Bio-scaffolds for ordered nanostructures and metallodielectric nanoparticles

The use of virus nanoparticles, specifically Chilo and Wiseana Invertebrate Iridovirus, as building blocks for iridescent nanoparticle assemblies and core substrates in the fabrication of metallodielectric nanostructures is discussed. Virus particles are assembled in vitro , yielding films and monoliths with optical iridescence arising from multiple Bragg scattering from close packed crystalline structures of the iridovirus. Bulk viral assemblies are prepared by centrifugation followed by the addition of glutaraldehyde, a cross-linking agent. Long range assemblies were prepared by employing a cell design that forced virus assembly within a confined geometry followed by cross-linking. In addition to these assemblies core-shell particles were created from the same virus. A gold shell is assembled around the viral core by attaching small gold nanoparticles to the virus surface by means of the inherent chemical functionality found within the protein cage structure of the viral capsid. These gold nanoparticles act as nucleation sites for electroless deposition of gold ions from solution. UV/Vis spectroscopy and electron microscopy, were used to verify the creation of the virus assemblages. The optical extinction spectra of the metallo-viral complex were compared to Mie scattering theory and found to be in quantitative agreement. These investigations demonstrate that direct harvesting of biological structures, rather than biochemical modification of protein sequences, is a viable route to create unique, optically active materials.