Electrochemical Immunosensor for Qualitative Diagnosis of the American Trypanosomiasis Based on Gold Modified with 3-Mercaptopropionic

This paper describes the development of a label-free electrochemical immunosensor for the qualitative detection of American trypanosomiasis in serum samples. The immunosensor was constructed using self assembled monolayer technique with gold substrate modified with monolayer of 3-mercaptopropionic acid. The T. cruzi antigens were immobilized after activation carboxylic groups in monolayer with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide. The parameters that can interfere the impedimetric response of the immunosensor response such as, concentration and incubation time in the solution of T. cruzi antigens, concentration of bovine serum albumin and incubation time in the solution of T. cruzi antibodies were optimized in the presence of the probe molecule hexacyanoferrate(II)/(III), using cyclic voltammetry and electrochemical impedance spectroscopy. The interaction between antigen-antibody was monitored using electrochemical impedance spectroscopy and the results were expressed in terms of the increase of the charge transfer resistance across the interface. The immunosensor showed selective and sensitive in the qualitative detection of T. cruzi antibodies in serum samples infected with toxoplasma antibodies. Therefore, the proposed methodology is a promising alternative for the development of a immunosensor for serological qualitative diagnosis of Chagas disease.