An intermolecular charge and electron transfer processes in photoluminescent ZnS- L-Cysteine: core-shell Nanoparticles (NPs) extend highly sensitive and variable valence at the core (ZnS)-shell (L-Cysteine) interface primarily due to an extensive mixing of materials frontier orbital (i.e. covalency). Water soluble, ZnS- L-Cysteine: core-shell photo luminescent NPs achieved by straight forward micellar route that is thrust area of research in nanoscience for the control particle size and remarkable properties through chemical co-precipitation method. In the paper we studied, the synthesis of CTAB capped ZnS NPs as well ZnS- L Cysteine: core-shell NPs and examined by their composition, particle size and optical and luminescent properties. The NPs stabilized with CTAB and demonstrated the regular ZnS blue emission on recombination over ZnS band-crevice from shallow electron traps at 490 nm. The onset of the absorption was 80 nm blue shifts moved from 345 nm (bulk) to 265 nm, showing a quantum size impact. Quantum mechanical effect of light applied especially in semiconducting NPs through optoelectronic orbital model, which detect and control the light through electronic devices.