Using viruses as nanomedicines
"The field of nanomedicine involves the design and fabrication of novel nanocarriers for the intracellular delivery of therapeutic cargo or for use in molecular diagnostics.
[...] Inherently biodegradable, the outer capsids of viruses are composed entirely of protein building blocks, which can be genetically or chemically engineered with molecular imaging reagents, targeting ligands and therapeutic molecules. While there are several examples of viruses as in vitro molecular cargo carriers"

[link to www.ncbi.nlm.nih.gov (secure)]