Biopolymer-based Surface-enhanced Raman Scattering Substrates from Agricultural Waste for Pharmaceutical Product Detection

Coffee silverskin is the only by-product from coffee roasting. Recently this biomaterial demonstrated potential as a polymer matrix filler because of its antioxidant, mechanical, and thermal properties. Furthermore, surface-enhanced Raman scattering (SERS) is becoming the technique of preference to detect emerging contaminants due to the straightforward sample preparation required and the rapid data acquisition. This research relates to the synthesis of silver-coated chitosan/coffee silverskin films to detect acetaminophen and caffeine in water at trace levels using the SERS technique. Chitosan/coffee silverskin thin films synthesized by the solution casting method contained CSS ranging from 60-80 v/v%. Afterword, a magnetron sputtering unit allowed coating the films with silver for 15, 30, and 60 seconds. Then, the films were exposed to 10^-3M acetaminophen/water and acetaminophen/alcohol solutions using immersion and drop casting. Finally, we studied the feasibility of the sensor using SERS. The sensor showed a slight enhancement of the Raman spectra compared to the acetaminophen powder. Tensile test results from uncoated 70 v/v% coffee silverskin thin films revealed an ultimate tensile stress (UTS) of 16.09 MPa and elongation at break of 27.9%. Ongoing structural and optical analysis to the Ag-coated samples will render insight into the mechanisms of molecule interaction with the sensor surface.