Construction And Application Of Light-addressable Photoelectrochemical Microelectrode Arrays For Single-cell Heterogeneity Analysis

Cells are known as the basic unit of life.Research of cell metabolites and proteins on a single-cell level is of great significance for understanding some special cell functions in the cell population and exploring the causes,development and treatment of major diseases.The biggest challenges of single-cell analysis arise from the small size of cells,the tiny absolute number of target molecules and the heterogeneity among single cells,so single-cell analysis technology should have the characteristics of high selectivity,high sensitivity,and high throughput.Photoelectrochemical(PEC)sensor combines the traditional electrochemical detection system with the PEC principle and naturally inherits the advantages of electrochemical analysis and optical analysis,such as low background signal,remarkable sensitivity,simple instrumentation and easy miniaturization.Besides,due to the addressable ability of the light source,PEC sensing has also been proven to be an efficient method for high-throughput analysis.In this thesis,a cell-sized PEC microelectrode array was prepared by a template method,which was firstly applied in the high-throughput PEC single-cell detection by combining the light-addressing strategy and injected new vitality into the field of single-cell analysis.The main work of this paper is as follows:(1)A high-performance PEC microelectrode array was prepared and used for the sensitive detection of hydrogen sulfide(H₂S).First,we prepared a polydimethylsiloxane(PDMS)stencil on an array of SU-8 micro-pillars by a spin-coating method.Then,Ag In S₂photoactive material with high photoelectric conversion efficiency and low toxicity was synthesized by a facile one-step method.And the Ag In S₂-based microelectrode array was formed by a drop-coating-dying-uncovering stencil method on the electrode surface modified with PDMS stencil.Finally,a PEC microelectrode array for hydrogen sulfide(H₂S)detection was constructed by using Bi³⁺/Ag In S₂formed on the Ag In S₂microarray by an electrostatic adsorption method to selectively recognize H₂S and in situ produce bismuth sulfide(Bi₂S₃)as the exciton quenching central to reduce photocurrent.The detection limit was 1 n M.(2)On the basis of previous studies,we performed PEC high-throughput detection of H₂S released by single cells to reveal the heterogeneity of the cells.To achieve this goal,we first used the same array of SU-8 micro-pillars to prepare a cell-sized PDMS microwell array,and the single cells can be trapped in the microwell by gravity.By adjusting the microwell size and cell density,we obtained a single-cell array with high occupancy.Then we dropped a stimulant solution on the surface of the array to promote the release of H₂S from the cells and the fabricated PEC microelectrode array was quickly cover on the surface of the single-cell array to form a sealed reaction array.After 15minutes,the single-cell array was removed and a laser light source with an ultra-small spot was used for addressable excitation of the PEC microelectrode array.The photocurrent signals of different zones were recorded,which realized the heterogeneity analysis of H₂S released by single cells.