PNNL

Abstract

Silica biomineralization is a naturally occurring process wherein organisms use proteins and other biological structures to direct the formation of complex, hierarchical nanostructures. Discovery and characterization of such proteins and their underlying mechanisms spurred significant efforts to identify routes for biomimetic mineralization that reproduce the exquisite shapes and size selectivity found in nature. A common strategy has been the use of short peptide sequences with chemistry mimicking those found in natural systems, like the use of the silaffin-derived R5 peptide. While progress has been made using this approach, there are many limitations that have prevented breakthroughs in biomimicry. To advance our ability to use charged macromolecules for silica formation, we propose to use sequence-defined synthetic polymers known as peptoids, or N-substituted polyglycines, that present significant capability for precise tuning of sequence and structure beyond what can often be achieved with peptides alone. This study presents a computationally predicted design of these polymers that lead to the controlled formation of silica nanomaterials. We investigate surface adsorption and the mineralization process through analysis of binding mechanisms and energetics of R5 system. Next, we synthesize two R5-inspired peptoids and validate our prediction in the design of mineralization polymers through characterization using surface plasmon resonance and electron microscopy. This computationally guided study holds great promise for designing new sequences with unprecedented control of the placement of chemical functional groups, thus allowing for further unraveling of silicification mechanisms and eventual design of sequence-defined synthetic polymers leading to the predictive synthesis of nanostructured functional materials.