Application Of Molecularly Imprinted Polymer Composite Gold-silver Nanoparticle SERS Sensor In Sensitive/specific Detection

The selective identification of Molecularly imprinted polymers?MIPs?combined with the high sensitivity of Surface Enhanced Raman Scattering?SERS?technology has proven to be the very good tool for detecting specific analytes in complex environments.The introduction of SERS active substrates?precious metals?into the MIPs matrix is the most important strategy to improve the performance of MIPs combined with SERS.Therefore,this paper studied the different combinations of MIPs with noble metal Ag,Au and Ag@Au composite nanoparticles.We explored the effect of the combination of noble metal nanoparticles and imprinted matrix on the performance of the material for SERS detection.Finally,the quantitative and sensitive detection of environmental pollutants,biomarkers and endocrine disruptors can be realized.Specific research contents are as follows:?1?By simple in situ reduction of AgNPs,we introduced SERS active substrate into the imprinted matrix of bulk polymerization to prepare MIPs@AgNPs-SERS sensor for selective and sensitive detection of BPA.A series of characterizations were used to investigate the adsorption of BPA by MIPs@AgNPs.By introducing interferences similar to those of BPA,the selective recognition of imprinted molecules was investigated and the minimum detection limit for BPA detection was determined.This sensor was reliable for quantitative detection of BPA,compared with the results from HPLC measurements.This easily prepared sensor revealed excellent stability and reusability.MIPs@AgNPs could detect BPA in polycarbonate plastic in real samples.?2?MIPs of bulk polymerization in the above work require cumbersome processes such as grinding,sieving,etc.,and and will cause damage to some imprinted cavity in the process.Therefore,we successfully prepared the MIPs@Ag monolithic column by introducing the monolithic column scheme and simplifying the preparation process by one-step polymerization into the rod-shaped polymer in capillary.The MIPs@Ag monolithic column combined with molecularly imprinted monolithic column and SERS detection technology had the larger pore structure to improve the mass transfer and binding rate of the analytes.The adsorption and binding experiments were carried out by adsorption isotherm model.It was proved that the MIPs@Ag monolithic column had the good binding rate and maximum saturated adsorption capacity for cortisol adsorption.Through a series of adsorption experiments,the adsorption of cortisol and the adsorption mechanism by MIPs were discussed.It was confirmed that this sensor could recognize cortisol specifically and detect sensitively by SERS.This easy-to-prepare sensor had excellent stability and reusability,and can sensitively detect cortisol in saliva of dogs to monitor cortisol levels in body.?3?We chose Au@Ag nanoparticles as the SERS active substrate to further improving the sensitivity to the analyte.In order to further improve the functionality of materials in previous work,the thermosensitive monomer PNIPAAm was introduced into the polymer matrix.The temperature-responsive intelligent composite PNIPAAm-MIPs@Au@Ag was synthesized to achieve selective binding and sensitive detection of malachite green?MG?and invisible malachite green?LMG?.The effects of changes about material state above and below the LCST temperature on analyte binding and SERS detection were examined.It was confirmed that when the temperature rised,the hydrophobic shrinkage of PNIPAAm allowed the agglomeration of Au@Ag nanoparticles in the imprinted matrix to facilitate SERS detection,exhibiting the temperature-sensitive properties of the material.This temperature-responsive material PNIPAAm-MIPs@Au@Ag could achieve ultra-sensitive detection of MG.The minimum detection limit for MG was 1x10^-10mol L^-1,which was lower than the EU minimum detection limit for MG residues in fish.In addition,the minimum detection limit for metabolites of MG with high toxicity and carcinogenicity was 1x10^-7 mol L^-1.