Multifunctional green-emitting fluorescent carbon dots: A versatile fluorometric probe for glyphosate detection and applications in food

In the study, dissolvable green fluorescent carbon dots (G-CDs) were synthesized utilizing 4-aminobutyric acid (GABA) and p-phenylenediamine (p-PDA) precursors through a single-step hydrothermal method. The synthesized G-CDs were characterized using UV–visible, fluorescence, Fourier-transform infrared (FT-IR), fluorescence lifetime, high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and zeta potential studies. HR-TEM analysis revealed spherical G-CDs with a uniform particle size of ∼ 4.4 nm. The prepared G-CDs showed remarkable stability under varying physiological properties, photostability, and diverse fluorescence properties in a variety of solvents. The solvatochromic behavior has been exploited to detect water molecules in organic solvents. The G-CDs emitted bright green fluorescence at 513 nm when excited at 370 nm and were used as a fluorometric probe for glyphosate (GLY) detection. Selective quenching of G-CDs fluorescence by GLY was confirmed through Stern-Volmer and time-resolved fluorescence analysis. The calculated limit of detection for GLY was 0.044 μM. These probes exhibited excellent selectivity towards GLY even in the presence of other interfering compounds. These properties of G-CDs have also been utilized to detect a GLY herbicide in real food applications.