrations of soluble sol–gel components applied to the well of the Pt disk electrode. The enzyme is cross-lined with the 3-aminopropyltriethoxysilane, one of the composite component of sol–gel glass using glyoxal at 4°C for 4 h. The response of non-mediated enzyme sensor is studied based on cyclic voltammetry and amperometric measurements. A typical amperometric response of the enzyme sensor having varying thickness of the modified sol–gel glass film is reported. The variation of the response time as a function of the film thickness is reported. The stability of cross-linked GOD to sol–gel glass is found to be more than a month without loss of enzymatic activity when the enzyme sensor is stored at 4°C.     

A novel electrochemiluminescence glucose biosensor based on alcohol-free mesoporous molecular sieve silica modified electrode

In this study, a thin-film glucose electrochemiluminescence (ECL) biosensor was developed. Ru(bpy)₃²⁺ was doped in alcohol-free low-volume shrinkage mesoporous silica sol-gel with PEG-400 as the template, and glucose dehydrogenase (GDH) was immobilized in polymer Resydrol. NADH, which is produced by the reaction of co-enzyme NAD⁺ and glucose catalyzed by glucose dehydrogenase, reacts with immobilized Ru(bpy)₃²⁺ to generate ECL emission. Among the three types of design including two-layer, mixed and sandwich configuration, the sandwich configuration showed the best sensitivity with the calibration range of 25-2000 μM and the limit of detection of 0.5 μM in a flow injection analysis of glucose. The alcohol-free mesoporous sol-gel and the sandwich design made the biosensor potentially applicable in flow-injection analysis of samples.     

Gold nanowire array electrode for non-enzymatic voltammetric and amperometric glucose detection

The non-enzymatic voltammetric and amperometric detection of glucose using a gold nanowire array electrode is described. The voltammetric detection of glucose was performed by cyclic and differential-pulse voltammetry. The detection of glucose by partial and direct oxidation of glucose during the anodic and cathodic potential sweeps was shown in cyclic voltammetry. An unusual decrease in overpotential for partial oxidation of glucose on a Au NW array electrode was observed. A linear differential-pulse voltammetric response for partial oxidation of glucose was observed up to a glucose concentration of at least 20 mM with a sensitivity of 41.9 μA mM⁻¹ cm⁻² and detection limit below 30 μM (signal-to-noise ratio of 3) for glucose oxidation at low potentials, where the influence of possible intermediates can be avoided. The amperometric response was also linear up to a glucose concentration of 10 mM with a sensitivity of 309.0 μA mM⁻¹ cm⁻². The wide dynamic range and high sensitivity, selectivity and stability, as well as good biocompatibility of the Au NW electrode make it promising for the fabrication of non-enzymatic glucose sensors.     

Adsorption of glucose oxidase at platinum-multiwalled carbon nanotube-alumina-coated silica nanocomposite for amperometric glucose biosensor

Glucose oxidase (GOx) has been immobilized in platinum-multiwalled carbon nanotube-alumina-coated silica (Pt-MWCNT-ACS) nanocomposite modified glassy carbon electrode by adsorption to provide a novel amperometric glucose biosensor. The morphology, nature, and performance of the resulting GOx-Pt-MWCNT-ACS nanobiocomposite modified glassy carbon electrode were characterized by field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, cyclic voltammetry, and amperometry. The influence of various experimental conditions was examined for the determination of the optimum analytical performance. The optimized glucose biosensor displayed a wide linear range of up to 10.5 mM, a high sensitivity of 113.13 mA M⁻¹ cm⁻², and a response time of less than 5 s. The sensitivity for the determination of glucose at the GOx-Pt-MWCNT-ACS nanobiocomposite modified glassy carbon electrode is better than at common GOx-Pt-CNT nanobiocomposite modified electrodes. The proposed biosensor has good anti-interferent ability and long-term storage stability after coating with Nafion, and it can be used for the determination of glucose in synthetic serum.     

A miniaturized glucose biosensor based on the coimmobilization of glucose oxidase and ferrocene perchlorate in nafion at a microdisk platinum electrode

A miniaturized glucose biosensor based on the coimmobilization of Fc⁺ (ferrocene perchlorate)/GOD (glucose oxidase) in nafion film at the surface of a microdisk platinum electrode was fabricated and successfully used for the amperometric determination of glucose. The influences of various experimental conditions, including the relative amounts of glucose oxidase in diluted nafion aqueous solution, the concentration of ferrocene perchlorate and oxygen etc., were investigated in this paper. Ferrocene perchlorate as a redox mediator could catalyze the oxidation of the generated H₂O₂ based on the enzymatic reaction of glucose in the presence of glucose oxidase and oxygen at a favorable lower working potential (ca. 0.25 V vs. SCE). Moreover, it could also oxidize the reduced flavin adenine dinucleotide (FADH₂) of glucose oxidase directly in anaerobic environment. The response time and the detection limit under an optimal parameters were 2 min and 1 × 10⁻⁵ M, respectively. The interferences of ascorbic acid and uric acid could be obviously reduced because of the ion-selective characteristics of nation film and a favorable lower working potential. From the Michealis-Menten analysis, the apparent Michaelis constants for glucose and the maximum limiting currents determined were 10.7 mM and 5.1 nA for the incorporation of Fc⁺ in 1.00 mM Fc⁺ solution, 7.06 mM and 5.85 nA in 2.00 mM Fc⁺, respectively. Moreover, using water instead of organic solvents for nafion dilution made this enzyme electrode exhibit a good stability and reproducibility for a long-term use.     

用于血糖无创检测的葡萄糖传感器研究

研制一种新型葡萄糖传感器,初步实现用于反离子电渗透技术提取皮下组织液的葡萄糖的浓度测量。用铁氰化钾作为电子媒介体,固定在聚环氧乙烷凝胶里的葡萄糖氧化酶与溶液中的葡萄糖催化氧化生成葡萄糖酸和亚铁氰化钾,通过检测该反应产生的氧化还原电流的大小来计算葡萄糖溶液的浓度。新型葡萄糖传感器的检测浓度范围2～22 mmol/L内线性度较好,传感器的一致性测试表明:同一传感器多次测量的偏差不超过2%,反应时间较短,接近于1 s。     

Bioelectrochemical sensor based on PQQ-dependent glucose dehydrogenase

Bioelectrochemical responses of pyrroloquinoline quinone (PQQ) dependent glucose dehydrogenase (PQQ-GDH) have been studied with the use of two principal electrode configurations: (i) glassy carbon electrode, coated with Nafion layer, containing sorbed N-methylphenazonium (NMP), and overcoated by an enzyme layer, crosslinked by glutaraldehyde, and (ii) glassy carbon electrode, containing an electropolymerized layer of either Toluidine blue, or o-phenylenediamine, or pyrrole, and overcoated by a crosslinked enzyme layer. When operated within the potential window of 0.0–0.3 V, Nafion-coated and NMP-soaked bioelectrode shows an anodic current response to glucose without the presence of electron transfer mediator in solution. The current–concentration profile obtained resemble to that, typical for enzyme catalyzed reaction. Other configurations studied showed bioelectrochemical response to glucose only in the presence of soluble mediator NMP. Without any mediator, no electrochemical responses have been registered. It indicates that direct electron transfer between PQQ-GDH and all types of electrodes modified during current work is undetectable.     

Fiber optic glucose sensor based on bionanofilms

In this paper a glucose fiber optic biosensor based on electrostatic self-assembly adsorption technique is proposed. Up to 35 bilayers biofilm was achieved from alternate deposition of enzyme glucose dehydrogenase and polyelectrolytes polyethyleneimine and poly(sodium 4-styrenesulfonate). The layer thickness was characterized using an in situ optical near infrared interferometry method, which showed formation of nanoscale multilayer structure as a function of alternate adsorption cycles. Experiments showed highly efficient adsorption. The catalytic effect of the multilayer film on the reduction of nicotinamide adenine dinucleotide was studied utilizing ultraviolet fiber optic spectroscopy. The performance of this nanobiofilm onto both the cleaved end of an optical fiber pigtail and a tapered optical fiber structure were compared. As a result enzymes kept their activities after immobilization; the biosensor showed high sensitivity and stability during storage.     

Nanosized titania derived from a novel sol-gel process for ammonia gas sensor applications

Highly redispersible anatase nanoparticles were prepared by a novel sol-gel based hydrothermal process for gas sensing applications. Thin titania films composed of nanoparticles were deposited on Au interdigital electrodes by dip-coating, annealed and tested in a gas test bench at 350 °C. The anatase films showed a very high sensitivity towards ammonia and no cross interference by CO₂, O₂ and C₃H₈. To classify the sensor as an ammonia gas sensor, a comparison with other sensor designs from literature has been performed.     

Inhibitive determination of metal ions by an amperometric glucose oxidase biosensor: Study of the effect of hydrogen peroxide decomposition

An amperometric glucose biosensor based on glucose oxidase immobilized in electrosynthesized poly-o-phenylenediamine was successfully applied to the determination of a wide group of heavy metals of environmental interest. The inhibition effects of Hg²⁺, Ag⁺, Cu²⁺, Cd²⁺, Pb²⁺, Cr³⁺, Fe³⁺, Co²⁺, Ni²⁺, Zn²⁺, Mn²⁺ and also CrO₄²⁻ on glucose oxidase were studied. Collected data showed a reversible inhibition mechanism. Results about the quantitative analysis of metal ions in terms of detection limit, linear range, sensitivity and R.S.D. are discussed for each tested metal ion. The biosensor was able to discriminate two different oxidation states of chromium being able to reject Cr³⁺ and to detect the toxic species CrO₄²⁻. Also biosensor storage stability and response reproducibility were investigated.

Moreover, this study represents the first attempt of evaluating the effect of the hydrogen peroxide decomposition by metal ions on the response of an enzymatic biosensor based on the amperometric detection of the hydrogen peroxide. Experiments were performed with the aim to quantitatively evaluate, for any single metal ion, if this process is competitive with the inhibition of enzymatic reaction in the adopted experimental conditions.     

A printable glucose sensor based on a poly(pyrrole)-latex hybrid material

A printable glucose sensor was obtained by immobilisation of glucose oxidase onto the surface of poly(pyrrole)-coated latex spheres, which were mixed with a conducting ink. The obtained hybrid material was able to amperometrically detect glucose under aerobic as well as anaerobic conditions, without the use of electron mediators. Since all of the steps involved in the preparation of this latex-poly(pyrrole)-based ink are performed in solution, in-expensive mass production will be possible. A possible mechanism for this sensor is proposed based on the direct communication between the enzyme and the conducting polymer under anaerobic conditions.     

The nanocomposite of PtPd nanoparticles/onion-like mesoporous carbon vesicle for nonenzymatic amperometric sensing of glucose

A facile and fast microwave irradiation method was developed to prepare PtPd bimetallic alloy nanoparticles on onion-like mesoporous carbon vesicle (MCV). With MCV acts as a template, its high surface area favors the formation of nanosized PtPd particles. The PtPd/MCV nanocomposite was characterized by transmission electron microscopy (TEM), scanning electron micrographs (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). A nonenzymatic amperometric sensor of glucose based on the PtPd/MCV modified glassy carbon (GC) electrode is developed. Compared with the Pt/MCV nanocomposite, the PtPd/MCV modified electrode displays enhanced current response towards glucose and gives linear range from 1.5 to 12 mM. The particular lamellar structure of the MCV results in favorable transport passage for glucose. The modified electrode achieves 95% of the steady-current within 3 s. This nonenzymatic glucose sensor also exhibits good ability of anti-interference to electroactive molecules. The fast response and facile preparation method make PtPd/MCV nanocomposite promising for the development of enzyme-free sensor for glucose.     

溶胶-凝胶法制备纳米TiO2的凝胶机理研究

以硝酸为催化剂,钛酸丁酯为前驱物,用溶胶-凝胶法制备TiO2凝胶,研究了不同的掺水量、硝酸含量、反应温度、搅拌速度等反应条件下的凝胶过程,采用X射线衍射和透射电镜对纳米粒子的性能进行分析,找出制备纯度较高的锐钛矿型的纳米TiO2粉体的最佳工艺条件。     

Highly sensitive and linear calibration optical fiber oxygen sensor based on Pt(II) complex embedded in sol-gel matrix

A simple, low-cost technique for fabrication of high performance optical fiber oxygen sensor is described. An organically modified silicate (ORMOSIL) as a matrix for the fabrication of oxygen sensing film was produced. The technique is based on coating the end of an optical fiber with ORMOSIL composite xerogel films film sequestered with luminophore platinum (II) meso-tetrakis(pentafluorophenyl)porphyrin (PtTFPP) prepared by a sol-gel process. The composite xerogels studied are 3,3,3-trifluoropropyltrimethoxysliane (TFP-TriMOS) or n-propyltrimethoxysilane (n-propyl-TriMOS)/tetraethylorthosilane (TEOS)/n-octyltriethoxysilane (Octyl-triEOS). Results show that, expect for PtTFPP-doped TFP-TriMOS or n-propyl-TriMOS/TEOS/Octyl-triEOS composite xerogels show the high sensitivity and linear Stern-Volmer relationship which indicate the homogenous environment of the luminophore. The sensitivities of the two oxygen sensors are quantified in terms of the ratio I_N2/I_O2, where I_N2 and I_O2 represent the detected fluorescence intensities in pure nitrogen and pure oxygen environments, respectively. The experimental results reveal that the PtTFPP-doped TFP-TriMOS/TEOS/Octyl-triEOS and n-propyl-TriMOS/TEOS/Octyl-triEOS oxygen sensors have sensitivities of 101 and 155, respectively. The experimental results confirm that the current oxygen sensors exhibit the linear Stern-Volmer plots and high-sensitive based on the oxygen indicator embedded in TFP-TriMOS or n-propyl-TriMOS/TEOS/Octyl-triEOS composite xerogels.     

A novel photometric glucose biosensor based on decolorizing of silver nanoparticles

A novel glucose biosensor based on chromophore (silver nanoparticles) decolorizing for the photometric determination of glucose was developed. Silver nanoparticles are directly synthesized in the sol-gel matrix by a one-step method based on the reduction of the inorganic precursor AgNO₃ and were used for the preparation, characterization and calibration of a highly sensitive and cost-effective localized surface plasmon resonance-based glucose biosensor. In the presence of glucose oxidase (GOx) and due to the enzyme-substrate (glucose) reaction, H₂O₂ was produced and silver nanoparticles in the sol-gel glass have the ability for the decomposition of hydrogen peroxide. Due to the degradation of silver nanoparticles a remarkable change in the localized surface plasmon resonance absorbance strength could be observed which have been monitored as a suitable signal for determination of substrate concentration. Beer's law is obeyed in the range from 50 to 800 mg/L glucose and the limit of detection is 23 mg/L. The proposed optical biosensor has been successfully applied to the determination of glucose in various real samples.     

Benzene monitoring by micro-machined sensors with SnO2 layer obtained by using micro-droplet deposition technique

SnO₂ thin layers were deposited by the way of the micro-droplet technique. The sensor substrate consisted of a thin membrane developed on oxidised silicon wafer. The sensing layers were deposited by means of the micro-droplet technique into thin layers of about 100 nm. Such devices were tested for benzene detection. The obtained results showed a very high sensitivity for this chemical compound since 500 ppb were detected.The results presented in this paper were not focused on the reactional mechanism of benzene detection but rather on the development of a cheap and sensitive sensor using sol-gel and micro-droplet processes. Since these layers were elaborated using solely tin oxide, the as-obtained sensors are not selective but these one are intended to be used by coupling with additional devices such as chromatographic micro-column and micro-pre-concentrators.     

Characterization of carbon paste electrodes modified with manganese based perovskites-type oxides from the amperometric determination of hydrogen peroxide

This work proposes the amperometric determination of hydrogen peroxide reduction and oxidation as a tool for the characterization of La_1−xA_xMnO₃ perovskites dispersed in a graphite composite electrode (carbon paste electrode, CPE). The catalytic activity of perovskites towards the oxidation and reduction of hydrogen peroxide is highly dependent on the nature of the A cation and on the temperature and time of calcination employed during the synthesis. Therefore, the selection of the optimal synthesis conditions to obtain the best catalytic activity towards hydrogen peroxide can be performed from amperometric determinations.We also report the analytical application of the perovskite modified CPE through the quantification of hydrogen peroxide in two real samples. Some preliminary results about the usefulness of La_0.66Sr_0.33MnO₃–CPE to develop a glucose biosensor by incorporation of the enzyme glucose oxidase (GOx) within the electrode are also reported. The difference in sensitivity to glucose at CPE–GOx and CPE–La_0.66Sr_0.33MnO₃–GOx (11.9 μA mol⁻¹ L and 158.1 μA mol⁻¹ L, respectively), clearly demonstrate the advantages of the association of the biocatalytic activity of GOx and the catalytic activity of perovskites towards hydrogen peroxide oxidation/reduction, and opens the doors to the development of new sensors for other important bioanalytes.     

Development of a dehydrogenase-based glucose anode using a molecular assembly composed of nile blue and functionalized SWCNTs and its applications to a glucose sensor and glucose/O2 biofuel cell

A simple and new way to immobilize glucose dehydrogenase (GDH) enzyme onto nile blue (NB) covalently assembled on the surface of functionalized single-walled carbon nanotubes (f-SWCNTs) modified glassy carbon (GC) electrode (GDH/NB/f-SWCNTs/GC electrode) was described. The GDH/NB/f-SWCNTs/GC electrode possesses promising characteristics as glucose sensor; a wide linear dynamic range of 100-1700 μM, low detection limit of 0.3 μM, fast response time (1-2 s), high sensitivity (14 μA cm⁻² mM⁻¹), anti-interference ability and anti-fouling. Moreover, the performance of the GDH/NB/f-SWCNTs/GC bioanode was successfully tested in a glucose/O₂ biofuel cell. The maximum power density delivered by the assembled glucose/O₂ biofuel cell could reach 32.0 μW cm⁻² at a cell voltage of 0.35 V with 40 mM glucose. The present procedure can be applied for preparing a potential platform to immobilize different enzymes for various bioelectrochemical applications.     

High-performance glucose sensor based on glucose oxidase encapsulated in new synthesized platinum nanoparticles supported on carbon Vulcan/Nafion composite deposited on glassy carbon

In this study we synthesized Pt nanoparticles supported on carbon Vulcan (Pt/C), a cheap and high surface area carbon. Compared to the commercialized Pt/C, which showed a moderate activity towards the oxidation of H₂O₂ and a high catalytic activity to the interferences specially AP; the synthesized Pt/C illustrated a high activity towards the oxidation of H₂O₂ and negligible response towards the oxidation of the interferences at high applied potentials (>0.6 V). This difference in the catalytic behavior was attributed to the homogenous distribution of the synthesized Pt nanoparticles in the supporting carbon Vulcan as well as, to their relatively bigger size (8-9 nm) compared to (1-2 nm) estimated for the commercialized Pt/C. This particular and interesting behavior of the synthesized Pt/C was used to encapsulate glucose oxidase along with a small amount of Nafion for the manufacturing of a glucose sensor. The resulting glucose sensor has a high sensitivity of 1.25 μA/mM mm², which compares very well with other glucose sensors based on precious metal nanoparticles and carbon nanotubes, an extended linear range up to 45 mM without using any outer polymer layer, low interference from endogenous species, short response time (<5 s), was stable for at least 1 month and, found to be dependable for glucose determination in human serum.