Eletropolimerização e caracterização de filmes poliméricos derivados de ácido 3-aminosalicílico em eletrodos de carbono impressos

Abstract

Electroanalytical, a branch of analytical chemistry that justifies charge transfer processes in electrodes, enables sensitive and selective analyses for application in a variety of fields. Among its techniques, voltammetry stands out for its study of redox processes and the basis it provides for the development of innovative methodologies. In this context, electropolymerization emerges as an efficient method for synthesizing polymers with conductive characteristics directly on electrodes. Conductive polymers, obtained from the oxidation of heteroaromatic monomers, combine electrical conductivity with mechanical and chemical properties, favoring their application in biosensors. 3-Aminosalicylic acid shows promising potential in this process due to its structural characteristics that facilitate redox processes and biomolecule immobilization. The integration of conductive polymers and nanomaterials, such as carbon nanotubes, enhances the sensitivity, selectivity, and stability of the system by increasing the surface area available for adsorption of the polymer film. This work addresses the construction of electrodes modified by electropolymerization, performed through the Cyclic Voltammetry technique, of 3-aminosalicylic acid, associated with carbon nanotubes, promoting the future detection of the fungicide fenpropimorph. Although effective in controlling agricultural pests, the indiscriminate use of fungicides has impacts on human health, the environment, and biodiversity, aligning this study with the need for solutions that promote safe monitoring and contribute to the Sustainable Development Goals. The results showed that, for electrochemical measurements, electrodes require pretreatment with sulfuric acid and hydrogen peroxide in a saline phosphate buffer. The results showed that, for electrochemical measurements, electrodes require pretreatment with sulfuric acid and hydrogen peroxide in a phosphate buffered saline solution. The potassium ferricyanide system exhibited diffusional characteristics; with the monomer, the radical cation was formed from the oxidation of 3-aminosalicylic acid in an acidic medium, resulting in the removal of one electron and one proton, indicating a formed material with conductive, irreversible and adsorptive characteristics, but with a certain diffusional nature at high velocities—indicating slow kinetics in electron transfer between the electrode and the forming polymer. A proposed mechanism is presented based on the already known mechanism of 2-aminophenol. The stability of the polymer film was evaluated for 14 days and the polymer activity dropped by approximately 20%. Finally, the presence of multiwalled carbon nanotubes increased the surface area and conductivity of the system and may be an interesting strategy for immobilizing a biomolecule, a subsequent step in this work.