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Bioinspired Silicification Reveals Structural Detail in Self-Assembled Peptide Cages

Research output: Contribution to journalArticle

Original languageEnglish
Pages (from-to)1420–1432
Number of pages13
JournalACS Nano
Volume12
Issue number2
Early online date25 Dec 2017
DOIs
DateAccepted/In press - 24 Dec 2017
DateE-pub ahead of print - 25 Dec 2017
DatePublished (current) - 27 Feb 2018

Abstract

Understanding how molecules in self-assembled soft-matter nanostructures are organized is essential for improving the design of next-generation nanomaterials. Imaging these assemblies can be challenging and usually requires processing, e.g. staining or embedding, which can damage or obscure features. An alternative is to use bioinspired mineralization, mimicking how certain organisms use biomolecules to template mineral formation. Previously, we have reported the design and characterization of Self-Assembled peptide caGEs (SAGEs) formed from de novo peptide building blocks. In SAGEs, two complementary, three‑fold symmetric, peptide hubs combine to form a hexagonal lattice, which curves and closes to form SAGE nanoparticles. As hexagons alone cannot tile onto spheres, the network must also incorporate non-hexagonal shapes. While the hexagonal ultrastructure of the SAGEs has been imaged, these defects have not been observed. Here, we show that positively charged SAGEs biotemplate a thin, protective silica coating. Electron microscopy shows that these SiO2‑SAGEs do not collapse, but maintain their 3D shape when dried. Atomic force microscopy reveals a network of hexagonal and irregular features on the SiO2‑SAGE surface. The dimensions of these (7.2 nm ± 1.4 nm across, internal angles 119.8° ± 26.1°) accord with the designed SAGE network and with coarse-grained modelling of SAGE assembly. The SiO2‑SAGEs are permeable to small molecules (<2 nm), but not to larger biomolecules (>6 nm). Thus, bioinspired silicification offers a mild technique that preserves soft‑matter nanoparticles for imaging, revealing structural details <10 nm in size, whilst also maintaining desirable properties, such as permeability to small molecules.

    Structured keywords

  • BrisSynBio
  • Bristol BioDesign Institute

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  • Full-text PDF (accepted author manuscript)

    Rights statement: This is the accepted author manuscript (AAM). The final published version (version of record) is available online via ACS Publications at http://doi.org/10.1021/acsnano.7b07785 . Please refer to any applicable terms of use of the publisher.

    Accepted author manuscript, 1 MB, PDF-document

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