Label-free and real-time monitoring of photoaging with high spatiotemporal resolution using an nIR fluorescent nanosensor array.

Reactive oxygen species (ROS) bursts from photoaging cause skin damage and chronic conditions. Understanding spatiotemporal ROS dynamics is critical for developing therapies and cosmetic strategies to enhance skin health. Conventional assays and fluorescence microscopy lack the resolution for real-time ROS quantification due to photobleaching and labeling issues. Here, we developed a label-free, real-time monitoring platform with high spatiotemporal resolution using a near-infrared (nIR) fluorescent single-walled carbon nanotube (SWNT) nanosensor array to quantify ROS bursts from daily photoaging. The SWNT array, dual-functionalized with DNA and poly-l-lysine, achieved selective HO recognition and skin cell compatibility. The skin cell-friendly nanosensor interface (SNI) enabled attomole-level detection of HO bursts in a two-dimensional keratinocyte model under natural ultraviolet exposure, revealing photoadaptation behavior. Distinct oxidative stress wave profiles were identified via nIR data and numerical modeling. Using SNI, we introduced the anti-ROS score to evaluate skin care antioxidants, providing insights into photoaging pathways and cosmetic advancements.