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Published online: 5 December 2007 | doi:10.1038/nchina.2007.259

Cryopreservation: Electrically frozen

Tim Reid

Introduction

© (2007) istockphoto.com/Plainview

When biological materials are preserved at low temperatures they are often damaged by ice forming inside cells. Sun Wei at Xi'an Jiaotong University and co-workers¹ have demonstrated that the problem could be avoided by controlling the ice-formation process using an electric field.

When water is placed in a cold environment, the freezing process begins with cooling of the water, followed by nucleation of ice into small particles, before the final solidification. In biological cells, the formation of harmful ice is highly dependent on the temperature at which nucleation occurs.

In their study, the researchers placed one millilitre of water in a container between two copper plate electrodes in a cooling cabinet held at -30 °C. The voltage difference between the plates was set at values between 0 V and 2,000 V.

The researchers found that by raising the electric-field strength, they could increase the nucleation temperature by up to 1.6 °C. This occurs because water molecules have a strong electric dipole moment that aligns along the field direction, making the molecules more likely to form ice nuclei.

A better understanding of the electrical control over ice formation could help more cells to survive the cryopreservation process.

The authors of this work are from:
State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Xi'an, China; School of Electronics and Information Engineering, Jiangsu University, Zhenjiang, China.

Reference

1. Sun, W., Xu, X., Zhang, H. & Xu, C. Effects of dipole polarization of water molecules on ice formation under an electrostatic field. Cryobiol. doi: 10.1016/j.cryobiol.2007.10.173 (2007). | Article |