Self-assembly of globular protein-polymer conjugates provides a compelling method to control the nanostructure of materials built from biofunctional components such as enzymes.  Using materials built from a model red fluorescent protein block mCherry and synthetic polymer blocks with a variety of different hydrogen bonding and ionic interaction capabilities, we demonstrate here that the polymer block has a large effect on both ordering transitions and the type of nanostructures formed during self-assembly. Three types of globular protein-polymer block copolymers mCherry-PHPA, mCherry-POEGA, and mCherry-PDMAPS with three different coil fractions were constructed and their phase behavior in concentrated aqueous solution was studied as a function of temperature and concentration. The comparison to previously studied mCherry-PNIPAM provides insight into the effect of protein-polymer interaction on the self-assembly. mCherry-PHPA block copolymers undergo order-disorder transition as concentration increases similarly to mCherry-PNIPAM, but mCherry-PHPA starts to order at higher concentration which suggests less driving force for self-assembly . mCherry-PHPA showed a much smaller region of macrophase separation and showed rich phase behavior forming different phases at similar coil fractions.  Formation of gyroid sturcture was observed in the transition region from lamellae to hexagonal structure in symmetric mCherry-PHPA conjugate.

Effect of polymer chemistry on globular protein-polymer block copolymer self-assembly

246th National Meeting (2013)

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