Tumor Response and NIR-II Photonic Thermal Co-Enhanced Catalytic Therapy Based on Single-Atom Manganese Nanozyme

Single-atom nanozymes (SAzymes) can effectively mimic the metal active centers of natural enzymes at the atomic level owing to their atomically dispersed active sites, thereby maximizing atom utilization efficiency and density of active sites. Hence, SAzymes can be considered the most promising candidates to replace natural enzymes. Herein, a PEGylated mesoporous Mn-based single-atom nanozyme (PmMn/SAE) employing a coordination-assisted polymerization pyrolysis strategy that uses polydopamine for photothermal-augmented nanocatalytic therapy is designed. PmMn/SAE exhibits excellent multiple enzymatic performance, including catalase-like, oxidase-like, and peroxidase (POD)-like performance, due to the atomically dispersed Mn active species. As a result, PmMn/SAE not only catalyzes the decomposition of endogenous H2O2 to generate O-2 for relieving hypoxia inside the tumor but also transfers electrons to O-2 to produce superoxide radicals to kill tumor cells. Meanwhile, PmMn/SAE is able to trigger Fenton-like reactions to generate highly toxic hydroxyl radicals to induce cancer cell apoptosis. The POD-like catalytic mechanism of mMn/SAE is revealed using experimental results and density functional theory. Furthermor, PmMn/SAE shows good photothermal conversion efficiency (eta = 22.1%) in the second near-infrared region (1064 nm). Both the in vitro and in vivo experimental results indicate that PmMn/SAE can effectively kill cancer cells through photothermal-enhanced catalytic therapy.

Automated summary

Single-atom nanozymes have great potential to replace natural enzymes by mimicking their metal active centers at the atomic level. A PEGylated mesoporous Mn-based single-atom nanozyme has been designed, exhibiting excellent enzymatic performance and photothermal conversion efficiency. It can effectively kill cancer cells through catalytic and photothermal therapy.