Smart polymer-based theranostic agents often exist the problem of low drug release rate and are difficult to reach the site of brain tumors for magnetic resonance imaging (MRI). To synthesize a theranostic agent for brain tumor MRI with high drug release rate, a paramagnetic, pH and temperature-sensitive polymeric particle (PPP) is synthesized using simplified processes in this work. These dually sensitive polymeric particles show negligible cytotoxicity against HeLa and glioma (C6) cells. The obtained polymeric particles can effectively load anticancer drug doxorubicin (DOX). In vitro drug release measurements exhibit retarded release profile when subjected to varying pH or temperature. Moreover, DOX-loaded PPP exhibits obvious antitumor properties for C6 cells. The percentage of cumulative DOX release is higher than 95 % while both pH and temperature are changed. The T 1 -weighted relaxivity values at 3 T are 12.41 mM -1 s -1 (pH = 6.3) and 10.75 mM -1 s -1 (pH = 7.4). In vivo MRI reveals that the PPPs can be effectively imaged in brain tumor (glioma).These results indicate that the PPPs have great potential in diagnosing and treating glioma.

Paramagnetic, luminescent, and temperature/pH-responsive polymeric particles with MR/optical imaging and antitumor drug delivery capability are prepared by emulsifier-free emulsion polymerization.