Mannosylated chitosan-zinc sulphide nanocrystals as fluorescent bioprobes for targeted cancer imaging

A novel nanomaterial based on chitosan-zinc sulphide:Mn (ZnS:Mn) conjugated with mannose ligand has been developed for targeted cancer imaging. The nanobioconjugates, prepared through simple aqueous chemistry, possessed high colloidal stability and strong fluorescence emission at ∼600 nm. Characterization using XRD, DLS, SEM, AFM and FTIR revealed that the bioconjugated particles are appropriately functionalized and stable, with average size ∼150 nm. The presence of polysaccharide chitosan bestowed enhanced biocompatibility to the nanocrystals and provided suitable functionality for mannosylation. In vitro cytotoxicity studies on mouse fibroblast (L929) and oral epithelial carcinoma (KB) cells confirmed their cytocompatibility. Bioconjugation with mannose provided specificity and targeted cellular labelling characteristics as demonstrated using KB cells which over-express mannose receptors on their surface. Our investigations highlight the applicability of polysaccharide protected and mannosylated fluorescent ZnS nanoprobes for active targeting of cancer cells.