Differences in the biophysical properties of membrane and cytoplasm of apoptotic cells revealed using dielectrophoresis.
ABSTRACT We have used dielectrophoresis to determine the dielectric properties of human chronic myelogeneous leukaemic (K562) cells during apoptosis (programmed cell death). Our results indicate that K562 cells increase markedly in cytoplasmic conductivity from 0.28 S/m to 0.50 S/m within the first 4 h following treatment with staurosporine, which then lasts beyond 12 h, whilst cell shrinkage increases the capacitance of the membrane from 9.7 mF/m2 to 20 mF/m2. After 24 and 48 h of incubation with staurosporine, multiple sub-populations were detected, highlighted by the dielectric changes that the cell undergoes before death. By comparing these results with those obtained by common apoptosis monitoring techniques Annexin V and TMRE (tetramethylrhodamine ethylester), it is possible to infer the role of ion efflux in the progress of apoptosis. The use of dielectrophoresis for monitoring apoptosis offers a number of benefits as it is both rapid and non-invasive. It can also be used in parallel with other assays in high-throughput screening applications.
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ABSTRACT: This paper presents the use of electrodeformation as a method for single cell mechanical characterization in which mechanical properties of SiHa and ME180 cells (two cervical cancer cell lines) were quantified. Cells were directly placed between two microelectrodes with a rectangular ac electric field applied, and cell deformation was recorded under certain experimental conditions. Numerical simulations were performed to model cell electrodeformation based on the Maxwell stress tensor formulation. In these simulations, effects of cell electrical property variations on their electrodeformed behavior were investigated. By comparing the measured morphological changes with those obtained from numerical simulations, we were able to quantify Young's modulus of SiHa cells (601 ± 183 Pa) and ME180 cells (1463 ± 649 Pa). These values were consistent with Young's modulus values (SiHa: 400 ± 290 Pa and ME180: 1070 ± 580 Pa) obtained from conventional micropipette aspiration.J. Micromech. Microeng. J. Micromech. Microeng. 01/2011; 21(21):242-54012.
Article: Dielectric measurement of cell death[show abstract] [hide abstract]
ABSTRACT: Dielectric techniques, which include dielectric spectroscopy as well as AC electrokinetic methods such as dielectrophoresis, electrorotation and electro-orientation, can be provide important information about cell viability. A review is given of the different dielectric techniques that have been used for measuring cell viability and their utility. The changes that occur in the cell dielectric properties during apoptotic and different forms of traumatic cell death are discussed and interpreted in terms of the main parameters involved (membrane capacitance and conductance and internal conductivity).Enzyme and Microbial Technology 12/2008; · 2.37 Impact Factor