Tuning Stability of Mesoporous Silica Films under Biologically Relevant Conditions Through Processing with Supercritical CO₂

Abstract

Mesoporous materials have been proposed for use in numerous biological environments such as substrates for cell culture and controlled release for drug delivery. Although mesoporous silica synthesis is facile, recent reports (Dunphy et al. Langmuir 2003, 19, 10403; Bass et al. Chem. Mater. 2007, 19, 4349) have demonstrated instability (dissolution) of pure mesoporous silica films under biologically relevant conditions. In this work, we demonstrate a simple processing handle (pressure) to control the dissolution of mesoporous silica films that are synthesized using preformed template films and supercritical CO2. Spectroscopic ellipsometry is utilized to quantify changes in both the film thickness and porosity; these properties provide insight into the dissolution mechanism. The pore size increases as the films are exposed to phosphate-buffered saline (PBS) through preferential dissolution at the pore wall in comparison to the film surface; a mechanism reminiscent of bulk erosion of scaffolds for drug delivery. Thin mesoporous silica film lifetimes can be extended from several hours using traditional sol-gel approaches to days by using CO2 processing for identical film thickness. Osteoblast attachment and viability on these films was found to correlate with their increased stability. This enhanced stability opens new possibilities for the utilization of mesoporous silica for biological applications, including drug delivery and tissue engineering.

Department(s)

Chemical and Biochemical Engineering

Keywords and Phrases

Biological applications; Biological environments; Bulk erosions; Controlled releases; Dissolution mechanisms; Enhanced stabilities; Film surfaces; Langmuir; Life-times; Mesoporous silica films; Mesoporous silicas; Osteoblast attachments; Pore walls; Preferential dissolutions; Supercritical CO; Template films, Biological materials; Cell culture; Colloids; Controlled drug delivery; Dissolution; Drug delivery; Gelation; Magnetic films; Molecular beam epitaxy; Osteoblasts; Oxides; Silica; Sol-gels; Spectroscopic ellipsometry; Tissue engineering, Mesoporous materials, biomaterial; carbon dioxide; silicon dioxide, adsorption; article; biophysics; biotechnology; chemistry; drug delivery system; methodology; particle size; physical chemistry; porosity; spectrophotometry; surface property; time; tissue engineering, Adsorption; Biocompatible Materials; Biophysics; Biotechnology; Carbon Dioxide; Chemistry, Physical; Drug Delivery Systems; Particle Size; Porosity; Silicon Dioxide; Spectrophotometry; Surface Properties; Time Factors; Tissue Engineering

International Standard Serial Number (ISSN)

0743-7463

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2008 American Chemical Society (ACS), All rights reserved.

Publication Date

01 Oct 2008

PubMed ID

18795807

Link to Full Text

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