التفاصيل البيبلوغرافية
| العنوان: |
Effect of Pore Size on the Growth of Hydroxyapatite from Mesoporous CaO−SiO2Substrate. |
| المؤلفون: |
Yan Deng1, Xiaoke Li1, Qiang Li1 |
| المصدر: |
Industrial & Engineering Chemistry Research. Oct2009, Vol. 48 Issue 19, p8829-8836. 8p. |
| مصطلحات موضوعية: |
*HYDROXYAPATITE, *MESOPOROUS materials, *SUBSTRATES (Materials science), *SILICON oxide, *LIME (Minerals), *SURFACE active agents, *CHEMICAL engineering, *SCANNING electron microscopy, *BIOACTIVE compounds |
| مستخلص: |
In this work, a new approach for controlling the formation rate of hard tissue mineral hydroxypapatite (HAP) through the control of inner pore sizes of CaO−SiO2bioactive material is proposed. Highly ordered mesoporous CaO−SiO2(MCS) bioactive material with different pore sizes were synthesized through two types of surfactants, cetyltrimethyl-ammonium bromide (CTAB) and triblock copolymer EO106PO70EO106(Pluronic F127). These two surfactants were selected for their different pore size formation tendencies, about 2.7 nm for CTAB template and 4.9 nm for F127 template. These two types of MCS materials have identical chemical composition but differ only in their pore sizes. Their bioactivities were evaluated by the incubation of the MCS in phosphate buffer solution at 37 °C for different periods of time. SEM showed that incubated MCS with 2.7-nm pore size could rapidly form a dense layer of HAP crystallites on its surfaces within a few hours, while incubated MCS with 4.9-nm pore size just formed a sparse layer of HAP after one week of incubation, with XRD to further confirm the HAP phase. This unique phenomenon was explained from theoretical calculations in which the critical nucleation diameter, 2r* of the HAP on the MCS substrate is above 2.7 nm but below 4.9 nm. HRTEM observation proved that HAP nuclei indeed formed inside the pores of the F127 templated MCS sample with 4.9-nm pore size, which could block inner pore channels and obstruct the transportation of dissolved Ca ion to the outer surface, and then hindered the subsequent surface HAP formation. However, no HAP nuclei were found in the pores of the CTAB-templated MCS sample with 2.7-nm pore size, due to the thermodynamic instability of HAP nuclei below their critical size, r*, for which the unblocked pore channels facilitate the quick transportation of Ca ions and result in a much higher surface HAP growth rate. This finding provides a new material design strategy to accelerate the HAP formation rate simply by tuning its inner pore sizes below 2r* of HAP, without the need for modification of the material’s chemical composition. [ABSTRACT FROM AUTHOR] |
| قاعدة البيانات: |
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