Detection Of Current Pulses Of Non-ionic Polymers And SsDNA Based On A Single Biological Nanopore Interface

Macro biomolecules own complex structure and often combine with other molecules in different states.Traditional analytical technology,only the overall information of the solution could be obtained.While with single molecule detection technology,the structure and function could be studied at single molecule level.Nanopore-based single molecule analysis technology is promising due to its advantages in low cost,fast speed and label-free.In the first chapter,the classification,characteristics and formation methods of nanopores are systematically introduced.In addition,the applications and developing trends of nanopore analysis technology in different fields were summarized.Finally,the research contents and significance of this work are summarized.In the second chapter,in order to construct biological nanopore sensing interface,we tested different membrane supporting materials and teflon film was selected as the micro-pore support.To analyze neutral polymers polyethylene glycol(PEG)and polyvinylpyrrolidone(PVP)with?-hemolysin(?-HL)nanopore,the electrostatic interaction between PEG and K+and ion-dipole interaction between PVP and azo dye were adopted to make the two kinds of neutral molecules charged.For PEG(Mr 1000-4000 g/mol),current pulses with blocking depth of more than 48%and residence time of several milliseconds were obtained under a certain bias voltage.PVP K16-18 and PVP K40 also produced current pulses with blocking depth of 26%,100%respectively and with residence time of hundreds microseconds.In the third chapter,the effect of ion liquid supporting electrolyte,viscosity gradient and acidity on the translocation of ssDNA was studied.Preliminary results showed that long blocking current pulses with high current suppression ratio can be obtained for poly(dC)15,poly(dC)20,poly(dC)30 and poly(dC)50 under this established system.The blocking depth reached more than 95%.The duration time of long blocking events prolonged to tens or hundreds of milliseconds.Meanwhile,the peak-to-peak value of baseline noise is reduced by 30%.The possible mechanism of this phenomenon was discussed.In conclusion,current pulses of PEG and PVP with different molecular weight were detected based on the single ?-HL nanopore interface.Meanwhile,ionic liquid was used to control the translocation behavior of ssDNA,with which both of the blocking depth and duration time of ssDNA increased.