Study On Redox-responsive Controlled Release System Based On Mesoporous Silica Nanoparticles

A unique redox responsive system for glutathione (GSH) triggeredcontrolled release was constructed based on mesoporous silicananoparticles (MSNs) in this study. The system was prepared by surfacemodification of the MSNs in the way of post-synthesis. Based on twotypes of MSNs, SBA-15and MCM-41, the corresponding systems wereobtained by modifying the MSNs with L-cystine ester linked mPEG chains,in which the former was served as the nanoreservoir of guest moleculesand the latter was applied as gatekeepers to block the mesopores. Thedisulfide-bond in L-cystine ester can be effectively cleaved by redoxreaction in the presence of GSH with a concentration at cancer cell level,and then the guests encapsulated in the pores were released.Chemical structure and composition of the functionalized MSNs wascharacterized by FTIR, TGA,29Si MAS NMR and EA and the resultsshowed that the MSNs were successfully modified by the organics. The mesoporous structure was analyzed by TEM, SEM, XRD and nitrogenadsorption. The results showed that both SBA-15and MCM-41possessevident2D-hexangonal mesostructure, which become less ordered with thegrafting of organic portions. Compared with MCM-41based MSNs,SBA-15based MSNs showed larger pore sizes and lower surface areas.Besides, DLS tests indicated that the introduction of mPEG enhancedstability of the MSNs in aqueous solution and an anionic surface of theMSNs was observed by zeta potential tests.Fluorescein dye as the model drug was loaded into the MSNs andreleased in PBS with10mM GSH and without GSH respectively to testthe controlled release properties of the MSNs using UV-Vis spectra as thedetector. The results showed that fluorescein dye in PBS with10mM GSHwas released much more rapidly. Moreover, a different release behaviorwas discovered when changing the MSN matrix. The SBA-15basedsystem showed a distinctive release behavior of steadily releasing whilethe MCM-41based system showed a burst effect followed by a very slowrelease. According to the results above, the MSNs synthesized from bothSBA-15and MCM-41can be used as an effective drug controlled releasesystem for biomedical applications, and the systems based on differentMSN matrix can meet different requirements of drug administration in practical application.