| Visible light responsive channel of rhodopsin plays an important role in life.Visible light causes the isomerization of natural chromophores of retinal resulting in opening and closing of natural channel,which ultimately regulate the transmission of ions across the channels.This process realize the energy conversion,signal transduction,etc.Further,abnormality in rhodopsin will result in organism tissue defects,such as visual dysopia,and cause a series of dysfunction.However,the structure of rhodopsin is unstable and fragile at in vitro,which limits further exploration of its physiological function.But,vast development in the field of biomimetic nanochannels provides a good chemical model to explore the molecular mechanism in the process of ions transport behavior from a chemical perspective,so as to deepen the understanding of transport mechanism of similar ions channels in living beings.As a widely distributed natural source of energy,visible light has the advantages of easy controllable and non-invasive,compared with UV light,this induced us to fabricate the biomimetic nanochannel functionalized with natural chromophore ’retinal’,which can regulate the transmission behavior of ions by visible light.Further,host-guest interaction was utilized to obtained the fine-tuned and reversible visible light controlled transport of ions across the membrane,due to potential multifunctional sites and hydrophobic cavity pillar[5]arenes was identified as the prominent candidate for this application.Through the above strategy,we fabricated a visible light responsive smart nanochannel,which operate based on the visible light controlled host-guest interaction between pillar[6]arenes and retinal and.These behaviors change the surface properties of the nanochannel,and realize the visible light regulation of ions transmission in final.1.Based on the changes in structure and size of retinal attained under visible light,functional pillar[n]arenes that can form visible-light responsive host-guest complex with retinal were designed and synthesized.Initially,completely functional ethyl urea/phenyl urea derivatives of pillar[5]arenes and pillar[6]arenes were synthesized.Subsequently,their visible light responsive binding ability with retinal were also analyzed.The second idea is to synthesized two-site functionalized pillar[4+1]arenes with the ethyl urea or phenyl urea and to study their visible light responsive binding ability with retinoic acid.All of the synthesized compounds have been characterized by 1H NMR,13C NMR and MS spectrum.2.Inspired by visible light responsive channel(rhodopsin),we have constructed the biomimetic visible light responsive nanochannel.It can help us for the better understanding of this important physiological process from chemical point of view.There are still many difficulties in constructing visible light responsive artificial nanochannels.In order to resolve this challenge,L-lysine was selected as the link unit to introduce retinal molecules into the surface of the nanochannel.Then,based on the visible light responsive structural changes of retinal,surface properties(surface potential and the density of surface charge)of the nanochannel can be regulated.Further,the transmission performance was characterized in the visible light responsive nanochannel.Positively charged fluorescent methylene blue was chosen as the target organic cation,to observe the effects of visible light influences for the cation transport behavior.Results show that the visible light cause the trans-cis isomerization of retinal structure,which led to the increase of surface negative potential in nanochannel,and promote positively charged organic cation of methylene blue transport.In final,we have successfully constructed the visible light responsive nanochannel,which can realize the regulation of the charged methylene blue transport.3.Visible light responsive ionic channels in living organisms are usually able to selectively transport ions.Inspired by the visible light responsive of chloride ionic channels like rhodopsin,we have designed and constructed an artificial nanochannel that can be regulated by visible light to selectively transport chloride ions through the host-guest interaction.As complementary host molecule to promote Cl’ transport across the biomimetic nanochannels regulated by visible light,ethyl urea functionalized pillar[6]arene was designed,synthesized and assembled into the nanochannels through its host-guest interaction with retinal.Selective transport of chloride ions were realized by the acceptor of pillar[6]arenes self-assembled in nanochannel.In mean time,visible light responsive trans-cis isomerization of retinal induced the inclusion and release of acceptor pillar[6]arene in nanochannel,which can facilitate the selective transport of chloride ions under the influence of visible light.This system provides a new chemical model for the construction of visible light regulating chloride ionic transport nanochannel.4.Anion channels in the living body usually serve as carriers for the transport of ATP,ADP and other biological small organic anions.Based on the biomimetic strategy,we further constructed functional nanochannels,which can regulate the selective transport of ATP by visible light.Compared with inorganic ionic transport,organic ionic transfer across the membrane in nano-spaces is more complex,because of the bigger size and steric effect.Here,we designed and synthesized the novel phenyl urea derived pillar[6]arene as ATP receptor.Based on the visible light responsive host-guest interaction between pillar[6]arene and retinal,phenyl urea derived pillar[6]arene can be assembled and disassembled in nanochannel to regulate the selective ATP transport by visible light.Thus,we report a efficient chemical analysis method to investigate the influence of visible light on the transmembrane transport behavior of energy donor ATP.5.We have fabricated the visible light responsive ionic and molecular transport nanochannel in previous,however,the biological protein channel is usually sub-nanostructured in nature,which is more advantageous to regulate the transmission of ions and molecules in molecular level.To further improve the efficiency,we have constructed the pillar[n]arene molecular channel through the layer-by-layer selfassembly strategy to better fit with the organic channel structure.Then,PMMA polymer were filled into build pillararene molecule channel membrane.The visible light responsive retinal was further modified on the upper of pillararene by the schiff-base reaction to build visible light responsive molecular channel.Based on the size effect of ATP,pillar[6]arene assembled molecular channel can selective transport ATP and be regulated by visible light.This system realizes the visible light regulated ATP selective transport in sub-nanochannel by the inspiration of natural rhodopsin. |
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