Highly efficient, multiplexed SERS sensing of para-aminobenzoic acid using reusable silver nanoarrays for environmental monitoring

•Ag nanoarrays were fabricated on glass and silicon substrates by thermal evaporation.•Ag/Si substrates showed confined nanoparticles with a narrower size distribution.•As-fabricated sensors demonstrated high efficiency, reproducibility and recyclability.•Ag/Si sensors exhibited LOD down to 10−14  molar concentrations.•Multiplexed sensing of PABA and R6G was demonstrated using Ag/Si sensors.