Amperometric glucose biosensor based on boron-doped carbon nanotubes modified electrode

Doped carbon nanotubes are now extremely attractive and important nanomaterials in bioanalytical applications due to their unique physicochemical properties. In this paper, the boron-doped carbon nanotubes (BCNTs) were used in amperometric biosensors. It has been found that the electrocatalytic activity of the BCNTs modified glassy carbon (GC) electrode toward the oxidation of hydrogen peroxide is much higher than that of the un-doped CNTs modified electrode due to the large amount of edge sites and oxygen-rich groups located at the defective sites induced by boron doping. Glucose oxidase (GOD) was selected as the model enzyme and immobilized on the BCNTs modified glassy carbon electrode by entrapping GOD into poly(o-aminophenol) film. The performance of the sensor was investigated by electrochemical methods. At an optimum potential of +0.60 V and pH 7.0, the biosensor exhibits good characteristics, such as high sensitivity (171.2 nA mM(-1)), low detection limit (3.6 microM), short response time (within 6s), satisfactory anti-interference ability and good stability. The apparent Michaelis-Menten constant (K(m)(app)) is 15.19 mM. The applicability to the whole blood analysis of the enzyme electrode was also evaluated.     

Amperometric sensor based on carbon nanotubes and electropolymerized vanillic acid for simultaneous determination of ascorbic acid,dopamine, and uric acid

This paper describes the development of a simple and efficient nanostructured platform based on multi-walled carbon nanotubes (MWCNT) functionalized with an in situ generated vanillic acid (VA) polymer. It was used as an analytical sensor for the simultaneous determination of ascorbic acid (AA), dopamine (DA), and uric acid (UA). The electropolymerization process of VA, performed on MWCNT-modified glassy carbon electrode, produces three redox systems based on quinone/hydroquinone functionality, as observed by cyclic voltammetry. The amperometric sensor has as figures of merit for the simultaneous determination of AA, DA, and UA the following values: for AA, a linear range of 5–120 μM and detection limit of 3.5 μM; for DA, a linear range of 5–120 μM and detection limit of 4.5 μM; and for UA, a linear range of 5–120 μM and a detection limit of 1.5 μM. From the obtained performance, the development of the platform based on MWCNT/poly-VA is justified for the simultaneous determination of AA, DA, and UA.     

Amperometric sensor for ascorbic acid based on a glassy carbon electrode modified with gold-silver bimetallic nanotubes in a chitosan matrix

We report on an amperometric sensor for ascorbic acid (AA) that is based on highly dense gold-silver nanotubes in a chitosan film on a glassy carbon electrode. The nanotubes were synthesized by a poly(vinyl pyrrolidone)-mediated polyol method employing a replacement reaction with silver nanowires as templates, and were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. Under the optimal conditions, the sensor exhibits good electrocatalytic activity towards the oxidation of AA, and this enables the determination of AA in the 5 μM to 2 mM concentration range, with a detection limit at 2 μM (at an S/N of 3). The response time is 2 s. The sensor displays good reproducibility, selectivity, sensitivity, and long-term stability.

Amperometric glutamate biosensor based on self-assembling glutamate dehydrogenase and dendrimer-encapsulated platinum nanoparticles onto carbon nanotubes

A novel amperometric biosensor based on self-assembling glutamate dehydrogenase (GLDH) and poly(amidoamine) dendrimer-encapsulated platinum nanoparticles (Pt-PAMAM) onto multiwall carbon nanotubes (CNTs) has been developed for the determination of glutamate. The formation of the self-assembled (GLDH/Pt-PAMAM)_n/CNTs construction was investigated by ζ-potential and high resolution transmission electron microscopy (HRTEM). The results indicated the uniform growth of the layer-by-layer nanostructures onto carboxyl-functionalized CNTs. The electrocatalytic property of the (GLDH/Pt-PAMAM)_n/CNTs modified electrode to glutamate in presence of NAD⁺ (β-nicotinamide adenine dinucleotide, 0.1 mM) was investigated at a low overpotential 0.2 V by electrochemical measurements. The results showed it had series of attractive characteristics, such as a large determination range (0.2-250 μM), a short response time (within 3 s), a high sensitivity (433 μA/mM⁻¹ cm²) and good stability (85% remains after 4 weeks).     

Electrochemical enzymatic biosensor for tyramine based on polymeric matrix derived from 4-mercaptophenylacetic acid

Journal of Solid State Electrochemistry - In this paper, we investigated a novel functionalized polymeric film derived from 4-mercaptophenylacetic acid (MPAA). The polymerization was carried out...     

Amperometric biosensor based on thermally activated polymer-stabilized metal nanoparticles

Polymer-stabilized Pd nanoparticles on carbon support were synthesized by a low thermal procedure that does not involve the utilization of a reducing agent such as NaBH₄ or hydrogen gas for the formation of the metallic nanoparticles. The Pd-catalyzed graphite particles were then mixed with known amounts of glucose oxidase (GOx) enzyme and Nafion to prepare a GOx-immobilized ink. A glassy carbon electrode (GCE) modified with the GOx ink was used to evaluate the performance of the biosensor electrode. The results of TEM and AFM show that the Pd nanoparticles are uniformly distributed on top of the substrate. Results are presented for sensing glucose through the voltammetric measurement of H₂O₂. Coupled with the simplicity of preparation, the biosensor exhibited high sensitivity and extended linear range for glucose measurement. Further, the electrochemical characteristics of the nanocomposite biosensor were evaluated with respect to the electrochemistry of potassium ferricyanide by cyclic voltammetry. Whereas the presence of polymer and Nafion improved the stability of both the ink and biosensor electrode, the concentration of glucose was measured without interferences from oxygen, ascorbic acid and uric acid because of the Nafion.     

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.     

Amperometric determination of ascorbic acid on screen-printing ruthenium dioxide electrode

Ruthenium oxide (RuO₂) is commonly used in resistive pastes for screen printing. The electrochemical properties of a screen-printing planar RuO₂ electrode have hardly been studied. In this communication, planar electrochemical sensors with a RuO₂ working electrode, an Ag|AgCl reference electrode and a RuO₂ counter electrode are fabricated by screen printing. The electro-oxidation of ascorbic acid, uric acid, and hydrogen peroxide on these RuO₂ electrodes is investigated by means of cyclic voltammetry. Compared to uric acid and hydrogen peroxide, ascorbic acid can be easily oxidized at the low operating potential (<150 mV versus Ag|AgCl). The amperometric measurement of ascorbic acid at 100 mV on a RuO₂ electrode shows fast response and good linearity in the 0–4 mM range. Meanwhile, the electrochemical interference from uric acid and hydrogen peroxide at this potential is very small.     

Amperometric biosensor for the quantification of gentisic acid using polyphenol oxidase modified carbon paste electrode

The affinity of mushroom polyphenol oxidase (PPO) towards gentisic acid (GA), a metabolite of acetyl salicylic acid (ASA), is demonstrated by spectrophotometry and by electrochemical techniques. The enzyme can selectively recognize GA even in the presence of large excess of ASA and its metabolic derivatives (salicylic acid (SA) and salicyluric acid (SUA)). At -0.150 V, the sensitivity is (6.1+/-0.1)x10(4) NAM(-1), the response is linear up to 2.0x10(-4) M and the detection limit is 5.0x10(-5) M. The kinetic parameters, obtained from Eadie-Hofstee plots, are I(max)=51.4 nA and K(m)(app)=6.7x10(-4) M.     

Amperometric hydrogen peroxide biosensor based on a glassy carbon electrode modified with polythionine and gold nanoparticles

We report on a novel hydrogen peroxide biosensor that was fabricated by the layer-by-layer deposition method. Thionine was first deposited on a glassy carbon electrode by two-step electropolymerization to form a positively charged surface. The negatively charged gold nanoparticles and positively charged horseradish peroxidase were then immobilized onto the electrode via electrostatic adsorption. The sequential deposition process was characterized using electrochemical impedance spectroscopy by monitoring the impedance change of the electrode surface during the construction process. The electrochemical behaviour of the modified electrode and its response to hydrogen peroxide were studied by cyclic voltammetry. The effects of the experimental variables on the amperometric determination of H₂O₂ such as solution pH and applied potential were investigated for optimum analytical performance. Under the optimized conditions, the biosensor exhibited linear response to H₂O₂ in the concentration ranges from 0.20 to 1.6?mM and 1.6 to 4.0?mM, with a detection limit of 0.067?mM (at an S/N of 3). In addition, the stability and reproducibility of this biosensor was also evaluated and gave satisfactory results.

Amperometric biosensor based on D-aminoacid oxidase for the R-perindopril assay

A new amperometric biosensor based on D-aminoacid oxidase is described for the assay of R-perindopril. R-perindopril can be determined in the 400–¶20 nmol/L concentration range; the detection limit is ¶10 nmol/L. The selectivity was checked with S-perindopril, D- and L-proline, and polyvinylpyrrolidone. The main interfering species was D-proline. An automated system for the assay of R-perindopril based on the concept of flow injection with an amperometric biosensor (based on D-aminoacid oxidase) as detector is also described. The system is suitable for the on-line monitoring of R-perindopril at a sampling rate of 72 samples/h, in the linear range: 100 nmol/L –20 nmol/L with an RSD better than 0.09% (n = 10).     

Amperometric biosensor based on D-aminoacid oxidase for the R-perindopril assay

A new amperometric biosensor based on D-aminoacid oxidase is described for the assay of R-perindopril. R-perindopril can be determined in the 400-20 nmol/L concentration range; the detection limit is 10 nmol/L. The selectivity was checked with S-perindopril, D- and L-proline, and polyvinylpyrrolidone. The main interfering species was D-proline. An automated system for the assay of R-perindopril based on the concept of flow injection with an amperometric biosensor (based on D-aminoacid oxidase) as detector is also described. The system is suitable for the on-line monitoring of R-perindopril at a sampling rate of 72 samples/h, in the linear range: 100 nmol/L -20 nmol/L with an RSD better than 0.09% (n = 10).     

Amperometric determination of organophosphate pesticides using a acetylcholinesterase based biosensor made from nitrogen-doped porous carbon deposited on a boron-doped diamond electrode

Microchimica Acta - The authors describe an amperometric biosensor for the determination of organophosphate pesticides (OPs) via inhibition of the enzyme acetylcholinesterase (AChE). The enzyme was...     

Application studies of activated carbon derived from rice husks produced by chemical-thermal process--a review

The production of functional activated carbon materials starting from cheap natural precursors using environmentally friendly processes is a highly attractive subject in material chemistry today. Recently, much attention has been focused on the use of plant biomass to produce functional carbonaceous materials, encompassing economic, environmental and social issues. Besides the classical route to produce activated carbons from fossil materials, rice husk shows clear advantages in that it can generate a variety of cheap and sustainable carbonaceous materials with attractive nanostructure and functional patterns for a wide range of applications. From a comprehensive literature review, it was found that porous carbon that derived from rice husks, in addition to having wide availability, has fast kinetics and appreciable adsorption capacities too. Porous carbon materials also play a significant role in new applications such as catalytic supports, battery electrodes, capacitors, and gas storage. In this review, an extensive list of rice husks literature has been compiled. Conclusions have been drawn from the literature reviewed, and suggestions for future research are proposed.     

抗坏血酸在石墨烯微片修饰玻碳电极上的电化学行为及其测定

基于石墨烯微片修饰玻碳电极对抗坏血酸的电催化作用,建立了测定抗坏血酸的电化学分析方法。石墨烯微片修饰玻碳电极与裸玻碳电极相比,显著提高了抗坏血酸的氧化峰电流,降低了氧化峰电位,提高了测定的灵敏度。该电极测定抗坏血酸的线性范围为5.0×10-5～2.5×10-2mol/L,最低检测限为6.5×10-7mol/L(信噪比=3)。     

Amperometric phenol biosensor based on sol-gel silicate/Nafion composite film

An amperometric biosensor based on tyrosinase immobilized in silicate/Nafion composite film has been developed for the determination of phenolic compounds. The Nafion polymer in the composite was used not only to overcome the brittleness of the pure sol-gel-derived silicate film but also to increase the long-term stability of the biosensor. Tyrosinase was immobilized by a thin film of silicate/Nafion composite on a glassy carbon electrode. Phenolic compounds were determined by the direct reduction of biocatalytically-liberated quinone species at −200 mV versus Ag/AgCl (3 M NaCl). The process parameters for the fabrication of the enzyme electrode and various experimental variables such as pH and operating potential were explored for optimum analytical performance of the enzyme electrode. The biosensor can reach 95% of steady-state current in about 15 s. The sensitivities of the biosensor for catechol and phenol were 200 and 46 mA/M, respectively. A detection limit of 0.35 mM catechol was obtained with a signal-to-noise ratio of 3. The enzyme electrode retained 74% of its initial activity after 2 weeks of storage in 50 mM phosphate buffer at pH 7.     

Amperometric glucose biosensor based on platinum nanoparticle encapsulated with a clay

Electrically conductive hollow nanospheres with an average diameter between 100 and 200 nm were prepared via a one-step polymerization of aniline in the presence of lignosulfonate (LS) by using ammonium persulfate (APS) as the oxidant. The LS concentration and molar ratio between APS and aniline, the temperature and time for polymerization were adjusted to optimize morphology, structure and electrochemical properties. Uniform hollow nanospheres are best obtained at a concentration of 18 wt% of LS, at a polymerization temperature at 25 °C, at an APS/aniline molar ratio of 1:1, and at a polymerization time of 1 to 12 h. This kind of preparation of nanospheres represents a simple and general route to polymer hollow nanospheres of controllable size, high stability, and optimizable electroconductivity.     

Amperometric biosensor based on glucose dehydrogenase and plasma-polymerized thin films.

A novel design is described for an amperometric biosensor based on NAD(P)-dependent glucose dehydrogenase (GDH) combined with a plasma-polymerized thin film (PPF). The GDH is sandwiched between several nanometer thick acetonitrile PPFs on a sputtered gold electrode (PPF/GDH/PPF/Au). The lower PPF layer plays the role as an interface between enzyme and electrode because it is extremely thin, adheres well to the substrate (electrode), has a flat surface and a highly-crosslinked network structure, and is hydrophilic in nature. The upper PPF layer (overcoating) was directly deposited on immobilized GDH. The optimized amperometric biosensor characteristics covered 2.5-26 mM glucose concentration at +0.6 V of applied potential; the least-squares slope was 320 nA mM(-1) cm(-2) and the correlation coefficient was 0.990. Unlike conventional wet-chemical processes that are incompatible with mass production techniques, this dry-chemistry procedure has great potential for enabling high-throughput production of bioelectronic devices.     

Renewable silica sol–gel derived carbon composite based glucose biosensor

An amperometric mediated glucose biosensor has been developed based on a sol–gel derived carbon composite material. Glucose oxidase and the mediator vinylferrocene have been immobilised within the porous, rigid and organically modified silicate network in the composite material. The organic group in the silicate network controls the hydrophobicity of the electrode surface and thus limits the wettability of the electrode surface. Various important fabrication factors controlling the biosensor performance have been investigated systematically. The glucose biosensor can be renewed easily in a reproducible manner by a simple polishing step and it has a long operational lifetime. Applicability of the biosensor has been demonstrated in real samples and the results obtained by this biosensor corroborate well with a classical UV spectrophotometric technique.     

Amperometric biosensor for bisphenol A based on a glassy carbon electrode modified with a nanocomposite made from polylysine, single walled carbon nanotubes and tyrosinase

We have prepared a nanocomposite consisting of single-walled carbon nanotubes and polylysine. It was characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, and by UV/vis and FTIR spectroscopy. Tyrosinase was covalently immobilized on the nanocomposite, and the resulting bioconjugate deposited on a glassy carbon electrode to form a biosensor for bisphenol A. The biosensor was characterized by scanning electron microscopy and electrochemical impedance spectroscopy. Under optimized experimental conditions, the biosensor gives a linear response to bisphenol A in the 4.00 nM to 11.5 μM concentration range. Its sensitivity is 788 mA M^?1 cm^?2, and the lower detection limit is 0.97 nM (at an S/N of 3). The biosensor shows good repeatability, reproducibility and long-term stability. In a preliminary practical application, it was successfully applied to the determination of bisphenol A in leachates of plastic spoons.