Drug-Loaded Magnetic Microhydrogel as Microwave Susceptible Agents for Cancer Multimodality Treatment and MR Imaging

Microwave (MW) ablation has been widely recognized as one of prominent protocols for clinical cancer treatment with advantages of minimally invasive treatment, convenient operation and consistent intra-tumoral temperature. However, microwave therapeutic approach still has the risk of overheating the surrounding healthy tissues, which thus necessitates susceptible agent to concentrate the heat and enhance the treatment efficiency with lower microwave power while avoiding side effects. Herein, a doxorubicin (DOX)-loaded magnetic nanocomposite calcium alginate microhydrogel (Fe₃O₄@DOX/CAM) as microwave susceptible and MR contrast agent has been developed for in vivo tumor multimodality therapy. Membrane emulsification method was employed for the fabrication of the monodispersed microhydrogel with rather uniform size distribution. Even under microwave irradiation at extremely low microwave power (2 W), enough heat (∼50 °C) can be induced by the microhydrogel. Except for as an excellent susceptible agent for microwave thermotherapy, the as-prepared Fe₃O₄@DOX/CAM can achieve microwave responsive DOX delivery, as it was noticed that microwave heating can actually facilitate drug release. Moreover, such multifunctional Fe₃O₄@DOX/CAM can be administered by intra-tumoral injection to achieve MW thermotherapy combined with sustainable chemotherapy. Meanwhile, the magnetic nanoparticles incorporated within the microhydrogel can be applied for T₂-weighted MR image during the cancer treatment. In summary, our observations on such Fe₃O₄@DOX/CAM suggest an effective microwave susceptible agent for cancer multimodality treatment and imaging.