Multilayer Films Electrodes Consisted of Cashew Gum and Polyaniline Assembled by the Layer-by-Layer Technique: Electrochemical Characterization and Its Use for Dopamine Determination

Abstract

We take advantage of polyelectrolyte feature exhibited by natural cashew gum (Anacardium occidentale L.) (CG), found in northeast Brazil, to employ it in the formation of electroactive nanocomposites prepared by layer-by-layer (LbL) technique. We used polyaniline unmodified (PANI) or modified with phosphonic acid (PA), PANI-PA as cationic polyelectrolyte. On the other hand, the CG or polyvinyl sulfonic (PVS) acids were used as anionic polyelectrolytes. The films were prepared with PANI or PANI-PA intercalated with CG or with PVS alternately resulting in four films with different sequences: PANI/CG PANI-PA/CG, PANI/PVS and PANI-PA/PVS, respectively. Analysis by cyclic voltammetry (CV) of the films showed that the presence of gum increases the stability of the films in acidic medium. The performance of the modified electrode of PANI-PA/CG was evaluated in electro analytical determination of dopamine (DA). The tests showed great sensitivity of the film for this analyte that was detected at 10−5 mol L−1.

APLICAÇÕES FARMACOLÓGICAS E TECNOLÓGICAS DA GOMA DO CAJUEIRO (Anacardium occidentale L.) – UM PRODUTO OBTIDO DA FLORA BRASILEIRA

“…Também foi demonstrada a adequabilidade da GC como um agente de gelificação para a liberação do fármaco aceclofenaco por via tópica (KUMAR et al, 2009) e a síntese de nanopartículas à base de goma do caju acetilada para a liberação transdérmica de diclofenaco (DIAS et al, 2016). Assim como a preparação de filmes com polianilina, modificada com ácido fosfônico e intercaladas com GC, usadas na determinação de dopamina (BARROS et al, 2012 Também se buscou investigar a aplicabilidade das atividades farmacológicas deste polissacarídeo, utilizando-se os descritores: "Anti-inflammatory"; "Antidiabetic"; "Antitumor"; "Antioxidant"; "Antidiarrheal"; "Gastroprotective" e "Healing", mas não foram encontradas patentes relacionadas a essas palavras-chaves e a goma do cajueiro, como demonstrado na Tabela 3.…”

“…Nesta prospecção foram investigadas também aplicações nanotecnológicas da GC, focando na sua utilização farmacêutica, visto seu grande potencial (BARROS et al, 2012). Para isso, utilizou-se os descritores do grupo 2 e 3, mostrados na tabela 3, porém não foram obtidos resultados com estes descritores, apesar de que já é demonstrado na literatura que este agente possui grande potencial como agente encapsulante, podendo ser aplicado em sistemas de liberação de fármacos.…”

Layer-by-Layer films based on biopolymers extracted from red seaweeds and polyaniline for applications in electrochemical sensors of chromium VI

“…The gum of the cashew tree (Anacardium occidentale L.) is one example of a biopolymer that has been satisfactorily used as a cationic polyelectrolyte in the production of films for detecting the neurotransmitter dopamine [20,21]. Other gums from the trees Sterculia striata [22], Anadenanthera colubrina and Sterculia urens have also been immobilized in the form of LbL films for applications in electrochemical sensors [23].…”

“…This same effect was previously observed for PANI films prepared together with the cashew tree gum (Anac. occidentale) [21] and also for films of POMA, a derivative of polyaniline, interlaced with gums of the trees S. striata and Anadenanthera macrocarpa [42].…”

“…This same effect promoted by the presence of agar and carrageenan in the film was also described for multilayered films of PANI and cashew tree gum (Anac. occidentale) [21] and films of POMA with gums of S. striata and Anad. macrocarpa [42].…”