Self-assembling protein nanomaterials derived from viruses have properties that make them useful for applications in drug delivery, disease imaging and diagnostics. These properties include uniform sizes and shapes, biodegradability, and multiple sets of functional handles for chemical manipulation. Intact virus nanoparticles have been functionalized for applications in drug delivery in vivo, however, the injection of replication-competent viruses into subjects have limited their clinical appeal. The development of spherical and rod-shaped virus nanoparticles has in both cases resulted in differential tumor accumulation, demonstrating the need to further expand the shape library of protein nanomaterials. However, expressing non-spherical virus-based protein nanomaterials without the genetic material that functions as a backbone to the assembly architecture can lead to significant challenges including poly-diversity in size and shape, and change in assembly behavior in response to different conditions such as pH and ionic strength.
UC Berkeley researchers have developed a self-assembling nanoscale disk derived from a mutant of a recombinantly expressed viral coat protein. The disks display highly stable double-disk assembly states. The researchers functionalized the disks with the chemotherapy drug doxorubicin (DOX) and further modified the disks for improved solubility. The functionalized disks displayed cytotoxic properties similar to those of DOX alone when incubated with U87MG glioblastoma cells, but the unmodified disks did not cause any cytotoxicity.