Capsids derived from the bacteriophage P22 are robust and versatile nanoplatforms. Two distinct interfaces (exterior and interior) of these hollow, spherical nanocontainers allow for encapsulation of cargo and targeted delivery to desired tissues.  To encapsulate high payloads of small molecule cargos, we have utilized atom transfer radical polymerization (ATRP) to incorporate a cross-linked polymer network consisting of poly(2-aminoethyl methacrylate) (AEMA) monomers constrained to the inside of the P22 capsids. The AEMA can subsequently be derivatized with small molecules to achieve very high loading of the capsid. For applications in magnetic resonance imaging (MRI), we have attached 10,000 Gd per capsid, corresponding to an internal concentration of 150 mM Gd. At 60MHz (1.4T), this protein�polymer hybrid demonstrated ionic relaxivities (r1) of 22.0 mM-1s-1,  and an extremely high per particle relaxivity of 200,000mM-1s-1, placing these constructs comfortably in the upper end of observed macromolecular relaxivities.

Constrained atom transfer radical polymerization within the capsid of the bacteriophage P22

245th National Meeting (2013)

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