Fractal-like R5 assembly promote the condensation of silicic acid into silica particles

Levena Gascoigne (Corresponding author), Jose Rodrigo Magana, Dylan Luke Atkins, Christian C.M. Sproncken, Berta Gumi-Audenis, Sandra M.C. Schoenmakers, Deborah Wakeham, Erica J. Wanless, Ilja Karina Voets (Corresponding author)

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

HYPOTHESIS: Despite advances in understanding the R5 (SSKKSGSYSGKSGSKRRIL) peptide-driven bio-silica process, there remains significant discrepancies regarding the physicochemical characterization and the self-assembling mechanistic driving forces of the supramolecular R5 template. This paper investigates the self-assembly of R5 as a function of monovalent (sodium chloride) and multivalent salt (phosphate) to determine if assembly is phosphate ion concentration dependent. Additionally, we hypothesize that the assembled R5 aggregates do not resemble a micelle or unimer structure as proposed in current literature.

EXPERIMENTS: R5 peptides were synthesized, and aggregates evaluated for their size, morphology, and association state as a function of salt and ionic strength concentration via dynamic and static light scattering, small angle X-ray and neutron scattering and cryogenic transmission electron microscopy. Furthermore, we compare the proposed R5 template to precipitated silica by scanning electron microscopy.

FINDINGS: R5 peptides assemble into large aggregates due to multivalence bridging and the decrease in electrostatic repulsion due to ionic strength. We elucidate the structure of R5 aggregates as mass-fractals composed of small spherical aggregates. Moreover, we discover that phosphate ions not only have a significant role in driving the growth of the R5 scaffold, but additionally in driving the polycondensation of silicic acid during the bio-silification process via electrostatic interactions.

Original languageEnglish
Pages (from-to)206-212
Number of pages7
JournalJournal of Colloid and Interface Science
Volume598
Early online date15 Apr 2021
DOIs
Publication statusE-pub ahead of print - 15 Apr 2021

Bibliographical note

Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.

Keywords

  • supramolecular chemistry
  • Peptides
  • template synthesis
  • Self assembly
  • silica
  • silaffin
  • Biomineralization
  • Template synthesis
  • Self-assembly
  • Silaffin
  • Silica
  • Supramolecular chemistry

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