The present work deals with the synthesis and characterization of capped ZnS nanostructures and their optical and morphological studies. Tunable emission in semiconductor nano sized II-VI materials was observed by changing particle size. Also doped ZnS nanoparticles are also useful for tuning emission color. For that different samples having different particle size or different dopants were required. But here we present tunable emission in single sample by changing excitation conditions. Tunable emission in whole visible region including white light is observed in a single sample. These synthesized nanoparticles are also tested for their bisensing ability by tagging them with staphylococcus aueurs (SAU) bacteria. Some introductory results of capping ZnS NPs with DNA and their enzyme sensing studies have been presented.