Materials World Network: Microscopic Models of Cross-Linked Active Gels

Syracuse University, Syracuse NY

Investigators

Abstract

This award supports an international collaboration for research and education among Syracuse University in the USA, Bristol University in the United Kingdom, and the University of Stellenbosch in South Africa. This collaboration is for theoretical studies that will dramatically improve our understanding of the structure and mechanical properties of networks of cytoskeletal filaments and associated motor proteins, under both in vitro and in vivo conditions. An important outcome will be the identification of the relative importance of physical and biochemical mechanisms in controlling many cell functions, such as motility, force generation and division. The success of the proposed research relies crucially on the complementary expertise of the collaborating research teams in hydrodynamics and nonequilibrium physics (USA), in semiflexible polymer physics (UK) and on theories of polymer gels (South Africa). The first part of the research builds on work by the US and UK groups on purified (in vitro) cell extracts of cytoskeletal filaments and motor proteins (active liquids). By working closely with experimentalists in the US, UK and Germany, the researchers will focus on understanding how filament flexibility and microscopic properties of the motile elements (e.g., motor stiffness, dynamical properties and processivity) affect the macroscopic behavior of the active fluid. The second and major part of the proposal considers the new area of active solids: the cell cytoskeleton (in vivo) and in vitro gels of cytoskeletal filaments linked by both active (motor proteins) and passive crosslinkers. The proposed research will lead to an understanding of the fascinating linear viscoelastic behavior of active gels. Regular student exchange visits planned during this award period will provide mechanisms for close collaboration among the three groups and exceptional educational opportunities and international research experience. The achievement of the scientific goals will be closely linked with a number of more general benefits. First, the research will provide significant scientific progress in areas relevant to physics, biology and biological and biomimetic materials. A better understanding of the processes controlling the complex mechanical properties of the cytoskeleton, the internal framework of a cell, can lead to important advances for the design of a new generation of smart materials at the nanoscale. The collaboration will also open the door, through visits to the African Institute for Mathematical Sciences (AIMS) located near Cape Town, to the establishment of contacts with gifted students in the mathematical sciences from throughout the African continent. Finally, student and postdoctoral researcher exchange among the collaborating groups will expose all team members, including undergraduate students, to research in an international setting. The relationships developed during these exchanges will serve as the foundation for continued collaborations, while promoting long-term International networking. This award is jointly funded by the Division of Materials Research in the Mathematical and Physical Sciences Directorate and the Office of International Science and Engineering.