“When you remove the tissue [of the sponge] you’re left with a handful of fibreglass needles as fine as spun glass or cotton,” said Daniel Morse of the University of California, Santa Barbara. “This primitive skeleton supports the structure of the sponge, and we’ve discovered how this glass is made biologically.”
Morse and colleagues found that protein filaments acted as both catalysts and templates for the formation of the sponge’s silica needles. Analysis of the proteins revealed that they are members of a “super-family” of proteolytic and hydrolytic enzymes.
The researchers mimicked the naturally occurring enzyme by attaching nucleophilic and hydrogen-bonding amines to gold nanoparticles. Then they mixed the resulting two types of nanoparticles together and added tetraethoxysilane.
The structures catalysed the hydrolysis of silicon alkoxide and promoted condensation of silica and polysilsesquioxanes at 22°C. The silica had an amorphous structure and entrapped the gold nanoparticles.
The researchers believe the technique could have applications in making nanocomposites, photonic crystals and core-shell quantum dots.
What’s more, the scientists reckon they should be able to apply the same strategy to synthesize metal oxides at low-temperature. They are currently investigating functionalizing the nanoparticles with different chemical groups.
The researchers reported their work in Advanced Materials.