Generating long-wavelength absorption bands with enhanced deep red fluorescence and photothermal performance in fused carbon dots aggregates

Carbon dots (CDs) with long-wavelength absorptions and emissions are highly desired for biological applications. Herein, we report a new supra-CDs strategy to construct long-wavelength absorption bands based on fused CDs aggregates (f-CDAs) through a concentration-induced interparticle dehydration process among green emissive CDs (r-CDs) under solvothermal treatment. The obtained fused f-CDAs exhibit an obvious absorption band in 550-700 nm and significantly enhanced deep red fluorescence in N,N-dimethylformamide with photoluminescence quantum yields of 15.6% and high photothermal conversion efficiency up to 26.1% in water. Benefiting from the high photothermal performance, in vivo tumor photothermal therapy has been realized via intratumoral injection of f-CDAs under 655 nm laser irradiated at 0.5 W/cm(2).