title: Nanoscale probing of the enamel nanorod surface using polyamidoamine dendrimers.
abstract: Although it is known that noncollagenous proteins of dental origin bind to the hydroxyapatite crystal surfaces, no measure of their binding strength has been calculated. This experiment used -COOH-capped generation 7 PAMAM dendrimers as nanoprobes of the biological hydroxyapatite nanorod surfaces. Dendrimer distribution was characterized using AFM. The results showed dendrimers to be spaced at intervals along the c-axis of the crystals. From these observations and assuming a fully ionized -COOH dendrimer, a mathematical model of the binding capacity of the crystal surface with the dendrimer was developed. The Monte Carlo method was used to simulate the binding process between the dendrimer and crystal surface, and the binding strength of the -COOH groups to the surface was calculated to be 90 +/- 20 kJ/mol. These results support the CFM studies which have described alternating bands of charge domains on the crystal surface and that the binding strength will be dependent on both the intensity of the charge on the protein and the crystal surface.
authors.affiliation: School of Dentistry, Department of Physics, Program in Macromolecular Science and Engineering, Center for Biologic Nanotechnology, University of Michigan, Ann Arbor, Michigan 48109-1078, USA.
authors.forename: Haifeng
authors.initials: H
authors.lastname: Chen
authors.forename: Yunqing
authors.initials: Y
authors.lastname: Chen
authors.forename: Bradford G
authors.initials: BG
authors.lastname: Orr
authors.forename: Mark M Banaszak
authors.initials: MM
authors.lastname: Holl
authors.forename: Istvan
authors.initials: I
authors.lastname: Majoros
authors.forename: Brian H
authors.initials: BH
authors.lastname: Clarkson
mesh_terms: D050091:Dendrimers; D003746:Dental Enamel Proteins / Q000737:chemistry*; D017886:Durapatite / Q000737:chemistry*; D006801:Humans; D018625:Microscopy, Atomic Force; D015335:Molecular Probes; D011485:Protein Binding; D055672:Static Electricity; D013499:Surface Properties
chemical_list: D050091:Dendrimers; D003746:Dental Enamel Proteins; D015335:Molecular Probes; D017886:Durapatite