Filme de poiestireno nanoestruturado aplicado ao sensoriamento espectroscópico de glifosato em água

Abstract

The present study describes the development, characterization, and application of polystyrene thin films functionalized with gold nanoparticles for glyphosate sensing in water. The polystyrene thin films were deposited on glass substrates using Spin Coating, allowing the control of film thickness based on the applied rotational speeds. The optical characterization of the films was performed using UV-Vis spectroscopy combined with the Swanepoel method, enabling the calculation of film thickness and refractive indices. For rotation speeds ranging from 600 to 4500 rpm, the film thickness varied between 489 and 1140 nm, while the refractive indices ranged from 1.57 to 1.74 in the wavelength range of 370 to 990 nm. The films were functionalized with gold nanoparticles synthesized with cysteamine, using sodium borohydride as the reducing agent. The functionalized films demonstrated the ability to detect specific variations in the absorption spectrum after contact with glyphosate solutions at concentrations ranging from 0.4 ¼M to 4 mM. A calibration curve was generated using allometric fitting, resulting in a detection limit of 424 ¼g/L, which is below the maximum permissible level set by Brazilian legislation for glyphosate in water. The sensor system proved to be cost-effective compared to traditional detection methods, utilizing low-cost materials and a simple fabrication process. The operation of the sensor also stood out for its simplicity, relying solely on the direct interaction between the functionalized film and the analyte, without requiring complex protocols during the analysis.