The zinc sulphide (ZnS) quantum dots (QDs) and the Mn-doped ZnS QDs are interesting materials that can be used for the cost-effective, sensitive, and selective detection of molecules in plant cells and for the good antibacterial agents. The Mn-doped ZnS QDs with smaller sizes (~3 nm) may offer the good antibacterial activity and the selectivity for detecting metal ions or other chemical components in biomolecular complex. We are interested in studying the ZnS QDs and the Mn-doped ZnS QDs conjugated with organic molecules (hybrid organic–inorganic material) for the biological applications.