Manganese-Doped Prussian Blue Nanoparticles-Engineered\nNeutrophils for T<sub>1</sub>–T<sub>2</sub> Dual-Modal MRI-Guided\nPhotothermal Therapy

In\nrecent years, photothermal therapy (PTT), as a highly clinically\nvaluable anticancer treatment, has been the focus of attention on\nhow to achieve higher efficacy for tumor treatment, such as improving\nthe tumor accumulation of nanophotothermal agents (NPTA) and reducing\ntumor recurrence after PTT. Herein, we subtly designed nanoengineered\nneutrophils (Ne) of manganese-doped Prussian blue nanoparticles (PMNP)\nloaded onto healthy-derived Ne, called PMNP@Ne. The combination of\nPMNP’s favorable T<sub>1</sub>–T<sub>2</sub> dual-modal\nmagnetic resonance imaging (MRI) and excellent photothermal properties\nwith the high tumor targeting and cancer-killing activity of Ne, the\nconjunctive therapy of PTT and Ne was realized. Under the guidance\nof T<sub>1</sub>–T<sub>2</sub> bimodal MRI, the accumulations\nof PMNP@Ne within the tumor site were significantly augmented compared\nwith free PMNP. With near-infrared (NIR) radiation, the heat generated\nfrom PMNP and PMNP@Ne could ablate tumor cells directly. Afterward,\nthe tumors relapsed with treating PTT of PMNP only. Surprisingly,\nthe tumors of PMNP@Ne-treated 4T1 (mouse breast carcinoma cells) tumor-bearing\nmice were eliminated completely without recurrence during the whole\ntreatment. This therapeutic strategy not only demonstrated the great\npromise of NPTA-engineered neutrophils for highly efficient PTT but\nalso represented a treatment platform for precision nanomedicine.