title: Bacterial biosynthesis of a calcium phosphate bone-substitute material.
abstract: A species of Serratia bacteria produces nano-crystalline hydroxyapatite (HA) crystals by use of a cell-bound phosphatase enzyme, located both periplasmically and within extracellular polymeric materials. The enzyme functions in resting cells by cleaving glycerol-2-phosphate (G-2-P) to liberate free phosphate ions which combine with calcium in solution to produce a cell-bound calcium phosphate material. Bacteria grown as a biofilm on polyurethane reticulated foam cubes were challenged with calcium and G-2-P in a bioreactor to produce a 3-D porous bone-substitute material. The scaffold has 1 mm macropores and 1 microm micropores. XRD showed the crystallites to be 25-28 nm in size, resembling HA before sintering and beta-tricalcium phosphate (beta-TCP, whitlockite) after. When biofilm was grown on titanium discs and challenged with calcium and G-2-P, a calcium phosphate layer formed on the discs. Biomineralisation is therefore a potential route to production of precursor nanophase HA, which has the potential to improve strength. The scaffold material produced by this method could be used as a bone-filler or as an alternative method for coating implants with a layer of HA.
authors.affiliation: Biomaterials Department, School of Dentistry, The University of Birmingham, St Chad's Queensway, Birmingham, B4 6NN, UK.
authors.forename: Aniac C
authors.initials: AC
authors.lastname: Thackray
authors.forename: Rachel L
authors.initials: RL
authors.lastname: Sammons
authors.forename: Lynne E
authors.initials: LE
authors.lastname: Macaskie
authors.forename: Ping
authors.initials: P
authors.lastname: Yong
authors.forename: Harriet
authors.initials: H
authors.lastname: Lugg
authors.forename: Peter M
authors.initials: PM
authors.lastname: Marquis
mesh_terms: D018786:Bone Substitutes / Q000737:chemistry* / Q000378:metabolism*; D002130:Calcium Phosphates / Q000737:chemistry* / Q000378:metabolism*; D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D003460:Crystallization / Q000379:methods; D008422:Materials Testing; D010865:Pilot Projects; D012705:Serratia / Q000254:growth & development / Q000378:metabolism*; D013499:Surface Properties; D013696:Temperature; D014025:Titanium / Q000737:chemistry*
chemical_list: D018786:Bone Substitutes; D002130:Calcium Phosphates; D020099:Coated Materials, Biocompatible; C020243:calcium phosphate; D014025:Titanium