Magnetic viruses via nano-capsid templates

Biological templating of inorganic nanoparticles provides promising opportunities to address the grand challenge in nanoscience of realizing the full potential of self-assembled materials. We implement such biotemplating to create magnetic nanoparticles by utilizing native protein capsid shells derived in high yield from the T7 bacteriophage virus. The magnetic nanoparticles are grown via bio-mineralization reactions inside of hollowed-out capsids that retain their original chemical recognition properties. The resultant "magnetic viruses" are uniform in geometry, physical properties, and biochemical functionality. We first coax the DNA out of the T7 virus by means of an alkaline treatment, and then grow magnetic cobalt particles inside the remaining hollow capsid shell. Related methods of fabricating bio-functional magnetic nanoparticles have utilized either recombinant, single-protein-type capsids, or involve coating previously synthesized inorganic particles with bio-ligands. Given the richness of the protein types that form the native T7 capsid, our magnetic viruses can be tailored to tune the bio-functionality and/or bio-tagging of a sample. As an example, we consider a nano-biomagnetic sensing scheme that would utilize the T7 capsid to control the magnetic nanoparticle size distribution.