Bioinspired Silicification Reveals Structural Detail in Self-Assembled Peptide Cages.

Area of Science:

• Soft-matter nanotechnology
• Bioinspired materials science
• Nanomaterial design and imaging

Background:

• Imaging soft-matter nanostructures is challenging due to processing damage.
• Self-Assembled peptide caGEs (SAGEs) form nanoparticles with a hexagonal lattice structure.
• Structural defects in SAGEs have not been previously observed.

Purpose of the Study:

• To investigate bioinspired mineralization for preserving SAGE nanoparticles.
• To characterize the structural integrity and surface features of silica-coated SAGEs (SiO2-SAGEs).
• To assess the permeability of SiO2-SAGEs for potential applications.

Main Methods:

• Positively charged SAGEs were used to biotemplate silica coating.
• Electron microscopy and Atomic Force Microscopy were employed for imaging.
• Permeability was tested using small (<2 nm) and large (>6 nm) molecules.

Main Results:

• SiO2-SAGEs maintained their 3D shape after drying, unlike uncoated SAGEs.
• Atomic force microscopy revealed hexagonal and irregular surface features consistent with SAGE design.
• SiO2-SAGEs demonstrated selective permeability, allowing small molecules but blocking larger biomolecules.

Conclusions:

• Bioinspired silicification is a mild technique for preserving soft-matter nanoparticles for imaging.
• This method reveals structural details down to 10 nm without damaging the nanostructures.
• Silica coating maintains desirable properties like small-molecule permeability in SAGE nanoparticles.