Study Of Electrochemical Biosensors Based On Nanomaterials And Mesoporous Matetials

Third-genetation amperometric biosensors, which are based on the direct electron transfer, are gaining more attention in recent years since it has the advantages including low coat, nice selectivity, high sensitivity, as well as easy preparation and miniaturization. They have potential applications in clinical diagnosis, environmental, monitoring and food industry. Due to the electroactive centers of the proteins and enzymes embeded deeply in the protein structure, and proteins and enzymes easy denaturated in the suface of electrode, it is diffucut to carry out a direct electrochemical reaction. Therefore, much attention has been paid to develop new technologies and materials for the design and fabrication of electrochemical biosensors. Nanomaterials and mesoporous materials have been uesd widely to construct biosensor with outstanding performance. The performance of biosensor could be improved greatly by the introduce of nanomaterials, which is due to their novel physical, chemical, catalytic propertise and favorable biocompatibility. The mesoporous materials could as an ideal matrix due to their large specific surface area, high specific pore volume, and open pore structure with pore size adjustable from 2 to 50 nm. In this paper, we fabricated some biosensors with platinum nanoparticle, meroporous ZrO2 and titania hollow spheres. The resulting biosensors exhibit direct ekectrochemical reaction and can be used to determine hydrogen peroxide in low potential with high sensitivity. The details are summarized as follows:1,A highly efficient H2O2 biosensor was fabricated based on the mixture of hemoglobin (Hb) and Quaternized Poly(4-vinyl pyridine)(QPVP) and nano-Pt modified glassy carbon electrode. The electrochemical characteristics of the biosensor were studied by cyclic voltammetry and chronoamperometry. Under optimized conditions, the biosensor exhibited a dynamic range of 3.5×10-6 to 3.15×10-3mol/L to H2O2 with a detection limit of 1.5×10-6 mol/L and a correlation coefficient of 0.9992. Moreover, the biosensor exhibited high sensitivity, good repeatability, selectivity and stability.2.A novel hydrogen peroxide biosensor has been presented through fabricating mesoZrO2-Hb film onto gold electrode surface based on one-step coelectrodeposition. FT-IR and UV-vis spectroscopy demonstrated that hemoglobin (Hb) in the mesoporous ZrO2(mesoZrO2) matrix could retain its native secondary structure. Transmission electron microscopy (TEM) image and N2 adsorption/desorption isotherm show that the obtained mesoZrO2 material presents disordered porous structure and appropriate pore size suitable for the immobilization of Hb. The performance and factors influencing the resulting biosensor were studied in detail by means of cyclic voltammetry (CV) and chronoamperometry. Analytical parameters such as pH and applied potential were also studied. The electrochemical parameters of Hb in the mesoZrO2 matrix was calculated with the results of the electron transfer coefficient (a) and the apparent heterogeneous electron transfer rate constant (ks) as 0.64 and 1.47 s-1 respectively, indicating good facilitation of the electron transfer between Hb and the modified electrode. The immobilized Hb retains its biological activity well and shows high catalytic activity to the reduction of hydrogen peroxide (H2O2). And the linear range to H2O2 was from 1.75×10-7 to 4.9×10-3 mol/L with a detection limit of 1.0×10-7 mol/L (S/N=3). In addition, the studied biosensor exhibited high sensitivity, good reproducibility and stability.3. A novel titania hollow spheres (THS) were chosen as an immobilization matrix, to construct a mediator-free third-generation biosensor. UV-Vis and Fourier transform infrared (FT-IR) spectra analysis displayed that no significant denaturation occurred to the immobilized protein. Transmission electron microscopy (TEM) image shows the obtained THS presents hollow spherical structure. The performance and factors influencing the resulting biosensor were studied in detail by means of cyclic voltammetry (CV) and chronoamperometry. The immobilized Hb retains its biological activity well and shows high catalytic activity to the reduction of hydrogen peroxide (H2O2). And the linear range to H2O2 was from 1.4×10-6 to 6.14×10-4mol/L with a detection limit of 5.0×10-7 mol/L (S/N=3). In addition, the studied biosensor exhibited high sensitivity, good reproducibility and stability.