Microelectrode-based dielectric spectroscopy of glucose effect on erythrocytes

The dielectric response of biconcave erythrocytes exposed to d-glucose and l-glucose has been investigated using a double array of planar interdigitated microelectrodes on a glass microchip. Erythrocytes are analyzed under physiological conditions suspended in hypo-osmolar balanced solutions containing different glucose concentrations (0–20 mM). The glucose effect on the cellular dielectric properties is evaluated by analyzing the spectra using two different approaches, the equivalent circuit model and a modified model for ellipsoidal particles. The results show that at elevated glucose concentration (15 mM) the membrane capacitance increases by 36%, whereas the cytosol conductivity slightly decreases with a variation of about 15%. On the contrary, no variation has been registered with l-glucose, a biologically inactive enantiomer of d-glucose. The paper discusses the possible mechanism controlling the membrane dielectric response. As the external d-glucose increases, the number of activated glucose transporter in the erythrocyte membrane raises and the transition from sugar-free state to sugar-bounded state induces a change in the dipole moments and in the membrane capacitance.

► Dielectric spectroscopy is used to monitor glucose effect on biconcave erythrocytes.
► A dual array of microelectrodes on glass chip allows differential measurements.
► Equivalent circuit and ellipsoidal models are applied for spectra analysis.
► d-glucose induces changes in plasma membrane capacitance and cytosol conductivity.
► The increase of glucose activates the transporters raising the membrane capacitance.