Cynodon dactylon derived fluorescent N-doped carbon dots: Implications of photocatalytic and biological applications

CQDs possess various appealing properties like excellent light harvesting capability, unique photo-induced electron transfer ability, low toxicity, and good biocompatibility. This work aims to demonstrate the potential of CQDs from natural waste resources in wastewater treatments and biomedical applications. Herein we report the eco-friendly approach for preparing nitrogen-doped carbon quantum dots (N-CQDs) using the Cynodon dactylon (grass) as a carbon precursor via a highly effective hydrothermal process. The structural aspects and chemical nature of N-CQDs were considered using FTIR, XRD, SEM & EDX, TEM, AFM, EPR, and XPS. In addition, UV-vis and fluorescence spectroscopy elucidated the optical performance of N-CQDs. N-CQDs possess stable fluorescent properties, good biocompatibility, and acceptable quantum yield (24.44%). In this study, five dyes, namely Toluidine Blue (TB), Amido Black (AB), Congo Red (CR), and Xylol Orange (XO), were chosen to investigate the photocatalytic performance of the nanomaterial under UV-vis light irradiation. The synthesized N-CQDs exhibited remarkable photocatalytic activity for various model dyes of varying concentrations (5, 10, 50, and 100 ppm), highlighting the pivotal role of N-CQDs in promoting the separation migration efficiency of photoexcited e(-) - h(+) pairs. Moreover, the impact of pH, contact time, and amount of catalyst on the degradation of dyes were also examined. Additionally, we investigated the interaction of N-CQDs with lysozyme protein using fluorescence quenching. Thus, the developed nanomaterial efficiently treats wastewater and holds great promise in biosensing applications.