Preparation of magnetic fluorescent nanoparticles with quaternary ammonium chitosan derivatives and its properties

To explore a novel solution to the challenges in constructing polymer coated magnetic fluorescent nanoparticles, HTCC/Fe3O4/CdTe magnetic fluorescent nanoparticles (MFCNPs) that can be well dispersed in water were prepared via the electrostatic interaction of the cationic N-(2-hydroxyl) propyl-3-trimethyl ammonium chitosan chloride (HTCC) and the anion precoated water-soluble cadmium telluride (CdTe) quantum dots (QDs) and the sodium citrate-coated Fe3O4 (SC-Fe3O4) magnetic nanoparticles (MNPs), which overcame the performance defects of hydrophobic polymer for surface coating and the possible toxicity of cross-linking agent induced by the hydrophilic polymer coating materials. The structural characterizations by FTIR, XRD and XPS reveal that the surfaces of SC-Fe3O4 MNPs and CdTe QDs are coated with HTCC. TEM imaging suggests that the MFCNPs are spherical particles with the diameters of ∼15–20 nm. The MFCNPs exhibit good biocompatibility. Further investigation suggests that the UV-Vis and fluorescence spectral properties and surface electrical properties of HTCC/Fe3O4/CdTe MFCNPs are mainly affected by the relative ratios of SC-Fe3O4 MNPs, CdTe QDs and HTCC. The adsorption and release properties of the MFCNPs were studied using bovine serum albumin (BSA) as the model. The results indicate that the chitosan-based magnetic fluorescent composite is a promising delivery carrier candidate with excellent comprehensive properties for both magnetic response and fluorescence imaging.