Sustainable silver/polylactic acid coated papers as efficient surface-enhanced Raman scattering substrates for detecting contaminants of emerging concern

• Sustainable and low-cost SERS substrates developed for water contaminants detection. • AgNPs deposited on paper coated with PLA NPs form the sensing substrates. • PLA NPs create a nano-rough film that reduces the porosity and hydrophilicity of paper. • Substrate performance depends on the PLA drying temperature. • Efficient detection of paraquat and ciprofloxacin in mineral water. Developing cost-effective and sensitive Surface-Enhanced Raman Spectroscopy (SERS) paper platforms represents a significant step forward for detecting specific water contaminants at ultra-low concentrations in remote regions of the globe. However, the hydrophilic, irregular, and porous nature of common paper often results in poor reproducibility and lack of uniformity of paper sensors. In this study, we developed efficient SERS substrates by combining office paper, polylactic acid nanoparticles (PLA NPs), and silver nanoparticles (AgNPs) using a two-step drop-casting method. In these substrates, the PLA NPs create a nano-rough film that reduces porosity and hydrophilicity of paper, while the AgNPs provide SERS activity. The film’s packaging ability was optimized by adjusting the drying temperature of the PLA colloid, which significantly influenced the paper’s wettability. Additionally, the drying temperature was found to substantially affect the loading of AgNPs on the substrate surface. Initial tests with rhodamine 6G as a model analyte showed that the optimal SERS response was achieved at a drying temperature of 100 °C, with a sixfold concentration of the Ag colloid. The effectiveness of these paper-based sensors was further demonstrated by detecting pesticides and antibiotics in mineral water, specifically paraquat and ciprofloxacin, with detection limits of 1 µM and 200 µM, respectively.