Dual-Single-Atom Ruthenium–Copper Anchored on Magnesium–Aluminum Layered Double Hydroxide Enhancing Dual-Enzymatic Activities for Synergistic Anti-Liver Cancer Therapy

Single-atom nanozymes (SANs), with their tunable metal active centers, enable the modulation of various enzyme activities for antitumor therapy. However, these materials encounter substantial challenges in cancer therapy owing to their limited biocompatibility and biodegradability. Additionally, the high-temperature pyrolysis process involved in their synthesis significantly restricts their practical, large-scale application. To address these challenges, we propose the construction of an LDH-based SAN exhibiting peroxidase-like (POD-like) activity and glutathione depletion capability. We successfully developed a SAN containing ruthenium (Ru) and copper (Cu) bimetallic atoms (MgAl-LDH/Ru/Cu), where Ru and Cu are distributed in single-atom dispersed states, forming nanodomains. The synergistic effects of the Ru/Cu bimetallic system enable MgAl-LDH/Ru/Cu to demonstrate superior POD-like and glutathione peroxidase-like (GPx-like) catalytic activities compared to those of MgAl-LDH/Ru or MgAl-LDH/Cu alone. Density functional theory calculations indicate that both Ru and Cu sites in MgAl-LDH/Ru/Cu exhibit lower energy barriers for POD-like and GPx-like reactions, likely due to enhanced electron loss states at the Ru/Cu bimetallic single-atom sites compared to those at Ru or Cu sites individually. Both in vitro and in vivo experiments demonstrate that the Ru/Cu bimetallic loading significantly outperforms the individual metal loadings of Ru or Cu in terms of anti-liver cancer efficacy. Importantly, by leveraging the precise correlation between the catalytic structural unit of MgAl-LDH-based SANs and enzyme activity, we further elucidated the potential contributions of POD-like and GPx-like activities to cancer therapy. MgAl-LDH-based multimetal SAN represents a synergistic multienzyme nanoplatform with a tunable elemental composition, paving the way for further investigations into the interplay between multienzyme activity and antitumor effects.