Characterization of AuNPs+rGO as a functionalized layer for LSPR sensors

•Portable low-cost point-of-care diagnostic is required for next future medical cares.•The active plasmonic sensing layer is Au+rGO capped by tea polyphenols (EGCG)•Interaction between the EGCG, the rGO and AuNPs enhance LSPR wavelength selectivity. Graphene-based materials have been extensively explored in recent years as valuable candidates as the key material for novel structures in the field, among many other applications, of sensing devices. This work reports a study about the applicability of rGO as a support for gold nanoparticles (AuNPs) prepared with an economic and eco-friendly method using phytochemicals present in tea extract at room temperature. The overall analysis is supported by simulation results about the LSPR effect in AuNPs-rGO, obtained by Mie theory and FDTD method. The residual phytochemicals are analysed as capping agent of the nanoparticles and their influence on the LSPR properties of the nanoparticles is outlined. The resulting composite is suitable for application as a low-cost sensing layer in biomedical LSPR sensor devices.