Manganese-Doped Prussian Blue Nanoparticles-Engineered Neutrophils for T₁–T₂ Dual-Modal MRI-Guided Photothermal Therapy

In recent years, photothermal therapy (PTT), as a highly clinically valuable anticancer treatment, has been the focus of attention on how to achieve higher efficacy for tumor treatment, such as improving the tumor accumulation of nanophotothermal agents (NPTA) and reducing tumor recurrence after PTT. Herein, we subtly designed nanoengineered neutrophils (Ne) of manganese-doped Prussian blue nanoparticles (PMNP) loaded onto healthy-derived Ne, called PMNP@Ne. The combination of PMNP’s favorable T₁–T₂ dual-modal magnetic resonance imaging (MRI) and excellent photothermal properties with the high tumor targeting and cancer-killing activity of Ne, the conjunctive therapy of PTT and Ne was realized. Under the guidance of T₁–T₂ bimodal MRI, the accumulations of PMNP@Ne within the tumor site were significantly augmented compared with free PMNP. With near-infrared (NIR) radiation, the heat generated from PMNP and PMNP@Ne could ablate tumor cells directly. Afterward, the tumors relapsed with treating PTT of PMNP only. Surprisingly, the tumors of PMNP@Ne-treated 4T1 (mouse breast carcinoma cells) tumor-bearing mice were eliminated completely without recurrence during the whole treatment. This therapeutic strategy not only demonstrated the great promise of NPTA-engineered neutrophils for highly efficient PTT but also represented a treatment platform for precision nanomedicine.