Smart polymeric particle encapsulated gadolinium oxide and europium: theranostic probes for magnetic resonance/optical imaging and antitumor drug delivery

Smart polymeric particles possessing the advantages of paramagnetism, luminescence, and controlled drug delivery in a single entity are reported. Gadolinium oxide and europium-encapsulated temperature/pH-responsive polymeric particles (PLTPPs) synthesized by emulsifier-free emulsion polymerization show good biocompatibility with C6 cells and anticancer drug (doxorubicin, DOX) loading capability. In vitro drug release assessment discloses release abatement under acidic conditions or at high temperature, and the DOX-loaded PLTPPs have obvious antitumor properties for C6 and H22 cells. Cellular uptake tests confirm that the materials can be taken up by C6 cells thereby facilitating optical imaging. The T₁-weighted relaxivity value at 3 T is 6.13 mM^-1 s^-1 which is 39% higher than that of the clinical Magnevist®. In vivo MR and optical imaging reveal that the PLTPPs are effective dual probes. The results indicate that the PLTPPs have great potential in tumor diagnosis and treatment.