Desenvolvimento de dispositivo eletroquímico e sua aplicação na detecção de anticorpos voltados para o diagnóstico de hanseníase

Abstract

Leprosy is a neglected tropical disease, caused by the bacteria Mycobacterim leprae that mainly affects the peripheral nerves, and its diagnosis is mostly carried out through clinical examination. In this work, a magneto-immunoassay was developed for the detection of anti-M. leprae in serum using silver nanoparticles as an electrochemical marker, aiming for its application in the diagnosis of leprosy. For this purpose, electrochemical devices were made screen-printed with carbon ink and magnets were glued to the base of each working electrode. Silver nanoparticles (AgNPs) were synthesized and characterized by both UV-visible spectroscopy (UV-vis) and Transmission Electron Microscopy (TEM). Magnetic particles (PM) modified with synthetic peptides obtained from the M. leprae protein 85B were used. Furthermore, the AgNPs were labeled with an anti-human IgG secondary antibody, so that the final PM/Pep-Anti-M bioconjugate was formed. leprae-Anti-IgG/AgNP, which is used to perform electrochemical measurements on electrodes printed using the Differential Pulse Voltammetry (DPV) technique. The nanoparticles presented adequate and satisfactory characteristics for immunoassays, being consistent with the reference. Confirmation of the connection between the secondary antibody and the silver nanoparticle occurred through UV-vis characterization. Univariate optimizations of the method were carried out, as well as experimental planning. With both, it was possible to find the best conditions among those evaluated, ultimately obtaining a ROC curve with an area over the curve (AUC) value of 0.813. In this way, it was possible to differentiate healthy samples from samples infected with multibacillary leprosy, being considered a cheaper method as it uses silver nanoparticles as an electrochemical marker, when compared to other nanomaterials such as gold nanoparticles. It can also be considered a promising method to be used in the diagnosis of leprosy.