Effects of pore size on in vitro and in vivo anticancer efficacies of mesoporous silica nanoparticles

Mesoporous silica nanoparticles (MSN) have been widely applied for drug delivery systems. To investigate the effects of pore size on anticancer efficacies, MSN with different pore sizes but similar particle sizes and surface charges were synthesized via a microemulsion method. The pore structures of MSN were characterized by transmission electron microscopy (TEM), small-angle X-ray scattering (SAXS), and N(2) adsorption–desorption isotherms. Doxorubicin loaded MSN (DOX/MSN) were prepared and the minimum drug loading capacity was detected in DOX/MSN with a pore size of 2.3 nm (DOX/MSN2). DOX/MSN with a pore size of 8.2 nm (DOX/MSN8) showed a comparable drug loading amount in comparison with ones with a pore size of 5.4 nm (DOX/MSN5). In vitro drug release profiles showed that DOX/MSN5 could release DOX quickly and completely. Compared with DOX/MSN2 and DOX/MSN8, DOX/MSN5 showed the higher cellular uptake and nucleic concentration of DOX in QGY-7703 cells, which led to efficient cell-apoptosis induction and anti-proliferation effect, and thus the optimal in vivo anticancer activities. Taken together, these results highlighted the importance of pore size in anticancer efficacies, which would serve as a guideline in the rational design of MSN for cancer therapy.