Self-assembled "bridge" substance for organochlorine pesticides detection in solution based on Surface Enhanced Raman Scattering.

Pesticide residues pose a great threat to human health, and it is an urgent matter to realize fast and accurate detection of pesticide. SERS (Surface Enhanced Raman Scattering), as a nondestructive detection technology, performs a prominent role in fast detection field due to the strong surface plasmon resonance from short range effect between analyte and nanoparticle. Therefore, in order to solve the incompatibility between organochlorine pesticides molecules and noble metal nanoparticles, this paper proposed a concept of "bridge" substances acting as an interconnect function role to achieve a binding model (object-binder-metal (OBM)) and developed a droplet concentration method to enhance Raman signals. Both combination mode of pesticide molecules to bridge molecules and energy transfer of SERS experiment may relate to the compound ring according to the changes of peaks based on surface plasmon resonance. The selectivity and stability of different bridge substances interacting with pesticides molecules were illumined via binding energy of these two substances obtained by DFT calculations. A droplet can capture nanoparticles and analytes, which is conducive to SERS performance. Chloride ions in the solution contribute to rearrangement of nanoparticles and can validly promote surface activation of Ag nanoparticles to improve energy transfer efficiency of plasma resonance, resulting in superior SERS effect.