Preparation And Application Of Electrochemical Sensor Basedon Molecularly Imprinted Copolymers-Ionic Liquids-Multi-walled Carbon Nanotubes Composites

Molecularly imprinted polymer（MIP）is a species of material including specific recognition sites,whose size,shape and functional groupsmatch with template molecule.In recent years,MIP has been extensivelyutilized in biological/chemical sensors,food and drug analysis,drug delivery and release andcatalytic degradation fields,etc.However,traditional MIPs still have some shortcomings,such as poor conductivity,low selectivity and long enrichment and elution time,which influence theirapplication to certain extent.To improve and enhance MIP performances,herein we carried out a series of exploration and research on MIP basedelectrochemical sensors.The central contents and results of this study are as below:（1）An ionic liquid（[BMIM]PF₆）functionalized multi-walled carbon nanotubes（MWCNTs@IL）composite was produced by using ion-exchange reaction to modify a bare galssy carbon electrode（GCE）.L-tryptophan（L-Trp）was used as template molecule,and 4-vinyl benzoic acid and styrene（PS）as functional monomers,a semi-covalentmolecularly imprinted copolymer（MIP）was prepared by emulsion polumerization.Then,the MIP was coated on the MWCNTs@IL/GCE,followed by Nafion forenhancing the stability and electrostatic effect.The resulting electrochemical sensor persentedgood conductivity and selectivity for L-Trp.Furthermore,the enrichment and elution process of template molecules was facilitated.Under the optimal conditions,the linear range of the sensor was 0.008-26μmol.L^-1and the detection limit was0.006μmol.L^-1（S/N=3）.The sensorhas been successfully applied to the determination of L-Trp inamino acid oral liquids and human serum samples.（2）An ionic liquid（[APMIM]Br）functionalized multi-walled carbon nanotubes（MWCNTs@IL）was mixed with gold nanoparticles（Au NPs）undera mild conditionto fabricate MWCNTs@IL-Aucomposite.Then,5-hydroxytryptamine（5-HT）was used as template molecular,and itaconic acid（IA）and acrylamide（Aam）as functional monomers to prepare surface imprinted copolymer（DSMIP）on the MWCNTs@IL-Au by precipitation polymerization.The obtained DSMIP-MWCNTs@IL-Au was coated on GCE to construct sensor directly.The sensor showed a linear response range of 0.20-10μmol.L^-1for 5-HT,and the detection limit was 0.08μmol.L^-1（S/N=3）.Itpresentedhigh selectivity and reproducibility,moreover,it alsowas successfully applied to the determination of 5-HT in human serums andurine samples.