Letters to Nature

Nature 393, 152-155 (14 May 1998) | doi:10.1038/30211; Received 22 October 1997; Accepted 11 February 1998

Host–guest encapsulation of materials by assembled virus protein cages

Trevor Douglas1 & Mark Young2

  1. Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122-2585, USA
  2. Department of Plant Pathology, Montana State University, Bozeman, Montana 59717-0314, USA

Correspondence to: Trevor Douglas1Mark Young2 Correspondence and requests for materials should be addressed to T.D. (e-mail: Email: tdouglas@nimbus.ocis.temple.edu) or M.Y.(e-mail: Email: uplmy@gemini.oscs.montana.edu.)

Self-assembled cage structures of nanometre dimensions can be used as constrained environments for the preparation of nanostructured materials1,2 and the encapsulation of guest molecules3, with potential applications in drug delivery4 and catalysis5. In synthetic systems the number of subunits contributing to cage structures is typically rather small3,6. But the protein coats of viruses (virions) commonly comprise hundreds of subunits that self-assemble into a cage for transporting viral nucleic acids. Many virions, moreover, can undergo reversible structural changes that open or close gated pores to allow switchable access to their interior7. Here we show that such a virion — that of the cowpea chlorotic mottle virus — can be used as a host for the synthesis of materials. We report the mineralization of two polyoxometalate species (paratungstate and decavanadate) and the encapsulation of an anionic polymer inside this virion, controlled by pH-dependent gating of the virion's pores. The diversity in size and shape of such virus particles make this a versatile strategy for materials synthesis and molecular entrapment.