Electrorotation: Diagnostic Tool for Abnormality of Marine Phytoplankton Cells

Abstract

This work proposes a method to estimate cell dielectric properties using a rotating electric field. Signals given to four platinum electrodes were from a phase shift unit, which splits an input signal into four of pi/2 phase difference. The unit performs well under frequency below 5 MHz. Rotation patterns of pretreated Tetraselmis sp. were utilized to reveal dielectric information of the cells. The rotation of boiled cells diminished at the lower frequency range, while that of the arsenic pretreated cells was smaller than that of the control when higher arsenic concentration was used. The specific membrane conductance was increased from 0.5 kS.m-1 for the control to 90 kS.m-1 boiled cells. Pretreated cells with arsenic solution at 10 to 100 ppm levels increased the membrane conductance to 8.8 kS.m-1, much less effect compared to the boiled cells. Moreover, 24 hrs pretreatment was long enough for arsenic to penetrate the membrane, and the cytoplasmic permittivity was reduced from 39epsivO to about 13e0, independent of the arsenic levels used. The study can distinguish the viability from the non-viability cells by carefully selected field, frequency, and solution conductivity.