Antifreeze proteins and the inhibition of ice growth
We study the ice-binding mechanism of Antifreeze proteins (AFPs) and Antifreeze glycoproteins (AFGPs) by growing and manipulating ice crystals in fluorescence-labeled AF(G)P solutions under the microscope. We discovered that AFGPs bind irreversibly to ice regardless of their size.
The temperature resolution and stability of our systems are ±0.002 °C, which allows us to effectively control the growth of ice crystals sized 10 - 100 microns.
Our two main systems in the lab are (1) microfluidic devices coupled to a custom-made cold-stage paired with fluorescence microscopy and (2) a custom-made nanoliter osmometer.
The adsorption rate of AFGPs is directly correlated with their thermal hysteresis (TH) activity. Borate reacts with the carbohydrates' diols and reduces adsorption rate (black) compared to pure AFGP (blue). Borate was also found to significantly lower the TH activity of AFGPs. Read more here.
Antifreeze proteins bind to ice surfaces and inhibit further growth.
This video shows a 100 microns ice crystal growing in a solution with a plant AFP. The temperature is ~0.05 °C below the melting point of the crystal. The c-axis of the crystal is pointing to the viewer and the hexagon in the middle of the crystal is the basal face. Notice the macro-steps advancing on the prism/pyramidal planes as the crystal is growing. Experiment done by Nechama Dembitzer using a nanoliter osmometer .
LpAFP 7-3-18_1.mp4Inverted fluorescence microscope with a mounted cold-stage
A sketch of a our microfluidic device
Inhibition of gas hydrates growth
We also study the dynamics of gas hydrates and try to find new kinetic inhibitors for these crystals. We grow THF hydrates under the microscope and we recently developed a method that allows us to grow THF hydrates in microfluidic devices. Scale bar = 20 μm. Check out our paper describing kinetic inhibition of THF hydrates here. A description of the methods we use to study hydrates is described here.
Micro-thermography
We are developing a new method to image ice crystal growth in various samples using micro-thermography. In the image below, the Infra-red camera is held above a cold-stage on which the sample rests. The video on the right shows ice crystal (initially 1 mm in diameter) growing in a 40% sucrose solution. The growing surface is always warmer than the solution as heat is released from the advancing ice front.
Read the paper describing this system here.
Micro-thermography system
Ice crystallization in 40% sucrose solution
Untitled video - Made with Clipchamp (2).mp4