A comparative study of graphene-based electrodes for electrochemical detection of visceral leishmaniasis in symptomatic and asymptomatic patients

Background

Visceral Leishmaniasis is a neglected tropical disease with a high rate of infection and mortality in affected areas. Around 50,000 to 90,000 new cases of visceral leishmaniasis (VL) are estimated every year. Individuals asymptomatic for the disease should also be considered in epidemiological surveillance of the disease, as they can help spread the parasite. Thus, the development of low-cost diagnosis methods that allow the identification of infected and asymptomatic individuals is required, especially in developing countries where this disease is endemic.

Results

In this work, we developed an immunosensor for recognizing anti-Leishmania antibodies in asymptomatic individuals and avoiding cross-reaction with Chagas disease (CD). For that, we used carbon-based screen-printed electrodes, modified with graphene oxide and gold. Reproducibility was assessed by calculating the relative standard deviation (RSD < 5 %) from cyclic voltammograms of [Fe(CN)₆]^3-/4− using three different electrodes, screen-printed carbon electrodes (DPR-110) and graphene modified screen-printed electrodes (DPR-110 GPH) were purchased from DropSens (Oviedo, Asturias, Spain).

Significance

As an electrochemical methodology, we use cyclic voltammetry. After the tests were carried out, we considered that carbon electrodes adsorbed with reduced graphene oxide and modified with gold nanoparticles were the best platforms for detecting anti-Leishmania antibodies. In the study carried out, the limit of quantification (LOQ) for anti-Leishmania antibodies was established at 16.75 mg/mL, while the limit of detection (LOD) was 5.58 mg/mL. These limits indicate the minimum antibody concentration values that can be quantified and detected accurately and reliably in the analyzed sera.