Shape Transformation of Polymer Vesicles

Abstract

Metrics & MoreArticle Recommendations CONSPECTUS: Life activities, such as respiration, are accomplished through the continuous shape modulation of cells, tissues, and organs.Developing smart materials with shape-morphing capability is a pivotal step toward life-like systems and emerging technologies of wearable electronics, soft robotics, and biomimetic actuators. Drawing inspiration from cells, smart vesicular systems have been assembled to mimic the biological shape modulation. This would enable the understanding of cellular shape adaptation and guide the design of smart materials with shape-morphing capability. Polymer vesicles assembled by amphiphilic molecules are an example of remarkable vesicular systems. The chemical versatility, physical stability, and surface functionality promise their application in nanomedicine, nanoreactor, and biomimetic systems. However, it is difficult to drive polymer vesicles away from equilibrium to induce shape transformation due to the unfavorable energy landscapes caused by the low mobility of polymer chains and low permeability of the vesicular membrane. Extensive studies in the past decades have developed various methods including dialysis, chemical addition, temperature variation, polymerization, gas exchange, etc., to drive shape transformation. Polymer vesicles can now be engineered into a variety of nonspherical shapes. Despite the brilliant progress, most of the current studies regarding the shape transformation of polymer vesicles still lie in the trial-and-error stage. It is a grand challenge to predict and program the shape transformations of polymer vesicles. An in-depth understanding of the deformation pathway of polymer vesicles would facilitate the transition from the trial-and-error stage to the computing stage. In this Account, we introduce recent progress in the shape transformation of polymer vesicles. To provide an insightful analysis, the shape transformation of polymer vesicles is divided into basic and coupled deformation. First, we discuss the basic deformation of polymer vesicles with a focus on two deformation pathways: the oblate pathway and the prolate pathway. Strategies used to trigger different deformation pathways are introduced. Second, we discuss the origin of the selectivity of two deformation pathways and the strategies used to control the selectivity. Third, we discuss the coupled deformation of polymer vesicles with a focus on the switch and coupling of two basic deformation pathways. Last, we analyze the challenges and opportunities in the shape transformation of polymer vesicles. We envision that a systematic understanding of the deformation pathway would push the shape transformation of polymer vesicles from the trial-and-error stage to the computing stage. This would enable the prediction of deformation behaviors of nanoparticles in complex environments, like blood and interstitial tissue, and access to advanced architecture desirable for man-made applications.

Review of Shape Transformation Pathways of Polymersomes: Implications for Nanomotor, Biomedicine, and Artificial Cell Mimics

“…Although lipid-based vesicles or liposomes have also shown a broad topological landscape, the main difference is that liposomal shape changes tend to be transient, whereas in polymersomes the different topologies can be kinetically trapped. − Studies, such as those by Zhang and Eisenberg, have underscored the significance of nonspherical geometries and shape transformation methods, shaping the focus of research in the past two decades. With the focus on the shape transition of polymer vesicles, this has also been summarized in several reviews in recent years, ,,− but the discussions regarding polymer types, shape transformation methodologies and pathways, as well as the applications of metastable shapes, were not sufficiently comprehensive. This limitation arises from the rapid recent advancements in the field of artificial cells and a deeper understanding of out-of-equilibrium system.…”