Stability of Mesoporous Oxide and Mixed Metal Oxide Materials under Biologically Relevant Conditions
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- 作者：John D. Bass ; David Grosso ; Cé ; dric Boissiere ; Emmanuel Belamie ; Thibaud Coradin ; Clé ; ment Sanchez
- 刊名：Chemistry of Materials
- 出版年：2007
- 出版时间：August 21, 2007
- 年：2007
- 卷：19
- 期：17
- 页码：4349 - 4356
- 全文大小：360K
- 年卷期：v.19,no.17(August 21, 2007)
- ISSN：1520-5002
文摘
The dynamic behavior of nanoscale mesoporous oxide materials exposed to aqueous solutions underbiologically relevant conditions is shown to be highly dependent on composition, porosity, and calcinationtemperature. Dynamic processes were followed as a function of exposure on thin oxide films amenableto environmental ellipsometry porosimetry for the analysis of mechanical strength and pore sizedistributions as a function of exposure. Additionally, X-ray photoelectron spectroscopy was used for theelucidation of compositional changes as a function of exposure. Combined, this approach gives the firstdetailed, quantitative information of the degradation of nanoscale oxide materials under biologically relevantconditions. This approach also shows the utility of using film geometry as a convenient model systemfor the study of dynamic properties, as films are amenable to sensitive ellipsometric characterization.Pure silica films underwent a rapid degradation, occurring on the time scale of hours, while silica filmsmixed with 10% or less of zirconia or alumina were significantly more stable. These mixed metal oxidefilms showed structural changes on two time scales, undergoing a rapid partial degradation followed bya stabilization of the structure as the composition of the films evolved toward a depleted silica state. Thetime scales of these two processes were on the order of hours and days, respectively, and could be tunedby varying the composition and the calcination temperature of the films. These time scales are especiallyrelevant to the culture and growth of mammalian cells and for drug release applications. Titania materialswere shown to be stable under all conditions studied, making them suitable candidates for applicationswhere the scaffold functions as a permanent support. These results yield unprecedented levels of detailon the kinetics of degradation and the dynamic structural and compositional changes occurring in thesenanostructured materials.