Photoinitiated destruction of composite Porphyrin-Protein polymersomes

Gregory P. Robbins, Masaya Jimbo, Joe Swift, Michael J. Therien, Daniel A. Hammer, Ivan J. Dmochowski

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Bilayer vesicles assembled from amphiphilic diblock copolymers (polymersomes) adopt asymmetric structures when loaded with moderate concentrations (≥1.5 mg/mL) of horse spleen ferritin (HSF) or its iron-free variant (HSAF). Incorporation of both ferritin and a zinc porphyrin dimer (PZn 2) generates photoresponsive vesicles: irradiation with focused light of near-UV to near-IR wavelengths induces polymersome deformation and destruction on the minute time scale. To investigate this phenomenon, polymersomes were loaded with dye-labeled ferritin and PZn 2. Confocal microscopy identified BODIPY-FL-labeled ferritin at the membrane, whereas Cy3-labeled ferritin was found both at the membrane and throughout the aqueous core. Fluorescence recovery after photobleaching (FRAP) experiments confirmed that Cy3- and BODIPYFL- labeled ferritin and PZn 2 exhibited slow diffusion at the membrane, consistent with membrane association. Furthermore, micropipette aspiration experiments revealed increased elastic moduli and altered bending rigidity in vesicles incorporating HSAF. Finally, a small molecule (biocytin) was encapsulated within the ferritin-PZn 2 vesicles and released upon exposure to light. These data indicate synergy between ferritin, whose membrane association lowers the barrier to deformation, and PZn 2, which embeds in the membrane, harvests light energy and produces local heating that may lead to membrane budding. This appears to be a general protein-polymer membrane phenomenon, as replacement of ferritin with bovine serum albumin or equine skeletal myoglobin resulted in vesicles with similar asymmetric morphology and photosensitivity. © 2009 American Chemical Society.
    Original languageEnglish
    Pages (from-to)3872-3874
    Number of pages2
    JournalJournal of the American Chemical Society
    Volume131
    Issue number11
    DOIs
    Publication statusPublished - 25 Mar 2009

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