Stimuli‐Responsive Polymersomes as Nanocarriers for Drug and Gene Delivery

Abstract

Polymeric formulations (micelles, vesicles etc.) have emerged as versatile drug carriers due to their increased stability, site specificity, blood circulation resistance and thus overall potential therapeutic effects compared to liposomes. Furthermore, stimuli‐responsive systems have been developed whose properties change after applying certain external triggers. Polymersomes are mainly composed of amphiphilic block copolymers that are held together in water due to strong physical interactions between the insoluble hydrophobic blocks, thus forming a bilayer morphology or, in the case of triblock copolymers, a bilayer‐like morphology. Formation and destabilization of these assemblies is a consequence of external stimuli (temperature, pH, oxidation/reduction conditions etc.). This review focuses on recent developments concerning stimuli‐ responsive polymersomes made of amphiphilic block copolymers and their potential applications within the biomedical field.magnified image

Functionalization of Block Copolymer Vesicle Surfaces

“…Meier and co-workers pioneered the field of membrane-protein equipped polymersomes. They created polymer vesicles with defined, tunable permeability that resulted from the presence of channel proteins and porins in the membrane [5,10,13,23,100,101]. However, channel proteins provide not only pores, but can also act as binding sites for viral phages through their surface-exposed regions.…”

“…Furthermore, polymersomes can be designed to be biocompatible [8]. With regard to potential applications of artificial membranes in life science, for instance in drug and gene delivery, cell surface recognition and nanoreactors, the development of so-called smart polymersomes that respond to internal or external stimuli such as temperature, pH, oxidative stress, light, magnetic fields and ultrasound has been highly promoted during the last few years [9][10][11][12][13]. One example of such smart materials are membranes consisting of biohybrid block copolymers that are inherently functional and respond to external stimuli [14].…”

“…One example of such smart materials are membranes consisting of biohybrid block copolymers that are inherently functional and respond to external stimuli [14]. Especially in the field of drug delivery, such triggers are of interest in order to release a hydrophilic agent at certain disease sites in an organism by changing the permeability or even the morphology of the vesicle membrane [10]. For efficient therapeutic applications, another essential issue is the targeting of specific sites, such as diseased cells or tissue, by an active receptor-ligand mechanism [15].…”

Bio-Decorated Polymer Membranes: A New Approach in Diagnostics and Therapeutics

“…Different aspects of block copolymer membranes have recently been summarized in various reviews that provide a good overview of the current state of the art [8][9][10][11][12]. Therefore, in the following, we will primarily focus on selected aspects and newer developments related to bio-decorated membranes.…”

“…However, the polymer membrane does not allow the passage of bigger molecules, such as substrates or products, and in this respect the insertion of biopores/channels proteins is essential for the design of efficient therapeutic systems that allow the encapsulated drug to act in situ. By using membrane proteins to facilitate transport across membranes, it is also possible to control the molecular efflux using engineered membrane proteins [12]. Polymer vesicles with engineered membrane proteins for controlled transport advance the optimal use of polymeric vesicles, especially for applications related to sensitive biological entities as, for example, sRNA, or enzymes.…”