An apparatus comprising a substrate and at least two nanowires on the substrate, the nanowires comprising a core and a metal shell, wherein the core is selected from the group consisting of a semiconductor and a dielectric, thereby forming a nanowire-composite to allow plasmon coupling for enhancements of the electric fields and enhancements of the surface enhanced Raman signal (SERS) and enhancements of the chemical or biological specificity and sensitivity. A method of making a SERS-active substrate comprising providing a substrate and affixing a plurality of nanowires on the substrate thereby forming a nano-composite, creating plasmon coupling leading to enhanced electric fields in the vicinity of the nanowires and enhancements of the surface enhanced Raman signal (SERS) and enhancements of the chemical or biological specificity and sensitivity.