Sb. Cho et al., APATITE FORMATION ON SILICA-GEL IN SIMULATED BODY-FLUID - ITS DEPENDENCE ON STRUCTURES OF SILICA-GELS PREPARED IN DIFFERENT MEDIA, Journal of biomedical materials research, 33(3), 1996, pp. 145-151
It has been shown that the prerequisite for glasses and glass-ceramics
to bond to living bone is the formation of a layer of biologically ac
tive bonelike apatite on their surfaces, The hydrated silica formed on
the surfaces of glasses and glass-ceramics plays an important role in
nucleating the apatite, In the present study, the structure of the hy
drated silica responsible for the apatite nucleation was investigated
in an accellular simulated body fluid with ion concentrations nearly e
qual to those of human blood plasma, Three kinds of porous silica gels
were prepared by hydrolysis and polycondensation of tetraethoxysilane
in pure water or in aqueous solution containing polyethylene glycol o
r polyacrylic acid, The silica gels prepared in aqueous solution conta
ining polyethylene glycol or polyacrylic acid had micron-size intercon
nected pores, whereas the gel prepared in pure water did not, All the
gels contained a large volume of nanometer-size pores, almost the same
amounts of silanol groups and D2 defect, and showed a high dissolutio
n rate of the silica, Despite this, only the gel prepared in the solut
ion containing polyethylene glycol formed the apatite on its surface i
n the simulated body fluid, This indicates that only a certain type of
structural unit of the silanol group is responsible for the apatite n
ucleation. (C) 1996 John Wiley & Sons, Inc.