Rm. Kowalchuk et al., PARTICLE MICROELECTROPHORESIS OF CALCIUM-DEFICIENT HYDROXYAPATITE - SOLUTION COMPOSITION AND KINETIC EFFECTS, Journal of biomedical materials research, 27(6), 1993, pp. 783-790
Concurrent work demonstrates that the zeta potential of bone is multiv
alued and systematically alterable by changes in sample preparation, s
teeping fluid composition, and steeping time. Since bone mineral is a
mixture of carbonated calcium-deficient hydroxyapatites, and since the
zeta potential of calcium-deficient hydroxyapatite (CDHA) is altered
by pH and time in HNO3-KOH solutions, the zeta potential of CDHA in ph
ysiologic Neuman's fluid (NF) compared with that seen in bone could re
veal important information on the contribution of the mineral phase to
the zeta potential of bone. In addition, such information may be valu
able in designing and evaluating calcium-phosphate ceramics for increa
sed bone ingrowth. Results demonstrate that the zeta potential of CDHA
in NF is negative. With increasing calcium in NF, the zeta potential
magnitude of CDHA decreases and inverts to positiVe values given suffi
cient calcium concentration and steeping time. This result is opposite
to that seen in bone, suggesting that exposed CDHA is not the predomi
nant bone microsurface and implicating a bone surface protein componen
t. With increasing phosphate in NF, the zeta potential magnitude incre
ases to more negative values. While low concentrations of fluoride sho
wed no effect, the possibility of an effect with higher concentrations
is still to be determined.