Atomically preserved MXene quantum dots as a redox-responsive nanoplatform for light-controlled bidirectional ROS engineering.

MXene quantum dots (MQDs) combine the intrinsic reductive properties of MXenes with the photoactivity induced by quantum confinement, positioning them as promising agents for dynamic redox regulation in therapeutic applications. However, their translation into practice has been limited by persistent synthetic issues, including transition-metal leaching and oxidative degradation. To address these challenges, a sodium ascorbate-mediated coordination and reduction strategy was developed for hydrothermal synthesis of structurally intact Ti2C MQDs with improved crystallinity and high titanium retention. The resulting MQDs exhibit a unique extension of optical absorption into the visible range, which facilitates efficient ROS generation under visible-light irradiation and confers potent antibacterial properties against pathogenic bacteria. Concurrently, the MQDs demonstrate broad-spectrum ROS scavenging ability. At the cellular level, they effectively reduced oxidative stress and inflammation while promoting M2 macrophage polarization. Capitalizing on these dual redox activities and excellent biocompatibility, a collagen-alginate microneedle patch (MQDs@Col-SA MN) was designed to evaluate their therapeutic potential. In a diabetic wound model, this system achieved ∼80 % smaller wound area than untreated controls at Day 10, while also outperforming a positive control dressing. This study represents the first report of structurally preserved MQDs capable of adaptive redox regulation, underscoring their utility as a versatile platform for microenvironment modulation and regenerative medicine.