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.
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