Flow Potentiometric Injection Analysis of Uric Acid Using Lipid Stabilized Films with Incorporated Uricase on ZnO Nanowires

A novel potentiometric uric acid biosensor was fabricated by immobilization of uricase into stabilized lipid films using zinc oxide (ZnO) nanowires as measuring electrode. Uricase was incorporated into the lipid film prior polymerization on the surface of well aligned ZnO nanowires resulting in a sensitive, selective, stable and reproducible uric acid biosensor. The potentiometric response was twice as large from previously reported values due to the presence of a cationic lipid in the lipid film. The sensor response had no interferences by normal concentrations of ascorbic acid, glucose, urea, proteins and lipids.     

Potentiometric Cholesterol Biosensor Based on ZnO Nanowalls and Stabilized Polymerized Lipid Film

A novel potentiometric cholesterol biosensor was fabricated by immobilization of cholesterol oxidase into stabilized lipid films using zinc oxide (ZnO) nanowalls as measuring electrode. Cholesterol oxidase was incorporated into the lipid film prior polymerization on the surface of ZnO nanowalls resulting in a sensitive, selective, stable and reproducible cholesterol biosensor. The potentiometric response was 57 mV/ decade concentration. The sensor response had no interferences by normal concentrations of ascorbic acid, glucose, and urea, proteins and lipids. The present biosensor could be implanted in the human body because of the biocompatibility of the lipid film.     

Theoretical analysis of growth of ZnO nanorods on the amorphous surfaces

Semiconductor nanorod arrays on a substrate have a preferential alignment orientation that minimizes the excessive free energy of the system. In the case of wet chemically synthesized zinc oxide (ZnO) nanorod on the amorphous surfaces, the thermodynamic driving force determines the orientation to be normal to the surface. Among the various kinds of amorphous surfaces, the spherical seed layer composed of ZnO precursors gives isotropic radially aligned arrays. For other surfaces, such as wrinkled and planar ZnO precursor thin film, nanorod arrays are aligned to be perpendicular to the tangential line of the surface. The maximum value of the aspect ratio of the nanorod is determined by the thermodynamic relationship. The number density of nanorods per unit precursor particles decreases with increasing contact angle of the seed particles.     

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。     

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.     

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).     

Ceramic Carbon/Polypyrrole Materials for the Construction of Bienzymatic Amperometric Biosensor for Glucose

Amperometric enzymatic biosensors have high selectivity and simplicity in use. It has advantages over other analytical methods in biochemistry, pharmacology, so it evokes strong interests1,2. Generally, the detection mode involved in oxidase based biosensors is often based on the electrochemical detection of hydrogen peroxide directly3,4. However the direct oxidation of hydrogen peroxide requires a relative high working potential (exceeding ca. 0.6 V vs. SCE), at which many biological sub…     

Glucose Biosensor Based on Multi‐Walled Carbon Nanotube Modified Glassy Carbon Electrode

An amperometric glucose biosensor based on multi‐walled carbon nanotube (MWCNT) modified glassy carbon electrode has been developed. MWCNT‐modified glassy carbon electrode was obtained by casting the electrode surface with multi‐walled carbon nanotube materials. Glucose oxidase was co‐immobilized on the MWCNT‐modified glassy carbon surface by electrochemical deposition of poly(o‐phenylenediamine) film. Enhanced catalytic electroreduction behavior of oxygen at MWCNT‐modified electrode surface was observed at a potential of ?0.40 V (vs. Ag|AgCl) in neutral medium. The steady‐state amperometric response to glucose was determined at a selected potential of ?0.30 V by means of the reduction of dissolved oxygen consumed by the enzymatic reaction. Common interferents such as ascorbic acid, 4‐acetamidophenol, and uric acid did not interfere in the glucose determination. The linear range for glucose determination extended to 2.0 mM and the detection limit was estimated to be about 0.03 mM.     

Amine-terminated organosilica nanosphere functionalized prussian blue for the electrochemical detection of glucose

A new glucose biosensor had been developed by immobilizing positively charged gold nanoparticles (PGNs) on organosilica nanosphere functionalized prussian blue (OSiFPB)-modified gold electrode. The OSiFPB compound could not only effectively prevent the leakage of the PB mediator during measurements, but also easily form stable film on the electrode surface with efficient redox-activity and excellent conductivity. Furthermore, with the negatively charged surface of OSiFPB, this film could be used as an interface to adsorb the PGNs, which provided a congenial microenvironment for adsorbing biomolecules and decreased the electron-transfer impedance. So, with glucose oxidase as a model biomolecular, the proposed sensor showed rapid and highly sensitive amperometric response to glucose and this immobilization approach effectively improved the stability of the electron-transfer mediator. This work would be promising for construction of biosensor and bioelectronic devices.     

Plasma-Polymerized Thin Films for Enzyme Immobilization in Biosensors

Abstract

Polymer films deposited on thin film noble metal electrodes on silicon chips, utilizing plasma polymerization are shown to be suited for immobilization of enzymes. Glucose oxidase is covalently coupled via amino- or carboxyl-groups of polymer films made by plasma polymerization of 2-amino-benzotrifluoride, acrylic or methacrylic acid. The concentration of these active surface groups increases by after-treatment in an ammonia- or oxygen-plasma. A biosensor consisting of a thin film metal electrode, plasma polymer film and immobilized glucose oxidase shows an amperometric response to glucose with a fast response time.     

An amperometric glucose biosensor based on glucose oxidase immobilized in electropolymerized poly(o-aminophenol) and carbon nanotubes composite film on a gold electrode.

An amperometric glucose biosensor is developed that is based on immobilization of glucose oxidase (GOD) in a composite film of poly(o-aminophenol) (POAP) and carbon nanotubes (CNT), which are electrochemically co-polymerized at a gold (Au) electrode. Because of the high surface per volume ratio and excellent electrical conductivity of CNT, the biosensor based on an Au/POAP/CNT/GOD electrode has lower detection limit (0.01 mM), larger maximum response current (0.24 mA cm(-2)) and higher sensitivity (11.4 mA M(-1) cm(-2)) than the values of the biosensor based on an Au/POAP/GOD electrode. Additionally, the biosensor shows fast response time, large response current, and good anti-interferent ability for ascorbic acid, uric acid and acetaminophen. Good reproducibility and stability of the biosensor are also observed.     

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.     

ZnO纳米棒阵列基-芴类共轭聚合物膜的制备及对TNT的检测评价

将共轭芴类荧光聚合物涂覆在纳米Zn O棒阵列上,制成荧光传感膜检测痕量TNT。通过水热法生长的Zn O纳米棒阵列具有较好的取向性,作为衬底可有效增大荧光膜荧光强度,同时,Zn O纳米棒阵列的高比表面积可提高膜对TNT气体的响应效率,使20s内的荧光猝灭率可达72%。     

Highly Sensitive Amperometric Glucose Biosensor Based on Glassy Carbon Electrode with Copper/Palladium Coating

A highly sensitive amperometric glucose biosensor based on immobilizing glucose oxidase in electropolymerized poly(o‐phenylenediamine) film on glassy carbon electrode coated sequentially with copper and palladium layers has been developed. The steady‐state amperometric response to glucose was determined by means of the oxidation of hydrogen peroxide generated by the enzymatic reaction at a potential of either +0.70 or +0.40 V (vs. Ag|AgCl reference). The deposited copper/palladium layer showed great enhancement in the performance of the enzyme electrode, possibly due to its better electrocatalytic activity for hydrogen peroxide oxidation and large surface area. Effects of the relative loading of palladium, enzyme and polymer on the electrode performance were examined in detail. Sensitivity and detection limit for glucose determinations at +0.70 V were about 7.3 μA/mM and 0.1 μM, respectively. A wide linear range up to 6.0 mM glucose could be achieved. Electrode performance was superior to similar works reported in the literature. The response time was less than 2 s and its lifetime was longer than three months. The permeable polyphenylenediamine film also offered good anti‐interference ability to ascorbic acid, uric acid and acetaminophen, especially when a detection potential of +0.40 V was employed.     

Electrocatalytic Reduction of H2O2 and Oxygen on the Surface of Thionin Incorporated onto MWCNTs Modified Glassy Carbon Electrode: Application to Glucose Detection

A new H₂O₂ enzymeless sensor has been fabricated by incorporation of thionin onto multiwall carbon nanotubes (MWCNTs) modified glassy carbon electrode. First 50 μL of acetone solution containing dispersed MWCNTs was pipetted onto the surface of GC electrode, then, after solvent evaporations, the MWCNTs modified GC electrode was immersed into an aqueous solution of thionin (electroless deposition) for a short period of time <5–50 s. The adsorbed thin film of thionin was found to facilitate the reduction of hydrogen peroxide in the absence of peroxidase enzyme. Also the modified electrode shows excellent catalytic activity for oxygen reduction at reduced overpotential. The rotating modified electrode shows excellent analytical performance for amperometric determination of hydrogen peroxide, at reduced overpotentials. Typical calibration at ?0.3 V vs. reference electrode, Ag/AgCl/3 M KCl, shows a detection limit of 0.38 μM, a sensitivity of 11.5 nA/μM and a liner range from 20 μM to 3.0 mM of hydrogen peroxide. The glucose biosensor was fabricated by covering a thin film of sol–gel composite containing glucose oxides on the surface of thionin/MWCNTs modified GC electrode. The biosensor can be used successfully for selective detection of glucose based on the decreasing of cathodic peak current of oxygen. The detection limit, sensitivity and liner calibration rang were 1 μM, 18.3 μA/mM and 10 μM–6.0 mM, respectively. In addition biosensor can reach 90% of steady currents in about 3.0 s and interference effect of the electroactive existing species (ascorbic acid–uric acid and acetaminophen) is eliminated. The usefulness of biosensor for direct glucose quantification in human blood serum matrix is also discussed. This sensor can be used as an amperometric detector for monitoring oxidase based biosensors.     

Amperometric Glucose Biosensor on Layer by Layer Assembled Carbon Nanotube and Polypyrrole Multilayer Film

An amperometric glucose biosensor on layer by layer assembled carbon nanotube and polypyrrole multilayer film has been reported in the present investigation. Homogeneous and stable single wall carbon nanotubes (SWNTs) and polypyrrole (PPy) multilayer films were alternately assembled on platinum coated Polyvinylidene fluoride (PVDF) membrane. Since conducting polypyrrole has excellent anti‐interference ability, protection ability in favor of increasing the amount of the SWNTs on platinum coated PVDF membrane and superior transducing ability, a layer by layer approach of polypyrrole and carbon nanotubes has provided an excellent matrix for the immobilization of enzyme. The layer‐by‐layer assembled SWNTs and PPy‐modified platinum coated PVDF membrane is shown to be an excellent amperometric sensor over a wide range of concentrations of glucose. The glucose oxidase (GOx) was immobilized on layer by layer assembled film by a physical adsorption method by cross linking through Glutaraldehyde. The glucose biosensor exhibited a linear response range from 1 mM to 50 mM of glucose concentration with excellent sensitivity of 7.06 μA/mM.     

A Nanocomposite Chitosan Based on Ferrocene‐Modified Silica Nanoparticles and Carbon Nanotubes for Biosensor Application

A novel amperometric biosensor for glucose was developed by entrapping glucose oxidase (GOD) in a chitosan composite doped with ferrocene monocarboxylic acid‐aminated silica nanoparticles conjugate (FMC‐ASNPs) and multiwall carbon nanotubes (MWNTs). The entrapped FMC‐ASNPs conjugate performed excellent redox electrochemistry and the presence of MWNTs improved the conductivity of the composite film. This matrix showed a biocompatible microenvironment for retaining the native activity of the entrapped GOD and was in favor of the accessibility of substrate to the active site of GOD, thus the affinity to substrates is improved greatly. Under optimal conditions this biosensor was able to detect glucose with a detection limit of 10 μM (S/N=3) in the linear range of 0.04 to 6.5 mM. The proximity of these three components FMC‐ASNPs, MWNTs and GOD enhanced the electron transfer between the film and electrode. This composite film can be extended to immobilize other enzymes and biomolecules, which will greatly facilitate the development of biosensors and other bioelectrochemical devices.     

铂纳米颗粒修饰直立碳纳米管电极的葡萄糖生物传感器

基于Pt纳米颗粒修饰直立的碳纳米管电极制备了葡萄糖生物传感器.铂纳米颗粒是利用电位脉冲沉积法修饰到直立碳纳米管上的,可以增强电极对酶反应过程当中产生的过氧化氢的催化行为.用扫描电镜和透射电镜观察了直立碳纳米管在修饰Pt纳米颗粒前后的形态.该酶电极对葡萄糖的氧化表现出很好的响应,线性范围为1×10-5～7×10-3mol/L,响应时间小于5s,并且有很好的重现性.     

Morphology evolution of ZnO thin films from aqueous solutions and their application to solar cells

This paper reports a reproducible low-temperature solution-based process for the preparation of ZnO films of nanorod arrays and their application to dye-sensitized solar cells (DSSCs). A two-step approach was employed for the epitaxial growth of ZnO. We began with the preparation of a (002)-oriented ZnO seed layer by the electrochemical deposition method. After the treatment the substrate was soaked in an aqueous solution containing ZnCl2 and complex agents. A large-scale fabrication of ZnO nanorod arrays on transparent conductive oxides has been achieved after soaking at 95 degrees C for 1-48 h. The as-deposited ZnO film has a large surface area, therefore permitting a great amount of dye loading. The individually separated nanorod forms a linear nanoroad which should show more effective electron transportation than that in the film derived from ZnO powders. The DSSCs using these ZnO films as photoelectrodes show a conversion efficiency of about 0.6% at AM1.5.     

Bienzymatic amperometric biosensor for glucose based on polypyrrole/ceramic carbon as electrode material

A novel amperometric biosensor utilizing two enzymes, glucose oxidase (GOD) and horseradish peroxidase (HRP), was developed for the cathodic detection of glucose. The glucose biosensor was constructed by electrochemical formation of a polypyrrole (PPy) membrane in the presence of GOD on the surface of a HRP-modified sol-gel derived-mediated ceramic carbon electrode. Ferrocenecarboxylic acid (FCA) was used as mediator to transfer electron between enzyme and electrode. In the hetero-bilayer configuration of electrode, all enzymes were well immobilized in electrode matrices and showed favorable enzymatic activities. The amperometric detection of glucose was carried out at +0.16 V (versus saturated calomel reference electrode (SCE)) in 0.1 M phosphate buffer solution (pH 6.9) with a linear response range between 8.0×10⁻⁵ and 1.3×10⁻³ M glucose. The biosensor showed a good suppression of interference in the amperometric detection.