title: Bifunctional small molecules are biomimetic catalysts for silica synthesis at neutral pH.
abstract: Silicatein is an enzyme isolated from the biosilica produced by the marine demosponge, Tethya aurantia. Once isolated from the sponge, silicatein can be used in vitro to catalyze the hydrolysis and direct polycondensation of a wide variety of alkoxide, ionic, and organometallic precursors to the corresponding chalcogens at standard temperature and pressure and neutral pH. On the basis of these results, an array of small molecules that mimic the unique physiochemical environment found in the enzyme active site was investigated for catalytic activity in the formation of silica from silicon alkoxides at neutral pH. The most successful of these biomimetic catalysts (cysteamine) was used to encapsulate firefly luciferase, green and blue fluorescent proteins (GFP, BFP), and Escherichia coli cells expressing GFP in silica matrixes. The benign conditions required for the catalysis of synthesis of these silica composites does not impair the activities of the encapsulated enzyme, fluorescent proteins, or live cells as shown by fluorescence measurements. In conjunction with microcontact printing, this biomimetically catalyzed encapsulation method has been used to produce patterned functional arrays of silica nanoparticulate composite materials.
authors.affiliation: Institute for Collaborative Biotechnologies, Materials Research Laboratory, University of California, Santa Barbara, California 93106, USA.
authors.forename: Kristian M
authors.initials: KM
authors.lastname: Roth
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhou
authors.forename: Wenjun
authors.initials: W
authors.lastname: Yang
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Morse
mesh_terms: D000818:Animals; D040761:Biomimetic Materials / Q000737:chemistry*; D002384:Catalysis; D002403:Cathepsins / Q000737:chemistry* / Q000378:metabolism; D003543:Cysteamine / Q000737:chemistry* / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D019856:Ethanolamine / Q000737:chemistry* / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000096:biosynthesis / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D008156:Luciferases / Q000096:biosynthesis / Q000235:genetics; D046529:Microscopy, Electron, Transmission; D011161:Porifera / Q000201:enzymology; D012821:Silanes / Q000737:chemistry / Q000378:metabolism; D012822:Silicon Dioxide / Q000737:chemistry* / Q000378:metabolism
chemical_list: D012821:Silanes; C112571:silicatein alpha; D049452:Green Fluorescent Proteins; D019856:Ethanolamine; D003543:Cysteamine; C061205:tetramethoxysilane; D012822:Silicon Dioxide; D008156:Luciferases; D002403:Cathepsins