(560c) Sequence-Tunable Materials for Silica Biomimetic Mineralization

Biomineralization is a naturally occurring process in marine diatoms that allows the silaffin and other proteins present in cell walls to form complex silica nanostructures. Synthetically, biomimetic mineralization can be performed using only the R5 peptide domain of the silaffin protein under simple reaction conditions for applications in bio-catalysis, microfluidics, and biosensors, but without the same morphological complexity of the natural process. There is still much to be learned about the structure, and thus the underlying mechanisms, of clusters of peptides that can promote biomineralization. Furthermore, peptides may not be ideal for all types of applications given the presence of strong hydrogen bonding in the backbone and a limited palette of sidechain chemistries. A new class of designed biomolecules known as peptoids, or N-substituted polyglycines, offer a wider diversity of side chains and present a better opportunity to tune sequence and structure under simple reaction conditions to influence silica morphology and target specific applications. This difference in sidechain connectivity provides more backbone flexibility, which coupled with a wider array of potential side chains, could potentially provide enhanced control over silica morphology through sequence alone as compared to traditional R5 bio silica production methods.

This talk will highlight recent developments in computational methods for understanding the relationship between aggregate structure, silica surface adsorption, silicate interactions, and morphology in the biomineralization process through comparison of R5 peptide and the R5 peptoid along with some preliminary experimental validation from our collaborators. The talk primarily discusses results based on MD simulations of peptides and peptoids in solution and at a silica water interface. Enhanced sampling based on the metadynamics family of methods is used to compute thermodynamic quantities such as binding energies. Differences in the synthesis outcomes based on different peptides and peptoids are rationalized through detailed comparisons of the binding mechanisms identified in the simulations. We also suggest future directions for peptoid-based biomineralization efforts, including the development of tunable three-dimensional peptoid biomineralization scaffolds.