Loading zedoary oil into pH-sensitive chitosan grafted mesoporous silica nanoparticles via gate-penetration by supercritical CO2 (GPS)

Nanocarriers of the stimuli-responsive mesoporous silica nanoparticles (MSNs) have exhibited great potential on target-specific and controlled-release drug delivery. However, it is still a challenge to load drugs into this promising nanocarriers because of its gated structure. In this study, we developed a method named gate-penetration by supercritical CO2 (GPS) to successfully prepared zedoary oil loaded chitosan grafted MSNs (ZO@CS-MSNs). Quantitative analysis by high performance liquid chromatography demonstrated the composition ratio of six primary ingredients in zedoary oil remained constant after the drug loading process. Several process parameters of GPS were optimized, and the drug load of ZO reached 41.4 +/- 1.2%. Morphology characterization by scanning electron microscope showed that ZO@CS-MSNs were spheres with diameter about 80 nm and a 'gate' structure was formed by chitosan on the surface of MSNs. Infrared and thermogravimetric analysis were performed to further confirm the structure of ZO@CS-MSNs. in vitro drug release test under different pH conditions indicated that ZO had a well pH-response release behavior, proving that ZO was transported into the inner channels of MSNs. The results state GPS is a promising way of high-efficacy and non-destructive to overcome the drug loading problems for stimuli-responsive MSN and further extend its application.