Ag nanodisks decorated filter paper as a SERS platform for nanomolar tetracycline detection

A simple and cheap filter paper-based SERS substrate has been developed for the sensing of tetracycline (TC) traces. In fact, antibiotics could represent a danger for environment and human health and TC is, in detail, one of the most wide-spread antibiotics entering the food chain and as water contaminant. According to this aim, Ag nanodisks (AgNDs) synthesis procedure was designed for tailoring the plasmonic peak position and, so, the SERS effect. Synthetized AgNDs were then used to simply decorate the surface of common filter paper, chosen because of its biocompatible, porosity and cheapness features. The obtained substrates based on filter paper and AgNDs allow the fast and easy analysis of aqueous solution containing first methylene blue used as standard and then TC samples. Fixed volume (20 μL) of TC solutions at different concentrations was simply dropped on the SERS support. The SERS spectrum was acquired before the complete water evaporation allowing TC detection down to the concentration of 10−9 M in aqueous solution. The results demonstrated that the SERS substrate obtained with the proposed facile, low-cost and relatively green fabrication process and the possibility to tune the plasmon excitation can be implemented for TC low concentration samples.