In biology, stimuli-responsive multisubunit assemblies are ubiquitous, and mimicking these systems via synthetic approaches is of increasing interest. Interfacing such synthetic materials with biological systems is particularly promising for a range of biomedical applications including targeted drug delivery and molecular diagnostics. Within this class of materials are particles capable of changing morphology in response to stimuli. Enzymes are attractive and unique stimuli with great potential in this regard, as they propagate an amplified response via catalytic reactions, can be highly substrate specific, and have expression patterns sometimes associated with disease states. Nanoscale assemblies of block copolymer amphiphiles are well-suited for the development of functional, stimuli-responsive systems because changes in the chemical or physical nature of the amphiphile can lead to formation, destruction, or morphological transformations. Here, the first example of enzymatic switches of micellar morphology will be demonstrated. Micelles were prepared from polymer-peptide block copolymer amphiphiles containing substrates for protein kinase A, protein phosphatase-1, and matrix metalloproteinases 2 and 9. Reversible switching of the morphology of these micelles through a phosphorylation-dephosphorylation cycle and peptide-sequence directed changes in morphology in response to proteolysis will be described. Furthermore, the exceptional uniformity of these polymer-peptide particles makes them amenable to cryo-TEM reconstruction techniques lending insight into their internal structure.

Controlling and switching the morphology of micellar nanoparticles with enzymes

243rd National Meeting (2012)

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