title: Effects of amelogenin on the transforming surface microstructures of Bioglass in a calcifying solution.
abstract: Topographies of a bioactive glass (45S5 type Bioglass(R)) during 0-4 h of immersion in a supersaturated calcifying solution (SCS) and the SCS containing recombinant porcine amelogenin rP172 (SCS(rP172)) were observed by atomic force microscopy. Other techniques including X-ray diffraction, scanning electron microscopy coupled with energy dispersive X-ray spectroscopy, and transmission electron microscopy were used for some complementary microstructural investigations. The smooth Bioglass surface changed to be very rough after 0.5 h of SCS immersion because of glass network dissolution. Spherical silica-gel particles with diameters of 150-300 nm consisting of substructures of 20-60 nm across had formed on the sample surfaces after 1 h of SCS immersion. The chemisorption of amorphous calcium phosphate and crystallization of nanophase apatite were seen to occur epitaxially on the silica-gel structures during 1-4 h of SCS immersion. During the first 0.5 h of SCS(rP172) immersion, more than 95% of rP172 protein in solution was adsorbed onto the sample surfaces and generated spherical assemblies of 10-60 nm diameters. During 0.5-4 h of SCS(rP172) immersion, the protein assemblies of rP172 remarkably induced the formation of orientated silica-gel plates (approximately 100-nm wide and 50-nm thick) and subsequently of long and thin apatite needle crystals. The recombinant amelogenin rP172-modulated apatite crystals resembled those formed in the early stage of tooth enamel biomineralization, suggesting the functional roles of amelogenins during the oriented growth of enamel crystallites and a great potential for amelogenins in applications designed to fabricate enamel-like calcium phosphate biomaterials.
authors.affiliation: Center for Craniofacial Molecular Biology, School of Dentistry, University of Southern California, 2250 Alcazar Street, CSA 1st Floor, Los Angeles, California 90033, USA. hbw@hsc.usc.edu
authors.forename: H B
authors.initials: HB
authors.lastname: Wen
authors.forename: J
authors.initials: J
authors.lastname: Moradian-Oldak
authors.forename: J P
authors.initials: JP
authors.lastname: Zhong
authors.forename: D C
authors.initials: DC
authors.lastname: Greenspan
authors.forename: A G
authors.initials: AG
authors.lastname: Fincham
mesh_terms: D000327:Adsorption; D053523:Amelogenin; D001672:Biocompatible Materials / Q000737:chemistry*; D002130:Calcium Phosphates; D002516:Ceramics / Q000737:chemistry*; D003460:Crystallization; D003743:Dental Enamel / Q000737:chemistry; D003746:Dental Enamel Proteins / Q000494:pharmacology*; D017886:Durapatite / Q000737:chemistry*; D004577:Electron Probe Microanalysis; D005898:Glass; D007101:Immersion; D008422:Materials Testing; D018625:Microscopy, Atomic Force; D008854:Microscopy, Electron; D008863:Microspheres; D058428:Silica Gel; D012822:Silicon Dioxide / Q000737:chemistry*; D012996:Solutions; D013057:Spectrum Analysis; D013499:Surface Properties; D014965:X-Rays
chemical_list: D053523:Amelogenin; D001672:Biocompatible Materials; C022107:Bioglass; D002130:Calcium Phosphates; D003746:Dental Enamel Proteins; D012996:Solutions; C519480:amorphous calcium phosphate; C425330:bioactive glass 45S5; D058428:Silica Gel; D012822:Silicon Dioxide; D017886:Durapatite