title: Simplified procedure for encapsulating cytochrome c in silica aerogel nanoarchitectures while retaining gas-phase bioactivity.
abstract: Cytochrome c (cyt. c) has been encapsulated in silica sol-gels and processed to form bioaerogels with gas-phase activity for nitric oxide through a simplified synthetic procedure. Previous reports demonstrated a need to adsorb cyt. c to metal nanoparticles prior to silica sol-gel encapsulation and processing to form aerogels. We report that cyt. c can be encapsulated in aerogels without added nanoparticles and retain structural stability and gas-phase activity for nitric oxide. While the UV-visible Soret absorbance and nitric oxide response indicate that cyt. c encapsulated with nanoparticles in aerogels remains slightly more stable and functional than cyt. c encapsulated alone, these properties are not very different in the two types of aerogels. From UV-visible and Soret circular dichroism results, we infer that cyt. c encapsulated alone self-organizes to reduce contact with the silica gel in a way that may bear at least some resemblance to the way cyt. c self-organizes into superstructures of protein within aerogels when nanoparticles are present. Both the buffer concentration and the cyt. c concentration of solutions used to synthesize the bioaerogels affect the structural integrity of the protein encapsulated alone within the dried aerogels. Optimized bioaerogels are formed when cyt. c is encapsulated from 40 mM phosphate buffered solutions, and when the loaded cyt. c concentration in the aerogel is in the range of 5 to 15 μM. Increased viability of cyt. c in aerogels is also observed when supercritical fluid used to produce aerogels is vented over relatively long times.
authors.affiliation: Chemistry & Biochemistry Department, Fairfield University, 1073 North Benson Road, Fairfield, Connecticut 06824, USA. aharper@fairfield.edu
authors.forename: Amanda S
authors.initials: AS
authors.lastname: Harper-Leatherman
authors.forename: Mariam
authors.initials: M
authors.lastname: Iftikhar
authors.forename: Adela
authors.initials: A
authors.lastname: Ndoi
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Scappaticci
authors.forename: George P
authors.initials: GP
authors.lastname: Lisi
authors.forename: Kaitlyn L
authors.initials: KL
authors.lastname: Buzard
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Garvey
mesh_terms: D045304:Cytochromes c / Q000737:chemistry*; D005740:Gases / Q000737:chemistry; D005782:Gels / Q000737:chemistry*; D006046:Gold / Q000737:chemistry; D049329:Nanostructures / Q000737:chemistry*; D009569:Nitric Oxide / Q000032:analysis; D012822:Silicon Dioxide / Q000737:chemistry*
chemical_list: D005740:Gases; D005782:Gels; D009569:Nitric Oxide; D006046:Gold; D012822:Silicon Dioxide; D045304:Cytochromes c