Tannin as a gatekeeper of pH-responsive mesoporous silica nanoparticles for drug delivery

Tannin grafted on mesoporous silica nanoparticles (tannin-MSNs) was synthesized by the amidation reaction of carboxyl benzyl borate with amino group modified MSN. Tannin-MSNs were an MCM-41 type of mesoporous material with a uniform diameter of about 150 nm. The XRD and N2 adsorption/desorption isotherm results demonstrated that the rhodamine was effectively loaded and the pores of MSN were blocked by tannin. Rhodamine as a model cargo was used to evaluate the loading and releasing behaviors of tannin-MSNs. The drug release rate of tannin-MSNs was pH dependent. An in vitro cellular cytotoxicity test indicated that tannin-MSNs were highly biocompatible and suitable to be used as drug carriers. The cellular uptake was investigated by confocal laser scan microscopy. The results showed that tannin-MSNs are promising platforms to construct a pH-responsive controlled drug delivery system for cancer and stomach therapy.