The Construction Of Electrochemical Sensors Based On Porous Nanomaterials Of Silica And Titania

Electrochemical sensors have been attracted great attention due to its high sensitivity, ease of use, short response time, mostly low cost and relatively simple technology. With the springing up of nanometer materials, sensors got further development. Semiconductor nanomaterials were widely used to construct the sensitive interface of sensors not only because of their high active surface areas, regular structures as other nanomaterials, but also its special electronic transmission, catalysis, photoelectric conversion, chemical and biological affinity performance made them show excellent performance at the signal amplification and biocompatibility towards the bioactive substances(enzymes, proteins, DNA, cells, organelles, organization, etc.). This paper provided a new method for modifying electrodes with redox meditor by using silica as the support. The direct electrochemical behaviors of titania nanotube arrays which were prepared by electrochemical anodic oxidation towards H2O2 were also studied. And for the first time we proposed whether it could improve sensitivity towards the reduction of H2O2 by modifying with enzymes on titania nanotube arrays. The specific content was as follows:(1) We proposed a new method for modifying electrodes with electronic media by using constant current method in the coexistence solution of(NH4)2Si F6 and thionine. Thionine was carried to the electrode surface in the formation process of silica porous membrane. Silica/thionine nanocomposition kept redox properties of thionine and was very stable. A simple strategy of an amperometric immunosensor for clostridium difficile toxin B was developed based on multi-walled carbon nanotubes, silica/thionine nanocomposition, gold nanoparticles as matrix and the immunosensor was specific to detect clostridium difficile toxin B from 1.0 to 80.0 ng/m L;(2) Non-modified titania nanotube arrays which were prepared by electrochemical anodic oxidation could be used as a sensor for direct determination of H2O2. The effect of p H, working voltage, interferences and linear range toward H2O2 was studied. The electrode showed very fast response and gave a wide linear range 5.0 μM~12.0 m M and 15~83 m M. Titania nanotube arrays were further applied to glucose sensing without mediator. The glucose biosensor was fabricated by immobilizing glucose oxidase on the surface. The biosensor exhibited good electrocatalytic activity and fast response toward glucose and enabled the determination of glucose in the 20 μM to 1 m M and 1 m M to 10 m M.(3) We discussed the three methods of modifying titania nanotube arrays electrode with redox mediator: physical adsorption, electrochemical polymerization and codeposition. In addition, we discussed whether titania nanotube arrays electrode modified with horseradish peroxidase could enhance sensitivity towards H2O2 from theory and experiments for the first time.