title: Concentration-dependent effects of fibronectin adsorbed on hydroxyapatite surfaces on osteoblast adhesion.
abstract: Fibronectin (Fn) is an essential protein that is involved in cell attachment, migration, and differentiation. It is known that the conformation of Fn changes depending on its surrounding environment or on the surface properties of the substrate to which it is adsorbed. Here, we show that Fn adopts different conformations in physiological solutions and can play different roles in osteoblast adhesion on hydroxyapatite (HAp) depending on its concentration. The results of in situ observations showed that the adsorption configuration of Fn was an oblate ellipsoidal structure at low concentrations and a fibrillar structure at high concentrations, suggesting that individual Fn molecules attach to HAp with a side-on or end-on orientation, under low and high concentrations, respectively. Osteoblasts adhered more to the HAp surface under low concentrations of adsorbed Fn than under high concentrations. These observations suggest that the Fn concentration gradient is important for regulating biomaterial-cell interactions in regenerative medicine.
authors.affiliation: Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda, Tokyo 101-0062, Japan; Department of Materials Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan.
authors.forename: Natsuno
authors.initials: N
authors.lastname: Matsui
authors.affiliation: Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda, Tokyo 101-0062, Japan.
authors.forename: Kosuke
authors.initials: K
authors.lastname: Nozaki
authors.affiliation: Department of Materials Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Ishihara
authors.affiliation: Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda, Tokyo 101-0062, Japan.
authors.forename: Kimihiro
authors.initials: K
authors.lastname: Yamashita
authors.affiliation: Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda, Tokyo 101-0062, Japan. Electronic address: nag-bcr@tmd.ac.jp.
authors.forename: Akiko
authors.initials: A
authors.lastname: Nagai
mesh_terms: D000327:Adsorption; D002448:Cell Adhesion; D002460:Cell Line; D017886:Durapatite / Q000737:chemistry*; D005353:Fibronectins / Q000737:chemistry*; D006801:Humans; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism*
chemical_list: D005353:Fibronectins; D017886:Durapatite
keywords: AFM; Concentration effect; Fibronectin; Hydroxyapatite; QCM-D