Development of flexible substrate-based sensors for pesticide detection via SERS

• Grant number: 20/16269-2
• Support type: Scholarships in Brazil - Post-Doctorate
• Effective date (Start): February 01, 2021
• Effective date (End): January 31, 2023
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal researcher: Carlos José Leopoldo Constantino
• Grantee: Grazielle de Oliveira Setti Gibin
• Home Institution: Faculdade de Ciências e Tecnologia (FCT). Universidade Estadual Paulista (UNESP). Campus de Presidente Prudente. Presidente Prudente , SP, Brazil
• Associated research grant: 18/22214-6 - Toward a convergence of technologies: from sensing and biosensing to information visualization and machine learning for data analysis in clinical diagnosis, AP.TEM

Abstract

The SERS technique has extended the applications of Raman spectroscopy due to its ability to detect very low analyte concentrations. Combined with the advantage of "fingerprint" spectra provided by Raman spectroscopy, the SERS technique has been the subject of research in several areas, including sensors. Paper is a widely studied material for sensors using different detection methods, including SERS. Among the paper main characteristics, it can be mentioned high availability and low cost, flexibility, high hydrophilicity, intrinsic capillarity and very low Raman scattering, reason that make it a strong candidate as flexible SERS substrates. It is known that the use of pesticides is important in modern agricultural practices, as it allows increasing food productivity thanks to the reduction of pests. However, these substances are highly harmful to human and other animal health when applied out of regulations, which is why their use must be meticulously controlled under current laws. Thus, monitoring of pesticides in both, food samples and aqueous media is essential. Chromatographic techniques are the most used for their reliability and repeatability. It has been invested in research looking for alternatives which perform analyzes with similar results, less time, lower cost, portability and lower (or no) use of organic solvents. The challenge lies in its analytical (quantitative) application, because the reproducibility of SERS signal intensity depends on obtaining homogeneous SERS substrates in terms of size, shape and spatial distribution of metallic nanoparticles, which are responsible for the amplification of the Raman signal (= SERS). In this context, the objective of this project is to develop a paper-based sensor as a flexible SERS substrate to detect pesticides in aqueous medium, such as irrigation waste water in general.