Optical Properties of Metacrystals Based on Protein Nanocages

Abstract

The optical properties of 3D metacrystals made of gold nanoparticles in protein nanocages are studied. These metacrystals have sizes of tens of micrometers and are of high structural and optical quality. Through microspectroscopy measurements and model calculations it is demonstrated that the metacrystals show plasmonic absorption in the green wavelength range and are largely transparent in the red and infrared ranges. By using empty nanocages as placeholders in the metacrystal lattice, it is possible to control how strongly the metamaterial absorbs. Measurements on a pyramidal metacrystal show that it deflects visible light. The deflection shows evidence for anomalous refraction at short wavelengths and normal refraction at long wavelengths. The refractive dispersion is ascribed to the optical dispersion relation of the plasmonic metamaterial.

BODIPY directed one-dimensional self-assembly of gold nanorods

“…These organized nanostructures have immense potential in therapeutic sensors, 9–11 catalysis, 12–14 and optoelectronic device applications including photonic wave-guiding 15 and optical switching. 16 The characteristics of these nanoparticle assemblies are intricately intertwined not only with the size and geometry of the constituent nanoparticles but also with the spatial organization of these building blocks. As a result, the field of nanoscience is on a quest to develop innovative methods for assembling nanomaterials into functional devices.…”

Assembly Requirements for the Construction of Large-Scale Binary Protein Structures

“…Assembling customized materials with the help of biomolecules can lead to properties not found either in the individual building blocks or an unordered assembly of building blocks, 33 as exemplified by the construction of metacrystals based on gold nanoparticles and protein cages for the manipulation of light. 34 Moreover, ordered protein assemblies can also find applications in bionanotechnology, for example, as filter materials. 3 To direct assembly toward specific structures, it is necessary to understand the contacting interfaces and interactions present in the assembled systems.…”

“…In contrast, the packing of pure nanoparticle assemblies usually suffers from slight variations in the size and shape of the nanoparticles, limiting the attainable material size. Assembling customized materials with the help of biomolecules can lead to properties not found either in the individual building blocks or an unordered assembly of building blocks, as exemplified by the construction of metacrystals based on gold nanoparticles and protein cages for the manipulation of light . Moreover, ordered protein assemblies can also find applications in bionanotechnology, for example, as filter materials …”