title: Ceramic nanoparticle assemblies with tailored shapes and tailored chemistries via biosculpting and shape-preserving inorganic conversion.
abstract: A novel biosynthetic paradigm is introduced for fabricating three-dimensional (3-D) ceramic nanoparticle assemblies with tailored shapes and tailored chemistries: biosculpting and shape-preserving inorganic conversion (BaSIC). Biosculpting refers to the use of biomolecules that direct the precipitation of ceramic nanoparticles to form a continuous 3-D structure with a tailored shape. We used a peptide derived from a diatom (a type of unicellular algae) to biosculpt silica nanoparticle based assemblies that, in turn, were converted into a new (nonsilica) composition via a shape-preserving gas/silica displacement reaction. Interwoven, microfilamentary silica structures were prepared by exposing a peptide, derived from the silaffin-1A protein of the diatom Cylindrotheca fusiformis, to a tetramethylorthosilicate solution under a linear shear flow condition. Subsequent exposure of the silica microfilaments to magnesium gas at 900 degrees C resulted in conversion into nanocrystalline magnesium oxide microfilaments with a retention of fine (submicrometer) features. Fluid(gas or liquid)/silica displacement reactions leading to a variety of other oxides have also been identified. This hybrid (biogenic/synthetic) approach opens the door to biosculpted ceramic microcomponents with multifarious tailored shapes and compositions for a wide range of environmental, aerospace, biomedical, chemical, telecommunications, automotive, manufacturing, and defense applications.
authors.affiliation: School of Materials Science and Engineering, Georgia Institute of Technology, 771 Ferst Drive, Atlanta, Georgia 30332-0245, USA.
authors.forename: M B
authors.initials: MB
authors.lastname: Dickerson
authors.forename: R R
authors.initials: RR
authors.lastname: Naik
authors.forename: P M
authors.initials: PM
authors.lastname: Sarosi
authors.forename: G
authors.initials: G
authors.lastname: Agarwal
authors.forename: M O
authors.initials: MO
authors.lastname: Stone
authors.forename: K H
authors.initials: KH
authors.lastname: Sandhage
mesh_terms: D032701:Biomimetics / Q000295:instrumentation / Q000379:methods*; D002516:Ceramics / Q000737:chemistry; D011232:Chemical Precipitation; D003460:Crystallization / Q000379:methods*; D017377:Diatoms / Q000378:metabolism*; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D010455:Peptides; D016062:Porosity; D011506:Proteins / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*
chemical_list: D010455:Peptides; D011506:Proteins; C400535:silaffin 1A; D012822:Silicon Dioxide