Study And Application Of The Novel Electrochemical Biosensors Based On Nanomaterials Modified Electrodes

Electrochemical biosensors have been highly favored by researchers due to its quick response, high sensitivity, low cost, simplicity, and wide application. Modifying the biosening interface sensor has always been not only the focus of the researchers in order to improve the sensitivity and stability of the electrochemical biosensors. Nanofabrication of biosensing interface has opened up an active research area due to the emergence of nanomaterials. Nanomaterials have many unique properties, such as high conductivity, biocompatibility, high surface area, biocompatibility, easy for surface chemical modification. Therefore, nanofabrication of electrode surface is a desirable strategy to develop electrochemical biosensors with improved analytical performance.The studies in this paper include the following three parts:(1) To modify the gold electrode surface with the mixture of aminophenyl and benzene aryl diazonium salts followed by the attachment of the single-walled carbon nanotube(SWCNTs) through the C-C bondings, then the enzyme horseradish peroxides (HRP) is covalently attached on SWCNTs by a peptide bond to build an enzyme biosensors. The fabricated biosensor can be used to determine H2O2, and the analytical performance of the biosensor is discussed in details.(2) To modify the aminophenyl aryl diazonium salts on glassy carbon (GC) electrode surface followed by converting the amine groups on the GC electrode to the unstable diazonium salt moleculars through diazotization reduction. The formed diazonium salt molecules changed into free radicals under the effect of certain reduction potential, and attached to gold nanoparticles (AuNP) in solution by C-Au bonding. Subsequently the AuNP were successfully modified on GC electrode surface through step-by-step method. The amount of AuNP on electrode surface were optimized through optimizing the attachment of aminophenyl on GC electrodes. Then AuNP modified GC surfaces were modified with4-carboxylphenyl molecules followed by the attachment of methyl parathion hydrolase by amide bonds to develop an electrochemical biosensor. This fabricated biosensor can be used to detect pesticide methyl parathion, and the analytical performance of the biosensor is discussed in details.(3) In order to make further improvement on the efficiency of AuNP modification on the sensor interface, we changed the modification strategy to one-step covalent anchoring of AuNP on electrode surfaces. Firstly AuNPs functionalized with amine groups were synthesized. The preparation and storage of multifunctionalized AuNPs, were studied, and the surface analysis techniques such as Uv-Vis, TEM, SEM and XPS were carried out to characterize the prepared AuNPs. Meanwhile, the performance of multifunctionalized AuNPs was studied by electrochemistry.Then, the prepared multifunctionalized AuNPs were modified on electrode surface by Au-C bonding through one-step strategy. Finally, the HRP biosensor based on the one-step covalent anchoring of AuNPs on electrode surfaces was developed, and can be used for the detection of H2O2.