The Separation Of Chiral Single-wall Carbon Nanotubes And Construction Of Electrochemical Chiral Sensors

Chirality is an intrinsic property of living world and most drug molecules.Thus,chiral discrimination has attracted great interest in chemical and biological research and modern medicine.Most commonly for chiral recognition are chromatography and circular dichroism that suffer from time-consuming and high cost process.Electrochemical chiral sensors have attracted much attention in recent years owing to their exceptional advantages such as simple operation,easy to miniaturize and low cost.The researchers have developed various enantioselective recognition materials to construction chiral interface.However,the development of electrochemical chiral analysis is still limited by the design of new sensing interfaces with an effective chiral selection.Single-walled carbon nanotubes(SWCNTs)that have excellent electrical conductivity and large specific surface area are widely used as electrode materials in electrochemistry.However,most of the current synthesis techniques of SWCNTs generally produce mixtures of different structures.With the development of singlechirality separation of SWCNTs,we proposed a method for preparing electrochemical chiral sensor using chiral SWCNTs as electrode material.Different from other nanomaterials,chiral SWCNTs have great application prospects in the construction of electrochemical chiral sensors due to their inherent chirality diversity and good conductivity and without introducing other chiral molecules or conductive materials.The full text is divided into four parts,as follows: Charpter 1: OverviewThis chapter first introduce the chiral recognition methods,which mainly focusing on the development of electrochemical chiral sensors and the commonly used chiral recognition materials.Secondly,the structure of chiral SWCNTs,single-chirality separation methods and the characterization techniques of SWCNTs are discussed.Finally,the significance and content of this paper are expounded.Charpter 2: Chiral recognition of 3,4-dihydroxyphenylalanine isomers by chiral single-walled carbon nanotube modified electrodeIn this chapter,we developed an ethanol-assisted gel chromatography for the chirality separation of SWCNTs,in which ethanol was employed to finely tune the coverage of sodium dodecyl sulfate(SDS)on nanotubes,and thus the interactions between chiral SWCNTs and an allyl dextran-based gel.Incrementally increasing the ethanol content in a low concentration SDS eluent leads to successive desorption of the different structure SWCNTs adsorbed on the gel.Finally,we separated higher purity(6,5),(8,4)and(7,6)chiral SWCNTs.And then the chiral SWCNTs were used to prepare chiral sensors and to enantioselective recognize of DOPA enantiomers.The experimental results show that the chirality of carbon nanotubes has an effect on the enantioselectivity of the electrode.This experiment provides a new idea for the application of chiral carbon tubes in electrochemistry.Charpter 3: Enantiomers of Single Chirality Nanotube as Chiral Recognition Interface for Enhanced Electrochemical Chiral Analysis of DOPA and AAEach chiral SWCNTs has a pair of left(M)and right(P)-handed structure.Small difference in atomic arrangements among SWCNTs causes striking differences in their electronic properties.In this work,the enantiomers from(6,5)single-chirality SWCNTs were separated using a mixed surfactant multi-column gel chromatography method.And then the enantioselectivity was imparted to a glass carbon electrode by modifying its surface with the left handed(M-(6,5))or right handed(P-(6,5))SWCNTs.Electrochemical chiral distinguish of DOPA and AA enantiomers can be achieved by differential pulse voltammetry(DPV),in which different magnitudes of peak currents were observed.Then we combined the density functional theory(DFT)theory to study the chiral recognition mechanism and proposed the chiral space theory.The obtained chiral electrodes were also applied to determine the enantiomeric excess(ee)of DOPA,indicating the potential applications of proposed chiral SWCNTs sensors.Charpter 4: Dual-signal amplification electrochemical sensor based on chiral single carbon nanotube array electrode and SWV technologyIn this chapter,we provided a simple and effective chemical modification method to prepare(6,5)chiral carbon tube array electrode.This improved the electrochemical chiral discrimination performance by forming a more ordered and effective chiral space on the electrode.In addition,combined with square wave voltammetry(SWV)technology that could extend the interaction time between DOPA enantiomer and chiral SWCNTs,and thus making the recognition site reused,which can amplify the efficiency of chiral recognition.This experiment shows that chiral carbon tubes can be assembled to different interfaces through functional methods,which provides new ideas for the application of chiral carbon tubes in other fields.