Chitosan-based magnetic/fluorescent nanocomposites for cell labelling and controlled drug release

A chitosan-based drug delivery system, composed of Fe3O4 magnetic nanoparticles (MNPs), CdTe@ZnS quantum dots (QDs) and the anti-cancer drug doxorubicin (DOX), was designed and fabricated. The surfaces of MNPs were modified with carboxymethyl chitosan (CMCS) to minimise the possible fluorescence quenching triggered by magnetic cores. Glutaraldehyde was used as a crosslinking agent to create chemical covalent conjunction between different components, thus enhancing the stability of the obtained nanocomposites. The resulting nanocomposites retain favourable magnetic and fluorescence properties and can be used for bimodal cellular imaging. A sustained pH dependent DOX release with more release at pH = 5.3 was observed. The nanocomposites exhibited low cytotoxicity and CLSM images confirmed the cell fluorescence labelling properties and time-dependent cellular uptake. In summary, the chitosan-based nanocomposites developed in this work provided highly integrated functionalities and are promising for controlled drug delivery and also suitable for in situ cellular imaging.