Sophorajaponica L. flower mediated carbon dots with nitrogen and sulfur co-doped as a sensitive fluorescent probe for amoxicillin detection

This article first reported the green synthesis of N, S co-doped fluorescent carbon dots (N, S-CDs-Sop) and sought to establish the fluorescence detection system for amoxicillin (AMX). By using Sophora japonica L. flower as the green precursor and dl-homocystine as the co-dopant, N, S-CDs-Sop were successfully prepared via a one-pot hydrothermal method, exhibiting good water solubility and excellent photoluminescence. It was revealed that the surface of N, S-CDs-Sop was abundant in amino, hydroxyl and carboxyl groups after being characterized by a variety of techniques. When Fe3+ was added, Fe3+ could be complexed with N, S-CDs-Sop to from N, S-CDs-Sop-Fe3+ chelation leading to a significant static quenching of fluorescence. However, when N, S-CDs-Sop, Fe3+ and AMX coexisted, AMX would coordinate with Fe3+ and form the strong chelate due to the favorable chemical structure, resulting in the rapid fluorescence recovery. Such a fast, simple and sensitive fluorescence “off–on” strategy with a low LOD and a relatively wide range was successfully applied to the detection of AMX, which is closely correlated with human health.