Simple and promising paper-based electrochemical platform for serological detection of American tegumentary leishmaniasis

Abstract

American tegumentary leishmaniasis (ATL) is an endemic neglected tropical disease (NTD), that causes considerable morbidity in affected patients. Worse still, its conventional treatment is relatively toxic, slow, and invasive; therefore, rapid diagnosis is crucial for the clinical management of suspected patients. The development and use of low-cost, miniaturized, easy-to-use, and environmentally friendly devices, such as biosensors, could be the key to rapid diagnosis in these areas to achieve appropriate treatment. Considering that paper-based electrochemical devices are excellent examples of low-cost eco-friendly sensors, this work aimed to develop a simple paper-based electrochemical platform for the serological detection of ATL. The platform consists in an origami structure fabricated in Whatman N°1 chromatography paper and contains a hydrophobic zone, generated by wax printing technique. It also includes two pencil graphite electrodes and uses specific crude extracts (CA) antigens for the immuno-determination of Leishmania (Viannia) braziliensis. The platform performance was analyzed by a double titration test, measuring the relative change in impedance for different antigen-antibody combinations, before and after the addition of pooled serum samples. The variation in the charge transfer resistance (ΔRct) and in the interface reactance (ΔXc), allowed establishing the platform optimal working conditions (1/60 serum dilution and 180 µg/mL CA extract concentration), and a linear behavior for the operation of the platform in the analyzed parameters. Then, using the paper platform, 10 serum human samples previously diagnosed by the gold standard (5 positive ATL cases and 5 non-ATL cases) were evaluated. The simple paper-based platform made possible to distinguish significantly (p < 0.05), between ATL and non-ATL human serum samples. Considering that there is currently no rapid test on the market to diagnose ATL cases, our platform could allow the diagnosis, management, and monitoring of leishmaniasis treatment using an extremely simple and environmentally friendly technology in the future.