Ice control by antifreeze proteins: From interfacial thermodynamics, and engulfment resistance, to thermal hysteresis activity using theory and computation

Farag, Hossam

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https://hdl.handle.net/2142/125824 Copy

Description

Title

Ice control by antifreeze proteins: From interfacial thermodynamics, and engulfment resistance, to thermal hysteresis activity using theory and computation

Author(s)

Farag, Hossam

Issue Date

2024-07-12

Director of Research (if dissertation) or Advisor (if thesis)

Peters, Baron

Doctoral Committee Chair(s)

Stubbins, James F

Committee Member(s)

• Schroeder, Charles
• Xi, Jianqi

Department of Study

Nuclear, Plasma, & Rad Engr

Discipline

Nuclear, Plasma, Radiolgc Engr

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Antifreeze proteins
• nucleation
• ice growth
• metastable liquids
• thermal hysteresis
• growth inhibitors

Abstract

Mitigating ice damage is crucial in various applications, including aircrafts and nuclear power plants, where ice formation in feed water systems can cause significant operational challenges. Antifreeze proteins (AFPs) play a vital role in enabling organisms to survive freezing temperatures by binding to ice surfaces and inhibiting ice growth. Ice growth inhibition can be sustained until a certain limit of supercooling temperature, below which ice irreversibly overgrows the pinning AFPs. The difference between the ordinary freezing temperature of water (0 °C) and the lowered freezing temperature caused by AFPs is termed thermal hysteresis (TH) activity. Mechanistically, TH is first achieved through the adsorption of AFPs on ice crystals. Each adsorbed AFP creates a nanometer-scale metastable depression on the ice surface, locally resisting ice growth. As supercooling increases, these metastable dimples deepen until metastability is lost in an engulfment event where the ice irreversibly swallows the AFP. This engulfment process is akin to nucleation, and we develop a theoretical model using variational optimization to estimate the free energy barrier for the engulfment of a single AFP as a function of supercooling, AFP size, and isolation radius from neighboring AFPs. The results of the model are summarized in a symbolic regression closed-form expression. On a larger length scale, where an ensemble of AFPs is adsorbed to a micrometer-scale ice surface, the collective resistance to engulfment is estimated through a Voronoi tessellation of the surface. This approach maps the 2D configurational distribution of AFPs to a distribution of isolation radii from neighboring AFPs. The isolation radii distribution is used to statistically weigh individual AFP engulfment rates, resulting in an estimation of the collective engulfment rate of the entire ensemble of adsorbed AFPs. Kinetic Monte Carlo simulations have shown that the first engulfment event can trigger an avalanche of subsequent events, leading to unrestrained ice growth. Hence, TH activity can be estimated to be the temperature at which the first engulfment event occurs. This temperature is estimated using an inhomogeneous survival probability model that accounts for AFP surface coverage, ice surface area, and cooling rate. Theoretically estimated TH values were compared with experimental data and showed agreement. Lastly, the developed framework was used to rationalize how the TH activity of irreversibly adsorbed AFPs on the ice surface can be dependent on the AFPs' bulk concentration in the solution interfacing the restrained ice crystal. Our model predicts a collapse of different bulk concentrations and exposure times, resulting in similar AFP surface coverage to a single TH value. Re-analysis of literature experimental data confirmed this collapse, verifying the recently developed model's accuracy. Our model is the first in the literature to predict the sudden burst of ice growth exactly as observed in experiments. The findings provide a comprehensive understanding of the factors influencing AFP effectiveness, align well with experimental observations, and offer insights into the design of synthetic antifreeze agents for practical applications.

Graduation Semester

2024-08

Type of Resource

Thesis

Handle URL

https://hdl.handle.net/2142/125824

Copyright and License Information

Copyright 2024 Hossam Farag

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