Investigation Of Translocation Of DNA And Its Interaction With Chelerythrine By Current Pulses Through Single Bio-Nanopore Interface

Due to no labeling,high signal-to-noise ratio,nanopore single-molecule detection technique has become a new analysis method for the next-generation of DNA sequencing,DNA and RNA structure analysis.However,the biggest challenge is that the translocation speed of DNA molecules is too fast to identify individual molecule in the process of DNA sequencing,so reducing the translocation speed of DNA molecules plays a crucial role in DNA sequencing.DNA molecules play an important role in controlling gene expression and providing binding sites for exogenous drugs and foreign proteins.Therefore,it is also of great significance to study the interaction between biological molecules.In the first chapter,the basic sensing principle and the classification of nanopores were systematically introduced,and the developing status and application of nanopore detection technology in different fields were elaborated.Finally,the research contents and significance of this work were summarized.In the second chapter,the impact of translocation behavior for ssDNA with different base types(poly(dT)25,poly(dA)25 and poly(dC)25)and different base numbers(poly(dT)15,poly(dT)25 and poly(dT)35)was studied by replacing the traditional potassium salt electrolyte with lithium salt electrolyte based on wild-type ?-HL nanopore and variant hemolysin interface.Under the same experimental conditions,the translocation speed of ssDNA in LiCl both reduced,however,the translocation speed was significantly reduced for poly(dT)n,n=(15-35)molecules.Based on the established system,the possible mechanism of this phenomenon was analyzed and discussed.In the third chapter,the stability of hairpin DNA with the same stem structure and different loop structure,and its interaction with chelerythrine were studied using nanopore single molecule detection technology.Preliminary results showed that the characteristic current pulses of different hairpin DNA molecules could be recognized,and the stability of different hairpin DNA molecules could be distinguished according to dwell time and relative blocking current depth based on this established system.Not only the blocking time of hairpin DNA was significantly increased,but also a differentiation in term of current ratio was also noticed due to interaction with CHE.Based on this,nanopore single-molecule technology is expected to provide a new mean for drug screening.