Green-synthesized N/S co-doped carbon dots for inner filter effect-based fluorescent detection of doxycycline with antibacterial activity.

Nitrogen/sulphur co-doped carbon dots (N/S-CDs) were synthesised on turmeric processing residue using a hydrothermal procedure. These carbon dots were subsequently analysed as antibacterial nanoparticles and as versatile carbon dots that could be used in fluorescent sensing. A fluorescent sensing platform was designed by utilising the inner filter effect (IFE) to detect doxycycline, which is characterised by an efficient spectral overlap with the excitation/emission bands of N/S-CDs. A high sensing response rate and a LOD at 0.131 µM of ions was identified within a linear response range of 0.5-50 µM. The platform exhibited satisfactory stability in a diverse range of solvents, temperatures, and pH levels, as well as a high tolerance to ionic strength. Selectivity was attained with respect to metal ions and common antibiotics. The method was found to be practical, with exceptional recoveries (98.5-99.3) and low RSD values (1.28-1.74), as evidenced by the actual sample analysis of river, lake, and pond water. Furthermore, it offers the added benefit of nanomaterials that are derived from biomass for biomedical and environmental applications.