Driving forces for the adsorption of a His-tag Chagas antigen.A rational approach to design bio-functional surfaces

VALENTI L; SMANIA AM; DE PAULI C; GIACOMELLI C

Colloids and Surfaces B: Biointerfaces

Elsevier

Año: 2013 vol. 112 p. 294 - 301

0927-7765

tIn order to rationally design a bio-functional surface based on the adsorption of a His-tag antigen, threerequirements have to be considered: the bio-recognition element, the driving forces for the adsorptionprocess and the detection mode of the bio-recognition event. This work is focused on the study of theadsorption mechanism of the His-tag H49 Chagas antigen on Ni(II) modified substrates. In order to con-struct the bio-functional surface, the gen of the H49 Chagas antigen was modified to incorporate His6moiety at the N-terminal (His6-H49). Then, its physical adsorption and bio-affinity interaction with thesolid substrate was studied by reflectometry. Besides His-Ni(II) bio-affinity interactions, His6-H49 wasalso physically adsorbed on Ni(II) modified substrates, leading to randomly oriented antigens. Theseloosely attached bio-molecules were partially removed using conditions of electrostatic repulsion. Onthe other hand, bio-affinity interactions, resulting in site-oriented molecules on the substrate, were onlyremovable by specific competitors for Ni(II) surface sites. Finally, the surface bio-activity was determinedfrom the peak separations of voltammetry waves due to the change of the electron transfer kinetics of aredox probe through the bio-functional surface (working electrode).