title: 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 CO 2. 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 CO 2 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.
authors.affiliation: Department of Chemical Engineering, Arizona State University, Tempe, Arizona 85284, USA.
authors.forename: Xinxin
authors.initials: X
authors.lastname: Li
authors.forename: Sutapa
authors.initials: S
authors.lastname: Barua
authors.forename: Kaushal
authors.initials: K
authors.lastname: Rege
authors.forename: Bryan D
authors.initials: BD
authors.lastname: Vogt
mesh_terms: D000327:Adsorption; D001672:Biocompatible Materials / Q000737:chemistry; D001703:Biophysics / Q000379:methods; D001709:Biotechnology / Q000379:methods; D002245:Carbon Dioxide / Q000737:chemistry*; D002627:Chemistry, Physical / Q000379:methods; D016503:Drug Delivery Systems; D010316:Particle Size; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry*; D013053:Spectrophotometry / Q000379:methods; D013499:Surface Properties; D013997:Time Factors; D023822:Tissue Engineering / Q000379:methods
chemical_list: D001672:Biocompatible Materials; D002245:Carbon Dioxide; D012822:Silicon Dioxide