Design of Pyrrolic-N-Rich Carbon Dots with Absorption in the First Near-Infrared Window for Photothermal Therapy

Pyrrolic-N-rich carbon dots (CDs) that exhibit an absorption peak in the first near-infrared (NIR) window region were developed using a one-step microwave-assisted hydrothermal synthesis. A high concentration of urea enabled the introduction of a large amount of pyrrolic-nitrogen on the CD surfaces. Upon optimization of the experimental conditions, the absorption peak of the CDs red-shifted from 550 to 650 nm. The resulting pyrrolic-N-rich CDs exhibited photothermal effects with high NIR photothermal efficiency (54.3%) and photoluminescence. The prepared CDs, which show a first NIR window absorption peak, photoluminescence, and negative surface charge, have the potential to be used as multifunctional nanocarriers for cell imaging and drug delivery and as photothermal agents in cancer therapy.