Various live microorganisms and mammalian tissue cells can be encapsulated in porous inorganic gels for such possible applications as sensors, pharmaceutical bioreactors, and artifical internal organs. For example, saccharomyces cerevisiae has been encapsulated in a transparent matrix of porous, gel-derived silica. After gelation, aging, and prolonged storage at 5 deg C, S. cerevisiae bioactivity could be triggered. Bioactivity was followed by evolution of alcohol within the S. cerevisiae as a function of time during incubation by the molecular probe molecule pyranine using fluorescence spectrophotometry. In addition, mammalian tissue cells, such as pancreatic islet cells, adrenal cells, and hepatocytes, have all been encapsulated into silica gels.
