Semiconductors from sea sponges

Because it resembles a giant cheese puff, the marine organism Tethya aurantium—also known as the orange puffball sponge—might seem like a tasty snack. But T. aurantium is actually loaded with tiny glass spicules. The sponge makes these spicules with the help of silicatein enzymes, which feature a nucleophilic hydroxyl group and a hydrogen-bonding imidazole group in their catalytic center. These moieties catalyze the hydrolysis and structurally direct the polycondensation of silicon alkoxide precursors into silica and poly(silsesquioxanes). Now materials scientists have developed a synthetic mimic of these biological catalysts for creating semiconductor materials (Proc. Natl. Acad. Sci. USA 2006, 103, 5652). Daniel E. Morse of the University of California, Santa Barbara, and coworkers created a micropatterned surface containing hydroxyl and imidazole groups in the proper juxtaposition to be hydrolytically active. They then used the assembly to catalyze the hydrolysis of a gallium oxide precursor and then to template the gallium oxide and GaOOH products.