NSF-BSF: Protein-based biomaterials: from single molecule to complex network behavior

Non-technical Summary

Unboiling an egg is hard. When you boil an egg you are creating a biomaterial. When heated, the proteins inside the egg unfold and get entangled in a disordered form and cooling a boiled egg does not revert its proteins to their initial folded state.

Inspired by nature, here we aim to develop and characterize novel types of biomaterials made from globular proteins. By first crosslinking the proteins while still folded and then using force rather than temperature to denature them, we can obtain materials made from proteins that can reversibly denature and refold back to their initial state. Globular proteins are typically soluble in water and play a variety of roles, such as enzymes that drive chemical reactions, transport molecules such as hemoglobin that carries oxygen to organs, or regulators, such as insulin that controls the sugar level inside our blood.

Yet, developing biomaterials that emulate and, subsequently improve on nature’s refined designs is no easy task, as globular proteins need to be assembled into a solid biomaterial while preserving their function. Furthermore, the behavior of a protein-based biomaterial is not simply the sum of its parts, as different levels of organization influence its final response.

Finally, when protein-materials made from globular proteins are exposed to force, they show a unique response resulting from the denaturation of the 3D structure of protein domains. All these complex processes will be studied using an eclectic approach that combines methods examining the response of proteins at single molecule level, with methods focusing on understanding their macroscopic structure.

In our journey, we will develop and improve outreach programs that involve K-12 students to drive them toward STEM. Also, through international collaboration, graduate students will also be able to travel and work abroad as part of this project. Technical Summary

This proposal aims to develop a bottom-up approach to characterize this new type of biomaterials synthetized from purified globular proteins, which can regulate their mechanical response through domain unfolding. Under changing stress, these biomaterials show a time-dependent visco- and poro-elastic response that can be directly related to mechanical unfolding.

Here we intend to combine single molecule approaches with ensemble characterization methods to connect the response of proteins to protein-based materials. Using this knowledge, we then plan to advance a modeling tool to speed up the development of these materials. In this project we will tackle three objectives: (1) to experimentally characterize the mechanical response of the protein building blocks as a function of force, tethering geometry and solution environment; (2) to directly relate domain unfolding to the mechanical response of protein-based materials; and (3) to develop a scaling model for protein biomaterials based on the response of their molecular components inside a cross-linked network.

Understanding the macroscopic response of protein-based materials from single molecular components will address an unmet need of utilizing folded globular proteins as building blocks to produce bio-inspired solutions. The proposed education and outreach activities will be integrated with the research aims of this project and will involve students at all levels, as well as the public, through research at the cross-section of biology, chemistry, engineering, and physics.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.