Degradable chiral mesoporous silica nanoparticles and carboxymethyl chitosan/cystamine hydrogels for selective loading and controlled release of S-naproxen

Degradable chiral mesoporous silica nanoparticles (DCMSN) are synthesized for selective loading and controlled release of S-naproxen (S-NPX). Chiral silane coupling agent (APTES-L) and degradable silane coupling agent (APTES-CN) are synthesized, respectively, which are used for the synthesis of DCMSN. APTES-L endows the DCMSN with chirality, while APTES-CN endows the DCMSN with degradability. Owing to the same rotatory directions of DCMSN and S-NPX, the DCMSN can be used for the selective loading of S-NPX, and the higher selectivity of DCMSN toward S-NPX is further confirmed by the thermodynamic computations. Further, the S-NPX loaded DCMSN (DCMSN-S-NPX) is encapsulated in the hydrogels cross-linked by carboxymethyl chitosan (CMCS) and cystamine (Cys). The TEM characterization reveals that the DCMSN has a regular and spherical shape, and the BET analysis demonstrates that the DCMSN is a typical mesoporous material. The thermogravimetry reveals that the contents of the silane coupling agents in the DCMSN are about 23.9 %. The results of UV and circular dichroism (CD) spectra indicate a higher selectivity of DCMSN toward S-NPX. The release of S-NPX from the hydrogels is controlled by pH and glutathione (GSH), and the release of S-NPX follows a zero-order equation. Cytotoxicity assay indicates that the drug-free hydrogels have excellent biocompatibility.