Modificação superficial de um sensor eletroquímico Flexível com polipirrol e nanotubos de carbono pela técnica Lbl para detecção de paraquat

Abstract

Due to their various characteristics such as low cost, flexibility, and mechanical strength, polymers have increasingly fostered interest as a platform for sensors. These characteristics are ideal for application in wearable, point-of-care, and other types of electrochemical devices. The use of various polymeric materials with the addition of graphite — an easily obtained and low cost compound — allows the substrate to be used as a sensor for electroanalytical detection. Thus, this work aims first to fabricate flexible sensors based on biodegradable polymer (poly(adipate co-butylene terephthalate)) and graphite and then modify this flexible sensor from the technique of self-assembled films or Layer-by-Layer (LbL). This technique allows nanostructured films to be obtained by alternating layers of anionic and cationic materials, and thus, materials such as carbon nanotubes (NTCs) and polypyrrole (PPY) will be used for the production of self-assembled bilayers in order to improve the electrochemical properties of the sensor that will be used in the detection of Paraquat — an extremely toxic herbicide for animals and humans. The physical-chemical characterization of the modified electrodes confirmed the nanostructured modification in the gPBAT, which showed a decrease of about 16° in the contact angle in relation to the pure gPBAT, indicating that the LbL film made the electrode more hydrophilic. The FTIR analysis identified the presence of a band in the region of 3360 cm-1 attributed to the O-H, the pyrrole hydroxyl group. The modified electrode was used for PQ detection using differential pulse electrochemical (DPV) technique. The concentration range for detection was 0.1–2.1 μM, with a limit of detection 0.073 μM and R² equal to 0.996. Modification of gPBAT with LbL film in architecture (PPY/NTC)7 resulted in a sensor with excellent sensitivity, selectivity and stability. In addition, the electrode is simple, easy to build, requiring small amounts of materials for surface modification and promising for application in the detection of pollutants in the environmental area.