Polydopamine-based coordination nanocomplex for T1/T2 dual mode magnetic resonance imaging-guided chemo-photothermal synergistic therapy.

Despite the progress in the design and synthesis of theranostic agents, limitations on efficiency and safety offer significant room for improvement in these agents. Inspired by the natural binding ability of polydopamine nanospheres (PDAs) with iron ion, a simple and versatile synthesis strategy is developed to prepare biodegradable coordination polymer (CP) encapsulated PDAs nanocomplex (PDAs@CPx, x = 3, 6, 9). We found that the PDAs@CP3 can serve as a T1/T2 dual mode contrast agent (DMCA) for magnetic resonance imaging (MRI), which possesses high longitudinal (r1 = 7.524 mM(-1) s(-1)) and transverse (r2 = 45.92 mM(-1) s(-1)) relaxivities. In this system, benefitting from the high photothermal conversion efficiency derived from PDAs, DOX loaded PDAs@CP3 nanocomplex is able to not only destroy the tumor directly by heat, but also stimulate the chemotherapy by enabling NIR-responsive on demand delivery of DOX. To the best of our knowledge, this is the first example exploring the potential of PDAs@CPx nanocomplex for T1/T2 dual mode MRI-guided chemo-photothermal synergistic therapy. This work extends the currently available theranostic agents, and opens up new avenues to rationally design the high-performance T1/T2 DMCA.