Fabrication Of Micro/nanostructured Superhydrophobic Surfaces On Metal For Surface Enhanced Raman Scattering

With the frequent occurrence of pesticide pollution and abuse of food additives,the detection of pollutants has become an important technical support to ensure food safety,which is of great significance to the maintenance of people's lives and health.In the detection of pesticide residues,the content of target molecules is very low(only mg,?g,even ng exists in the sample).The target molecules must be concentrated before detection,and this process easily leads to the loss of analyte,which seriously affects the detection results.How to effectively detect low concentration and small amount of molecules is one of the hot topics and important challenges in the frontier.Surface enhanced Raman scattering(SERS)effect can greatly enhance the detection signal of adsorbed target molecules,which has a good application prospect in trace detection.How to construct a high sensitive SERS substrate has become a bottleneck problem.The superhydrophobic micro/nanostructured surfaces have unique advantages in enriching target molecules,being the focus of current research.In this paper,a simple and fast method for fabricating superhydrophobic SERS substrate on copper surface by femtosecond laser processing is proposed.Large-area superhydrophobic micro/nanostructures were prepared on copper surfaces by changing the characteristic parameters of laser energy,scanning speed,interval and so on.After chemical treatment with trimethoxysilane,the contact angle of surfaces can reach 148.7°.With the superhydrophobicity of the surface,the droplets containing the measured molecules can be quasi-spherical.Meanwhile,the concentration and enrichment of the measured molecules can be realized during the evaporation of water.On the other hand,in order to achieve surface-enhanced Raman scattering effect,silver nanoparticles with a certain concentration were injected into the droplets containing the measured molecule,so that the residual solute mixture of the measured molecule and silver nanoparticles could be obtained after evaporation of the droplets.The Raman detection signal is enhanced by using the local electric field enhancement effect of silver nanoparticles.The detection limit of the superhydrophobic SERS substrate can reach 10-13M,and the Raman signal enhancement factor can reach 1.2×105 under the detection concentration,which meets the detection requirements.At the same time,the superhydrophobic SERS substrate has been successfully applied to the detection of pesticides(parathion-methyl),and the detection of methyl parathion solution with concentration of 10-7M can be realized.