The use of some biological agents gives a potential to control the crystallization processes of ice. Living organisms (polar fish, insects) produce anti-freeze proteins to survive in subfreezing environments. Some agents are used in medicine for preservation and transplantation of cells and tissues [1]. Carboxylated ε-poly-L-lysine (PLL) is a new cryoprotector which shows lower cytotoxicity [2].
    In this study we have investigated the effects of carboxylated ε-poly-L-lysine as an impurity on crystallization of ice in supercooled water. Seed crystals of ice of hexagonal modification (space group P6₃/mmc) were created in a glass capillary and then were grown up in a growth cell filled with supercooled water with PLL concentrations 0-150 mg/ml H₂O. The accuracy of temperature control in the growth chamber was within ±0.02 °C. Measurements of growth rates R were performed by optical microscopy at supercoolings ΔT from 0 to 1.5°C. Images of growing crystal were captured at every fixed time interval by a video-system and processed by specially developed software. Ice crystal has a disk-like shape at small supercoolings (0.2-0.3°C) where the top and bottom planes are basal faces {0001}. Further increase in supercooling leads to formation of dendrites with branches parallel to the {0001} faces. The change to dendritic growth in the presence of PLL impurity occurs at lower supercoolings than in pure deionized water. An increase in PLL concentration inhibits growth rate of the faces of ice crystals at fixed supercooling. Growth rate sharply increases when supercooling reaches a certain critical value. Depression of melting point of ice has not been detected in water with PLL additions. Blocking effect of impurity is explained on the basis of Gibbs-Thomson law and under the assumption of Langmuir's dynamics of PLL adsorption. Retardation of ice growth in the presence of PLL occurs due to following factors: blocking of the surface by molecules of impurity and increase in the viscosity of solution with PLL addition. We used Punin's model for non-equilibrium adsorption [3] as a basis for theoretical description of the shape of kinetic curves R(ΔT) at different PLL concentrations. Calculated values for the growth rate correspond with the results of our experiments.

1. K. Matsumura, J.Y. Bae, S.H. Hyon. Cell Transplantation. 2010. V. 19. P. 691-699.
2. K. Matsumura, S.H. Hyon. Biomaterials. 2009. V. 30. P. 4842-4849.
3. Yu.O. Punin, O.I. Artamonova. Kristallographiya. 1989. V. 34. P. 1262-1266.

• Legal notice:
  

  Copyright (c) Pielaszek Research, all rights reserved.
  The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
  In every case, proper references including Author(s) name(s) and URL of this webpage: https://science24.com/paper/28923 must be provided.

1. Direct measurement of growth kinetics of elementary steps on ice basal faces
2. Thermodynamic stabilities of two types of quasi-liquid layers on basal faces of ice crystals
3. Atomic or molecular resolution investigation of soluble crystals in liquid by frequency-modulation (non-contact) AFM
4. Gypsum crystal growth: from fast growth in the laboratory to ultraslow growth in Nature
5. Growth Mechanism of Lysozyme Crystals in The International Space Station Based on The Analysis  of  In-Situ Interferometric Observation
6. Growth mechanisms that trigger self-purification during protein growth
7. The attachment/detachment process of lysozyme molecules on a monoclinic lysozyme crystal surface studied by single-molecule visualization
8. In-situ observation of emergences of quasi-liquid layers from ice basal faces by advanced optical microscopy
9. Thermodynamic stabilities of two types of quasi-liquid layers on basal faces of ice crystals