Construction Of Functionalized Hour Glass Nanochannels And Regulation Of Proteins Transport

Protein is the main material bearer of life activities,and plays a variety of roles in the physiological process,such as the catalytic role of enzymes,hormone regulation and so on.However,proteins need to be synthesized at specific sites and then transported to specific sites for their functions.In order to maintain normal gene transcription efficiency,200 chromatin protein molecules need to be transported every minute in the septal pore.However,the nucleus is very fragile and cannot continuously study the protein transport behavior in vitro.Therefore,the development of simple and robust models for high-flux protein transport remains a major challenge.Unlike biological channels,artificial nanochannels,which have emerged in recent years,have stable physical properties and the surface chemistry can be modified in various ways.Therefore,artificial nanochannels provide a potential material platform for the construction of simple,stable and sustainable models to regulate protein transport.In recent years,artificial nanochannels have not only constructed a variety of functional nanochannels with ion response and molecular response,but also constructed a variety of nanochannels for the regulation of ion transport and molecular transport.Due to the large size of biomacromolecular proteins,it is very difficult to transport in restricted channels.The high-flux transport of biomacromolecular proteins is a meaningful and challenging task.One of the key problems is how to achieve high throughput protein transport in limited channels and achieve controllable protein transport.This paper focuses on this scientific problem and mainly carries out the following three research works:1.Hour glass channels are more likely to allow ions or molecules to enter and leave because of their open outward shape at both sides.Typical hour glass channels in living organisms include Cl-channel(CLC),water molecule channel and nuclear pore,which can realize efficient transport of Cl-,water molecule and proteins respectively.Therefore,in this paper,we use hour glass channels to regulate protein transport.In the first work,we constructed a binary asymmetric hour glass channels by assembling L-Phenylalanine-Pillararene[5](L-Phe-P[5])on one side of the channels based on the binary structure of a nuclear pore.Afterwards,we regulated the transport of template protein lysozyme based on binary asymmetric channels,and studied the flux.The results showed that the transport flux of lysozyme in the binary asymmetric channel was higher than that in the bare nanochannels and the nanochannels fully assembled with L-Phe-P[5].The transport flux of lysozyme in the binary asymmetric channel is 3.7 times that of the channel fully assembled with L-Phe-P[5],and 40.4 times that of the bare nanochannels.This result brings more research prospects for binary asymmetric hour glass channels.2.In the previous work,we constructed a binary asymmetric channel,which achieve high-flux protein transport in a limited channel.But it can't regulate the transport of proteins in the limited channel.Through investigation,it was found that there is a special protein transport system in escherichia coli-double arginine(TAT)transport system.This transport system regulates the transport of proteins,not relying on ATP hydrolysis for energy supply,but based on the proton concentration difference on both sides of the membrane.The most important part of the TAT transport system is the arginine in the alkaline region.And the increase with proton concentration can protonate arginine,change the charge polarity and charge amount at both sides of the channel,and form a higher membrane potential to drive protein transport.Inspired by the TAT transport system,we introduced arginine to one side of the hour glass channel to construct a pH-responsive channel and regulate protein transport.When the proton concentration increases in the functionalized side of pH-responsive channels will get larger ion rectification,thus accelerating the migration speed of ions in the channels.Through further study,when pH is reduced to 3 and 2,hydrogen protons will migrate and the other end of the protonated channel will be less asymmetric.We realized that as the pH value of one side of the pH-responsive channel decreased from 7 to 4,that is,as the asymmetry of one end of the channel increased,the transmission flux of proteins in the channel gradually increased,the protein flux in the channel increased gradually.Therefore,we believe that the degree of channel asymmetry is related to the flux of protein transport.3.As a kind of fast and controllable regulation means without affecting the chemical properties of the inner surface of the nanochannel,light has been widely used to regulate the behavior of ion transport or molecular transport in the nanochannel.In the previous two chapters,we constructed two types of functionized hour glass nanochannels that could not intelligently regulate protein transport through the chemical properties in the rapidly converted channels Moreover,bovine serum protein(BSA)with relatively large volume and negative charge can not be regulated to transmit in the limited domain.Therefore,a kind of light-response hour glass channel is constructed here to regulate the transmission behavior of BSA.The functional channels under the dual regulation of ultraviolet(UV)/visible(Vis)light,can form a variety of different state.We studied four main state regulated BSA transport behaviors,and found that asymmetric hour glass channels have a regulatory effect on protein transport similar to that of diodes,allowing only BSA to be transmitted from one side to the other,but hindering its reverse transmission.