Carbon Dots via Synergistic Surface‐Oxidation and Rigidity Enhancement with Ultra‐Narrow Emission for Sensitive Near‐Infrared Imaging and Sepsis Therapy

Sensitivity remains a central challenge in optical imaging, particularly due to interference from autofluorescence, stray light scattering, and spectral overlap between excitation and emission wavelengths in biological samples. To address this, photoluminescent probes with large Stokes shifts and narrow full width at half maximum (FWHM) are critical for reducing background noise and enhancing signal‐to‐noise ratios. Here, we report near‐infrared photoluminescent carbon dots (NIR CDs), synthesized via a simple, one‐step solvothermal method using reduced glutathione as the sole precursor in formamide. These NIR CDs exhibit an exceptionally large Stokes shift of 266 nm and a narrow FWHM of 25 nm. Experimental and theoretical investigations demonstrate that this superior photophysics results from surface oxidation and core conjugation mechanisms. Owing to their minimal autofluorescence, robust photostability and resistance to environmental interference, the NIR CDs demonstrate high sensitivity and precision in lysosome tracking and prolonged monitoring in live cells. Significantly, the inherent antioxidant properties translate to a dual theranostic function, exhibiting outstanding therapeutic efficacy in a mouse model of sepsis. This work establishes a clear structure–property relationship for CDs with the synergistic effect of surface states and core states, highlighting their immense potential in advanced theranostics encompassing both real‐time biological monitoring and disease treatment.