The Electrochemical Behavior Of Novel Sensing Interface And Its Application

How to construct high sensitive and selective sensing interface is a key for the preparation of novel chemically modified electrode and electrochemical biosensor, which has become one of the research subject for analysts. In this thesis, novel chemically modified electrodes and electrochemical biosensors were fabricated based on three types of sensing interfaces, after which the electrochemical behaviors were studied in details. The new chemically modified electrodes and electrochemical biosensors were used for amperometric determination of H₂O₂, glucose and DNA. These studies may provide new thoughts for the construction of high sensitive and selective electrochemical biosensing interfaces and extending the application of electroanalytical techniques in nanobiomimetry and bioanalysis. The main contributions are summarized and presented as follows:A systematic overview on the construction of novel sensing interface and its applications in Sol-Gel derived carbon ceramic electrodes (CCEs) and electrochemical biosensors in recent years was presented. On the basis of which, the content of the dissertation was proposed. 210 references were cited.Sol-gel derived CCEs were used as the substrate electrodes for the preparation of chemically modified electrodes. Three kinds of modified electrodes, pyrocatechol violet modified carbon ceramic electrode (PCV/CCE), neodymium hexacyanoferrate modified carbon ceramic electrode (NdHCF/CCE) and bismuth hexacyanoferrate modified carbon ceramic electrode (BiHCF/CCE) were fabricated by adsorption, mechanism immobilization, and electrodeposition, respectively. The electrochemical behaviors and electrocatalytic abilities of the modified electrodes were investigated by electrochemical methods. The results indicated that PCV/CCE and NdHCF/CCE show good electrocatalytic activity toward the reduction of H₂O₂, and BiHCF/CCE shows good electrocatalytic activity towards the oxidation of N₂H₄. The prepared modified electrodes were used for the determination of H₂O₂ and N₂H₄.Five kinds of composite film modified electrodes, GOD-Au NPs-CHIT/GCE, GOD-NdPO₄ NPs-CHIT/GCE, GOD-PCNFs-BMIM·PF₆-CHIT/GCE, hemeproteins-PCNFs-BMIM·PF₆-CHIT/GCEs and Hb-C₆₀-BNNT-CHIT/GCE, was fabricated by embedding redox proteins (enzymes) in the Au NPs-CHIT, NdPO₄ NPs-CHIT, PCNFs-BMIM·PF₆-CHIT and C₆₀-BNNT-CHIT composite films and coating them on the surface of GCEs, respectively. Results indicated that GOD could retain their native structures in the composite films and the direct electron transfer between entrapped GOD and the underlying electrode was achieved. Heme-proteins modified electrodes fabricated by embedding Hb, Cyt c and Mb in the PCNFs-BMIM·PF₆-CHIT and C₆₀-BNNT-CHIT composite films and the electrochemical and electrocatalytical characters of these modified electrodes were investigated throughly. The results indicated that those redox proteins (enzymes) could retain their native structures in the composite films and realize their direct electrochemistry. Moreover, the proposed modified electrodes showed excellent bioelectrocatalytic activities for the oxidation of glucose and the reduction of H₂O₂ and were used for ampermetric detection of glucose and H₂O₂. The above studies indicated that novel nanomaterial-based composite films with good biocompatibility can not only accelerate the direct electron transfer of redox proteins (enzymes).Four biosening systems ultalizing the biocatalytically induced formation of neodymium hexacyanoferrate nanoparticles (NdHCF NPs) and conducting polyaniline (PANI) were proposed. The first two glucose biosensors were based on the accumulation of NdHCF NPs on carbon paste electrode and GOD-CHIT/GCE surfaces. The third and fourth biosensing interfaces, ultalizing bienzyme and monoenzyme for biocatalytically deposition of PANI, were constructed for the amperometric detection of glucose and DNA with good sensitivity and selectivity. The above studies showed that the construction of electrochemical biosensors ultalizing biocatalytic reaction for the accumulation of electroactiye nanoparticles or polymers offer new prospects for electrochemical transduction of biocatalytic events and provides a general platform for the construction of bioelectronic devices, and the design of novel biosensors.The last is the research summary and suggestions for the future work.