Preparation Of Sliver-molecularly Imprinted SERS Substrate And Study On Detection Of Benzimidazole Pesticide Residues

The benzimidazole pesticide residued in the water has seriously affected the water quality and threatened the health of humans.Highly sensitive detection of pesticide residues has become an urgent problem to be solved.The surface enhanced Raman scattering(SERS)uses rough metals as the detection substrate,which can achieve highly sensitive detection of the detected objects,can provide information on the molecular structure,and has been developed in the fields of biology,medicine,food,environment,etc.,promoting its practical Application,but there are shortcomings such as no test selectivity,unstable substrate and easy oxidation,and need to be continuously improved.Molecular imprinting technology(MIT)is a technology for synthesizing polymers that can achieve specific identification of targets.By synthesizing molecularly imprinted polymers,specific identification of targets can be achieved.It has selectivity,repeatability,and low cost.,Widely used in the field of separation and detection.In this experiment,silver nitrate was used as the silver source,and ascorbic acid was used as the reducing agent.L-cysteine,dopamine,glycine,and cysteamine hydrochloride were used as the directing agents,respectively.A good morphology distribution and good SERS performance were synthesized.The silver ball serves as the base core.Using carbendazim as the target molecule and methacrylamide as the functional monomer,the molecularly imprinted polymer(MIPs)was coated on the functionalized silver microspheres to prepare a composite substrate Ag @ MIPs,and the SERS signal strength of the substrate was increased again.It has good selectivity and sensitivity,and its detection target concentration reaches 1×10-5mol L-1.In order to improve the problem of template leakage background interference of molecular imprinting technology,in this experiment,carbendazim was used as a dummy template molecule,and the MIPs film was coated on the silver ball.The thickness of the film is only 4.5 nm,which can achieve the Highly sensitive detection,while avoiding the problem of background interference,and the substrate preparation process is stable,the composite substrate with stable SERS performance can be repeatedly prepared.In order to study the reason for the enhancement of the SERS signal of the target detected by the silver-molecular imprinted composite substrate,we used Raman imaging to investigate its mechanism.It was found that the cavities could adsorb the matching target molecules to enrichmoleculal,besides,the molecularly imprinted layer in the gap of the nanostructure can provide more hot spots to enhance the SERS signal.