pH-Sensitive Tubular Polymersomes: Formation and Applications in Cellular Delivery

Abstract

Optimizing the shape of a nanovector influences its interaction with a cell and determines the internalization kinetics. Block copolymer amphiphiles self-assemble into monodisperse structures in aqueous solutions and have been explored extensively as drug delivery vectors. However, the structure of self-assembled block copolymers has mainly been limited to spherical vesicles or spherical and worm-like micelles. Here we show the controlled formation and purification of tubular polymersomes, long cylindrical vesicles. Tubular polymersomes are purified from other structures, and their formation is manipulated by incorporating the biocompatible membrane components cholesterol and phospholipids. Finally we show that these tubular polymersomes have different cellular internalization kinetics compared with spherical polymersomes and can successfully encapsulate and deliver fluorescent bovine serum albumin protein intracellularly.

Shape characterization of polymersome morphologies via light scattering techniques

“…12,13 In addition, the shape of these polymersomes can be transformed into a large array of morphologies. [14][15][16] In general, vesicles can change shape from an initially spherical morphology via two possible routes: deflation via oblates (discs) or deflation via prolates (rods) as is shown in Figure 1 In order to gain more information about the shape of the formed structures, dry and cryoelectron microscopy techniques, both in scanning (SEM) and transmission (TEM) mode, are the method of choice. 18 In some cases differentiation between different morphologies (e.g.…”

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

“…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.…”

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].…”