Solution effects on the surface reactions of three bioactive glass compositions.
The in vitro five-stage surface reactions of two bioactive glass compositions, 45S5 and 52S4.6, and one bioinert glass, 60S3.8, exposed to three simulated body fluids (SBF) were analyzed using Fourier Transform infrared Spectroscopy (FTIR). There was little effect of SBF composition on ion exchange, silica hydrolysis, and silica polymerization (stages 1-3) of glass with silica content up to 52 wt%. However, calcium and phosphate ions in SBF accelerated the formation of an amorphous calcium-phosphate (a-CP) layer (stage 4), and crystallization (stage 5) of the hydroxycarbonate apatite (HCAp) layer. The magnesium ions had a retardation effect on the kinetics of stages 4 and 5, but little effect on stages 1-3. In SBF solutions which contained calcium and phosphate ions an amorphous calcium-phosphate (a-CaP) layer formed on even a 60S3.8 glass which was not bioactive in vivo. However, the a-CaP layer did not crystallize to form HCAp. Thus, there is a significant contribution from the ions present in the SBF solutions to the HCAP formation and crystallization of HCAp on bioactive glasses. Also, silanol repolymerization is necessary for rapid crystallization of HCAp.
Filgueiras
M R
MR
Advanced Materials Research Center, University of Florida, Gainesville 32615.
LaTorre
G
G
Hench
L L
LL
D001031:Apatites / Q000737:chemistry*; D001672:Biocompatible Materials; D001826:Body Fluids / Q000737:chemistry*; D002130:Calcium Phosphates / Q000737:chemistry*; D002254:Carbonates / Q000737:chemistry*; D003460:Crystallization; D005898:Glass / Q000737:chemistry*; D006868:Hydrolysis; D007474:Ion Exchange; D007700:Kinetics; D012822:Silicon Dioxide / Q000737:chemistry; D012996:Solutions; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties
D001031:Apatites; D001672:Biocompatible Materials; D002130:Calcium Phosphates; D002254:Carbonates; D012996:Solutions; C485828:alpha-tricalcium phosphate; C519480:amorphous calcium phosphate; C485830:tetracalcium phosphate; C485838:calcium phosphate, monobasic, anhydrous; D012822:Silicon Dioxide; C020243:calcium phosphate; C485829:calcium phosphate, dibasic, anhydrous