The fabrication of excitation-dependent fluorescence boron/nitrogen co-doped carbon quantum dots and their employment in bioimaging

Synthesis of carbon quantum dots (CQDs) with high quantum yield (QY) and excitation-dependent fluorescence emission is of great importance and provides unquestionable opportunities in biomedical applications. In this study, we have proposed a novel strategy for the fabrication of boron (B) and nitrogen (N)-co-doped CQDs (B/N-CQDs) by a simple yet facile hydrothermal method. For this, for the first time, dopamine and sodium borohydride were employed as C/N and B sources, respectively. CQDs were synthesized with excitation-dependent emission nature and high QY (25 %, the highest). The B/N-CQDs exhibited low toxicity and good biocompatibility through the cell viability tests by using MRC5 and A549 cell lines with IC50 values of 981 and 583 ppm, respectively. Lastly, the incubation of B/N-CQDs with an A549 cell line led to the emergence of blue and green colors under an excitation wavelength of 405 and 488 nm, respectively, indicating the excitation-dependent nature.