TY - JOUR
T1 - Calcium and zinc ion release from polyalkenoate cements formed from zinc oxide/apatite mixtures
AU - Towler, M. R.
AU - Kenny, S.
AU - Boyd, D.
AU - Pembroke, T.
AU - Buggy, M.
AU - Guida, A.
AU - Hill, R. G.
PY - 2006/9
Y1 - 2006/9
N2 - Calcium and zinc ion release from hydroxyapatite-zinc oxide-poly(acrylic acid) (HAZnO-PAA) composite cements into deionised water was investigated as a function of HA content, PAA concentration, PAA molecular weight and maturation time. At any given maturation time, zinc ion release was constant until the HA content was at the maximum loading (60 wt%) resulting in the cement matrix breaking up, allowing exacerbated ion release. The calcium ion release increased with increased HA content in the composite until the maximum loading where the release drops off. Up to this point, the release of both ionic species was proportional to square root time for the initial 24 hour period, indicating that the release is diffusion controlled. In agreement with related data from conventional Glass Polyalkenoate Cements (GPCs), it is the concentration of the PAA, not the molecular weight, that influences ion release from these materials. However, unlike GPCs, the release of the active ions results in a pH rise in the deionised water, more conventionally seen with Bioglass® and related bioactive glasses. It is this pH rise, caused by the ion exchange of Zn 2+ and Ca2+ for H+ from the water, leaving an excess of OH-, that should result in a favourable bioactive response both in vitro and in-vivo.
AB - Calcium and zinc ion release from hydroxyapatite-zinc oxide-poly(acrylic acid) (HAZnO-PAA) composite cements into deionised water was investigated as a function of HA content, PAA concentration, PAA molecular weight and maturation time. At any given maturation time, zinc ion release was constant until the HA content was at the maximum loading (60 wt%) resulting in the cement matrix breaking up, allowing exacerbated ion release. The calcium ion release increased with increased HA content in the composite until the maximum loading where the release drops off. Up to this point, the release of both ionic species was proportional to square root time for the initial 24 hour period, indicating that the release is diffusion controlled. In agreement with related data from conventional Glass Polyalkenoate Cements (GPCs), it is the concentration of the PAA, not the molecular weight, that influences ion release from these materials. However, unlike GPCs, the release of the active ions results in a pH rise in the deionised water, more conventionally seen with Bioglass® and related bioactive glasses. It is this pH rise, caused by the ion exchange of Zn 2+ and Ca2+ for H+ from the water, leaving an excess of OH-, that should result in a favourable bioactive response both in vitro and in-vivo.
UR - http://www.scopus.com/inward/record.url?scp=33748211142&partnerID=8YFLogxK
U2 - 10.1007/s10856-006-9843-0
DO - 10.1007/s10856-006-9843-0
M3 - Article
C2 - 16932866
AN - SCOPUS:33748211142
SN - 0957-4530
VL - 17
SP - 835
EP - 839
JO - Journal of Materials Science: Materials in Medicine
JF - Journal of Materials Science: Materials in Medicine
IS - 9
ER -