For F2 samples, the trend of Ca, P, Si content of the SBF as a function of time was similar, but with some differences in the ml-1 levels and in the dissolution rate. The amount of Ca μg species released was higher, reaching 320 ml-1 after 2 weeks (see Fig.4a). The release rate for Si μg species was slower in comparison to the previous material and the rate was almost linear from 72 h to 3 weeks, finally reaching 75 ml-1 (Fig.4b). The precipitation rate of P species was also μg slower, however P was mostly removed by 2 weeks (Fig.4c). The pH trend was similar to that for F1 samples. The highest value of 8 was reached after 2 weeks, after which the pH decreased to 7.95 between 2 weeks and 3 weeks. The initial rapid dissolution did not appear detrimental, since the pH fluctuation was within the buffering capability of culture medium. Fig. 4: Dissolution profiles for a) Ca, b) Si, c) P and d) pH trend as a function of time, for foams subjected to the complete synthesis cycle, after soaking in SBF for 21 days. Results are presented as mean ± SD, n=3 per each time point. Fig.5 compares FTIR (Fig.5a) spectra and XRD (Fig.5b) patterns of the samples before and after 3 week immersion in SBF. For unreacted samples of both formulations, the FTIR spectra contained vibration bands at 510, 900 and 1010 cm-1 which can be reasonably associated with wollastonite (CaSiO3). The same peaks were not detected in the FTIR spectra for the samples after soaking in SBF, meaning that wollastonite was progressively subjected to decomposition in SBF, in agreement with the calcium release (Fig.4). This is also confirmed by the XRD patterns for the samples after soaking in SBF (Fig.5b), which showed no evidence of wollastonite, but peaks attributable to SiO2, Ca2SiO4 (only for F2 samples) and to apatite phases were found, the latter partially constituted by apatite incorporating groups (labelled as HAp) and mainly by HCA. –OH
For F2 samples, the trend of Ca, P, Si content of the SBF as a function of time was similar, but with some differences in the μg ml-1 levels and in the dissolution rate. The amount of Ca species released was higher, reaching 320 μg ml-1 after 2 weeks (see Fig.4a). The release rate for Si species was slower in comparison to the previous material and the rate was almost linear from 72 h to 3 weeks, finally reaching 75 μg ml-1 (Fig.4b). The precipitation rate of P species was also slower, however P was mostly removed by 2 weeks (Fig.4c). The pH trend was similar to that for F1 samples. The highest value of 8 was reached after 2 weeks, after which the pH decreased to 7.95 between 2 weeks and 3 weeks. The initial rapid dissolution did not appear detrimental, since the pH fluctuation was within the buffering capability of culture medium. Fig. 4: Dissolution profiles for a) Ca, b) Si, c) P and d) pH trend as a function of time, for foams subjected to the complete synthesis cycle, after soaking in SBF for 21 days. Results are presented as mean ± SD, n=3 per each time point. Fig.5 compares FTIR (Fig.5a) spectra and XRD (Fig.5b) patterns of the samples before and after 3 week immersion in SBF. For unreacted samples of both formulations, the FTIR spectra contained vibration bands at 510, 900 and 1010 cm-1 which can be reasonably associated with wollastonite (CaSiO3). The same peaks were not detected in the FTIR spectra for the samples after soaking in SBF, meaning that wollastonite was progressively subjected to decomposition in SBF, in agreement with the calcium release (Fig.4). This is also confirmed by the XRD patterns for the samples after soaking in SBF (Fig.5b), which showed no evidence of wollastonite, but peaks attributable to SiO2, Ca2SiO4 (only for F2 samples) and to apatite phases were found, the latter partially constituted by apatite incorporating –OH groups (labelled as HAp) and mainly by HCA.
Fiocco%20Revised_Biomed%20Mater.docx