Physical Society Colloquium

Architecture, mechanics and remodelling of biomolecular scaffolds

Nancy Forde

Department of Physics
Simon Fraser University

Nature offers an engineer's dream of addressable materials, controlled through feedback to interact with their local environment. These materials create a balanced dynamic environment in which nonequilibrium nanoscale processes sustain cellular life, for example by acting as scaffolds which have the appropriate mechanics and chemistry to direct desired cell growth and which are in turn remodelled in response to cell-derived or extrinsic signals. My group is interested in understanding the interplay between mechanics, structure and chemistry in these types of materials, in order to guide the design of new nano- and microscale materials.

In this talk, I will first highlight some aspects of our work on collagen, the fundamental structural protein in our body, which offers a prime example of a biological material exhibiting these properties. Assembled from individual triple-helical proteins to make strong fibres, collagen is an example of a self-assembling hierarchical structural system. Using optical tweezers to perform microrheology measurements, we explore the dynamics of interactions between collagens responsible for their self-assembly and examine the development of heterogeneous mechanics during assembly into fibrillar gels. Using single-molecule techniques such as optical tweezers, atomic force microscopy (AFM) and centrifuge force microscopy, we are uncovering the relationship between triple helical stability and collagen flexibility, which has implications for its structural properties and ability to be broken down and remodelled by enzymes. Inspired by work that suggests these enzymes act as molecular motors powered by the cleavage of collagen, we are building synthetic motors conceived to act by this same mechanism in order to test its robustness for achieving directed motion on the nanoscale. I will discuss our strategy of coupling modular assembly of biological components such as DNA, peptides and proteins with inorganic devices such as quantum dots, to achieve insight into these systems.