Scientists from Ben-Gurion University of the Negev have reported the intrinsic ability of active contractile materials to spontaneously form 3D structures during contraction, in absence of external cues. Their findings were recently published in Nature Communications.
With respect to future applications, these bio-inspired active materials can be used for generating active self-organized three-dimensional structures of defined shape. They may also find applications as biomaterials that can improve human health. In particular, two-dimensional intrinsically contractile sheets may be used in the future as actively functional band-aids that speed up wound healing or in form of beating patches that could support heart function.
A central property of developing plant and animal tissues is their ability to form a diversity of folded patterns and to adopt curved shapes through mechanical instabilities that break the planar symmetry of growing sheets. Shape transitions in developing organisms can be driven by active contractility generated by myosin motor proteins. Yet, the mechanisms generating tissue folding are typically studied in epithelia where the interaction between cells within the tissue presents a major difficulty for studying contraction induced folding.
Recently, the group of Prof. Anne Bernheim-Groswasser (pictured above) from the Department of Chemical Engineering and The Ilse Katz Institute for Nanoscale Science and Technology in collaboration with Prof. Karsten Kruse (Geneva University) and Prof. Sam Safran (Weizmann Institute of Science) demonstrated that initially homogeneous, thin gel sheets composed of actin filaments and myosin motors, isolated from bounding surfaces can spontaneously contract and fold. These authors showed that the buckling instability resulted from system self-organization and the spontaneous emergence of density gradients driven by the active contractility. These new findings demonstrate that buckling can be spontaneously generated by active contractility and does not require mechanical coupling to the environment or pre-imposed gradients in the material properties of the sheet.