title: Driving forces for the adsorption of a His-tag Chagas antigen. A rational approach to design bio-functional surfaces.
abstract: In order to rationally design a bio-functional surface based on the adsorption of a His-tag antigen, three requirements have to be considered: the bio-recognition element, the driving forces for the adsorption process and the detection mode of the bio-recognition event. This work is focused on the study of the adsorption mechanism of the His-tag H49 Chagas antigen on Ni(II) modified substrates. In order to construct the bio-functional surface, the gen of the H49 Chagas antigen was modified to incorporate His6 moiety at the N-terminal (His6-H49). Then, its physical adsorption and bio-affinity interaction with the solid substrate was studied by reflectometry. Besides His-Ni(II) bio-affinity interactions, His6-H49 was also physically adsorbed on Ni(II) modified substrates, leading to randomly oriented antigens. These loosely attached bio-molecules were partially removed using conditions of electrostatic repulsion. On the other hand, bio-affinity interactions, resulting in site-oriented molecules on the substrate, were only removable by specific competitors for Ni(II) surface sites. Finally, the surface bio-activity was determined from the peak separations of voltammetry waves due to the change of the electron transfer kinetics of a redox probe through the bio-functional surface (working electrode).
authors.affiliation: Instituto de Investigaciones en Físico Química de Córdoba (INFIQC) CONICET-UNC, Departamento de Fisicoquímica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, X5000HUA Córdoba, Argentina.
authors.forename: Laura E
authors.initials: LE
authors.lastname: Valenti
authors.forename: Andrea M
authors.initials: AM
authors.lastname: Smania
authors.forename: Carlos P
authors.initials: CP
authors.lastname: De Pauli
authors.forename: Carla E
authors.initials: CE
authors.lastname: Giacomelli
mesh_terms: D000327:Adsorption; D000913:Antibodies, Protozoan / Q000032:analysis / Q000097:blood; D000953:Antigens, Protozoan / Q000737:chemistry* / Q000235:genetics; D015374:Biosensing Techniques / Q000379:methods; D014355:Chagas Disease / Q000175:diagnosis / Q000276:immunology / Q000469:parasitology; D006639:Histidine / Q000737:chemistry; D006801:Humans; D055767:Immobilized Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D009532:Nickel; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D055672:Static Electricity; D013499:Surface Properties; D014349:Trypanosoma cruzi / Q000235:genetics / Q000276:immunology*
chemical_list: D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D055767:Immobilized Proteins; D011994:Recombinant Proteins; D006639:Histidine; D009532:Nickel
keywords: Adsorption mechanism; Bio-affinity interaction; Direct non-labeled detection; H49 antigen; Immunosensor; Ni(II) modified substrates