Time-Lapse, in Situ Imaging of Ice Crystal Growth Using Confocal Microscopy

Abstract

Ice crystals nucleate and grow when a water solution is cooled below its freezing point. The growth velocities and morphologies of the ice crystals depend on many parameters, such as the temperature of ice growth, the melting temperature, and the interactions of solutes with the growing crystals. Three types of morphologies may appear: dendritic, cellular (or fingerlike), or the faceted equilibrium form. Understanding and controlling which type of morphology is formed is essential in several domains, from biology to geophysics and materials science. Obtaining, in situ, three dimensional observations without introducing artifacts due to the experimental technique is nevertheless challenging. Here we show how we can use laser scanning confocal microscopy to follow in real-time the growth of smoothed and faceted ice crystals in zirconium acetate solutions. Both qualitative and quantitative observations can be made. In particular, we can precisely measure the lateral growth velocity of the crystals, a measure otherwise difficult to obtain. Such observations should help us understand the influence of the parameters that control the growth of ice crystals in various systems.

Polyproline as a Minimal Antifreeze Protein Mimic That Enhances the Cryopreservation of Cell Monolayers

“…A non‐IRI‐active dye, sulforhodamine B, provided contrast against the ice (which appears dark). A control using pure PBS showed no shaping whilst zirconium acetate (ZrAc), which is a strong ice shaper, produced hexagonal crystals . PPro 19 did not induce shaping, supporting the concept that polyproline inhibits ice crystal growth without inhibiting the formation of a specific plane of ice; however, as these are relatively weak IRIs, the concentrations needed for ice shaping would be very high.…”

“…Aside from IRI activity, AF(G)Ps display unwanted ice shaping, which promotes the formation of needle‐like ice crystals, which damage cell membranes . Cryo‐confocal microcapillary microscopy has emerged as a tool for monitoring ice crystal shaping, and was also employed here (Figure ). A non‐IRI‐active dye, sulforhodamine B, provided contrast against the ice (which appears dark).…”

The lure of ice-templating: Recent trends and opportunities for porous materials

“…The recent developments of confocal microscopy [48], however, are an encouraging move in this direction. Optical microscopy, in particular in HeleShaw cells [49], have also certainly an important role to play in a near future.…”

A temperature-controlled stage for laser scanning confocal microscopy and case studies in materials science

“…We previously used confocal microscopy to image crystal growth in situ. 22 However, the previous setup provided little to no control over the cooling rate and temperature gradient, and the solidification front was moving through the observation window, making the operation difficult. With the current temperature-controlled stage, we have a complete control of the growth velocity, growth direction, and temperature gradient.…”