The Nanoliter Osmometer: Thermal Hysteresis Measurement

Abstract

The nanoliter osmometer is one of the most common tools in the study of ice-binding proteins (IBPs). It is used not only to measure the thermal hysteresis activity of IBPs but also to explore ice shaping, ice adhesion, and ice growth and melting rates and patterns. The advantage of the nanoliter osmometer for the IBP study and for studying single ice crystals lies in the small sample volume, in the range of nanoliters. Such a small volume enables precise determination and control of the temperature with precision in the range of millidegrees. This chapter describes in detail the process of determination of thermal hysteresis using a nanoliter osmometer operated by a LabVIEW interface. We describe the preparation of suitable capillaries and sample injection, which is a challenging step in the measurement. We then describe the procedure of single crystal formation and the determination of the melting and freezing temperatures. Insights on crucial parameters are emphasized.

Keywords: Antifreeze proteins; Crystal growth; Ice shaping; Ice-binding proteins; Nanoliter osmometer; Single ice crystal; Thermal hysteresis; Thermal hysteresis gap.