The Preparation And Electrochemical Study Of Novel Molecularly Imprinted Electrochemical Sensors

Molecular imprinted polymers(MIPs)could imitate the molecular recognition of biological molecules;it has an important application in the enrichment and separation,analysis,testing and other aspects of complex samples and has gradually becoming an important and active research field.At present,divinyl benzene and ethylene glycol dimethyl acrylate(EGDMA)were uased as crosslinking agents in the preparation of molecular imprinted polymers,the polymer in the solvent will gradually precipitation with the increasing of the crosslinking degree and molecular weight in the cross-linking polymerization process,the molecular imprinted polymers thus obtained often need to grind,sieve,and selecting the appropriate pore size of imprinted polymer,the preparation process of these crosslinking agents were complex and easy to cause the waste of materials.Therefore,selection of appropriate crosslinking agent has an important significance in molecular imprinted technology(MIT).In this paper,the preparation methods and application of molecular imprinted polymers were reviewed,and with the characteristics of siloxanes easy to crossliked with water,we use siloxanes as crosslinking agents with ethanol as solvent in the synthesis process of imprinted polymer to avoid the precipitation and crosslinking,the polymer solution with good fluidity and uniformly were obtained.When modified MIPs solution was added to the glass carbon electrodes with the process of solvent volatilied,thydrolysized and crosslinked,the electrochemical sensors were prepared and the electrochemical properties of procaine hydrochloride and catechol molecular imprinted electrochemical sensors was studyed by electrochemical measurement.The main experimental results were as follows:The performance of the polymer films has a certain influence on the imprinting effect of sensors,the sensors would have good imprinting effect and stability only when films with suitable hydrophilicity and flexibility.Siloxanes were crosslinked and cured with water,and with the disappearance of Si-O-C,the generation of Si-OH and Si-O-Si.The molecular imprinted sensors for procaine hydrochloride have a good linearity in the range of 4.0×10-8-2.4×10-5M,and the linear equation was IP/μA = 0.20834c/μM +0.50357(R2=0.9986).The detection limit with multi-measured was 1.02×10-8 M.In addition,when the interfering substance concentration in the nutrient solution were not higher than 1-fold concentration of procainamide hydrochloride,4-fold concentration of dopamine,50-fold concentration of ascorbic acid,40-fold concentration of levodopa and 20-fold concentration of epinephrine would do not interfere the detection of procaine hydrochloride.Moreover,the recovery of the sensors for the detection of procaine in human serum samples ranged from 97.13%to 106.41 with RSD less than 2.50%.We prepared catechol electrochemical sensors with different siloxane as crosslinking agents and studied on them.The results shows that when the volume ratio of the mixed siloxanes as crosslinjking agent with γ-(2,3-epoxypropoxy)propytrimethoxysilane(KH-560)and methyl triethoxy silane(M-TEOS)was 3:7,the catechol electrochemical sensors have the better imprinting effect.There is a good linearity between the oxidation peak current and the concentration of catechol in the range of 2.0×10-9-2.O×10-5 M and the linear equation was IP/(μA)= 0.08017c/μM + 0.58789(R2=0.9989),the detection limit was 6.24×10-10M.When the concentration of interfering substance in culture media was not higher than 2-fold concentration of phenol,2-fold concentration of nitro phenol,2-fold concentration of bisphenol A,0.8-fold concentration of benzodiazepines,0.8-fold concentration of hydroquinone,5-fold concentration of adrenaline,4-fold concentration of norepinephrine,3-fold concentration of dopamine and 40-fold concentration of ascorbic acid,it will have no effect to the detection of catechol,and the sensors has satisfactory results for catechol detection in the human serum samples and tap water samples with the recoveries ranged from 95.19 to 104.9%.