N-CDs were prepared with a high fluorescence quantum yield of 35.08%. N-CDs have been employed to detect metronidazole in commercial metronidazole tablets. N-CDs exhibited quick response time, high selectivity and sensitivity, and low cytotoxicity.

NS-CDs are employed as a sensitive sensor for the integration detection of Hg ²⁺ and GSH. Hg ²⁺ effectively quenching the fluorescence by static quenching. GSH is able to recover the fluorescence owing to the stronger binding between Hg ²⁺ and GSH.

Tetracycline (TC) is widely used as a veterinary drug, and its residue in livestock products could enter the human body and cause damage. In this study, we developed an eco-friendly approach that utilized pomelo peel as a carbon source to synthesize new water-soluble N-doped carbon dots (P-NCDs) with blue fluorescence, obtaining a high quantum yield of up to 76.47% and achieving the goal of turning waste into value. Our prepared P-NCDs can selectively recognized TC, and their fluorescence was quenched based on the IFE. P-NCDs could measure the TC concentration in the linear range of 0–100 μmol L⁻¹ with a detection limit (LOD, S/N = 3) as low as 0.045 μmol L⁻¹. Furthermore, we have successfully applied our P-NCDs to the detection of TC in milk samples with convincing results within 90 s. Overall, our newly synthesized fluorescent sensor, P-NCDs, demonstrated huge potential to become an alternative way to detect TC in a simple, efficient, sensitive way without using any special instruments.

Photoactive Bi/BiOBr/TiO ₂ NRA composites displayed an efficient visible light response and fast charge transport rate and were used to construct sensitive kanamycin photoelectrochemical aptasensors.