Functionalization of Thioctic Acid-Capped Gold Nanoparticles for Specific Immobilization of Histidine-Tagged Proteins

This paper presents an efficient strategy for the specific immobilization of fully functional proteins onto the surface of nanoparticles. Thioctic acid-derivatized gold clusters are used as a scaffold for further stepwise modification, leading to a cobalt(II)-terminated ligand shell. A histidine tag introduced by genetic engineering into a protein is coordinated to this transition metal ion. The specific immobilization has been demonstrated for the cases of a genetically engineered horseradish peroxidase and ferredoxin-NADP+ reductase, confirming the attachment of the fully functional proteins to the Co(II)-terminated nanointerface. The absence of nonspecific protein adsorption and the specificity of the binding site have been verified using several analogues of the enzymes without the histidine tag.J.M.A. acknowledges support from a Consejería de Educación de la Comunidad Autónoma de Madrid postdoctoral fellowship, co-financed by the European Social Fund, and a postdoctoral fellowship from Fundación Ramón Areces. M.P. acknowledges receipt of a Ph.D. fellowship from the Consejería de Educación de la Comunidad Autónoma de Madrid, co-financed by the European Social Fund. S.F.L.M. and D.J.S. acknowledge financial support from the EU Research Training Network SUSANA (Supramolecular Self-Assembled Interfacial Nanostructures) under contract HPRN-CT-2002-00185. V.M.F. acknowledges financial support from an intramural CSIC project under contract CSIC-200450F0340.Peer reviewe