Concanavalin A and polyvinyl butyral use as a potential dengue electrochemical biosensor

Immobilization of concanavalin A on gold electrode by means of gold nanoparticles and polyvinyl butyral was carried out and investigated by cyclic voltammetry and electrochemical impedance spectroscopy. The system was tested with sera from patients infected by dengue fever (DF) and dengue hemorrhagic fever (DHF). Electrochemical impedance spectroscopy (in the frequency range from 100 mHz to 100 KHz), and cyclic voltammetry (from −0.2 to 0.7 V vs. Ag/AgCl), was performed in phosphate buffer solution containing 10 mM K3[Fe(CN)6]/K4[Fe(CN)6] (1:1) mixture as a redox probe. As biomolecules accumulated on the electrode surface the voltammetric response changed from a clear diffusional to an irreversible behavior. Impedance spectroscopy showed a clear increase of the electron-transfer resistance when the sensor is exposed to contaminated sera (DF or DHF) as compared to exposure to uncontaminated serum (NDF). The results were analyzed through an equivalent circuit and values of charge transfer resistance and capacitance were obtained. Variations in charge transfer resistance were used to distinguish the sensor response for the different sera investigated (DF, DHF and NDF). Alternatively, a three-dimensional graph gave the best response for differentiation of all three blood sera. The distinctive patterns of impedimetric responses observed were ascribed to different glycoprotein patterns in the sera investigated. Therefore, the lectin immobilization on electrode surface with gold nanoparticles and polyvinyl butyral, combined with the three-dimensional impedance analysis introduced herein are valuable tools in the development of a biosensor for immunological response to diseases.