Fluorescent bimetallic nanocomposites (M 1@M2-NCs) of silver-gold (Ag@Au-NC) and silver-platinum (Ag@Pt-NC) are prepared by reducing silver nitrate (AgNO3) on gold nanoparticles (AuNPs) and platinum nanoparticles (PtNPs) using sodium borohydride (NaBH4) at alkaline pH=11, in the presence of a lysozyme that acts as a template, and in the presence of a capping and stabilizing agent. The biocompatible bimetallic nanocomposites (M1@M2-NCs) have promising multifunctional applications (cell imaging, bio-sensing, therapeutics) observed by both in vitro as well as in vivo experiments. The fluorescent bimetallic nanocomposites (M1@M2-NCs) of silver-gold (Ag@Au-NC) and silver-platinum (Ag@Pt-NC) may be useful as an alternative nanomedicine in cancer theranostics applications.