Construction And Application Of Photoelectrochemical Molecularly Imprinted Sensors Based On Semiconductor Nanocomposites

Photoelectrochemistry（PEC）is a chem ical reaction initiated by photogenerated car riers at the semiconductor/electrolyte interface.PEC method has attracted much attention because of its high sensitivity,simple operation,fast respon se speed and low detection cost.Generall y,the basic components of PEC sensor include photoelectric dev ice and identification part.Among them,the function of photoelectric device is to convert the incident light radiation into an electrica l signal related to the detected target concentration.In PEC system,the excitation signal and received signal are completely separated,which can greatly reduce the infl uence of background noise and obtain higher detection sensitivity.Molecular imprinting technology is a technology to construct specific rec ognition sites on synthetic polymers.Compared with biomass rec ognition units,it has the advantages of stable chemi cal properties and not easy to inactivate,and can improve the selectivity of the sen sor for the object to be detected.Therefore,photoelectrochemical sensin g technology and molecular imprinting technol ogy are combined to generate corresponding electrical signals by using photo responsive materials,record the changes of photocurrent,and use the speci al recognition sites of molecular imprinti ng to achieve the purpose of specific recognition and detectio n.This paper mainly includes the following two parts:（1）In this experiment,CdS@Cu₂O nanocomposites were prepared and a visible light r esponsive phot oelectric chemistry（PEC）sensing platform was constructed.CdS@Cu₂O was prepared by simple hydrothermal and liquid deposition methods.Polydopamine（PDA）films with a large number of cytochrome c（cyt c）recognition sites were formed on the surface of photoactive materials by electropolymerization.Experimental r esults show that the detection range of PEC s ensor is from 0.1 nM to 1000 nM,and the detection limit（LOD）is 0.07 nM.Meanwhile,the prepared PEC sensor showed excellent stability,reproducibility and selectivity to cyt c.The results show that this sens ing strategy has an important application val ue in the detection of cy t c with high sensitivity and specificity.（2）In this work,a novel self-powered electro-photoelectrochemical（PEC）molecular imprinted sensor integrated with photoanode and photocathode is creatively proposed for specific and se nsitive detection of sarcosine（SAR）.Under light,the photogenerated electrons of Au@TiO ₂photoanode are transferred along the outer circuit,while the holes left in the photocathode（Cu ₂O）valence band can be attracted by the electrons flowing out of the photoanode,thus reducing the electron-hole pair recombination and im proving the cathode photocurrent.Under the opt imal conditions,the constructed imprinted sensor has a linear range in the range of 10 nM-10μM,and the detection limit is 0.19 nM.In addition,the constructed sensor showed satisf actory selectivity,stability and reproducibility.This work verifies that the PEC sensing plat form has great potential in the field of miniaturi zed biosensing without external power supply.