title: Adsorption and stability of streptavidin on cluster-assembled nanostructured TiOx films.
abstract: The study of the adsorption of proteins on nanostructured surfaces is of fundamental importance to understand and control cell-surface interactions and, notably, cell adhesion and proliferation; it can also play a strategic role in the design and fabrication of nanostructured devices for postgenomic and proteomic applications. We have recently demonstrated that cluster-assembled nanostructured TiO x films produced by supersonic cluster beam deposition possess excellent biocompatibility and that these films can be functionalized with streptavidin, allowing the immobilization of biotinylated retroviral particles and the realization of living-cell microarrays for phenotype screening. Here we present a multitechnique investigation of the adsorption mechanisms of streptavidin on cluster-assembled TiO x films. We show that this nanostructured surface provides an optimal balance between adsorption efficacy and protein functionality. By using low-resolution protein arrays, we demonstrate that a layer of adsorbed streptavidin can be stably maintained on a cluster-assembled TiO x surface under cell culture conditions and that streptavidin retains its biological activity in the adsorbed layer. The adsorption mechanisms are investigated by atomic force microscopy in force spectroscopy mode and by valence-band photoemission spectroscopy, highlighting the potential role of the interaction of the exposed carboxyl groups on streptavidin with the titanium atoms of the nanostructured surface.
authors.affiliation: CIMAINA and Dipartimento di Fisica, University of Milano, via Celoria 16, 20133 Milano, Italy. luca.giorgetti@ifom-ieo-campus.it
authors.forename: Luca
authors.initials: L
authors.lastname: Giorgetti
authors.forename: Gero
authors.initials: G
authors.lastname: Bongiorno
authors.forename: Alesssandro
authors.initials: A
authors.lastname: Podestà
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Berlanda
authors.forename: Pasquale Emanuele
authors.initials: PE
authors.lastname: Scopelliti
authors.forename: Roberta
authors.initials: R
authors.lastname: Carbone
authors.forename: Paolo
authors.initials: P
authors.lastname: Milani
mesh_terms: D000327:Adsorption; D002627:Chemistry, Physical / Q000379:methods; D023281:Genomics / Q000379:methods; D007700:Kinetics; D018625:Microscopy, Atomic Force / Q000379:methods; D049329:Nanostructures / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry; D040901:Proteomics / Q000379:methods; D013053:Spectrophotometry / Q000379:methods; D019809:Streptavidin / Q000737:chemistry*; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*
chemical_list: C009495:titanium dioxide; D019809:Streptavidin; D014025:Titanium; D010100:Oxygen