Bioconjugation of quantum-dots with chitosan and N,N,N-trimethyl chitosan

► CdS quantum dots were prepared using chitosan and N,N,N-trimethyl chitosan as capping ligands. ► CdS quantum dots/chitosan bioconjugates were synthesized with the average nanoparticle size below 4.0 nm. ► The bioconjugates were produced using a “green” single-step procedure via aqueous colloidal chemistry at room temperature. ► Novel fluorescent water-soluble nano-hybrids were developed for potential biomedical applications.