Impedimetric sensor for Leishmania infantum genome based on gold nanoparticles dispersed in polyaniline matrix

BACKGROUND: In this work, an electrochemical sensor for specific detection of Leishmania infantum genome (LiG) was developed.The sensorial system is based on the immobilization of a DNA probe onto a gold electrode surface previously covered with a simple and effective layer of a SH-terminal group on polyaniline matrix containing gold nanoparticles (PANIAuNp). Scanning electron microscopy (SEM), cyclic voltammetry (CV), and electrochemical impedance (El) techniques were applied to evaluate the immobilization of L. infantum primer (LiP) on PANIAuNp. RESULTS: SEM images for AuNpPANI-probe systems indicate that the film of the hybridized biomolecules was homogenous, compact and dense. Experimental results indicate that even when immobilized the probe retained its bioactivity. The primer-genome interaction was evaluated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) using a K-4[Fe(CN)(6)](4-)/K-3[Fe(CN)(6)](3-) redox pair. Both CV and EIS results have shown unequivocal evidence that the sensor presents specific detection of LiG based on primer-genome interactions. The LiG detection is translated as observable changes in the charge transfer resistance and the cathodic/anodic peak current. A stepwise modification on the bare gold electrode is accompanied not only by a decrease in its amperometric response, but also by an increase in the peak -to -peak separation between the cathodic and anodic waves of the redox probe. The sensor response to actual positive samples obtained from contaminated dogs was also evaluated. CONCLUSION: Results indicate that it is feasible to use this biosensor to detect LiG even at low concentrations (0.01 pg m1-1). (C) 2016 Society of Chemical Industry