High-performing structural optimization of graphene quantum dots as glyphosate herbicide photoluminescent probes: real case studies and mechanism insights

• Published in: Journal of environmental chemical engineering Vol. 12; no. 4; p. 113193
• Main Authors: Dorontić, Slađana, Bonasera, Aurelio, Scopelliti, Michelangelo, Marković, Olivera, Verbić, Tatjana, Sredojević, Dušan, Ciasca, Gabriele, Di Santo, Riccardo, Mead, James L., Budimir, Milica, Bajuk-Bogdanović, Danica, Mojsin, Marija, Pejić, Jelena, Stevanović, Milena, Jovanović, Svetlana
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.08.2024
• Subjects: Environments pollutants; Gamma irradiation; Glyphosate; Graphene quantum dots; Photoluminescence detection; Gamma irradiation; Glyphosate; Graphene quantum dots; Photoluminescence detection; Environments pollutants
• ISSN: 2213-3437
• DOI: 10.1016/j.jece.2024.113193

The widespread usage of the herbicide glyphosate calls for urgent action, aiming at the development of new, simple, low-cost, and eco-friendly detection approaches. In the last decade, investigation of graphene quantum dots (GQDs) as potential optical probes for various pollutants rapidly grew, thanks to their easy-manipulative structure, remarkable photoluminescence (PL) in the visible part of the spectrum, good dispersibility, biocompatibility, and non-toxicity, as well. Herein, a fast, simple, and environmentally friendly method for GQDs structural modification is presented. GQDs raw powder was exposed to γ- rays at three different doses (100, 200, and 300 kGy) in air, without any solvent or reagents. Irradiation of dots under such affordable conditions led to the additional incorporation of oxygen-containing moieties in the GQD structure. For the first time, oxygen-rich GQDs irradiated at a 300 kGy dose were successfully applied as direct turn-off PL probe for glyphosate detection. The high coefficient of determination (R-squared (R2) = 0.99) and very low limit of detection (3.02 μmol L-1) reveal good linearity between the potential sensor and analyte, as well as sensitivity. Glyphosate was successfully detected in celery samples, with a recovery value of 107 ± 0.85%. To evaluate the biological safety of the proposed sensing probe, [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] (MTT) and the hemolysis assays were performed. Obtained results show that irradiated and non-irradiated GQDs did not cause the death of MRC-5 cells, and hemolysis of erythrocytes. The obtained results demonstrate that GQDs irradiated in an air medium can be potentially applied for glyphosate detection. [Display omitted] •Graphene quantum dots (GQDs) were modified in an ultra-fast, eco-friendly approach by gamma irradiation in an air .•GQDs were successfully applied as turn-off PL probes for non-selective herbicide glyphosate (LOD was 3.02 μmol L-1).•Glyphosate was detected in the celery sample, with a recovery value of 107% ± 0.85.•DFT calculations and FTIR spectroscopy indicated hydrogen bond formation between GQDs and glyphosate.