Encapsulation of Bacterial Endospores in Silica Aerogel Monoliths.

摘要

The encapsulation of whole cell bacteria into silica aerogel monoliths presents interesting possibilities for biosensing applications. A key obstacle in implementing such a system is the inherently biocidal nature of standard aerogel manufacture techniques. Initial attempts at encapsulating a bacterial system into a silica aerogel focused on the bacterium Escherichia coli, but were judged unsuccessful under all conditions examined. Attempts were made to protect the bacterial cells prior to silica encapsulation by pre-encapsulating them in a less biocidal procedure. Attempts were made to pretreat cells with polyelectrolyte bilayers (poly(allylamine hydrochloride (PAH) and poly(styrenesulfonate) (PSS)) of varying thickness (1-3 bilayers) and with alginic acid. Neither preparation resulted in any significant retention of cell viability on introduction to the gel solution.;The encapsulation of Bacillus subtilis endospores in silica aerogel monoliths fabricated using the low temperature, supercritical carbon dioxide method was significantly more successful. The tetraethyl orthosilicate (TEOS) based gels remained vary low density (0.14 +/-0.03 g/cm3) with good optical clarity in the visible and near-UV spectra. Encapsulated endospores display retained viability in excess of 23% after a period of 60 days under ambient conditions, and achieved attenuated logarithmic growth in the gel on rehydration in bacterial media. We also examined the production and detection of fluorescent reporter molecules produced by non-pathogenic Bacillus anthracis (34F2) cells encapsulated within silica aerogel monoliths. Encapsulated cultures readily produced the fluorescent reporter, which was detected microscopically and spectroscopically from outside the gel.