Au@Ag core-shell monolayer film with dense arrangement was built by a simple polyethylene glycol assembly method, and used as SERS substrate to detect organophosphorus pesticides with highly sensitivity and reproducibility. Au@Ag core-shell nanostructures were synthesized by simple seed growth method firstly, and then modified with methoxypolyethylene glycol mercapto(m PEG-SH) to obtain ordered dense monolayer structure. The formation of this structure attribute to an appropriate amount of m PEG-SH added to...