title: Molecular orientation of tropoelastin is determined by surface hydrophobicity.
abstract: Tropoelastin is the precursor of the extracellular protein elastin and is utilized in tissue engineering and implant technology by adapting the interface presented by surface-bound tropoelastin. The preferred orientation of the surface bound protein is relevant to biointerface interactions, as the C-terminus of tropoelastin is known to be a binding target for cells. Using recombinant human tropoelastin we monitored the binding of tropoelastin on hydrophilic silica and on silica made hydrophobic by depositing a self-assembled monolayer of octadecyl trichlorosilane. The layered organization of deposited tropoelastin was probed using neutron and X-ray reflectometry under aqueous and dried conditions. In a wet environment, tropoelastin retained a solution-like structure when adsorbed on silica but adopted a brush-like structure when on hydrophobized silica. The orientation of the surface-bound tropoelastin was investigated using cell binding assays and it was found that the C-terminus of tropoelastin faced the bulk solvent when bound to the hydrophobic surface, but a mixture of orientations was adopted when tropoelastin was bound to the hydrophilic surface. Drying the tropoelastin-coated surfaces irreversibly altered these protein structures for both hydrophilic and hydrophobic surfaces.
authors.affiliation: Bragg Institute , Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia.
authors.forename: Anton P
authors.initials: AP
authors.lastname: Le Brun
authors.forename: John
authors.initials: J
authors.lastname: Chow
authors.forename: Daniel V
authors.initials: DV
authors.lastname: Bax
authors.forename: Andrew
authors.initials: A
authors.lastname: Nelson
authors.forename: Anthony S
authors.initials: AS
authors.lastname: Weiss
authors.forename: Michael
authors.initials: M
authors.lastname: James
mesh_terms: D000327:Adsorption; D001672:Biocompatible Materials / Q000138:chemical synthesis* / Q000494:pharmacology; D002448:Cell Adhesion / Q000187:drug effects; D020405:Dermis / Q000166:cytology / Q000187:drug effects; D003890:Desiccation; D005347:Fibroblasts / Q000187:drug effects; D006801:Humans; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D011487:Protein Conformation; D012821:Silanes / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry*; D012996:Solutions; D013499:Surface Properties; D023822:Tissue Engineering / Q000379:methods*; D014333:Tropoelastin / Q000737:chemistry / Q000378:metabolism; D014867:Water
chemical_list: D001672:Biocompatible Materials; D012821:Silanes; D012996:Solutions; D014333:Tropoelastin; D014867:Water; D012822:Silicon Dioxide; C065893:trichlorosilane