Asymmetric wettability fibrous membranes: Preparation and biologic applications

Fibrous membranes with asymmetric wettability have attracted great interest. Benefiting from the inspiration of biological paradigms and the development of fabrication techniques, many asymmetric wettability membranes with well-designed surface topologies and chemical compositions have been reported in the literature. In this review, different structures of asymmetric wetted fibrous membranes are discussed, including Janus, sandwich, gradient, and hierarchy structure. Various top-down and bottom-up methods for the construction of asymmetric wetted fibrous membranes are summarized, including template, etching, surface modification, phase separation, self-assembly, electrospinning/electrospraying, and various composite methods. Furthermore, biological applications of asymmetric wetted fibrous membranes, such as smart fabrics, sensors, drug release, wound dressings, and tissue patches, are reviewed. Future challenges for asymmetric wettability fibrous membranes are suggested.