Photothermal Composite Nanomaterials for Multimodal Tumor Therapy under MRI Guidance

Multifunctional nanomaterials for cancer therapy has attracted researchers' attention for decades. In this study, a unique oxidative method using KMnO4 or K2MnO4 as oxidizing agents to oxidize dopamine (DA) to polydopamine (PDA) was reported. The oxidizing agent was reduced to MnOx to form MnOx/PDA composite NPs. Afterwards, the MnOx/PDA composite NPs were surface-modified with bovine serum albumin (BSA) to form a multifunctional theranostic agent, named MnOx/PDA@BSA NPs, with improved colloidal stability and biocompatibility. Such a material would become a photothermal nanoagent, since the PDA renders the composite NPs an admirable photothermal transforming ability with the photothermal conversion efficiency of 27.06%. Meanwhile, as a commonly used T1 contrast agent, manganese (Mn2+) endowed the MnOx/PDA@BSA NPs with MRI ability, rendering the as-synthesized MnOx/PDA composite NPs a capability of imaging guided multi-modal tumor therapy. Moreover, the formed MnOx/PDA@BSA NPs were used for drug loading, which was found to own the tunable drug loading and controlled drug releasing capacity. The as-prepared composite NPs were successfully used for the combined tumor chemotherapy and photothermal therapy in vitro and in vivo. This research provides insights into the development of conjugated polymer-based nanomaterial for various biomedical applications, especially in imaging guided cancer therapy.