Study Of The Construction And Properties Of Precisely Functional Nanochannels With Explicit Spatial Partition

In living organisms,biological ion channels distributed on the cell membrane play a vital role in maintaining the normal activities of cell,which are responsible for the transfer of ions,water,biological molecules and energy.Inspired by biological ion channels,scientists have designed and built a series of solid-state nanochannels by incorporation of functional elements.Currently,solid-state nanochannels show great application potential in numerous fields such as gene sequencing,protein structure analysis,single molecule or cell measurement,biochemical sensing,energy conversion,seawater purification,nanoelectrochemistry and nanofluid,etc.The construction of high-efficient functional solid-state nanochannels has been attracting attention form researchers all over the world.Scientific studies have found the high efficiency of biological ion channels originates from the regionalized distribution of functional proteins in the channels and the function corporation of these proteins.In this work,by learning for nature,we built different functional solid-state nanochannels through explicit spatial structure partition and precise functionalization of inner walls(IW)and outer surfaces(OS),and explored the role of functional elements at inner walls(FEIW)and outer surfaces(FEOS)in ion transport of nanochannels.The main research contents are as follows.(1)we reveal the role of grafting density of FEIW in the ion current detection signal of nanochannels.we investigated the effect from the grafting density of DNA probes on ionic signal for nucleic acid detection in a cylindrical nanochannel array by combing experiments and theories.We set up a theoretical model of charge distribution from close to inner wall of nanochannels at low probe grafting density to spreading in whole space at high probe grafting density.The theoretical results were well fitted with the experimental results.A reverse of ionic output from signal-off to signal-on occurs with increasing probe grafting density was observed.Low probe grafting density offered a high current change ratio that is further enhanced using long-chain DNA probes or the electrolyte with a low salt concentration.This work develops an approach to enhance performance of nanochannel-based sensors and explore physicochemical proper-ties in nanometric confine.(2)we build a nanochannel systems with function-element at outer-surface for antiinterference and function-element at inner-wall for ion-gating.We achieve explicit partition of FEOS and FEIW based on accurate regional-modification of OS and IW.Furthermore,the FEIW are served for ionic gating,and the chosen FEOS(hydrophobic or charged)are served for blocking interference molecules into the nanochannels,decreasing the false signals for the ionic gating in complex environments.Furthermore,we also define a composite factor,areas of a radar map,to evaluate the performance of FEOS for blocking interference molecules.This work could blaze a trial not only for the role of FEOS at OS in nanochannels,but even for the biomimetic system in the porous membrane.(3)we show that the FEOS independently regulate ion transport in a nanochannelsystem without FEIW.The numerical simulations,assigned the measured parameters of FEOS to the Poisson and Nernst-Planck(PNP)equations,are well fitted with the experiments,indicating the generally explicit regulating-ion-transport accomplished by FEOS without FEIW.Meanwhile,the FEOS fulfill the key features of the pervious nanochannel systems on regulating-ion-transport in osmotic energy conversion devices and biosensors,and show advantages to promote power density through concentrating FE at outer surface,bringing increase of ionic selectivity but no obvious change in internal resistance,and accommodate probes or targets with size beyond the diameter of nanochannels.Nanochannel-systems with only FEOS of explicit properties provide a quantitative platform for studying substrate transport phenomena through nanoconfined space,including nanopores,nanochannels,nanopipettes,porous membranes and twodimensional channels.