Manganese-doped liquid metal nanoplatforms for cellular uptake and glutathione depletion-enhanced photothermal and chemodynamic combination tumor therapy

Chemodynamic therapy (CDT) involves the catalysis of in situ overexpressed hydrogen peroxide (H2O2) into highly toxic reactive oxygen species (ROS) to treat tumors. However, the efficacy of CDT is greatly hampered by limited cellular internalization efficiency, ROS scavenging by glutathione (GSH), and slow reaction rate. To overcome the current limitations of CDT, a manganese-doped and polyethylene glycol (PEG)-modified liquid metal (LM)-silica nanoplatform (labeled as Mn-LMOP) with varying stiffness is constructed to achieve synergistic photothermal therapy (PTT) and CDT, which can further induce immunogenic cell death (ICD) in tumors to enhance the anti-tumour effects. Significantly, benefiting from the increased stiffness, the Mn-LMOP nanoparticles (NPs) can enhance cellular uptake and lysosomal escape, and gradually accumulate in tumor sites. Moreover, manganese-doped NPs exhibite good photothermal effects and can rapidly reacte with intratumoral GSH to produce Mn2+, inhibiting GSH-mediated ROS clearance and promoting the efficiency of CDT. This combined treatment strategy can activate the immune response of the tumors, which holds the promise of photothermal/chemodynamic/immune multimodal therapeutic effects. This LM-based nanosystem will provide a paradigm for enhanced CDT/PTT combination anti-tumour efficacy. Statement of significance: Chemodynamic therapy (CDT) is a promising drug-free treatment approach characterized by its low invasiveness and minimal side effect. However, CDT encounters challenges such as high levels of glutathione (GSH), low Fenton-like reaction rate, and inefficient cellular uptake in tumor tissues. Here, a manganese-doped liquid metal (LM) nanomaterial was designed to achieve synergistic photothermal therapy (PTT) and CDT. This innovative strategy enhanced cellular uptake by adjusting the mechanical property of nanoparticles (NPs) and facilitated the consumption of GSH, while simultaneously accelerating the Fenton-like reaction rate with the assistance of PTT-mediated hyperthermia. This combined CDT/PTT strategy also activated the immune response within the tumor, demonstrating significant therapeutic potential.