Sensitive and Selective Dual‐Mode Responses to Reactive Oxygen Species by Chiral Manganese Dioxide Nanoparticles for Antiaging Skin

Abstract Excessive accumulation of reactive oxygen species (ROS) can lead to oxidative stress and oxidative damage, which is one of the important factors for aging and age‐related diseases. Therefore, real‐time monitoring and the moderate elimination of ROS is extremely important. In this study, a ROS‐responsive circular dichroic (CD) at 553 nm and magnetic resonance imaging (MRI) dual‐signals chiral manganese oxide (MnO 2 ) nanoparticles (NPs) are designed and synthesized. Both the CD and MRI signals show excellent linear ranges for intracellular hydrogen peroxide (H 2 O 2 ) concentrations, with limits of detection (LOD) of 0.0027 nmol/10 6 cells and 0.016 nmol/10 6 cells, respectively. The lower LOD achieved with CD detection may be attributable to its higher anti‐interference capability from the intracellular matrix. Importantly, ROS‐induced cell aging is intervened by chiral MnO 2 NPs via redox reactions with excessive intracellular ROS. In vivo experiments confirm that chiral MnO 2 NPs effectively eliminate ROS in skin tissue, reduce oxidative stress levels, and alleviate skin aging. This approach provides a new strategy for the diagnosis and treatment of age‐related diseases.