In vivo distribution and antitumor activity of doxorubicin-loaded N-isopropylacrylamide-co-methacrylic acid coated mesoporous silica nanoparticles and safety evaluation.

The objective of this study was to develop and evaluate the antitumor activity and the safety of a delivery system containing mesoporous silica nanoparticles (MSN) coated with pH-responsive poly (N-isopropylacrylamide-co-methacrylic acid; P NIPAM-co-MAA) for doxorubicin (DOX) delivery (P-MSN-DOX) in vitro and in vivo. We reported that P-MSN-DOX nanoparticles (190 ± 30 nm) offered a DOX-loading coefficient of more than 20%. DOX release from the P-MSN-DOX formulation was pH-dependent with enhanced antitumor effects in vitro compared with traditional MSN-DOX, which was weakly cytotoxic due to negligible drug release at tested pHs. P-MSN-DOX circulated longer, with less cardiac and renal accumulation as shown by pharmacokinetics and biodistribution studies in vivo. Also, the P-MSN-DOX delivery system had greater antitumor activity in mice bearing a murine sarcoma S-180 cell line. This finding was correlated with both in vitro and in vivo. Subacute toxicity tests revealed a low P-MSN-DOX toxicity in vivo, as well. Thus, P-MSN-DOX appears to be an efficacious and safe cancer treatment strategy.