title: Self-assembly of protein-based biomaterials initiated by titania nanotubes.
abstract: Protein-based biomaterials are a promising strategy for creating robust highly selective biocatalysts. The assembled biomaterials must sufficiently retain the near-native structure of proteins and provide molecular access to catalytically active sites. These requirements often exclude the use of conventional assembly techniques, which rely on covalent cross-linking of proteins or entrapment within a scaffold. Here we demonstrate that titania nanotubes can initiate and template the self-assembly of enzymes, such as ribonuclease A, while maintaining their catalytic activity. Initially, the enzymes form multilayer thick ellipsoidal aggregates centered on the nanotube surface; subsequently, these nanosized entities assemble into a micrometer-sized enzyme material that has enhanced enzymatic activity and contains as little as 0.1 wt % TiO2 nanotubes. This phenomenon is uniquely associated with the active anatase (001)-like surface of titania nanotubes and does not occur on other anatase nanomaterials, which contain significantly fewer undercoordinated Ti surface sites. These findings present a nanotechnology-enabled mechanism of biomaterial growth and open a new route for creating stable protein-based biomaterials and biocatalysts without the need for chemical modification.
authors.affiliation: Department of Physics and Astronomy, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599-3255, United States.
authors.forename: Jacob H
authors.initials: JH
authors.lastname: Forstater
authors.forename: Alfred
authors.initials: A
authors.lastname: Kleinhammes
authors.forename: Yue
authors.initials: Y
authors.lastname: Wu
mesh_terms: D055162:Biocatalysis; D001672:Biocompatible Materials / Q000737:chemistry* / Q000378:metabolism; D004789:Enzyme Activation; D036103:Nanotechnology; D043942:Nanotubes / Q000737:chemistry*; D012259:Ribonuclease, Pancreatic / Q000737:chemistry* / Q000378:metabolism; D014025:Titanium / Q000737:chemistry* / Q000378:metabolism
chemical_list: D001672:Biocompatible Materials; C009495:titanium dioxide; D014025:Titanium; D012259:Ribonuclease, Pancreatic