Experimental Research On Detection Of Protein Molecules Using Nanopore Sensors

Human diseases sometimes are resulted from proteins’ abnormal expression in bodies.Precision medicine is capable of finding out the pathogeny accurately and realizing the accurate treatment for patients.The nanopore sensing device,one of the single-molecule detection methods,makes precision diagnosis possible.By detecting protein molecules in vitro using nanopore,the diagnostic accuracy is improved and the treatment cycle of patients is shorten.In this thesis,the nanopore sensors are used to study both the single protein and protein-protein interaction.The main research results are as follows:1)The basic physical properties of proteins were studied.It was found that the BSA(bovine serum albumin)molecules are easier to adhere to the nanopore wall than the strand DNA molecules.The diameter of the protein molecules could be estimated by nanopore.2)The effect of electrolyte solution properties on protein translocation were studied.It was found that the type and concentration of electrolyte solution could directly change the protein charges,and then delay or shorten the passing time.The pH of the electrolyte solution not only changes the protein charges,but also determines the charges is positive or negative.3)The unfolding process of protein under increasing voltage was studied.Combined with COMSOL simulation,it was found that the BSA molecules keep natural folded state both in capture area and in the pore at low voltage.At mediate voltage,the BSA molecules kept folded in capture area and were started to be unfolded in the pore.At high voltage,the BSA molecules were began to be unfolded firstly in capture area and further to be unfolded in the pore.4)The antibody molecules were detected and the specific immunological binding between antigen and antibody was monitored.Results were showed that the nanopore sensors could not only be used to detect antibody molecules,but also be used to distinguish the antigen,antibody and their specific binding.5)The efficiency of cancer immune checkpoint inhibitors in blocking the signal pathway between cancer cells and T-cells was evaluated.Using PD-1 antibody modified nanopore,the antibody-antigen complexes were detected and distinguished with PD-1 protein and its antibody.Finally,the temperature of the buffer solution was increased to inprove the binding rate of the antigen and antibody.