Novel Sensor Based On Silicon Sol-Gel Molecular Imprinting Technology

Molecularly imprinted polymer is a kind of material with specific recognition ability to template molecules.Because of its advantages of simple preparation,stable performance and low cost,it has been widely used in the fields of molecular recognition,drug delivery,solid phase extraction and so on.The method of surface molecularly imprinted technology is developed on the basis of traditional preparation,which realizing the polymerization on the surface of some material.Molecularly imprinted polymers prepared by surface molecularly imprinted technology have more effective number of binding sites,due to most of the binding sites are located on the surface of the material,which are different from those prepared by traditional method.As a result,the elution efficiency of template molecule and the recognition performance of molecular imprinted polymers are greatly improved.Gold nanoparticles（AuNPs）have good conductivity and Raman enhancement effect.However,AuNPs are not selective to target molecules,when they are used for object detection.Therefore,in this paper,we use AuNPs as substrate,preparing molecularly imprinted polymers on the surface of AuNPs.The prepared materials can detect target molecular in the complex system with sensitivity and selectivity.The main research contents are as follows:（1）The material of MIP-AuNPs was obtained by coating a layer of molecularly imprinted polymers on AuNPs surface,with L-phenylalanine（L-Phe）as the template molecule.And then MIP-AuNPs was used to construct the surface enhanced Raman scattering（SERS）sensor.In order to obtain better Raman enhancement effect,the thickness of molecular imprinted layer coated on AuNPs surface was optimized.The experimental results reflected that the SERS sensor we constructed exhibited high sensitivity and wide linear range to the target molecule L-Phe.When the concentration of L-Phe was 1.0×10^-8-1.0×10^-4 mol/L,the detected Raman signal presented a good linear relationship,with a linear correlation coefficient（R²）of 0.975.（2）The material of molecular imprinted polymers modified gold nanoparticles（Au-MIPs）was synthesized,with heroin as template molecule.After the modification of Au-MIPs on the surface of glassy carbon electrode,we can realize the detection of target molecule heroin by the method of differential pulse voltammetry.The experimental results showed that when the concentration of heroin solution was within the range of 3.0×10^-8-1.0×10^-5 mol/L,the detected electrochemical signals exhibited good linear relation and the linearly dependent coefficient（R）was up to 0.998.The detection limit was 1.0×10^-8 mol/L.In addition,the sensor can also determine heroin molecules in bovine serum solution,with the recovery rate between 96.7%and 104.1%.（3）Heroin is an aliphatic tertiary amine,which can be used as the co-reactant of luminescent material Ru（bpy）₃²⁺to produce light signal under the action of electrochemistry.In addition to this,it was discovered by us that Au-MIPs can enhance ECL signal of Ru（bpy）₃²⁺.Therefore,based on the enhanced electrochemiluminescence of Ru（bpy）₃²⁺,we developed a novel Electrogenerated chemiluminescence（ECL）sensor.During the modification of electrode,in order to realize the immobilization of Ru（bpy）₃²⁺,electrochemical deposition method was used to make Ru（bpy）₃²⁺deposite on the surface of electrode,and then the material of Au-MIPs was further modified on the Ru（bpy）₃²⁺surface.The prepared sensor had a good sensitivity,with a detection limit of 8.1×10^-16 mol/L,and the detected ECL signal exhibited great linear relation when the concentration of heroin solution in the range of 1.0×10^-15-3.0×10^-12 mol/L,with the linearly dependent coefficient（R²）of 0.995.At present,the prepared sensor had been successfully used to detect heroin in saliva samples.