Slow water dynamics in dehydrated human Jurkat T cells evaluated by dielectric spectroscopy with the Bruggeman–Hanai equation

Abstract

The picosecond orientational dynamics of intracellular water was measured by dielectric spectroscopy, with the aim of revealing the effects of cryoprotective agents (CPAs) on biological cells. As a first step, Jurkat cells (human T lymphocyte cells) suspended in aqueous sucrose solutions of different concentrations ranging from 0.3 M (isotonic) to 0.9 M (hypertonic) were examined at 25 °C with a frequency range up to 43.5 GHz. The Bruggeman–Hanai equation was employed to obtain a cellular dielectric spectrum without extracellular contributions from the measured complex permittivity of the cell suspensions. By analyzing the γ process around 10¹⁰ Hz based on the Debye relaxation function, two types of water (bulk-like water and hydration water with slower molecular dynamics) were observed. An increase in the fraction of intracellular slower water was observed in the dehydrated cells which had a highly concentrated environment of biomolecules.