The Characteristics Of Current In DNA And PS Nanoparticles Solution Through Micro/Nanofluidic Capillaries Under Continuous DC Electric Field Force

In practical applications of nano-chips and bio-sensors,electric field forces are most commonly employed to manipulate and analyze the characteristics of single bio-molecules.To accurately and flexibly control single-molecule removal within micro-/submicro-fluidic channels(inner diameter are 10 ?m,5?m,500 nm,200 nm,100 nm respectively),the characteristics of current signals at the initial stage of the fluid flow in DNA and PS nanoparticles are systematically studied based on a three-electrode system.Micro-/nano-channel has an important significance to research the current response DNA and PS nanoparticles.Experimental results demonstrate that the micro-/nano-channel size?pH?the concentration of buffer have effects on the current signal in the micro-/nano-fluidic.Meanwhile the critical voltage has appeared.All these research have great significance for the improvement of micro-/nano-fluidic technology and improve the signal-to-noise ratio.Main contents and achievements are as follows:(1)The initial current response transient increases and decreases current peak with the increase of time in the different channel size and then with the time increasing the current signal becoming eventually stabilized.This is the result of electrode polarization and the effect of the electrical double layer on the electrical flow.(2)The current signals of micro-/nano-scale channels filled with solutions of DNA molecules or PS nanoparticles are systematically studied.When there is only a pure TBE solution,the electric conductance does not monotonically decrease with the decreasing diameter of channel,but slightly increases with the decreasing diameter in submicro-scales.When the DNA molecules or PS nanoparticles are added into TBE buffer,the scale effect on electric conductance of the solutions are quite different.(3)It was found that in channels of different size,different bias voltage,buffer concentration,and pH values of these parameters have effects on current response when added ?-DNA and carboxylation PS nanoparticals to the chamber.And we analysis the above conditions influence on current signal mechanism with the method of surface charge,electroosmotic flow and electric double layer theory,finding that critical voltage decreases with the increase of buffer solution pH value and the channel size,and increases with the increase of buffer concentration.Furthermore,because of DNA and polymer(PS nanoparticals),the corresponding regulation is also have variance.(4)With the increasing of buffer pH,the steady current I also increased in the 100 nm nanochannel.The critical voltage is decreasing with the increasing of buffer pH values;and with the increasing of buffer concentration,the critical voltage decreases.When the bias voltage is less than the critical voltage,the absolute value of the steady current decreases with the increase of the voltage.These results provide a theoretical basis for the selection of suitable experimental parameters,and the analysis of the current response signal and the critical voltage,and then discuss the motion characteristics of DNA and PS-nanoparticles in the channel.These results are helpful for the design and fabrication of functional micro/nano-scale fluidic sensors and biochips.