Fabrication Of Artificial Ionic Gate Based On The Interaction Between Graphene Oxide And DNA

In living organisms,cells have a variety of ion channels that regulate many important cellular functions by constantly exchanging ions with the external environment.The ion transport characteristics of biological ion channels are of great significance in basic biology research.In recent years,the research on ion channels is blooming.The fabrication of artificial ion channels plays a vital role not only in the mechanism research of ion transport,but also in the application of intelligent instruments.Graphene oxide can bind to DNA via ?-? interaction,which has also been used in biosensor and nanodevice research.In this thesis,we fabricate artificial ionic gate based on the interaction between graphene oxide and DNA,coupled with optical isomeric properties of the azobenzene-inserted DNA,as well as T-Hg2+-T characterized structure.The fabricated ionic gate can be used for rhodopsin biomimetic chemistry,and Hg2+ detection.This method also provides instructive significance for other bionic device preparation and ion-driven artificial ionic gate construction.1.Rhodopsin-like ionic gate for efficient photocontrol of ion transport.Rhodopsin,composed of opsin and isomeric retinal,acts as the primary photoreceptor by converting light into electric signals.In this part,we have fabricated a light-regulated ionic gate based on the design of a graphene oxide(GO)-biomimetic DNA-nanochannel architecture.Inspired by rhodopsin,we introduce photo-switchable azobenzene(Azo)-DNA to the surface of porous anodic alumina(PAA)membrane.By modulating the interaction between the GO Blocker and Azo-DNA via flexibly regulating trans and cis states of Azo under the irradiation of visible and ultraviolet light,alternatively,the ionic gate is switched between "ON" and "OFF" states.This newly-constructed ionic gate can possess high efficiency for the control of ion transport due to the high blocking property of GO and the rather tiny path within the barrier layer which are both firstly employed to fabricate ionic gate.We anticipate that this rhodopsin-like ionic gate may provide a new model and method for the investigation of ion channel,ion function and ion quantity.In addition,owning to the advantages of simple fabrication,good biocompatibility and universality,this bioinspired system may have potential applications like optical sensors,photoelectric transformation,and controllable drug delivery.2.A mercury ion-driven ionic gate for one-step and ultra-sensitive matal ion detection.In this work of the thesis,an artificial ion gate has been reported based on the interaction between DNA and graphene oxide(GO),which can detect Hg2+ in aqueous solution by the formation of T-Hg2+-T structure.GO is an adsorbent that interacts strongly with single-stranded DNA.In this strategy,poly T sequence DNA has been modified on the barrier layer of porous anodic alumina(PAA)film.In the absence of Hg2+,GO can be adsorbed to the single-stranded DNA-modified PAA,which hinders the ion transport through the nanochannel,and the ionic gate is in "OFF" state in this case.When Hg2+exists,the poly T single strand forms double-stranded structure through T-Hg2+-T coordination chemistry.GO is then released by the double-stranded DNA product from the artificial ionic gate,which is switched to "ON" state.The artificial ion channel can also be used for Hg2+ detection,and the detection limit is very low.In addition,the ion-gated sensing system has the same application for other metal ions with the same properties,such as Ag+,which can form C-Ag+-C structure.This method has an enlightening significance for the construction of ion channel based on the interaction between GO and DNA and gets up the very good exemplary role for the application of metal ion analysis.