Biotechnology Reveals New Routes to Synthesis and Structural Control of Silica and Polysilsesquioxanes

Abstract

Introduction Overview of Silica Synthesis in the Experimental Systems Silicon Transport Search for Intracellular Silicon Carriers or Conjugates Control of Polycondensation Conclusions Acknowledgments

Silicatein and the Translation of its Molecular Mechanism of Biosilicification into Low Temperature Nanomaterial Synthesis

“…29 Using molecular modeling to refine the structures based on silicatein amino acid sequences, 3-D models of silicatein R were constructed based on the X-ray crystal structure of human cathepsin L, which is known to a 1.73-Å level of resolution. 34 Modeling indicates that, similar to cathepsin L, silicatein R is globular with a heart-shaped assembly composed of two domains. The resulting 3-D molecular model illustrates that the active site is found in a V-shaped cleft at the interface between the two domains; thus, the homology between cathepsin L and silicatein R most likely includes retention of the active site structure (Figure 5).…”

“…Likewise, the active site cleft in the silicatein R enzyme has a hydrogen bonding distance between the serine and the histidine of about 2 Å. 34 It was observed that little or no hydrolysis occurred when (1) only one class of functional gold nanoparticle was present, (2) either class of functional nanoparticle was replaced with a non-nucleophilic or nonhydrogen bond acceptor methyl group, and (3) nonfunctionalized gold nanoparticles were used. Upon hydrolysis and polycondensation, a silica network forms around the catalytic gold nanoparticles, effectively trapping them inside the inorganic network.…”

“…[1][2][3]24,25 A number of articles have been published in the past 10 years reviewing the discovery of proteins isolated from diatoms and sponges that participate in biosilicification. [31][32][33][34][35][36][37][38] This review highlights the discovery of one class of proteins, silicateins (named for silica proteins), isolated from a marine sponge and its dual function as an enzymatic catalyst and organic template for biosilicification. This article will comprehensively review the body of work since 1999 that utilizes silicatein as a biocatalyst and template for synthesis of not only silica-based materials but also other significant, inorganic materials that biological species have never produced.…”