Engineering Porous Nanoreactors Using Virus Like Particles Derived From Bacteriophage P22

Structures and functions found in nature have long been incorporated into the design of synthetic materials. Virus-like particles (VLPs) are non-infectious analogs of viruses and embody such design, where the repetitive and symmetrical structural features of viruses allow for predictable and tunable functionalization leading to the development of VLP-based nanotechnology. VLPs derived from bacteriophage P22 are an example of a remarkable system in which a porous shell self-assembles from a coat protein (CP) and a scaffolding protein (SP) into a T = 7 icosahedral shell. Incredible chemistry can be programmed using P22 VLPs by fusing a biomacromolecule of choice (including enzymes) to the SP and the process of assembly directs the SP-fusion protein to the interior cavity of the particle. The porosity of the particles allows for molecular communication between the interior and exterior environments, while access to several different pore-sizes permits finetuning of diffusant selectivity. The different pore sizes can be accessed through three available P22 morphologies- procapsid (~4.4 nm pores), expanded (~2.7 nm pores), and wiffle-ball (10 nm pores). Meanwhile, the symmetrical outer surface of P22 VLPs has granted us the ability to explore the exterior as means by which higher-order architectures can be designed. In this work, we investigate the structural features of P22 both chemically and mechanistically, probing the limitations of VLP porosity. In the last portion of this work, we will show how a P22-based 3D higher-order framework exhibits interesting and useful collective properties due to the intrinsic porosity of the VLPs coupled with the created interstices between individual particles leading to size and charge- selective molecular partitioning.