Unraveling the Molecular Basis for Superior Ice Nucleation Activity
Abstract
Although ice melts at 0 degrees C when exposed to atmospheric pressure, water has the unique ability to become supercooled and remain in a liquid state at temperatures below -40 degrees C. The ability to control the freezing temperature of supercooled water is of utmost importance to fields as diverse as atmospheric sciences (e.g. cloud seeding), biomedical applications (e.g. tissue storage), food security, and de-icing of critical infrastructure. The process of triggering ice nucleation requires the formation of nuclei that resemble the structure of hexagonal ice. These nuclei need to reach a critical size and rely on hydrogen bonding between water molecules for stabilization. Consequently, the temperature at which freezing occurs depends on the size and lifetime of these nuclei, and freezing temperatures critically depend on the ability to facilitate or impede the formation of nuclei. Freezing is facilitated through heterogeneous ice nucleators (INs), with biogenic substances being particularly effective. Despite their record-breaking activity, the molecular mechanisms of biological INs remain unknown, leading to limited technological applications based on them. The goal of this project is to decipher the fundamentals that enable biogenic INs to promote ice growth more effectively than any other substance. This knowledge would provide the needed input for structure-based approaches that will enable new technologies that mimic the concepts of biogenic freezing for cryopreservation, environmentally benign de- icing, and updated climate models. Such new freezing technologies are particularly relevant today, as the U.S. increasingly pursues activities in the Arctic, where ice has the potential to be a logistical burden or an operational enabler. To answer our central question -what makes biogenic INs so much better at nucleating ice-, our team and a network of established collaborators, will utilize a comprehensive approach using high-throughput ice nucleation measurements, surface-specific nonlinear spectroscopy, targeted sample modifications, and analytical modeling. The research objectives are designed to fundamentally advance our understanding of heterogeneous ice nucleation and to foster advancements in the development of superior ice-controlling agents. First, we will systematically investigate sets of known ice-binding macromolecules, focusing on organic crystals and ice-binding (bio)polymers. These samples enable a systematic variation of molecular properties, allowing for the exploration of how chemical modifications influence ice nucleation. This offers the possibility to obtain a comprehensive understanding of ice nucleation processes both at a macroscopic and microscopic level, and will establish which molecular motifs and physicochemical properties contribute to superior ice nucleation activity. We will further elucidate how nature assembles smaller ice-nucleating protein units into larger functional domains to achieve high subzero ice nucleation temperatures. Specifically, we will address what the structure and size of the aggregates are, which intermolecular forces stabilize them, and how they influence interfacial water molecules. In combination, the proposed research will provide fundamental insights into the interaction of ice-nucleating macromolecules with water on the molecular level, thereby elucidating the underlying nucleation mechanism and structural requirements. From such knowledge, we can determine general structure-function relationships and optimal functionalities, which will allow for the design of powerful new ice-nucleating materials.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 06, 2025
- Source ID
- FA95502410197
Entities
People
- Konrad Meister
Organizations
- Air Force Office of Scientific Research
- Boise State University
- Office of the Secretary of Defense