Giant Biodegradable Poly(ethylene glycol)-block-Poly(ε-caprolactone) Polymersomes by Electroformation

Abstract

Here, the formation of giant enzyme-degradable polymersomes using the electroformation method is reported. Poly(ethylene glycol)-block-poly(ε-caprolactone) polymersomes have been shown previously to be attractive candidates for the detection of bacterial proteases and protease mediated release of encapsulated reporter dyes and antimicrobials. To maximize the efficiency, the maximization of block copolymer (BCP) vesicle size without compromising their properties is of prime importance. Thus, the physical-chemical properties of the BCP necessary to self-assemble into polymeric vesicles by electroformation are first identified. Subsequently, the morphology of the self-assembled structures is extensively characterized by different microscopy techniques. The vesicular structures are visualized for giant polymersomes by confocal laser scanning microscopy upon incorporation of reporter dyes during the self-assembly process. Using time correlated single photon counting and by analyzing the fluorescence decay curves, the nanoenvironment of the encapsulated fluorophores is unveiled. Using this approach, the hollow core structure of the polymersomes is confirmed. Finally, the encapsulation of different dyes added during the electroformation process is studied. The results underline the potential of this approach for obtaining microcapsules for subsequent triggered release of signaling fluorophores or antimicrobially active cargo molecules that can be used for bacterial infection diagnostics and/or treatment.

Keywords: biodegradable polymersomes; electroformation; fluorescence lifetime imaging microscopy.