pH-Sensitive mesoporous silica nanoparticles anticancer prodrugs for sustained release of ursolic acid and the enhanced anti-cancer efficacy for hepatocellular carcinoma cancer.

Ursolic acid (UA) as a nature product exhibits good anti-cancer activity, low toxicity, and good liver protection features. However, the low-solubility and poor bioavailability restrict its further clinical application. To overcome this problem, a pH-sensitive prodrug delivery system (UA@MSN-UA) that incorporated acid-sensitive linkage between drug and silica-based mesoporous nanosphere (MSN) was successfully designed and synthesized. The physicochemical properties of the UA@MSN-UA nanoparticles were investigated for shape, particle size, zeta potential, nitrogen adsorption-desorption and infrared (IR) spectroscopy. The nanoparticles were further evaluated for in vitro cytotoxicity, including proliferation inhibition, cell cycle distribution and apoptotic effects against human hepatocellular carcinoma HepG2 cells. The TEM image showed that the size of synthesized MSN nanoparticle was a near-spherical shape with ~100nm diameter. In vitro cytotoxicity testing demonstrated that UA@MSN-UA nanoparticles prodrug exhibited higher proliferation inhibition, cell cycle arrest at the G2/M phase and significantly caused the early and late apoptosis in HepG2 cells, which would be contributed to high loading capacity, high cellular uptake and sustained release of UA. Overall, the UA-modified MSN prodrug delivery system can be a promising drug carrier for improving the bioavailability of UA, and further enhance its anti-cancer efficacy.