pH-Responsive Nanoparticles Based on Covalently Grafted Conjugates of Carboxymethyl Chitosan and Daunorubicin for the Delivery of Anti-Cancer Drugs

The drug controlled release responding to tumour microenvironment is a hotspot for cancer therapy research. Herein, pH-sensitive shell-core nanoparticles (NPs) were devised and fabricated for tumour treatment. The detailed characterisations of their structures demonstrated the successful formation of the precursors and NPs. More importantly, the NPs show excellent features, i.e., negative surface potential, narrow size distribution, and suitable dimension for cell penetration. And they have superior stability in pH 7.4 buffer (i.e., blood environment). In addition, owing to the existence of the pH-labile imine bond, a controlled release of drugs from NPs was achieved in drug release test. Confocal laser scanning microscopy (CLSM) and flow cytometry proved the internalization of NPs into HeLa cells and their further translocation into cell nuclei. The cytotoxicity results also revealed a remarkable cytotoxicity of the NPs to HeLa cells. Thus, this type of NP may be potentially useful for the efficient drug delivery.