A gold@silica core–shell nanoparticle-based surface-enhanced Raman scattering biosensor for label-free glucose detection

The gold nanostar@silica core–shell nanoparticles conjugated with glucose oxidase (GOx) enzyme molecules have been developed as the surface-enhanced Raman scattering (SERS) biosensor for label-free detection of glucose. The surface-immobilized GOx enzyme catalyzes the oxidation of glucose, producing hydrogen peroxide. Under laser excitation, the produced H₂O₂ molecules near the Au nanostar@silica nanoparticles generate a strong SERS signal, which is used to measure the glucose concentration. The SERS signal of nanostar@silica∼GOx nanoparticle-based sensing assay shows the dynamic response to the glucose concentration range from 25 μM to 25 mM in the aqueous solution with the limit of detection of 16 μM. The sensing assay does not show any interference when glucose co-exists with both ascorbic acid and uric acid. The sensor can be applied to a saliva sample.     

基于多壁碳纳米管和氧化锌纳米棒复合物的葡萄糖生物传感器(英文)

利用多壁碳纳米管(MWCNTs)和氧化锌(ZnO)纳米棒复合物膜构建了一种新的电流型葡萄糖生物传感器。MWCNTs-ZnO复合物在超声协助下通过静电配位的方式产生。其中,ZnO纳米棒的存在加强了该复合物催化氧化H2O2的能力,增加了响应电流。与单一的MWCNTs和ZnO相比,这种纳米复合物显示了更为有效地电催化活性。在此基础上,我们以MWCNTs-ZnO复合物膜为基底,用戊二醛交联法固定葡萄糖氧化酶,电聚合邻苯二胺(PoPD)膜为抗干扰层,构建了抗干扰能力强,稳定性好,灵敏度高,响应快的葡萄糖传感器。在+0.8V的检测电位下,该传感器对葡萄糖响应的线性范围为5.0×10-6~5.0×10-3mol·L-1(R=0.997),检测限为3.5×10-6mol·L-1(S/N=3),响应时间小于10s的葡萄糖生物传感器,常见干扰物质如抗坏血酸和尿酸不影响测定。     

Evaluation of glucose biosensors based on Prussian Blue and lyophilised, crystalline and cross-linked glucose oxidases (CLEC(R))

Glucose biosensors based on lyophilised, crystalline and cross-linked glucose oxidase (GOx, CLEC(R)) and commercially available lyophilised GOx immobilised on top of glassy carbon electrodes modified with electrodeposited Prussian Blue are critically compared. Two procedures were carried out for preparing the biosensors: (1) deposition of one layer of adsorbed GOx dissolved in an aqueous solution followed by deposition of two layers of low molecular weight Nafion(R) dissolved in 90% ethanol, and (2) deposition of two layers of a mixture of GOx with Nafion dissolved in 90% ethanol. The performance of the biosensors was evaluated in terms of linear response range for hydrogen peroxide and glucose, detection limit, and susceptibility to some common interfering species (ascorbic acid, acetaminophen and uric acid). The operational stability of the biosensors was evaluated by applying a steady potential of -50 mV versus Ag/AgCl to the glucose biosensor and injecting standard solutions of hydrogen peroxide and glucose (50 muM and 1.0 mM, respectively, in phosphate buffer) for at least 5 h in a flow-injection system. Scanning electron microscopy was used for visualisation of the Prussian Blue redox catalyst and in the presence of the different GOx preparations on the electrode surface.     

Amperometric uric acid sensors based on polyelectrolyte multilayer films

Uricase (UOx) and polyelectrolyte were used for preparation of a permselective multilayer film and enzyme multilayer films on a platinum (Pt) electrode, allowing the detection of uric acid amperometrically. The polyelectrolyte multilayer (PEM) film composed of poly(allylamine) (PAA) and poly(vinyl sulfate) (PVS) were prepared via layer-by-layer assembly on the electrode, functioning as H₂O₂-selective film. After deposition of the permselective film (PAA/PVS)₂PAA, UOx and PAA were deposited via layer-by-layer sequential deposition up to 10 UOx layers to prepare amperometric sensors for uric acid. Current response to uric acid was recorded at +0.6 V vs. Ag/AgCl to detect H₂O₂ produced from the enzyme reaction. The response current increased with increasing the number of UOx layers. Even in the presence of ascorbic acid, uric acid can be detected over the concentration range 10⁻⁶-10⁻³ M. The response current and deposited amount of UOx were affected by deposition bath pH and the addition of salt. The deposition of PAA/UOx film prepared in 2 mg ml⁻¹ solution (pH 11) of PAA with NaCl (8 mg ml⁻¹) and 0.1 mg ml⁻¹ solution (pH 8.5) of UOx with borate (100 mM) resulted in an electrode which shows the largest response to uric acid. The response of the sensor to uric acid was decreased by 40% from the original activity after 30 days.     

Minimization of Interferences in Flow Injection Amperometric Glucose Biosensor Based on Oxidation of Enzymatically‐produced H2O2

One of the major problems in amperometric biosensors based on detection of H₂O₂ produced by enzymatic reaction between oxidase enzymes and substrate is the interference of redox active compounds such as ascorbic acid (AA), dopamine (DA) and uric acid (UA). To minimize these interferences, sodium bismuthate was used for the first time as an insoluble pre‐oxidant in the flow injection (FI) amperometric glucose biosensor at a Glucose oxidase (GOx) immobilized Pt/Pd bimetallic modified pre‐anodized pencil graphite electrode (p.PGE). In this context, these interfering compounds were injected into a flow injection analysis (FIA) system using an injector which was filled with NaBiO₃. Thus, these interferents were converted into their redox inactive oxidized forms before reaching the electrode in the flow cell. While glucose was not influenced by the pre‐oxidant in the injector, the huge oxidation peak currents of the interferents decreased significantly in the biosensor. FI amperometric current time curves showed that the AA, DA and UA were minimized by 96 %, 86 %, and 98 % respectively, in the presence of an equivalent concentration of interferences in a 1.0 mM glucose solution. The proposed FI amperometric glucose biosensor exhibits a wide linear range (0.01–10 mM, R²=0.9994) with a detection limit of 2.4×10^?3 mM. Glucose levels in the artificial serum and two real samples were successfully determined using the fabricated FI amperometric biosensor.     

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.     

Preparation and characterization of Prussian blue nanowire array and bioapplication for glucose biosensing

Prussian blue nanowire array (PBNWA) was prepared via electrochemical deposition with polycarbonate membrane template for effective modification of glassy carbon electrode. The PBNWA electrode thus obtained was demonstrated to have high-catalytic activity for the electrochemical reduction of hydrogen peroxide in neutral media. This enabled the PBNWA electrode to show rapid response to H₂O₂ at a low potential of −0.1 V over a wide range of concentrations from 1 × 10⁻⁷ M to 5 × 10⁻² M with a high sensitivity of 183 μA mM⁻¹ cm⁻². Such a low-working potential also substantially improved the selectivity of the PBNWA electrode against most electroactive species such as ascorbic acid and uric acid in physiological media. A detection limit of 5 × 10⁻⁸ M was obtained using the PBNWA electrode for H₂O₂, which compared favorably with most electroanalysis procedures for H₂O₂. A biosensor toward glucose was then constructed with the PBNWA electrode as the basic electrode by crosslinking glucose oxidase (GOx). The glucose biosensor allowed rapid, selective and sensitive determination of glucose at −0.1 V. The amperometric response exhibited a linear correlation to glucose concentration through an expanded range from 2 × 10⁻⁶ M to 1 × 10⁻² M, and the response time and detection limit were determined to be 3 s and 1 μM, respectively.     

A biosensor prepared by co-entrapment of a glucose oxidase and a carbon nanotube within an electrochemically deposited redox polymer multilayer

A glucose biosensor based on a nanocomposite made by layer-by-layer electrodeposition of the redox polymer into a multilayer containing glucose oxidase (GOx) and single-walled carbon nanotubes (SWCNT) on a screen-printed carbon electrode (SPCE) surface was developed. The objectives of the electrodeposition of redox polymer are to stabilize further the multilayer using a coordinative cross-linked redox polymer and to wire the GOx. The electrochemistry of the layer-by-layer assembly of the GOx/SWCNT/redox polymer nanocomposite was followed by cyclic voltammetry. The resultant biosensor provided stable and reproducible electrocatalytic responses to glucose, and the electrocatalytic current for glucose oxidation was enhanced with an increase in the number of layers. The biosensor displayed a linear range from 0.5 to 6.0mM, a sensitivity of 16.4μA/(mMcm(2)), and a response time of about 5s. It shows no response to 0.05mM of ascorbic acid, 0.32mM of uric acid and 0.20mM of acetaminophen using a Nafion membrane covering the nanocomposite-modified electrode surface.     

A kinetic-spectrophotometric method for the determination of glucose in solutions

A kinetic-spectrophotometric method is proposed to determine glucose in solutions. Measurements were performed at 400 nm; the negative peak was obtained by subtracting the absorption spectra of myoglobin (Mb) before and after oxidation. In this method, glucose is added to a mixture of Mb and glucose oxidase. Glucose is oxidized by glucose oxidase and oxygen to gluconate and hydrogen peroxide is generated. The liberated hydrogen peroxide oxidizes the Mb heme (Fe²⁺) into Fe³⁺. The higher the glucose concentration added, the more the H₂O₂ generation, and the more the Mb oxidation (Fe²⁺ to Fe³⁺) and, as a result, the higher the absorbance at 400 nm (negative peak, lower absorbance value). The increments of added glucose are monitored by measuring the absorbance decay versus time (0–250 s) at 400 nm. Each glucose concentration has an accompanying unique absorbance value at 250 s. The higher the glucose concentrations, the lower the absorbance at 250 s (measured at 400 nm). The calibration curve for glucose was linear from 0.1 to 3.0 mM; the detection limit was found to be 0.025 mM. There was no interference from major substances present; the only interference was from species that react with H₂O₂ (ascorbic acid, uric acid, and urea) or that react with glucose (Cu²⁺ and Fe³⁺). Standard deviation in the determination was ±0.01 mM for a 1.3 mM glucose solution (n = 10). The text was submitted by the author in English.     

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.     

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.     

Cobalt nanoparticles anchored to porous silicon as a novel modifier for the construction of enzyme‐free hydrogen peroxide screen‐printed sensor

In this work, a screen‐printed carbon electrode (SPCE) was modified with a cobalt/porous silicon (Co@PSi) nanocomposite powder to develop a nonenzymatic sensor for the detection of hydrogen peroxide. The Co@PSi nanocomposite was synthesized through the chemical reaction between silicon powder in a HF/HNO₃ solution and cobalt cations. In this process, cobalt nanoparticles were anchored on the porous silicon. The structure and morphology of the synthesized nanocomposite were investigated by X‐ray diffraction, Fourier transform infrared spectroscopy, X‐ray photoemission spectroscopy, energy dispersive X‐ray spectroscopy, and field‐emission scanning electron microscopy. The constructed nonenzymatic, screen‐printed sensors based on the Co@PSi nanocomposite showed perfect electrocatalytic oxidation response to hydrogen peroxide over the range 1–170 and 170–3,770 μmol/L with the limit of detection of 0.8 μmol/L. In addition, the Co@PSi‐SPCE sensor exhibited good selectivity for the determination of H₂O₂ in the presence of common interfering species including glucose, ascorbic acid, uric acid, dopamine, nitrate, and nitrite ions. The constructed electrochemical sensor was successfully used for the determination of H₂O₂ in real samples.     

Activated platinum electrodes as transducer for a glucose sensor using glucose oxidase in a photopolymer membrane

A planar platinum electrode was covered by a photopolymer membrane containing glucose oxidase (GOD) to construct an amperometric glucose sensor. The application of a photopolymer system in membrane formation gives the opportunity to manufacture cheap biosensors with good reproducibility by means of automated techniques and to miniaturise sensors using photolithography. The electrodes were pretreated mechanically and chemically resulting in a half-wave potential (E_1/2) of the H₂O₂ oxidation shifted towards more negative potentials. This shift allows the determination of glucose at a low working potential (300 mV vs. SCE) without addition of mediators. The important advantage of such applied potential decreasing lies in minimising the interference of oxidisable substances such as uric acid, bilirubin and paracetamol. The selectivity to ascorbic acid could also be proved without the application of additional protection layers. The glucose sensor developed has a high life-time, selectivity and sensitivity and a linear working concentration range from 0.05 up to 10 mmol/l of glucose. The sensor was used for the glucose determination in human serum samples with a very good correlation to a common photometric reference method. Received: 13 July 1996 / Revised: 11 September 1996 / Accepted: 14 September 1996     

Enhanced amperometric response of a glucose oxidase and horseradish peroxidase based bienzyme glucose biosensor modified with a film of polymerized toluidine blue containing reduced graphene oxide

Reduced graphene oxide (RGO) was used to construct a bienzyme biosensor containing horseradish peroxidase (HRP) and glucose oxidase (GOx). A poly(toluidine blue) (pTB) film containing RGO acted as both enzyme immobilization matrix and electron transfer mediator. The bienzyme biosensor was characterized by electrochemical techniques and displays a highly sensitive amperometric response to glucose and hydrogen peroxide (H₂O₂) at a potential as low as −0.1 V (vs. SCE). It is shown that use of RGO causes a strong enhancement on the amperometric responses. H₂O₂ formed by the action of GOx in the presence of oxygen can be further reduced by HRP in the pTB film contacting the RGO modified electrode. In the absence of oxygen, glucose oxidation proceeds by another mechanism in which electron transfer occurs from GOx to the electrode and with pTB acting as the mediator. Amperometric responses to glucose and H₂O₂ follow Michaelis-Menten kinetics. The experimental conditions were optimized, and under these conditions glucose can be determined in the 80 μM to 3.0 mM range with a detection limit of 50 μM. H₂O₂, in turn, can be quantified in up to 30.0 μM concentration with a detection limit of 0.2 μM. The bienzyme biosensor is reproducible, repeatable and stable. Finally, it has been successfully applied to the determination of glucose in plasma samples.

Schematic representation of glocuse detection at GCE/RGO/pTB-HRP-GOx.

     

Optical determination of glucose and hydrogen peroxide using a nanocomposite prepared from glucose oxidase and magnetite nanoparticles immobilized on graphene oxide

Fe₃O₄ nanoparticles were deposited on sheets of graphene oxide (GO) by a precipitation method, and glucose oxidase (GOx) was then immobilized on this material to produce a GOx/Fe₃O₄/GO magnetic nanocomposite containing crosslinked enzyme clusters. The 3-component composite functions as a binary enzyme that was employed in a photometric method for the determination of glucose and hydrogen peroxide where the GOx/Fe₃O₄/GO nanoparticles cause the generation of H₂O₂ which, in turn, oxidize the substrate N,N-diethyl-p-phenylenediamine to form a purple product with an absorption maximum at 550 nm. The absorbance at 550 nm can be correlated to the concentration of glucose and/or hydrogen peroxide. Under optimized conditions, the calibration plot is linear in the 0.5 to 600 μM glucose concentration range, and the detection limit is 0.2 μM. The respective plot for H₂O₂ ranges from 0.1 to 10 μM, and the detection limit is 0.04 μM. The method was successfully applied to the determination of glucose in human serum samples. The GOx/Fe₃O₄/GO nanoparticles are reusable.

A highly sensitive nonenzymatic glucose sensor based on NiO-modified multi-walled carbon nanotubes

A highly sensitive and selective glucose biosensor has been constructed by using highly dispersed NiO nanoparticles supported on well-aligned MWCNTs (NiO/MWCNTs) as sensing interface. The NiO/MWCNTs nanocomposite was synthesized by magnetron sputtering deposition of NiO nanoparticles on vertically aligned carbon nanotubes. The nanocomposite electrode showed high electrochemical activity towards the oxidation of glucose in 0.20 M NaOH solution. At an applied potential of +0.50 V, it gives a fast response time (< 5 s) and a linear dependence (R?=?0.997) on the glucose concentration up to 7.0 mM with an extraordinarily high sensitivity of 1.77 mA mM^-1 cm^-2 and a detection limit of 2 μM. The interference by the oxidation of common interfering species such as ascorbic acid, dopamine, uric acid, lactose, and fructose is effectively avoided. The electrode was used to analyze glucose concentration in human serum samples. It allows highly sensitive, stable, and fast amperometric sensing of glucose, which is promising for the development of nonenzymatic glucose sensors.     

Nanoporous platinum–cobalt alloy for electrochemical sensing for ethanol,hydrogen peroxide,and glucose

Nanoporous platinum–cobalt (NP–PtCo) alloy with hierarchical nanostructure is straightforwardly fabricated by dealloying PtCoAl alloy in a mild alkaline solution. Selectively etching Al resulted in a hierarchical three-dimensional network nanostructure with a narrow size distribution at 3 nm. The as-prepared NP–PtCo alloy shows superior performance toward ethanol and hydrogen peroxide (H₂O₂) with highly sensitive response due to its unique electrocatalytic activity. In addition, NP–PtCo also exhibits excellent amperometric durability and long-term stability for H₂O₂ as well as a good anti-interference toward ascorbic acid, uric acid, and dopamine. The hierarchical nanoporous architecture in PtCo alloy is also highly active for glucose sensing electrooxidation and sensing in a wide linear range. The NP–PtCo alloy holds great application potential for electrochemical sensing with simple preparation, unique catalytic activity, and high structure stability.     

Electrodeposited glucose oxidase/anionic clay for glucose biosensors design

An amperometric glucose biosensor was developed using an anionic clay matrix (layered double hydroxide (LDH), Ni/Al-NO₃) for the immobilization of glucose oxidase (GOx). The biofilm was prepared by electrodeposition of the clay and GOx and subsequent cross-linking with glutaraldeyde. The Pt surface modified with the Ni/Al-NO₃ shows a much reduced noise, giving rise to a better signal to noise ratio for the currents relative to H₂O₂ oxidation, and a linear range for H₂O₂ determination wider than the one observed for bare Pt electrodes. Under the optimised operative conditions, the performances of the biosensor have been evaluated by measuring the steady-state currents (at +0.45 V versus SCE) to increasing concentrations of glucose in “air saturated” 0.1 M phosphate buffer (pH 7.0). Both batch and flow injection modes were explored. The response to glucose was linear up to 8.0 and 12.0 mM, and the sensitivities were 7.7 ± 0.1 and 19.1 ± 0.2 mA M⁻¹ cm⁻², respectively. The current response of the biosensors does not significantly change for 15 consecutive days in batch and for 10 days in flow, at least, if stored at 4 °C in phosphate buffer, when not in use. The effects of interferants and applicability to fruit juices and soft drinks analysis of the biosensor were also investigated.     

Enhancement of the sensitivity and selectivity of oxidation of H2O2 on platinum wire at low working potential by platinization and covering of heteropolypyrrole film for amperometric micro-biosensor construction

A microelectrode for glucose determination was constructed by immobilization of glucose oxidase (GOx) on a platinized platinum (Pt) by electrochemical polymerization of a solution containing GOx, pyrrole, and a substituted pyrrole, 4-(3-pyrrolyl)-4-oxobutyric acid. Due to platinization and covering with the polymerized heteropolypyrrole (hPPy) film, the electrode prepared showed high sensitivity to H₂O₂ at a low potential and significantly reduced the response to electroactive compounds, such as ascorbate, urate and 4-acetamidophenol. Working at 200 mV (vs. SCE) the electrode showed a linear response to glucose from 1.6 to 10 mM with a high sensitivity of 1 μA/mM, whereas the response to 1 mM ascorbate, urate, and 4-acetamidophenol was 0.53 μA, 18 nA and 4 nA, respectively, which was about 2.5%, 1.0% and 1.0% of that at a bare electrode. The stability of the electrode was tested at intervals of three or five days, and each test lasted about two hours. After 6 months examination, only 30% of its activity was lost.     

Amperometric glucose sensor based on glucose oxidase immobilized on gelatin-multiwalled carbon nanotube modified glassy carbon electrode

We investigated the direct electrochemistry of glucose oxidase (GOx) at gelatin-multiwalled carbon nanotube (GCNT) modified glassy carbon electrode (GCE). GOx was covalently immobilized onto GCNT modified GCE through the well known glutaraldehyde (GAD) chemistry. The immobilized GOx showed a pair of well-defined reversible redox peaks with a formal potential (E⁰′) of ? 0.40 V and a peak to peak separation (ΔE_p) of 47 mV. The surface coverage concentration (Г) of GOx in GCNT/GOx/GAD composite film modified GCE was 3.88 × 10^? 9 mol cm^? 2 which indicates the high enzyme loading. The electron transfer rate constant (k_s) of GOx immobilized onto GCNT was 1.08 s^? 1 which validates a rapid electron transfer processes. The composite film shows linear response towards 6.30 to 20.09 mM glucose. We observed a good sensitivity of 2.47 μA mM^?1 cm^? 2 for glucose at the composite film. The fabricated biosensor displayed two weeks stability. Moreover, it shows no response to 0.5 mM of ascorbic acid (AA), uric acid (UA), acetaminophen (AP), pyruvate (PA) and lactate (LA) which shows its potential application in the determination of glucose from human serum samples. The composite film exhibits excellent recovery for glucose in human serum at physiological pH with good practical applicability.