title: Biocatalytic synthesis of a nanostructured and crystalline bimetallic perovskite-like barium oxofluorotitanate at low temperature.
abstract: Silicatein, an enzymatic biocatalyst from the marine sponge Tethya aurantia, is demonstrated to catalyze and template the hydrolysis/condensation of the molecular precursor BaTiF6 at low temperature to form nanocrystalline BaTiOF4, an orthorhombic oxofluorotitanate. The kinetics of hydrolysis and growth were studied in-situ via pH profiling and quartz crystal microbalance (QCM) techniques. The composition and structure of the resulting BaTiOF4 microstructures on the silicatein surface were characterized using FT-IR spectroscopy, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, scanning electron microscopy, transmission electron microscopy, and selected area electron diffraction. The silicatein-mediated hydrolysis/condensation of BaTiF6 generates nanocrystalline BaTiOF4 (a high-temperature intermediate to BaTiO3) at 16 degrees C without any added acid or base, and the growth is templated along the protein filaments into floret microstructures. The unique combination of silicatein and the single-source molecular precursor has allowed a multimetallic perovskite-like material to be biocatalytically synthesized, in vitro, for the first time.
authors.affiliation: Institute for Collaborative Biotechnologies, California NanoSystems Institute, the Materials Research Laboratory, University of California, Santa Barbara, California 93106, USA.
authors.forename: Richard L
authors.initials: RL
authors.lastname: Brutchey
authors.forename: Edward S
authors.initials: ES
authors.lastname: Yoo
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Morse
mesh_terms: D017609:Barium Compounds / Q000737:chemistry*; D017610:Calcium Compounds / Q000737:chemistry*; D002384:Catalysis; D003080:Cold Temperature; D006868:Hydrolysis; D007700:Kinetics; D046529:Microscopy, Electron, Transmission; D049329:Nanostructures; D010087:Oxides / Q000737:chemistry*; D013057:Spectrum Analysis / Q000379:methods; D014025:Titanium / Q000737:chemistry*; D014965:X-Rays
chemical_list: D017609:Barium Compounds; D017610:Calcium Compounds; D010087:Oxides; C059910:perovskite; D014025:Titanium