Chloride ion-assisted self-assembly of silver nanoparticles on filter paper as SERS substrate

In this work, a robust and easy-to-handle strategy was developed to fabricate silver nanoparticles (Ag NPs)-decorated filter paper as surface-enhanced Raman spectroscopy substrate using dip-coating method only with the assistance of chloride ions. Filter paper was modified with chloride ions for chemisorption of Ag NPs, overcoming the electrostatic repulsion between Ag NPs and paper. The effect of laser-induced substrate deformation was studied. The enhancement factor of the substrate was higher than 6.4 × 105 with a limit of detection of 1 × 10−8 M for 4-mercaptobenzoic acid. The Ag NPs-decorated paper substrate exhibits a good uniformity and can be stored for more than 2 months with negligible degradation. This substrate has great potential for detecting food contaminations, environment polluters and biomolecules.