Silver-coated eggshell membrane as a cost-effective SERS platform for enhanced molecular sensing

Surface-enhanced Raman spectroscopy (SERS) is a surface-sensitive analytical technique that relies heavily on plasmonic substrates to enhance Raman scattering. In this study, we report the fabrication of a cost-effective SERS substrate by thermally evaporating silver (Ag) onto the eggshell membrane (ESM), a low-cost and biologically sourced material, to create substrates with controlled surface morphologies. The silver coating thickness has been varied to optimize the signal enhancement and was evaluated with three different standard Raman active molecules: 4-mercaptobenzoic acid (4-MBA), 4-mercaptophenylboronic acid (4-MPBA), and rhodamine 6G (R6G)- as analytes. The developed substrates exhibited remarkable SERS activity with an Enhancement Factor (EF) of 0.12 ×10⁶ for 4-MBA, 0.70 × 10⁵ for 4-MPBA and 0.36 × 10⁴ for R6G, respectively. The ESM with optimal silver deposition of a thickness of 20 nm exhibited significantly enhanced SERS signal, with improved sensitivity and detection limit for all the three molecular analytes. Present study also highlights the importance of precise control over the metal coating thickness on ESM by thermal evaporation to achieve optimal SERS performance. Notable contribution is the fabrication of silver-coated eggshell membrane (ESM/Ag) as a cost-effective promising SERS platform for high-performance molecular sensing applications.