Encapsulation of Biomolecules in Bacteriophage MS2 Viral Capsids

Nanometer-scale molecular assemblies have numerous applications in materials, catalysis, and medicine. Self-assembly has been used to create many structures, but approaches can match the extraordinary combination of stability, homogeneity, and chemical flexibility found in viral capsids. In particular, the bacteriophage MS2 capsid has provided a porous scaffold for several engineered nanomaterials for drug delivery, targeted cellular imaging, and photodynamic therapy by chemical modification of the inner and outer surfaces of the shell. This work describes the development of new methods for reassembly of the capsid with concomitant encapsulation of large biomolecules. These methods were then used to encapsulate a variety of interesting cargoes, including RNA, DNA, protein-nucleic acid and protein-polymer conjugates, metal nanoparticles, and enzymes.To develop a stable, scalable method for encapsulation of biomolecules, the assembly of the capsid from its constituent subunits was analyzed in detail. It was found that combinations of negatively charged biomolecules and protein stabilizing agents could enhance reassembly, while electrostatic interactions of the biomolecules with the positively charged inner surface led to encapsulation. To investigate the role protein shells play in encapsulated enzymatic processes, this method was then used to a model enzyme in a series of capsids with altered characteristics around the pores. The method was then used to develop a potential system for delivery of therapeutic proteins to the cytoplasm of cancer cells by encapsulating conjugates of these proteins to a negatively charged, membrane-lysing polymer