IMUNOSSENSOR ELETROQUÍMICO COM PEPTÍDEO SINTÉTICO MIMÉTICO DE HSP60: UMA NOVA ABORDAGEM PARA O DIAGNÓSTICO DA HANSENÍASE

Abstract

Leprosy is a chronic disease caused by Mycobacterium leprae, whose main symptoms include skin lesions and loss of sensitivity. Although the disease has a cure, it can leave sequelae if treatment is started late. In this sense, the World Health Organization (WHO) seeks new strategies for early diagnosis and to minimize its incidence. This work reports the use of MPML14, a peptide that mimics the heat shock protein HSP60 present in the bacillary wall of the M. leprae, for the manufacture of a label-free electrochemical immunosensor for the detection of anti-leprosy IgG antibodies. The peptide was immobilized on the surface of the gold screen-printed electrode by means of selfassembled monolayers and subsequently functionalized with EDC and NHS. MPML14 was then chemically adsorbed on the surface of the transducer. The modification steps were chemically characterized by cyclic voltammetry (VC) and electrochemical impedance spectroscopy (EIE), and physically by scanning electron microscopy coupled to dispersive energy spectroscopy (SEM-EDS). The performance of the biosensor was evaluated using differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) with positive and negative sera for leprosy, with the best response obtained obtained by DPV. The volume of peptide solution was evaluated and chosen as 7 μL. A study was carried out using different sample concentrations, in which the entire range of concentrations tested demonstrated a qualitative response capable of distinguishing positive sera from negative sera. The concentration that showed the best performance was 1:200 (v:v). Finally, the specificity of the biosensor was evaluated with samples from healthy children and adults with HIV or leishmaniasis. All these samples showed similar responses to the negative serum samples, proving the excellent specificity of the biosensor. This study suggests that the MPML14-based electrochemical biosensor is promising for use in leprosy diagnosis.