Metal/metal Oxide Core-shell Nanostructures With Tunable Electroactivities For Electrochemical Biosensor Applications

The metal/metal oxide core-shell nanomaterials with gold and silver nanoparticles as cores have the properties of both noble metal cores and metal/metal oxide shells.Moreover,the heterogeneous structure of core-shell nanostructures makes the hybrid nanomaterials exhibit intriguing local electromagnetic field,its corresponding optical,magnetic and electronic properties are all significantly changed,and thus synergistically produced amplified chirality,surface enhanced Raman activity and catalytic performances.While there are few researches on their electroactivities.In this paper,the metal/metal oxide core-shell nanomaterials with gold and silver nanoparticles as cores are studied as the object of research,their respective electroactivities were systematically investigated.And because of the good biocompatibility of gold and silver nanoparticles,the electrochemical biosensor applications of metal/metal oxide core-shell nanomaterials have been studied.The research work of this paper is mainly as follows:The main works of this paper are listed as follows:1.A series of Au@Cu₂O core-shell nanoparticles（Au@Cu₂O NPs）and Au@Ag core-shell nanoparticles（Au@Ag NPs）with different shell thicknesses were prepared by adjusting the volume of reducing agents and precursors of shell materials.The respective electrochemical oxidation activities were systematically studied and discussed and the factors influencing their electroactivities were explored.Shell-encoded Au NPs exhibited shell species-dominated peak potentials and shell thickness-driven peak intensity.By using Au@Cu₂O NPs and Au@Ag NPs with non-interfering and amplified DPV responses as novel electroactive labels,an ultra-sensitive electrochemical aptasensor was designed for the specific dual screening of carcinoembryonic antigen（CEA）and alpha-fetoprotein（AFP）.2.Attributing to the redox reaction between Au@Ag NPs and hydrogen sulfide（H₂S）,a novel and facile electrochemical sensor was proposed for the highly selective and sensitive detection of dissolved hydrogen sulfide（H₂S）using Au@Ag NPs as electroactive label.The LOD of H₂S is as low as 0.04 nM.In comparison with the traditional methylene blue method,the feasibility of this electrochemical sensor for detecting endogenous H₂S in HeLa cells was investigated.The stable electrochemical performance and excellent selectivity of the developed method contribute to the study of pathological processes related to the mechanism of H₂S production.3.Au@CdO core-shell particles（Au@CdO NPs）,Ag@CdO core-shell nanoparticles（Ag@CdO NPs）and Ag@ZnO core-shell nanoparticles（Ag@ZnO NPs）were synthesized by changing the types of metal cores and shell materials.The electrochemical reduction activities of these three metal/metal oxide core-shell nanomaterials were systematically studied and compared.Ag@CdO NPs with the best electrochemical reduction activity was selected to build a novel electrochemical aptasensor for the detection of prostate-specific antigen（PSA）by using magnetic glassy carbon electrode.And the specificity and accuracy of the electrochemical sensor were also detected.The electrochemical aptasensor based on electroactive Ag@CdO NPs can be applied to the efficient and accurate detection of PSA in real samples.