title: Biomimetic deposition of hydroxyapatite on a synthetic polypeptide with beta sheet structure in a solution mimicking body fluid.
abstract: Deposition of a hydroxyapatite layer with similar structure to bone mineral is an attractive approach to the fabrication of bioactive coating layers to achieve direct bonding to living bone. To get successful coating of a hydroxyapatite layer on an organic polymer using a biomimetic solution, it is essential to find organic substrates that can effectively induce heterogeneous nucleation of hydroxyapatite after exposure to the body environment. Our previous study showed that sericin, a type of silk protein, has the ability to induce hydroxyapatite nucleation in a biomimetic solution when the sericin has a beta sheet structure. To confirm the effectiveness of the beta sheet structure in hydroxyapatite nucleation, we focused on investigating hydroxyapatite deposition on a synthetic polypeptide with a beta sheet structure in a biomimetic solution. The beta sheet forming polypeptides with and without carboxyl groups, poly(FE)(3)FG, poly(FQ)(3)FG, poly(LE)(3)LG and poly(LQ)(3)LG, were synthesized in this study. All the polypeptides had mainly beta sheet structure. After soaking the polypeptide films in 1.5SBF, which has 1.5 times the inorganic ion concentrations of human blood plasma, hydroxyapatite formed on the surfaces of the polypeptides with carboxyl groups, poly(FE)(3)FG and poly(LE)(3)LG, within 2 days, but not on those without carboxyl groups, poly(FQ)(3)FG and poly(LQ)(3)LG. We confirmed that the beta sheet structure was effective for hydroxyapatite nucleation even in the synthetic polypeptide. This finding is useful for the future design of organic polymers that can effectively induce nucleation of hydroxyapatite.
authors.affiliation: Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5, Takayama, Ikoma, Nara 630-0192, Japan.
authors.forename: Akari
authors.initials: A
authors.lastname: Takeuchi
authors.forename: Chikara
authors.initials: C
authors.lastname: Ohtsuki
authors.forename: Masanobu
authors.initials: M
authors.lastname: Kamitakahara
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Ogata
authors.forename: Toshiki
authors.initials: T
authors.lastname: Miyazaki
authors.forename: Masao
authors.initials: M
authors.lastname: Tanihara
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry*; D032701:Biomimetics; D001826:Body Fluids / Q000378:metabolism*; D017886:Durapatite / Q000737:chemistry*; D006801:Humans; D007930:Leucine / Q000737:chemistry; D008422:Materials Testing; D008970:Molecular Weight; D010455:Peptides / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry; D017433:Protein Structure, Secondary; D013499:Surface Properties; D023822:Tissue Engineering / Q000379:methods; D014961:X-Ray Diffraction
chemical_list: D001672:Biocompatible Materials; D010455:Peptides; D011108:Polymers; D017886:Durapatite; D007930:Leucine