Experimental Research On Detection Of Nanoparticles Using Solid-stated Nanopores

The nanopores have widely been used to detect virus,cells and particles since developed in 1994,based on their numerous advantages,such as simple and convenient operation,high flux and precision.They have plenty of potential applications in virus detection,DNA sequencing and disease prevention.In this thesis,a few synthetic particles measurements have been conducted using solid-state nanopores.Based on the detection of nanoparticles,we can discover general laws and reveal potiential physical pictures.It also simplifies the translocations of biomolecules and provides necessary references for biomaterial detection.The main research results are as follows:1)Preparation and characterization of nanopores and nanoparticle solutions.Silicon nitride nanopores were prepared and characterized by means of a focused ion beam system.Silver nanoparticles were prepared by a reduction method,and their sizes,shapes,and charges were characterized by multiple means.2)Particle transport theory at nanoscale.The interface electrostatic theory shows that there is an electric double layer near the nanoparticles and the walls of nanopores.The interfacial electrodynamic theory studies the electroosmosis,electrophoresis,streaming potential,and sedimentation potential.3)Size identification of nanoparticles.The silicon nitride nanopores are used to detect nanoparticles of different sizes,and the characteristic information is analyzed to identify size of the nanoparticles,such as the amplitude of blockade current and the duration time.In addition,the bias voltage has an effect on the translocation signal of the nanoparticles.When the experimental conditions are consistent,a higher bias voltage will cause a larger blockade current amplitude and a shorter duration time.Moreover,different bias voltages will change the capture radius of the nanopores and the electric field force acting on the particles,thereby affecting the capture rate of the nanoparticles.4)Shape recognition of nanoparticles.The nanopores were used to detect nanoparticles of two different shapes.For the spherical nanoparticles,the distribution is symmetric and the Gaussian peaks are located at the center of the distribution,while for the cubic nanoparticles the distributions seem to have peaks on the right of the distributions.Using this rule to analyze the shape of mixed nanoparticles,different shapes of nanoparticles were recognized.Furthermore,molecular dynamics simulations have confirmed that the rotation of cubic nanoparticles while translocating definitely change the effective volume of the nanoparticle,thus the cubic nanoparticle will possibly have a nonsymmetric distribution histogram of the current blockade.