Improved Stability and Photothermal Performance of Polydopamine‐Modified Fe3O4 Nanocomposites for Highly Efficient Magnetic Resonance Imaging‐Guided Photothermal Therapy

Magnetic nanomaterials are a promising class of contrast agents for magnetic resonance imaging (MRI). However, their poor stability and low relaxivity are major challenges hindering their clinical applications. In this study, magnetic theranostic nanoagents based on polydopamine-modified Fe3 O4 (Fe3 O4 @PDA) nanocomposites are fabricated for MRI-guided photothermal therapy (PTT) cancer treatments. Their high transverse relaxivity of 337.8 mM-1 s-1 makes these Fe3 O4 @PDA nanocomposites a promising T2 -weighted MRI contrast agent for cancer diagnosis and image-guided cancer therapy. Due to the good photothermal effect of polydopamine (PDA), the tumors of 4T1 tumor-bearing mice are completely excised by PTT. Most importantly, the PDA shell also improves the stability of the Fe3 O4 @PDA nanocomposites, which contributes to their excellent, long-term performance in MRI and PTT applications. Their good stability, high T2 relaxivity, robust biocompatibility, and satisfactory treatment effect give these Fe3 O4 @PDA nanocomposites great potential for use in cancer theranostics.