Preparation and Characterization of Biocompatible Quaternized Chitosan Nanoparticles Encapsulating CdS Quantum Dots

Abstract

Nanoparticles were produced by encapsulating CdS quantum dots (QDs) with quaternized chitosan (N-(2- hydroxyl) propyl-3-trimethyl ammonium chitosan chloride, HTCC), in order to improve general biocompatibility and stability of pure QDs. The properties of CdS QDs encapsulated HTCC nanoparticles (HTCC/CdS QDs) can be controlled by changing the mass ratios of QD to HTCC (16:1, 8:1, 4:1, 2:1, 1:1, 1:2, 1:4, 1:8). Characterizations of HTCC/CdS QDs nanoparticles were performed using ultraviolet-visible, fluorescence spectrometry, and sizezeta analysis. As compared with nonencapsulated QDs, these HTCC/CdS QDs nanoparticles would keep their original optical properties, and greatly improve the quantum yield and stability in room temperature. The quantum yield can be improved from 9% to 23%. When the mass ratio of QD and HTCC was 1.0, the nanoparticles had the highest quantum yield (23%). After being stored for a week, the nanoparticles could still keep stable and high fluorescence intensity, while that of non-encapsulated QDs almost disappeared. In vitro 3-(4,5-dimethylthiazol-2-yl)- 2,5-diphenyltetrazolium bromide (MTT) cytotoxicity tests on primary myoblast cells suggested that the cytotoxicity of the QDs was greatly reduced after HTCC encapsulation. Therefore, due to the increase of biocompability, HTCC/ CdS QDs nanoparticles can be potentially used in biological applications and labeling of biomolecules.