Tubular Polymersomes: A Cross-Linker-Induced Shape Transformation

Abstract

Polymersomes, polymeric vesicles constructed of block copolymers, can undergo a sphere-to-tubule transition under the influence of a chemical modification of the polymeric bilayer. A strain-promoted alkyne-azide cycloaddition (SPAAC) reaction between azide handles inside the hydrophobic domain of the membrane and an excess of a bicyclo[6.1.0]nonyne (BCN)-cross-linker causes the vesicle to stretch in one dimension. Tubular polymersomes up to 2 μm in length can be obtained with this shape transformation. The introduction of a cleavable cross-linker makes this process reversible and opens the way for future drug delivery applications.

Shaping polymersomes into predictable morphologies via out-of-equilibrium self-assembly

“…The initial concentrations of PEG-PS before the addition of H 2 O was 3.33 mg ml −1 for sample1, 5 mg ml −1 for sample 2 and 10 mg ml −1 for sample 3. In this range, initially spherical polymersomes are formed232426. All samples turned cloudy when the amount of H 2 O reached 20%.…”

“…We showed that spherical polymersomes, assembled from poly(ethylene glycol)-polystyrene (PEG-PS), deflate into cup-shaped polymersomes called stomatocytes232425. Rod-shaped polymersomes have been created by using crosslinkers26 or rehydration27. Bicontinuous cubic structures have been reported as well28.…”

Using Dynamic Covalent Chemistry To Drive Morphological Transitions: Controlled Release of Encapsulated Nanoparticles from Block Copolymer Vesicles

“…41−47 In contrast, vesicle-to-worm or vesicle-to-sphere order–order transitions have been recently reported, which can also be used to trigger the on-demand release of encapsulated nanoparticle cargoes. 48−51 These latter transitions are typically the result of a subtle reduction in the geometric packing parameter 52 arising from the responsive behavior of either the stabilizer block or the membrane-forming block toward an external stimulus such as temperature, 53−57 pH, 58−61 CO 2 , 62 cross-linker, 63 enzyme, 64 or redox. 65 In principle, vesicles that undergo morphological transitions after selectively binding to specific analytes (either by covalent bond formation or by host–guest supermolecular interactions) present in the external solution offer new strategies for targeted delivery and release applications.…”

Controlling the morphology of copolymeric vectors for next generation nanomedicine

“…In particular, nanotubes (tubular polymersomes) are exciting candidates for the development of NVs due to their high aspect ratio and potential for immunotherapy, alongside drug delivery. Nanotubes have been engineered through chemical cross-linking using bio-orthogonal click chemistry [66] or polymer blending in a film rehydration process [67]. Recognising the importance of using biodegradable polymers in the design of materials for medical applications [68] we have recently developed a facile methodology for the generation of biodegradable nanotubes via the osmotically-induced elongation of PEG-polylactide polymersomes [69].…”