Investigation Of SsDNA And Its Interaction With Protamine By Current Pulses Through Single Bionanopore

DNA and Protein are important biological molecules.With conventional analytical methods,only study the overall properity of materials.With single-molecule detection(SMD)techniques developed in recent years,not only can observe and identify single molecules,but also can provide the information of single biomolecule.Single bionanopore current pulses method is an efficient and rapid single-molecule detection method.The nanochannel of protein is established into lipid bilayer membranes.The blockade signatures produced by single molecule translocation through nanopore represent the analytes’ characteristics information.In this paper,based on above principle of single nanopore current pulses method,we investigate ssDNA molecules and its interaction with protamines.In the first chapter,the detection mechanism of translocation current pulses through single nanopore,the development of DNA sequencing based nanopore,nanopores including biological nanopores,solid nanopores and hybrid nanopores were introduced.The establishment of phospholipid bilayer membranes in the process of builing bionanopore was also showed.The detection of various analytes including proteins,ions,intermolecular interactions and the challenges of single molecule detection were also summarized.In the second chapter,with a detection system of ultra-micro-current amplifier developed by East China University of Science and Technology,the problems in the process of biological nanopore formation were discussed.Compared with the commercialized eONE system,we disscussed the resolution based on the detection of poly(dC)50 molecules Additionally,different types of single-stranded DNA and the mixture of ssDNA were detected by the established sensing system.Finally,we adjusted the viscosity of the buffer solution by the low molecular weight polymer PEG200 and PEG400 to achieve reduction of DNA perforation rate.In the third chapter,the interaction between positively charged protamine and negatively charged ssDNA was reflected by the current pulses due to their translocation through the single α-hemolysin(α-HL)nanopore interface.Experiment results demonstrated that pulses from both protamine and ssDNA were well identified,and pulse amplitude and duration time of ssDNA were both obviously changed as a result of its interaction with protamine.This study shows that,with a detection system established based on the ultra-micro-current amplifier developed in china,we can not only monitor the behavior of single molecule perforation research,but also investigate the complexes caused by intermolecular interaction and the individual molecular changes in the characteristic pulse signals.