| Full text | |
| Author(s): |
Rubira, Rafael Jesus Goncalves
;
Furini, Leonardo Negri
;
Tuttolomondo, Maria Eugenia
;
Constantino, Carlos Jose Leopoldo
;
Sanchez-Cortes, Santiago
Total Authors: 5
|
| Document type: | Journal article |
| Source: | Journal of Raman Spectroscopy; v. 55, n. 10, p. 13-pg., 2024-07-15. |
| Abstract | |
The excessive use of pesticides has detrimental effects on the ecosystem, leading to soil contamination and the spread of pollution beyond the targeted areas. Concerns arise regarding the permissible limits of pesticides, typically around 10-8 mol/L. In this study, we employed surface-enhanced Raman spectroscopy (SERS), a highly sensitive and selective technique, to investigate the behavior of the pesticide ametrine (AMT) on silver colloids. The Ag nanoparticles (AgNPs) exhibited an average size of (26 +/- 2) nm and a zeta potential of (-30 +/- 1) mV in the absence of AMT, which decreased to (-24 +/- 1) mV in the presence of AMT, resulting in mild AgNPs aggregation, with the average diameter of AgNPs increasing to approximately 300 nm. This aggregation is advantageous, as they provide active sites for pesticide detection. Besides, the purification method employed ensured that AMT remained undegraded, and various conformations of AMT were simulated using Ag clusters to study the SERS effect. Comparison with the experimental spectra indicated that the SERS-4 conformer closely resembled the experimental spectrum, suggesting simultaneous interaction between the Ag surface and the sulfur (S) and nitrogen (N) atoms of the AMT triazine ring. Notably, changes in the AMT molecule were observed with pH variations: at pH below 5, hydroxylation occurred, resulting in an Ag-Cl stretching at 241 cm-1 in the SERS spectra. Conversely, at pH above 5 (pH 6-13), the presence of bands at 230 and 219 cm-1 in the SERS spectra indicate the formation of Ag-N and Ag-S bonds, respectively, between the AMT and the AgNPs. Furthermore, the study successfully detected AMT at pH 7, establishing a limit of detection (LOD) of 1.36 x 10-8 mol/L (3 ppb) based on the SERS spectra. These findings underscore the applicability of the SERS technique in the sensitive and selective detection of AMT, offering a promising approach for monitoring the presence of this pesticide in environmental samples. The study revealed two chemical species of AMT depending on pH, with hydroxylation at pH 5. Keto derivatives of hydroxylated AMT showed affinity with AgNP surface, yet pH instability posed detection challenges below 5. Theoretical calculations characterized AMT's structure and interaction with Ag, supporting the SERS technique for herbicide detection. LOD of 3 ppb surpassed drinking water MRL, indicating SERS potential for precise detection at low concentrations with established procedures. image (AU) | |
| FAPESP's process: | 18/22214-6 - Towards a convergence of technologies: from sensing and biosensing to information visualization and machine learning for data analysis in clinical diagnosis |
| Grantee: | Osvaldo Novais de Oliveira Junior |
| Support Opportunities: | Research Projects - Thematic Grants |
| FAPESP's process: | 20/05423-0 - Detection of pesticides (cocktails) used in sugarcane crops and their effect on biological systems |
| Grantee: | Rafael Jesus Gonçalves Rubira |
| Support Opportunities: | Scholarships in Brazil - Post-Doctoral |
| FAPESP's process: | 16/09634-0 - Interaction between biomembrane models based on Langmuir films and giant unilamellar vesicles (GUVs) with triazine herbicides and detection via SERS spectroscopy. |
| Grantee: | Rafael Jesus Gonçalves Rubira |
| Support Opportunities: | Scholarships in Brazil - Doctorate |
| FAPESP's process: | 18/04628-8 - Detection of triazine herbicides by SERS using silver nanoparticles synthesised via green chemistry |
| Grantee: | Rafael Jesus Gonçalves Rubira |
| Support Opportunities: | Scholarships abroad - Research Internship - Doctorate |