Silicateins are proteins responsible for the formation of silica skeletons in marine sponges. Silica, also known as silicon, is the primary material in most commercially manufactured semiconductors.
Lukmaan A. Bawazer, University of Leeds, Leeds, UK, and colleagues coated polystyrene microbeads with specific silicateins. These were put through a mineralization reaction by incubating the beads in a water-in-oil emulsion that contained either dissolved silicon or titanium as chemical precursors for mineralization. As the silicateins reacted with the dissolved metals, some of they precipitated them, integrating the metals into the resulting structure and forming nanoparticles of silicon dioxide or titanium dioxide.
The synthetic surrogates of biomineralizing cells were screened by flow sorting, with light-scattering signals used to sort the resulting mineralized composites differentially. Mineral composites of intermediate strength were preferentially selected to remain intact for identification during cell sorting, and then to collapse postsorting to expose the encoding genes for enzymatic DNA amplification. Some of the newly selected silicatein variants catalyze the formation of crystalline silicates, whereas the parent silicateins lack this ability.
The demonstrated bioengineered route to previously undescribed materials introduces in vitro enzyme selection as a viable strategy for mimicking genetic evolution of materials as it occurs in nature.
- Evolutionary selection of enzymatically synthesized semiconductors from biomimetic mineralization vesicles,
Lukmaan A. Bawazer, Michi Izumi, Dmitriy Kolodin, James R. Neilson, Birgit Schwenzer, Daniel E. Morse,
Proc. Nat. Acad. Sci. 2012.