A new enzyme-based amperometric biosensor for hydrogen peroxide was developed relying on the efficient immobilization of horseradish peroxidase (HRP) to a nano-scaled particulate gold (nano-Au) film modified glassy carbon electrode (GC). The nano-Au film was obtained by a chitosan film which was first formed on the surface of GC. The high affinity of chitosan for nano-Au associated with its amino groups resulted in the formation of nano-Au film on the surface of GC. The film formed served as an intermediator to retain high efficient and stable immobilization of the enzyme. H2O2,was detected using hydroquinone as an electron mediator to transfer electrons between the electrode and HRP. The HRP immobilized on nano-Au film maintained excellent electrocatalytical activity to the reduction of H2O2. The experimental parameters such as the operating potential of the working electrode, mediator concentration and pH of background electrolyte were optimized for best analytical performance of amperometry. The linear range of detection for H2O2 is from 6.1 x 10(-6) to 1.8 x 10(-3) mol L-1 with a detection limit of 6.1 mumol L-1 based on signal/noise = 3. The proposed HRP enzyme sensor has the features of high sensitivity (0.25 Almol(-1)cm(-2)), fast response time (t(90%) less than or equal to 10 s) and a long-term stability (> 1 month). As an extension, glucose oxidase (GOD) was chemically bound to HRP-modified electrode. A GOD/HRP bienzyme-modified electrode formed in this way can be applied to the determination of glucose with satisfactory performance.
[Yang, Y; Liu, ZM; Liu, YL; Shen, GL; Yu, RQ] State Key Laboratory of Chemo/Biosensing and Chemometrics , College of Chemistry and Chemical Engineering, Hunan University , Changsha, 410082, P.R. China;[Lei, CX] State Key Laboratory of Chemo/Biosensing and Chemometrics , College of Chemistry and Chemical Engineering, Hunan University , Changsha, 410082, P.R. China ;[Lei, CX] Department of Chemistry and Environmental Engineering , Hunan City University , Yiyang, P.R. China;Department of Chemistry and Environmental Engineering , Hunan City University , Yiyang, P.R. China
[Yu, RQ] Hunan Univ, Coll Chem & Chem Engn, State Key Lab Chemobiosensing & Chemometr, Changsha 410082, Peoples R China.;State Key Laboratory of Chemo/Biosensing and Chemometrics , College of Chemistry and Chemical Engineering, Hunan University , Changsha, 410082, P.R. China
A highly selective and sensitive electrochemical sensor modified with carboxymethylated β‐cyclodextrin (CM‐β‐CDP) polymer film was fabricated for the determination of dopamine (DA) in the presence of ascorbic acid (AA). The electrochemical behavior of DA and AA at the chemically modified electrode was investigated by cyclic voltammetry (CV) and differential pulse voltammetry. The response mechanism of CM‐β‐CDP film for DA was based on the combination of electrostatic and inclusion interaction of CM‐β‐CDP for DA, which was distinguished from the response mechanism of the charged polymer film modified electrode that only relied upon the electrostatic interaction between charged polymer film and DA (or AA) to realize the separation of overlapping peak potential of DA and AA. The CM‐β‐CDP film showed preferable analytical performance characteristics in catalytic oxidation of DA compared with the β‐CDP polymer film. Under optimized conditions, it was feasible for the electrode modified with the CM‐β‐CDP film to selectively determine DA in the presence of a large excess of AA. A linear calibration plot was obtained over the range 0.8–60 µM with a sensitivity of 65 nA/µM and a detection limit (signal/noise (S/N) = 3) of 0.2 µM in the presence of 1.0 mM AA. This electrochemical sensor showed excellent sensitivity, repeatability, stability, and recovery for the determination of DA. The interference of AA with the determination of DA could be efficiently eliminated.
A novel approach to assemble an H2O2 amperometric biosensor was introduced. The biosensor was constructed by entrapping horseradish peroxidase (HRP) labeled nano‐scaled particulate gold (nano‐Au) (HRP‐nano‐Au electrostatic composite) in a new silica sol‐gel/alginate hybrid film using glassy carbon electrode as based electrode. This suggested strategy fully merged the merits of sol‐gel derived inorganic‐organic composite film and the nano‐Au intermediator. The silica sol‐gel/alginate hybrid material can improve the properties of conventional sol‐gel material and effectively prevent cracking of film. The entrapment of HRP in the form of HRP‐nano‐Au can not only factually prevent the leaking of enzyme out of the film but also provide a favorable microenvironment for HRP. With hydroquinone as an electron mediator, the proposed HRP electrode exhibited good catalytic activity for the reduction of H2O2. The parameters affecting both the qualities of sol‐gel/alginate hybrid film and the biosensor response were optimized. The biosensor exhibited high sensitivity of 0.40 Al mol−1 cm−2 for H2O2 over a wide linear range of concentration from 1.22×10−5 to 1.46×10−3 mol L−1, rapid response of <5 s and a detection limit of 0.61×10−6 mol L−1. The enzyme electrode has remarkable stability and retained 86% of its initial activity after 45 days of storage in 0.1 mol L−1 Tris‐HCl buffer solutions at pH 7.
Sensors and Actuators, B: Chemical,2005年107(2):509-515 ISSN：0925-4005
[Yang, Haifeng; Wu, Xumei; Wu, Jing; Yu, Ruqin; Lei, Cunxi; Shen, Guoli] State-key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082, China;[Lei, Cunxi] Department of Chemistry and Environmental Engineering, Hunan City University, Yiyang 413049, China
[Long, Liping; Zhang, Qi; Zhong, Tongsheng; Liu, Rong; Lei, Cunxi] College of Chemistry and Environmental Engineering, Hunan City University, Yiyang, China;[Huan, Shuangyan; Liu, Rong; Wu, Zhaoyang] State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, China
[Lei, Cunxi] Hunan City Univ, Coll Chem & Environm Engn, Yiyang 413000, Peoples R China.
A neutralization hydrolysis route has been used to synthesize titanium oxide nanoparticles. Transmission electron microscopy(TEM) and X-ray diffraction(XRD) characterization results showed the TiO(2) nanoparticles were single anatase phases when calcined at 600 degrees C-800 degrees C for 2h. The particle diameter ranged from 15 to 30nm. The pH value was key factor for precursor composition. When pH value 2-4, the H(2)TiO(3) precursor with low agglomeration was obtained. As-prepared anatase TiO2 nanoparticles, during photodegradation of methylic orange under UV-light irradiation(lambda=254nm), exhibited excellent activity, more than 95.5% methylic orange was degraded in 1h.
A new strategy for constructing the capacitance immunosensor was developed based on gold nanoparticles, which were employed as the platform to immobilize immunospecies. Gold nanoparticles were fixed on the gold electrode, on which the oligomer layer of o-aminobenzenthiol was pre-formed via electrochemical polymerization. An interesting immunospecies was loaded on gold nanoparticles to complete the fabrication of capacitance immunosensor. The changes in morphology of the gold electrode during the experiments were revealed by atomic force microscopy (AFM). The properties of the gold electrode were investigated by cyclic voltammetry, in the presence of an electro-active species as indictor. Also, potentiostatic pulse technique was used in order to evidence the changes of electrode capacitance. The feasibility of the proposed capacitive immunosensor was evaluated for a non-competitive heterogeneous immunoassay of transferrin. The assay covers a relatively large dynamic range of 0.125-100 ng/ml transferrin with a detection limit of 80 pg/ml and a relative high signal-to-noise ratio. © 2004 Elsevier B.V. All fights reserved.