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

Sergio Bitencourt Araújo Barros,Valtencir Zucolotto,Cleide Maria Da Silva Leite,Carla Eiras,Ana Cristina Facundo De Brito,José Ribeiro Dos Santos Júnior

doi:10.1155/2012/923208

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.

Highlights

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 [1,2,3]
The films were prepared with polyaniline unmodified (PANI) or PANI-phosphonic acid (PA) intercalated with Cashew gum (CG) or with polyvinyl sulfonic (PVS) alternately resulting in four films with different sequences: PANI/CG PANI-PA/CG, PANI/PVS and PANI-PA/PVS, respectively
The modified substrate with (PAH/CG)6 shows that the presence of the LbL film activates the electrode surface increasing the double electrical layer of this system and catalyzes the processes of oxygen evolution observed in the forward sweep and hydrogen evolution observed in the reverse sweep

Summary

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 [1,2,3]. The cashew gum (Anacardium occidentale L.) is interesting because it is an exudate obtained from the cashew tree, very abundant in the northeast of Brazil It belongs to the same family of Arabic gum, widely used in the food industry, and presents similarities in their composition and in their physicochemical properties [12,13,14]. Cashew gum has antimicrobial properties for therapeutic treatment, as well as thickening and emulsifying properties [15, 16] used in foods and drugs industry These characteristics are due to its heterogeneous structure and high molecular weight of the polysaccharide chain, which interacts strongly with water, creating an effect of thickening or gelling in solution [16]. We investigated the ability of these nanocomposites to act as modified electrodes for dopamine sensing

Experimental

Results and Discussion

Method

Conclusions

Without analyte 3 0