Investigation of the interaction between Tc85-11 protein and antibody anti-T cruzi by AFM and amperometric measurements

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Ferreira, A. A. P.
Colli, W.
Alves, M. J. M.
Oliveira, D. R.
Costa, P. I.
Guell, A. G.
Sanz, F.
Benedetti, Assis Vicente [UNESP]
Yamanaka, Hideko [UNESP]
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Elsevier B.V.
This present work reports on development of an amperometric immunosensor for the diagnosis of Chagas' disease using a specific glycoprotein of the trypomastigote surface, which belongs to the Tc85-11 protein family of Trypanosoma cruzi (T cruzi). An atomically flat gold surface on a silicon substrate and gold screen-printed electrodes were functionalized with cystatrine and later activated with glutaraldehyde (GA), which was used to form covalent bonds with the purified recombinant antigen (Tc85-11). The antigen reacts with the antibody from the serum, and the affinity reaction was monitored directly using atomic force microscopy or amperometry through a secondary antibody tagged to peroxidase (HRP). Surface imaging allowed to us to differentiate the modification steps and antigen-antibody interaction allowed to distinguish the affinity reactions. In the amperometric immunosensor, peroxidase catalyses the L-2 formation in the presence of hydrogen peroxide and potassium iodide, and the reduction current intensity was measured at a given potential with screen-printed electrodes. The immunosensor was applied to sera of chagasic patients and patients having different systemic diseases. (c) 2006 Elsevier Ltd. All rights reserved.
Chagas' disease, Tc85-11 protein, amperometric immunosensor, AFM
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Electrochimica Acta. Oxford: Pergamon-Elsevier B.V., v. 51, n. 24, p. 5046-5052, 2006.