Journal of Dental Research, Vol 69, 1678-1685, Copyright © 1990 by International & American Associations for Dental Research Online Journals
Analysis of particle size distribution of hydroxyapatite crystallites in the presence of synthetic and natural polymers
G. H. Nancollas and J. A. Budz
Department of Chemistry, State University of New York, Buffalo 14214.
The particle size distribution (PSD) of suspended hydroxyapatite
crystallites both at equilibrium and during crystal growth has been
measured by a laser scattering technique. Addition of high-molecular-weight
polyacrylate (PAA/C) resulted in appreciable crystallite aggregation,
probably by polymer bridging of particles. In contrast, a
lower-molecular-weight PAA was unable to bridge the hydrodynamic gap
between particles and resulted in an overall dispersion. The addition of
human serum albumin also markedly influenced the PSD and, with concomitant
change in zeta potential to more negative values, resulted in dispersion
due to steric interaction and electrostatic repulsion between the
particles. The complex behavior of human saliva is illustrated by its
tendency both to aggregate and to disperse hydroxyapatite crystallites,
displaying the combined effects of different adsorbing macromolecules.
