Application Of Semiconductor-based Composite Materials In Photoelectrochemical Bioanalysis

Photoelectrochemical(PEC)bioanalysis is a newly emerged analysis technique and developed rapidly in recent years.The detection principle depends on the fact that the specific bio-recognition between the target molecule and the recognition element under illumination would result in the change in the electrical signal.The PEC bioanalysis has the advantages of low background signal,simple instrumentation,easy miniaturization,low price compared to electrochemiluminescence,and it has great potential in the future of biological detection.Therefore,it has attracted more and more attention and has made great progress.Semiconductor nano-particles have special photoelectrochemical properties due to the existence of quantum size effects,surface effects,and are widely applied in photoelectrochemical bioanalysis systems.However,some commonly used semiconductor quantum dots such as CdS QDs are toxic to biomolecules.Therefore,it is necessary to search for a novel green semiconductor material.In this paper,we studied the novel ternary semiconductor heterogeneous structure and build an enzyme biosensing detection system based on it.This work developed the foundation for the future application of photoelectric bioassay,and also provided the new thoughts for future photoelectrochemical biological detection system.In the first chapter,we systematically summarized the development of the PEC biological detection,and detailed its mechanism.The first part we introduced the current classification of photosensitive materials;the second part we described the applications of PEC;the third part we stated the novel ideas and design thoughts.In the second chapter,a novel cathodic PEC enzymatic bioanalysis of the sarcosine detection with hierarchical CuInS2-based heterostructure was reported.Heterostructured CuInS2/NiO/ITO photocathode was prepared and sarcosine oxidases(SOx)were integrated for the construction of the enzymatic biosensor.In the bioanalysis,the O2-dependent suppression of the cathodic photocurrent can be observed due to the competition between the as-fabricated O2-sensitive photocathode and the SOx-catalytic event toward O2 reduction.Based on the sarcosine-controlled O2 concentration,a novel photocathodic enzymatic biosensor could be realized for the sensitive and specific sarcosine detection.In the third chapter,we reported the preparation of the composite material which consists of BiOI and nitrogen-doped graphene hydrogels and its applications in PEC.BiOI is a new type of non-toxic semiconductor material,and has been widely studied by scientific researchers because of its non-toxic and excellent photoelectric properties.The graphene hydrogel has a larger specific surface area and better physical properties than the conventional graphene.Therefore,through the combination of the BiOI and the graphene hydrogel,we have obtained a novel semiconductor material that can be used for PEC bioassay.It was used in the enzyme detection system of sarcosine to verify the feasibility of the program.