IMMUNOSENSOR FOR THE DUAL DETECTION OF VISCERAL LEISHMANIASIS AND CHAGAS DISEASE USING HOMEMADE PRINTED ELECTRODES

The diagnosis of visceral leishmaniasis (VL) and Chagas disease (CD) has some limitations, including the possibility of cross-reactivity, low sensitivity in detecting asymptomatic cases, and difficulty in application in endemic areas [1]. The use of printed electrodes in biosensors offers a viable diagnostic alternative as it allows the production of detection devices on a large scale at a relatively low cost. Thus, this study aimed to develop a printed electrochemical device for the simultaneous detection of VL and CD. Two working electrodes (W1 and W2) were fabricated using homemade carbon ink and were functionalized with polymeric films derived from 4-hydroxyphenylacetic acid. Recombinant antigens of L. infantum (rLCi1,2) were immobilized on W1, and T. cruzi (IBMP 8,1) on W2. Subsequently, bovine serum albumin (BSA) was used to block the surfaces of both electrodes. Canine serum samples containing antibodies (anti-L. infantum or anti-T. cruzi) were diluted in HBS-EP buffer (pH 7.4) for immunosensor analysis. Electrochemical impedance spectroscopy (EIS) was performed using ferro-ferricyanide potassium. All stages of immunosensor construction were optimized to obtain 1 pg/mL for antigen immobilization at 20 min and 0.01% BSA for 10 min and 20 min for reaction time with a 1:2000 dilution. The immunosensor showed no cross-reactions with other infections, presenting an excellent distinction and selectivity for the detection of both infections. These results show that in addition to high sensitivity and the possibility of rapid diagnosis, the proposed immunosensor is highly selective for disease antibodies, making it a promising tool for the joint diagnosis of CD and LV.