Construction And Application Of Antifouling Photoelectrochemical Nanosensor For In-situ Single-cell Analysis

Single-cell analysis can promote the understanding of function of cells and disease states and has always been the focus of chemical and biomedical research.Electrochemical sensing based on nanoelectrodes is a commonly used single-cell analysis method,which possesses high spatiotemporal resolution and in-situ detection capabilities.However,external bias is usually required to trigger the redox reactions of the targets on the electrode surface,which may cause disturbance to cells and affect the accuracy of analysis results.In addition,when the nanoelectrode is inserted into the cell for analysis,it is difficult to avoid biofouling and passivation of the electrode interface by the complex intracellular environment,which leads to performance degradation.Photoelectrochemical(PEC)sensing uses light as the excitation source and electrical signals as the output signal,which is a highly potential self-powered single-cell analysis method.Moreover,due to the separation of excitation and detection signals,PEC sensing has high sensitivity.Besides,coating an antifouling film on the electrode surface is an effective strategy to reduce contamination.Therefore,we constructed an antifouling PEC nanosensor for the first time and used it for self-powered single-cell detection.And we have made significant progress in the synthesis of high-performance photoactive materials,the preparation of carbon fiber nanoelectrodes,and the construction of excellent anti-fouling films,which may provide new opportunities for the field of single-cell analysis.The main work of this thesis is as follows:(1)We constructed the photoelectric active interface with excellent antifouling performance.First,ZnInS and metal-doped ZnInS were prepared by a simple hydrothermal method,and Zn Ca In S nanosheets with excellent photoelectric properties were obtained.The photoactive material could selectively recognize dopamine(DA).A porous bovine serum albumin-multiwalled carbon nanotube-glutaraldehyde(BSA-MWNT-GA)film was formed on the surface of Zn Ca In S by a dip-coating method as an antifouling film,and 1 wt%BSA-MWNT-GA film obtained by optimizing the concentration of BSA showed good antifouling performance.(2)We achieved self-powered PEC detection of single-cell cytosolic dopamine.The carbon fiber nanoelectrode was fabricated by a flame etching method and modified with low-toxic Zn Ca In S nanosheets and 1 wt% BSA-MWNT-GA antifouling film by the layer-by-layer assembly and dip-coating method,respectively.Thus,a PEC nanosensor was constructed,which not only can realize the sensitive detection of DA at zero potential(with a limit of detection of 3.97 n M),but also can be inserted into a single cell without causing cell viability damage.The cytosolic DA of a single pheochromocytoma cell and its concentration increase/decrease under the treatment of levodopa/zinc ions were successfully measured by the constructed nanosensor.