Photoluminescence properties of self-assembled chitosan-based composites containing semiconductor nanocrystals.

The photoluminescence (PL) properties of composites obtained by embedding green-emitting semiconductor nanocrystals (NCs) of two different types (thiol-capped CdTe and CdSe/ZnS) into chitosan-based biopolymer particles were investigated. The synthesis of self-assembled particles from oppositely charged polysaccharides involved a preliminary electrostatic binding of positively charged chitosan chains by negatively charged functional groups of NC stabilizing ligands. The amount of NCs and the acidity of the solution were found to be important parameters influencing the PL. The PL properties were mainly discussed in terms of the colloidal stability of the particles and changes in energy gap of NCs. Generally, the obtained biocompatible composites with NCs randomly distributed within a biopolymer particle demonstrated a higher PL resistance to the solution acidity that expands the applicability range of thiol-capped NCs.