A Chemiluminescence Optical Fiber Glucose Biosensor Based on Co-immobilizing Glucose Oxidase and Horseradish Peroxidase in a Sol-gel Film

An optical fiber bienzyme sensor based on the luminol chemiluminescent reaction was developed and demonstrated to be sensitive to glucose. Glucose oxidase(GOD) and horseradish peroxidase(HRP) were co-immobilized by microencapsulation in a sol-gel film derived from tetraethyl orthosilicate(TEOS). The calibration plots for glucose were established by the optical fiber glucose sensor fabricated by attaching the bienzyme silica gel onto the glass window of the fiber bundle. The linear range was 0 2-2 mmol/L and the detection limit was approximately 0 12 mmol/L. The relative standard deviation was 5.3% ( n =6). The proposed biosensor was applied to glucose assay in ofloxacin injection successfully.

Third Generation Horseradish Peroxidase Biosensor Based on Self-assembling Carbon Nanotubes to Gold Electrode Surface

A third-generation horseradish peroxidase (HRP) biosensor has been developed by adsorbing HRP on multi-wall carbon nanotube (MWNTs) monolayer modified gold electrode surface. The assembly process was investigated by electrochemical and spectroscopic techniques. Results showed that the immobilized HRP exhibited direct electrochemical behavior toward the reduction of H2O2. The resulting biosensor shows a fast amperometric response (<2 s) to H2O2. The linear response range was from 5.0×10-7～1.0×10-5 mol/L with a detection limit of 1.0×10-7mol/L. Moreover, the biosensor has a good reproducibility, and long-term stability.

Development of an Amperometric Hydrogen Peroxide Biosensor based on the Immobilization of Horseradish Peroxidase onto Nickel Ferrite Nanoparticle-Chitosan Composite

Nickel ferrite(NiFe_2O_4) nanoparticles have been dispersed in chitosan solution in order to fab ricate nanocomposite films.Horseradish peroxidase(HRP) has been immobilized onto this chitosan NiFe_2O_4 nanocomposite film via physical adsorption.The size of the NiFe_2O_4 nanoparticles has been estimated us ing X ray diffraction pattern and scanning electron microscopy(SEM) to be 40±9 nm.The chitosan NiFe_2O_4 nanocomposite film and HRP/chitosan NiFe_2O_4 bioelectrode have been characterized using SEM technique.The HRP/chitosan NiFe_2O_4 nanocomposite bioelectrode has a response time of 4 s,linearity as 0.3 to 12 m M of H2O2,sensitivity as 22 n A/m M.The effects of p H and the temperature of the immobilized HRP electrode have also been studied.

Horseradish Peroxidase Biosensor to Detect Zinc Ions in Aqueous Solutions

Maize tassel-multiwalled carbon nanotube (MT-MWCNT) composite has been used as a matrix for physical adsorption of horseradish peroxidase (HRP) onto the surface of a glassy carbon electrode through electrostatic interactions. The HRP/MT-MWCNT biosensor was applied for the detection of Zn2+ in aqueous solution. The biosensor designed was able to determine Zn2+ in the range of 0.35 - 12 mg/L with a detection limit of 7.5 μg/L. The inhibition was found to be reversible and uncompetitive when data were modeled using the Dixon and Cornish-Bowden plots. The biosensor was found to have good repeatability, reproducibility and high selectivity. The developed biosensor can be used to detect other HRP inhibiting trace metal ions.

Nanobiocomposite Electrochemical Biosensor Utilizing Synergic Action of Neutral Red Functionalized Carbon Nanotubes

An amperometric hydrogen peroxide biosensor using a nanobiocomposite based on neutral red modified carbon nanotubes and co-immobilized glucose oxidase and horseradish peroxidase is reported. Modification of the nanobiocomposite electrode with neutral red resulted in a sensitive, low-cost and reliable H_2O_2 sensor. The use of carbon nanotubes, as the conductive part of the composite, facilitated fast electron transfer rates. The biosensor was characterized for the influence of p H, potential and temperature. A remarkable feature of the biosensor is the detection of H_2O_2 at low applied potentials where the noise level and interferences are minimal. The sensor has a fast steady-state measuring time of 10 s with a quick response(2 s). The biosensor showed a linear range from 15 n M to 45 m M of H_2O_2 and a detection limit of 5 n M. Nafion, which is used as a binder, makes the determination free from other electroactive substances. The repeatability, reproducibility,stability and analytical performance of the sensor are very good.

Hydrogen peroxide biosensor based on electrodeposition of zinc oxide nanoflowers onto carbon nanotubes film electrode

A new amperometric biosensor for hydrogen peroxide was developed based on adsorption of horseradish peroxidase at the glassy carbon electrode modified with zinc oxide nanoflowers produced by electrodeposition onto multi-walled carbon nanotubes （MWNTs） film. The morphology of the MWNTs/nano-ZnO electrode has been investigated by scanning electron microscopy （SEM）, and the electrochemical performance of the electrode has also been studied by amperometric method. The resulting electrode offered an excellent detection for hydrogen peroxide at -0.11 V with a linear response range of 9.9×10^-7 to 2.9×10^-3 mol/L with a correlation coefficient of 0.991, and response time 〈5 s. The biosensor displays rapid response and expanded linear response range, and excellent stability.

A Novel Biomolecular Immobilization Matrix Based on Nanoporous ZnO/Chitosan Composite Film for Amperometric Hydrogen Peroxide Biosensor

A novel ZnO/Chitosan composite matrix was developed to fabricate the H2O2 biosensor. This material combined the advantages of inorganic species, ZnO, and organic polymer, chitosan. Horseradish peroxidase immobilized in the material maintained its activity well as the usage of glutaraldehyde was avoided. The activity of enzyme was 7.9 times greater than the cross-linked enzyme. The parameters affecting the fabrication and experimental conditions of biosensors were optimized. With the aid of hydroquinone mediator, the biosensor had a fast response of less than 10 s. The linear range was 5.0×10-6 to 2.0× 10-3 mol/L with a sensitivity of 43.8 μA L/mmol. This matrix can also be used to immobilize other biomolecule.

Direct electrochemistry and electrocatalysis of horseradish peroxidase immobilized on L-glutathione self-assembled monolayers

A novel hydrogen peroxide biosensor has been fabricated based on covalently linked horseradish peroxidase （HRP） onto L- glutathione self-assembled monolayers （SAMs）. The SAMs-based electrode was characterized by electrochemical methods, and direct electrochemistry of HRP can be achieved with formal potential of-0.242 V （vs. saturated Ag/AgCl） in pH 7 phosphate buffer solution （PBS）, the redox peak current is linear to scan rate and rate constant can be calculated to be 0.042 s^-1. The HRP-SAMs- based biosensors show its better electrocatalysis to hydrogen peroxide in the concentration range of 1 × 10^-6 mol/L to 1.2 × 10^-3 mol/L with a detection limit of 4 × 10^-7 mol/L. The apparent Michealis-Menten constant is 3.12 mmol/L. The biosensor can effectively eliminate the interferences of dopamine, ascorbic acid, uric acid, catechol and p-acetaminophen.

A Novel Reagentless Biosensor Constructed by Layer-by-Layer Assembly of HRP and Nile Blue Premixed with Polyanion

A novel reagentless biosensor constructed by the organic dye nile blue (NB) and horseradish peroxidase (HRP) has been fabricated via layer-by-layer (LBL) self-assembly technique. NB premixed with polyanion poly (sodium-p-styrenesulfonate) (PSS) acts as the mediator between the immobilized HRP and the electrode surface. The response of the biosensor to hydrogen peroxide has been investigated. The linear range of the biosensor to hydrogen peroxide was from 0.20 mmol/L to 7.03 mmol /L with a sensitivity of 8.45 μA/(mmol/L).

Preparation of γ-Al_2O_3 Ultrafine Particlesand Its Application in Hydrogen Peroxide Biosensor

In this article, we illustrated the preparation method of γ Al 2O 3 ultrafine particles. The particle size and morphology were decided by a transmission electron microscopy (TEM) and crystal patterns were determined by an X ray diffractometer (XRD). γ Al 2O 3 ultrafine particles have ultra characters in physics and chemistry, and the hydrogen peroxide biosensors based on it display not only fast response and high sensitivity, but also good stability.

A New Amperometric Biosensor Based on HRP/Nano-Au/L-Cysteine/Poly（o-Aminobenzoic acid）-Membrane-Modified Platinum Electrode for the Determination of Hydrogen Peroxide

The third generation amperometric biosensor for the determination of hydrogen peroxide （H2O2） has been described. For the fabrication of biosensor, o-aminobenzoic acid （oABA） was first electropolymerized on the surface of platinum （Pt） electrode as an electrostatic repulsion layer to reject interferences. Horseradish peroxidase （HRP） absorbed by nano-scaled particulate gold （nano-Au） was immobilized on the electrode modified with polymerized o-aminobenzoic acid （poABA） with L-cysteine as a linker to prepare a biosensor for the detection of H2O2. Amperometric detection of H2O2 was realized at a potential of ＋20 mV versus SCE. The resulting biosensor exhibited fast response, excellent reproducibility and sensibility, expanded linear range and low interferences. Temperature and pH dependence and stability of the sensor were investigated. The optimal sensor gave a linear response in the range of 2.99×10^-6 to 3.55×10^-3 mol·L^-1 to H2O2 with a sensibility of 0.0177 A·L^-1·mol^-1 and a detection limit （S/N = 3） of 4.3×10^-7 mol·L^-1. The biosensor demonstrated a 95% response within less than 10 s.

Amperometric Biosensor for Hydrogen Peroxide Based on Electrodeposited Sub-micrometer Gold Modified Glassy Carbon Electrode

A new type of hydrogen peroxide amperometric biosensor was fabricated based on electrochemically deposited sub-micrometer Au particles (sm-Au) on a glassy carbon electrode (GCE). Electrochemical deposition condition was optimized for obtaining uniformly distributed sub-micrometer sized Au array on the electrode surface. The hy-drogen peroxide sensor was fabricated by adsorbing phenothiazine methylene blue (MB) molecules on the surface of sm-Au and covering a cross-linked horseradish peroxidase (HRP) layer, labeled as HRP/MB/sm-Au/GCE. The characteristics of this biosensor were evaluated with respect to applied potential and pH. The amperometric re-sponse of the sensor was linear to the H2O2 concentration over a wide range of 9.9×10-61.11×10-2 mol/L. A detection limit (s/n=3) of 3.0×10-6 mol/L H2O2 was estimated for a sampled chronoamperometric detection at 1.5 min after potential step of 200 to -400 mV vs. SCE. The immobilized MB molecules shuttled electrons at a=0.77 and an apparent electron transfer rate constant of 0'sk=0.053 s-1. Interference of ascorbic acid, dopamine and uric acid was investigated. This sensor has very good stability and reproducibility for long-term use.

A novel hydrogen peroxide biosensor based on the BPT/AuNPs/graphene/HRP composite

A novel hydrogen peroxide biosensor based on the BPT/AuNPs/graphene/HRP composite was developed. Firstly, graphene was prepared under the protection of polyvinylpyrrolidone (PVP), and then the AuNPs/graphene composite was synthesized via in situ decoration. Using biphenyldimethanethiol (BPT) as a connector, the AuNPs/graphene composite was immobilized on the surface of the Au electrode, and whereafter the horseradish peroxidase (HRP) was decorated on the surface of the composite by adsorption. The morphology and structure of the products were characterized by XRD, SEM, TEM and UV-visible spectroscopy. The electrocatalytic performance of the resulting BPT/AuNPs/grapheme/HRP composite (namely, biosensor) was studied by electrochemical instrument. The results show that the biosensor has high sensitivity and fast response to H2O2. In the solution of pH 7.4 with potential -0.2V, the linear response of the biosensor to H2O2 ranges from 5.0×10-6 to 2.5×10-3M with the detection limit of 1.5×10-6M.

Biosensor Sensitive to Hydrogen Peroxide via Methylene Blue Incorporated into Nafion Film as an Electron Transfer Mediator

Biosensor sensitive to hydrogen peroxide was made via methylene blue in Nafion gel as an electron transfer mediator. Cyclic voltommetry and chronoamperometry were for the first time used to illustrate the suitability of electrical communication between immobilized horseradish peroxidase and a glassy carbon electrode via methylene blue incorporated into a (Nafion) perfluorosulfonic acid cation exchange polymer film. The methylene blue mediator was strongly reatined inside Nafion film through hydrophobic interactions. Effects of applied potential, ionic strength, temperature and pH on the biosensor were investigated. The biosensor possessed a variety of advantages including high sensitivity, long term stability and rapid response to hydrogen peroxide with a detection limit of 0.1 μmol/L. The high sensitivity of the biosensor was due to the high efficiency of electron transfer between immobilized horseradish peroxidase and the electrode via methylene blue.

Direct Electrochemistry of Horseradish Peroxidase Immobilized in a Low Molecular Weight Gel

The ternary system of dodecylpyridinium bromide(DDPB)/acetone/H2O with appropriate composition can form a gel spontaneously and the gel is stable in hydrophobic ionic liquid 1-butyl-3-methylimidazolium hexafluorophos-phate([Bmim]PF_(6)).Based on the gelation phenomenon we observed,the low molecular weight gelator(LMWG)was first tried to immobilize horseradish peroxidase(HRP)on glassy carbon electrode(GCE).The scanning elec-tron microscope(SEM)images,the UV-Vis spectra and the bioactivity measurement indicate that the gel is suitable for the immobilization of HRP.The direct electrochemistry of the HRP-gel modified GCE(HRP-gel/GCE)in[Bmim]PF_(6)shows a pair of well-defined and quasi-reversible redox peaks with the heterogeneous electron transfer rate constant(ks)being 14.4 s^(−1),indicating that the direct electron transfer between HRP and GCE is fast.The HRP-gel/GCE is stable and reproducible.Also the electrode exhibits good electrocatalytic effect on the reduction of trichloroacetic acid(TCA),showing good promise in bioelectrocatalysis.

A photonanozyme with light-empowered specific peroxidasemimicking activity

Although nanozymes have been widely developed,directly utilizing light to drive catalytic reactions like natural photoenzymes still remains challenging.Herein,we propose that photonanozymes(PNZs),as a novel kind of nanozyme,exclusively possess enzyme-mimicking activity under illumination.Only in the presence of visible light,the as-synthesized TiO_(2) proposed in this contribution shows excellent specificity of peroxidase-like without any oxidase-or catalase-like activity.The driving force of the light-empowered peroxidase-like photonanozymatic activity is explicated in terms of the photogenerated hot charge carriers in TiO_(2) PNZs and the accompanied reactive oxygen species.The co-substrates for photonanozymatic reaction over TiO_(2) PNZs facilitate the formation of the precarious and reactive peroxo-oxygen bridge between TiO_(2) and H_(2)O_(2),enabling the catalytic specificity.With the TiO_(2) PNZ-based biosensing platform for visual glucose detection exemplifying the concept of the application of PNZs,this work may evoke more inspirations to explore strategies for enlarging the scope of photoenzyme mimics.

基于纳米酶构建比色生物传感器用于总抗氧化能力分析

总抗氧化能力(TAC)在评价抗氧化性食品和监测人体氧化应激水平方面具有重要作用。为实现对TAC的超灵敏检测,以3,3′,5,5′-四甲基联苯胺(TMB)为显色剂、高温热解策略制备的铁-氮共掺杂碳基纳米酶(Fe-N/C)为催化剂、抗坏血酸(AA)为抑制剂制备了一种新型比色传感器。结果表明:Fe-N/C具有良好的类过氧化物酶催化活性和较强的底物亲和力,此外,由于AA的还原性对反应体系的催化氧化有抑制效果,导致吸光度降低以及颜色褪去,从而可用于AA的灵敏检测;该传感器在AA浓度为0.1~160μmol/L范围内与吸光度呈良好的线性关系,R^(2)=0.9972,检出限为0.03μmol/L。以AA为抗氧化剂模型,测定了猕猴桃、橘汁和维生素C片的TAC,加标回收率为92.69%~105.45%,相对标准偏差<2%,为食品TAC的快速、简便检测提供了新策略。

基于静电吸附多层膜固定酶的过氧化氢生物传感器的研究

以玻碳电极为基底 ,电聚合 2 ,6 吡啶二甲酸 (PDC) ,使形成一带负电的界面 ,再通过静电吸附自组装一层聚阳离子聚丙烯胺 (PAH) ,用于静电吸附固定辣根过氧化物酶并以此方法固定多层酶膜制备过氧化氢传感器 .探讨了工作电位、介体浓度、pH对电极响应的影响 ,考察了电极的重现性、干扰及使用寿命 .该传感器在H2 O2 浓度 4 6× 10 -6～ 3 5× 10 -3 mol/L范围内有线性响应 ,检出限为 2× 10 -6mol/L .电极在用于实际试样回收率的测定中 。

基于聚硫堇和纳米金共修饰的过氧化氢生物传感器的研究

用循环伏安法将电子媒介体硫堇电聚合在铂电极上，使其表面形成均匀的带负电的聚合膜层，通过静电吸附作用固定表面带正电荷的辣根过氧化物酶，接着吸附纳米金，然后再利用纳米金吸附固定一层辣根过氧化物酶，制成了新型过氧化氢生物传感器。实验发现，该传感器增加了酶的吸附量，响应快、灵敏度高、稳定性好，对H2O2表现出良好的响应特性。检测范围为5．2×10^-7～2.0×10^-3moL／L，检出限为1，7×10^-7mol／L，并具有抗尿酸、抗坏血酸等干扰的特点。

聚苯胺修饰的辣根过氧化物酶电极的研究

采用电化学聚合法制备聚苯胺膜 ,并通过静电吸附固定辣根过氧化物酶 ,形成聚苯胺修饰的辣根过氧化物酶电极 .聚苯胺在电极与酶分子之间传递电荷 ,因此 ,在没有额外的电子媒介体的条件下 ,这种酶电极对H2 O2 的电流响应高达 2 5 μA ,响应时间小于 15s .酶电极与流动注射分析相结合构成实验系统 ,可以测量 0 1mmol·l-1H2 O2 ,表观米氏常数为Km=9 5 1mmol·l-1.