Size and crystallinity in protein-templated inorganic nanoparticles

Area of Science:

• Biomaterials science
• Nanotechnology
• Materials science

Background:

• Protein cages, including ferritins and virus capsids, serve as templates for synthesizing inorganic nanoparticles.
• While crystal phases are often identified, the detailed nanoscale structure of these protein-templated nanoparticles remains poorly understood.

Purpose of the Study:

• To investigate the nanoscale crystalline structure of various inorganic nanoparticles synthesized within ferritin cages.
• To determine the factors influencing crystalline domain size in protein-templated nanoparticles.

Main Methods:

• Utilized pair distribution function analysis of total X-ray scattering.
• Measured crystalline domain size in ferrihydrite, γ-Fe2O3, Mn3O4, CoPt, and FePt nanoparticles.
• Grew nanoparticles within ferritin cages from *H. sapiens* and *P. furiosus*.

Main Results:

• Determined crystalline domain sizes for multiple inorganic nanoparticle types templated by ferritin.
• Observed that nanoparticle properties are influenced by atomic-level chemistry, cage volume, and nucleation site arrangement.
• Found that intermediate-length scale crystalline domain size is constrained by the arrangement of nucleation sites within the ferritin cage.

Conclusions:

• The interior structure of protein cages, specifically nucleation site arrangement, plays a crucial role in controlling crystalline domain size.
• These findings suggest potential synthetic strategies for precisely controlling crystalline domain size in protein-templated nanoparticles.
• Understanding nanoscale structure is key to tailoring material properties of protein-templated inorganic nanoparticles.