New Method for Studying Electrical Orientation and Relaxation Effects in Aqueous Colloids: Preliminary Results with Tobacco Mosaic Virus

O’Konski, Chester T.; Zimm, Bruno H.

doi:10.1126/science.111.2875.113

Cited by 157 publications

(69 citation statements)

References 9 publications

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“…Experiments determining the orientation of TMV by low-frequency AC fields were performed as long ago as 1939 [24,25]. However, these results were governed by electrophoretic, rather than dielectrophoretic effects.…”

Section: Discussionmentioning

confidence: 99%

Dielectrophoretic manipulation of rod-shaped viral particles

Morgan

Green

1997

Journal of Electrostatics

210

176

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The dielectrophoretic manipulation of a rod-shaped virus, tobacco mosaic virus (TMV) by means of non-uniform AC electric fields is described. An expression is derived for the dielectrophoretic force on a homogeneous dielectric cylinder suspended in a liquid medium which shows that the dielectrophoretic force varies over a wide range of frequencies and medium conductivities. Measurements of the dielectrophoretic behaviour of TMV particles in microelectrode arrays have been made as a function of frequency and applied field strength. The results are shown to be in quantitative agreement with the derived expression for the dielectrophoretic force. By measuring the threshold field strength for the onset of dielectrophoresis, the force on a single TMV particle has been estimated. The results point to the potential use of dielectrophoresis for the collection and manipulation of sub-micron particles using microelectrode arrays. ~) 1997 Elsevier Science B.V.

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Section: Discussionmentioning

confidence: 99%

Dielectrophoretic manipulation of rod-shaped viral particles

Morgan

Green

1997

Journal of Electrostatics

210

176

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“…It was not possible to resolve single TMV particles with our optical system. The electric field induced orientation of TMV in low frequency AC fields was investigated as long ago as 1939 [23,24]. However, these studies investigated the electrophoretic effects, which depend on the fixed charge on the virus rather than the interaction of the local charges on the virus surface.…”

Section: Trapping Of Tobacco Mosaic Virus Particlesmentioning

confidence: 99%

Manipulation and trapping of sub-micron bioparticles using dielectrophoresis

Green

Morgan

Milner

1997

Journal of Biochemical and Biophysical Methods

159

127

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A non-uniform alternating electric field induces motion in polarisable particles called dielectrophoresis. The effect is governed by the relative magnitudes of the dielectric properties of the medium and the particles. The technology has been used to manipulate particles for biotechnological applications, including purification, fractionation and concentration of cells and microorganisms. However, the lower size limit for the dielectrophoretic manipulation of particles was believed to be about 1 m, but recent work has proved otherwise. The dielectrophoretic movement and properties of latex beads and a simple rod-shaped virus, tobacco mosaic virus (TMV), have been measured using microfabricated electrode structures. Measurements have been made over a range of suspending medium conductivities, applied frequencies and electric field strengths. It is shown that under appropriate conditions both latex beads and tobacco mosaic virus particles can be selectively attracted to regions of high electric field strength located at the tips of microfabricated electrode structures. The ability to selectively trap and separate bio-particles has many potential applications in the area of biotechnology. © 1997 Elsevier Science B. V.

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“…orientation changes of the bacteria during the pulse Being a rod, E. coli is affected by the field through its dipole induction [17]. The field polarizes the bacteria, which are thus submitted to a torque.…”

Section: Effect Of Pulse Parameters On Transformationmentioning

confidence: 99%

“…Light transmitted by a bacterial suspension is controlled by the orientation distribution [15]. It is known that an electric field applied to a non-spherical-cell suspension creates an optical anisotropy which can be measured by dichroism [I 81, changes in birefringence [17], light scattering [19] or light transmission [20]. An increase in transmitted light during the pulse (Fig.…”

Section: Effect Of Pulse Parameters On Transformationmentioning

confidence: 99%

Fast kinetics studies of Escherichia coli electrotransformation

Eynard

Sixou

Durán

et al. 1992

European Journal of Biochemistry

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Direct gene transfer is achieved in Escherichiu coli by use of square wave electric pulsing. As observed by vidco monitoring, the field pulse causes bacteria to orientate parallel to the field lines. Rapid kinetic turbidity changes indicate that this process happens quickly. In these circumstances, and in pulsing conditions prone to inducing transformation, only caps are affected by the field. Considerable cytoplasmic ion leakage occurs during the pulse, affecting the intcrfacial ionic concentration. The pulsing-buffer osmolarity has to be close to that used with protoplasts. Contact between the plasmid and the bacteria can be very short before the pulse but must be present during the pulse. The plasmid remains accessible to externally added DNases up to 5 days after the pulse, suggesting that the transfer step is slow. Electric-field-mediated transfer can be described in two steps: the anchoring process during the pulse, followed by the crossing of the membrane.The organization and properties of cell membranes can be altcred when the membrane-potential difference is brought to a critical value. This was shown by electropulsation for the first time in 1972, when the permeability of chromaffin granules was reversibly increased when vesicles were submitted to short high-intensity electric pulses (so called electropermeabilization) [I], a property which has since been observed in many cell systems. In 1982, gene transfer was mediated in eukaryotic cells by electropulsation (electrotransformation) [2] and gene expression was obtained showing genomic integration of the plasmid. Electrotransformation was successfully applied to many systems of mammalian cells and plant protoplasts [3]. More recently, gene transfer was obtained with walled systems, such as bacteria [4] or yeasts [5], and electrotransformation is, in [act, now routinely used in many bacterial-genetics laboratories. Yiclds as high as 20 -30% have been reported using strains which were known to be casily transformed by the CaC1, method [6 -1 I]. Nevertheless, mechanisms of electrotransformation remain unexplained in the case of bacteria, as with other systems. Optimization of thc procedure remains, in most cases, empirical. A correlation has nevertheless been shown by our group between electropermeabilization and electrotransformation in the case of Escherichiu coli and Salmonella thyphimurium [12].However, a lack of knowledge of the basic processes remains the major handicap to the definition of efficient transformation conditions. Several processes are induced at the cell level upon electropulsation. Thc well-known Joule-heating phenomenon cannot be neglected under electrical conditions inducing electrotransformation. Dipolcs are induced by the electric field and are oriented by a field effect and reorientation of the Corre.pmdence to J. Teissit, Centre de Recherche dc Biochimie et de Gtnetique Ccllulaires du Centre National de la Recherche Scieiitifiquc, 118 route de Narbonne, F-31062 Toulouse. Cedex, France pulsed vesicles may occur. The most dramatic...

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New Method for Studying Electrical Orientation and Relaxation Effects in Aqueous Colloids: Preliminary Results with Tobacco Mosaic Virus

Cited by 157 publications

References 9 publications

Dielectrophoretic manipulation of rod-shaped viral particles

Dielectrophoretic manipulation of rod-shaped viral particles

Manipulation and trapping of sub-micron bioparticles using dielectrophoresis

Fast kinetics studies of Escherichia coli electrotransformation

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