Study On Electrochemical Sensor Based On Polycyclodextrin Composite Nanomaterials

Electrochemical sensors are widely used in the detection of biological molecules because of their high efficiency,sensitivity,accuracy,simplicity and low cost.It has been found that small molecule cyclodextrin can disperse carbon nanotubes,but difficult to form films and further to prepare modified electrodes.The prepolymer of cyclodextrin,which is synthesized from four cyclodextrin molecules,is easy to form polymer films under certain conditions.However,cyclodextrin prepolymer can not disperse carbon nanotubes very well.In this paper,based on the unique properties of cyclodextrin,cyclodextrin cross-linking prepolymer with higher solubility in water was prepared.The prepolymer was then combined with nano-carbon materials and electronic mediators dispersed by cyclodextrin to form a composite modified film at the same time of further polymerization.On this basis,three kinds of electrochemical sensors were prepared and their performances were studied.Specific research contents are as follows:Firstly,water-soluble cyclodextrin prepolymer was synthesized.Cyclodextrin prepolymer,cyclodextrin and acidified multi-walled carbon nanotubes（MWCNTs）were mixed to prepare a composite membrane modified electrode of carbon nanotubes/cyclodextrin polymer（MWCNTs/CDP）under controlled conditions.The material preparation conditions were optimized and the modified electrodes with the best electrochemical performance were obtained.On this basis,lactic acid biosensors loaded with lactic acid oxidase have good linearity in the range of 10-2000μM.The sensitivity is 2.63 nAμM^-1,and the detection limit is 11.41μM.Secondly,a composite modified membrane with electronic mediator function was prepared by using the host-guest envelope interaction of cyclodextrin and ferrocene（Fc）.On this basis,a second generation glucose sensor was prepared by loading glucose oxidase.The concentration detection range of the sensor is 10-280μM.The sensitivity is 2.12 nAμM^-1 and the detection limit is 7.06μM.Finally,the modified electrode of cyclodextrin polymer/carbon nanotubes/graphene-platinum composite membrane was prepared,and the simultaneous detection of opamine（DA）,ascorbic acid（AA）,uric acid（UA）,tryptophan（TRP）and other common substances in serum was realized.The tested substances showed good linearity under simultaneous detection,and the sensitivity of the simultaneous detection are 0.39μAμM^-1、18.27μA mM^-1、0.16μAμM^-1、0.16μAμM^-1.The average recoveries obtained by repeated measurements were 99.67%,101.32%,98.74%and 100.47%,with good reproducibility.