Nitrogen-doped carbon quantum dots as a highly selective fluorescent and electrochemical sensor for tetracycline

Abstract

Fluorescent nitrogen-doped carbon dots (N-CQDs) were fabricated from R. graveolens leaves following a green and facile hydrothermal process, yielding an 18 % quantum yield (QY). Multiple characterization techniques were used to conduct the optical, chemical, and morphological examination. The surface of the N-CQDs is abundant in hydroxyl, carbonyl, and amino groups, which provide excellent solubility, stability and sensing ability to the N-CQDs in the solution medium. The zeta potential analysis indicated that the N-CQD surface is negatively charged (−26.5 mV). It functions as a highly efficient and selective photoluminescent (PL) and an electrochemical sensor for tetracycline (TC). They exhibited excitation-dependent emission behaviour as a PL sensor with an excellent linear range from 0 to 600 nM and a LOD of 60 nM via the inner filter effect (IFE). Excellent sensitivity and selectivity towards TC with a linear range of 0–30 nM and LOD of 0.28 nM exhibited N-CQD as a highly selective electrochemical sensor. Fluorescent paper strips were also designed for the simple and rapid detection of TC present in both solid and solution states. Both developed sensors were effectively exploited to detect TC in real samples.