Dye Aggregate-Mediated Self-Assembly of Bacteriophage Bioconjugates

One of the central themes of biomolecular engineering is the challenge of exploiting the properties of biological materials. Part of this challenge has been uncovering and harnessing properties of biological components that only emerge following their ordered self-assembly. One biomolecular building block that has received significant interest in the past decade is the M13 bacteriophage. There have been a number of recent attempts to trigger the ordered assembly of M13 bacteriophage into multivirion structures, relying on the innate tendency of M13 to form liquid crystals at high concentrations. These, in general, yield planar two-dimensional materials. Presented here is the production of multivirion assemblies of M13 bacteriophage via the chemical modification of its surface by the covalent attachment of the xanthene-based dye tetramethylrhodamine (TMR) isothiocyanate (TRITC). We show that TMR induces the formation of three-dimensional aster-like assemblies of M13 by providing "adhesive" action between bacteriophage particles through the formation of H-aggregates (face-to-face stacking of dye molecules). We also show that the H-aggregation of TMR is greatly enhanced by covalent attachment to M13 and is enhanced further still upon the ordered self-assembly of M13, leading to the suggestion that M13 could be used to promote the self-assembly of dyes that form J-aggregates, a desirable arrangement of fluorescent dye, which has interesting optical properties and potential applications in the fields of medicine and light harvesting technology.