Long-Lasting Near-Infrared Chemiluminescent Carbon Dots for Deep Tumor Imaging

Chemiluminescence (CL) imaging offers unique advantages over fluorescence (FL) imaging, including excitation-free operation, low background interference, and strong tissue penetration. However, current carbon dot (CD)-based CL systems still suffer from short emission wavelengths, limited signal duration, and insufficient brightness, which severely hinder their applications in deep-tissue imaging. In this work, we present a novel design strategy that leverages the persistent afterglow effect of CDs to construct a self-sustained, long-lasting CL system. Near-infrared emissive carbon dots (LKCDs) were synthesized through a green approach, exhibiting a sharp emission peak at 672 nm with a narrow full width at half-maximum of 34 nm, a high fluorescence quantum yield of 18.3%, and an afterglow lifetime over 31 min. By coassembling LKCDs with CPPO in Pluronic F-127 micelles, we developed hydrogen peroxide-responsive CL nanoprobe (LCF-NPs), in which the chemically initiated electron-exchange luminescence (CIEEL) process is coupled with the intrinsic afterglow of LKCDs to achieve persistent CL emission. In vivo experiments with 4T1 tumor-bearing mice demonstrated that LCF-NPs produced stable NIR CL signal at tumor site for over 12 h, substantially outperforming traditional fluorescence probes. This study not only establishes an efficient long-lasting NIR CL imaging platform but also provides methodological insights for designing persistent CL systems in bioanalytical applications.