%0 Journal Article
%T Multilayer Films Electrodes Consisted of Cashew Gum and Polyaniline Assembled by the Layer-by-Layer Technique: Electrochemical Characterization and Its Use for Dopamine Determination
%A Sergio Bitencourt Ara¨²jo Barros
%A Cleide Maria da Silva Leite
%A Ana Cristina Facundo de Brito
%A Jos¨¦ Ribeiro Dos Santos J¨²nior
%A Valtencir Zucolotto
%A Carla Eiras
%J International Journal of Analytical Chemistry
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/923208
%X 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. 1. Introduction The physicochemical properties of nanoscale composite are a result of molecular interaction between materials of interest, such as a conducting polymer, promoting greater structural control of the formed films [1¨C3]. Two of the most used methods to obtain nanostructured materials in the solid state are the Langmuir-Blodgett (LB) technique [4] and the process of layer-by-layer (LbL) assembly [5]. This last one emerges as a method of deposition of alternating layers formed through the electrostatic interaction between oppositely charged solutions, where the formation of the first monolayer on the substrate surface occurs initially through a process of adsorption. In addition to the possibility of controlling the structure formed at the supramolecular level, the LbL technique has the advantage of not requiring any sophisticated equipment or procedures such as the LB technique. The technological interest of several research groups in composites, and more recently in nanocomposites, comes mainly from the mechanical properties and biodegradability, which are both characteristic of natural polymers, allied to the conductive properties of some synthetic polymers, which provides a great versatility of applications in areas such as engineering, biotechnology, and medicine [6¨C8]. Natural gums are macromolecules formed from units of sugars, monosaccharides, linked by glycosidic bonds resulting in natural polymers with long chains and high molecular weight [9]. The gums may originate from plants exudates (e.g., Arabic gum and cashew gum), seaweed extract
%U http://www.hindawi.com/journals/ijac/2012/923208/