The Study Of Photolectrochemical Sensors Based On Inorganic Semiconductor Nanomaterials

In this work,we construct highly sensitive photoelectrochemical(PEC)immunosensors and cytosensors,which employ PEC as the main analytical technique and semiconductor nanomaterials as photoelectrochemical active material.In the first chapter,we introduce the basic principle of PEC,the strategy for designing and preparing electrode materials,and their applications in biosensing.In the second chapter we design a highly sensitive photoeletrochemical immunosensor based on CdSe nanocrystals,which are prepared by a controllable anion-exchange approach.The CdSe decorated ITO electrode possesses a strong and stable photoelctrochemical response in the visible light region(470 nm).Owing to the significant steric hindrance induced by cooperating biocatalytic precipitation(BCP)with avidin-biolin system,the proposed immunosensor exhibits highly improved sensing behaviors towards target antigen in a concentration range from 1.0 fg/mL to 10 ?g/mL with a detection limit of 0.50 fg/ml.In the third chapter we report a highly sensitive photoeletrochemical cytosensor based on CdS/ZnO nanorod arrays.The ZnO nanorod arrays were synthesized via a facile hydrothermal method and then CdS nanocrystals(NCs)were decorated on ZnO homogeneously by a simple chemical bath deposition method.The resultant CdS/ZnO hybrids show a stable photoelectrochemical response in the visible light region(470 nm).Using polyaminophenylboronic acid(poly(APBA))as sialic acid recongnizer,the poly(APBA)modified CdS/ZnO nanorods can effecively capture cancer cell(MCF-7)by the specific interaction between boric acid group and sialic acid in the condition of physiological pH.Our results demonstrate that the photocurrent differences are proportional to the logarithm of MCF-7 concentration in the range from 1.0×102?1.0×106 cells/mL.The limit of detection is 55 cells/mL.We also try to release the captured MCF-7 cells from the CdS/ZnO surface by electrochemical method,and re-capture them again with the same electrode,realizing the reuse of the PEC cytosensors.