Facile synthesis by a covalent binding reaction for pH-responsive drug release of carboxylated chitosan coated hollow mesoporous silica nanoparticles

In this study, a promising drug nano-carrier system consisting of mono-dispersed and pH sensitive carboxylated chitosan-hollow mesoporous silica nanoparticles (Ccs-HMSNs) suitable for the treatment of malignant cells was synthesised and investigated. At neutral pH, the Ccs molecules are orderly aggregated state, which could effectively hinder the release of loaded drug molecules. However, in slightly acidic environment, Ccs chains are heavily and flexibly entangled in gel state, which would enhance the subsequent controlled release of the loaded drug. Using doxorubicin hydrochloride (DOX•HCl) as the drug model, their results demonstrated that the system had an excellent loading efficiency (64.74 μg/mg Ccs-HMSNs) and exhibited a pH-sensitive release behaviour. Furthermore, confocal laser scanning microscopy revealed that the Ccs-HMSNs nanocomposite could effectively deliver and release DOX•HCl to the nucleus of HeLa cells, thereby inducing apoptosis. In addition, MTT assay also confirmed that DOX•HCl loaded Ccs-HMSNs (DOX•HCl@Ccs-HMSNs) exhibited a good anticancer effect on HeLa cells with a time-dependent manner. Finally, haemolysis experiment showed Ccs-HMSNs had no haemolytic activity at all the tested concentrations (5–320 μg/mL). Thus, this biocompatible and effective nano-carrier system will have potential applications in controllable drug delivery and cancer therapy.