Abstract: Aiming at the common problem of  low drug loading rate of polydopamine (PDA)-based nanocarriers,  we synthesized   Fe₃O₄@PDA nanoparticles (NPs) with a unique spindle-shaped structure, which could  achieve a drug loading rate of up to 90% (900 ug/mg),  significantly surpassing traditional PDA-based  carriers. The experimental results show that the spindle-shaped Fe₃O₄@PDA has good  biocompatibility,  efficient photothermal conversion ability,  and excellent  near-infrared (NIR) absorption ability,  which can control  drug release under pH/NIR dual response. Due to its embedded Fe₃O₄,   spindle-shaped Fe₃O₄@PDA NPs can be used as  contrast agents for photoacoustic and magnetic resonance imaging, and for  chemo-photothermal synergistic  therapy guided by dual-modal imaging.

Key words:  , polydopamine,  , polyethylene glycol modification, spindle-shaped nanocarrier