Electrochemical immunosensor construction using Lbk39 recombinant protein for leishmaniasis diagnosis

Electrochemical immunosensors have emerged as promising diagnostic tools due to their sensitivity, selectivity, cost-effectiveness, and rapid results. To enhance their analytical performance, the incorporation of recombinant proteins or peptides as bioreceptors has been proposed more recently. In this study, we developed an electrochemical immunosensor using a recombinant protein (Lbk39) immobilized on screen-printed electrodes (SPEs) for leishmaniasis (a vector-borne tropical disease) diagnosis. The immunosensor was able to detect anti-Leishmania antibodies in human and canine sera via voltammetric analysis, achieving a diagnostic cut-off of 78 % to distinguish positive and negative samples. Under optimized conditions, the proposed biosensor required 133-fold less Lbk39 protein (1.5 ng vs. 200 ng) for human cutaneous (CL) and visceral leishmaniasis (VL) diagnosis and 76-fold less (0.5 ng vs. 38 ng) for canine VL (CVL) compared to conventional ELISA test. Additionally, it exhibited high selectivity, differentiating leishmaniasis from Chagas disease (trypanosomiasis) and tuberculosis. With its minimal reagent consumption, simplified fabrication (unmodified carbon electrodes), and rapid results (<4 h), this immunosensor represents a scalable, point-of-care solution for leishmaniasis diagnosis in resource-limited settings.