Performance Analysis And Application Of Solid-state Nanopore

Solid-state nanopores possess advantages such as high stability,controllable geometry and diversified materials,become the research hotspot of novel nanosensors.Solid-state nanopore sensors have been used for qualitative and quantitative analysis of chemicals,such as DNA sequencing,molecular detection,ion detection.During sensing,signal detection and analysis is an important process,which is affected by various material and environmental factors.Besides,it's challenging to realize sensitive heavy metal ion detection with portable nanopore devices.Concerning the above two aspects and based on the current research status,this thesis explores experimentally the influencing factors for electrical characteristics related to solid nanopore signals,then constructs a mercury ion sensing device based on DNA aptamor functionalization for solid nanopore.The main content of the thesis includes the following two aspects:Firstly,in order to determine the influencing factors of solid nanopore signal and optimize detection conditions,a porous membrane detection system was constructed with polyethylene terephthalate porous membrane.This experiment explored the influence factors of ionic conductance and 1/f noise,including ion concentrations,pH values,ion species,bias voltages,pore surface modifications,etc.The experimental results show that the ionic conductance is determined by pore size,ion concentration and surface charge density,which is consistent with the theoretical prediction.At high ion concentrations,the ionic conductance depends on the ion concentration.When the ion concentration is lower than a certain concentration,the ionic conductance is mainly determined by the surface charge density of the interface.The 1/fnoise shown from the current power spectrum is mainly affected by the surface charge fluctuation of the pore channel and the number of carriers,which shows a strong dependence on voltage,ion concentration and ion type.Decreasing bias voltage,ion concentration,pH value and ion radius are beneficial to reduce the signal 1/f noise.In addition,modification of the nanopore with biotin and streptavidin also improves 1/f/noise.Secondly,a mercury ion sensor based on glass solid nanopore is constructed to realize sensitive detection of mercury ions.The single pore of glass at 40 nm was prepared and characterized by etching platinum wire.Then functional modification was performed on the surface of the nanopore,and DNA aptamers were introduced to the interface of the nanopore to achieve specific detection of mercury ions.The surface charge density of the nanopore is changed by the fixation of mercury ion with bivalent positive charge on the aptamer.The detection of different mercury ion concentrations is realized by detecting the I-V Fcurve and analyzing its rectification ratio.Experimental results show that the detection limit of this detection technology reaches 1 pmol/L,which is far below the drinking water standard(5 nmol/L).This technology is expected to be used for rapid,high sensitivity,low cost and ultra-trace detection of mercury ions.