Dielectrophoretic manipulation of ribosomal RNA

Abstract

The manipulation of ribosomal RNA ͑rRNA͒ extracted from E. coli cells by dielectrophoresis ͑DEP͒ has been demonstrated over the range of 3 kHz-50 MHz using interdigitated microelectrodes. Quantitative measurement using total internal reflection fluorescence microscopy of the time dependent collection indicated a positive DEP response characterized by a plateau between 3 kHz and 1 MHz followed by a decrease in response at higher frequencies. Negative DEP was observed above 9 MHz. The positive DEP response below 1 MHz is described by the ClausiusMossotti model and corresponds to an induced dipole moment of 3300 D with a polarizability of 7.8ϫ 10 −32 F m 2 . The negative DEP response above 9 MHz indicates that the rRNA molecules exhibit a net moment of Ϫ250 D, to give an effective permittivity value of 78.5 0 , close to that of the aqueous suspending medium, and a relatively small surface conductance value of ϳ0.1 nS. This suggests that our rRNA samples have a fairly open structure accessible to the surrounding water molecules, with counterions strongly bound to the charged phosphate groups in the rRNA backbone. These results are the first demonstration of DEP for fast capture and release of rRNA units, opening new opportunities for rRNA-based biosensing devices.

Functionality of dielectrophoretically immobilized enzyme molecules

“…Such an effect has also been reported for viruses , metallic nanoparticles , and protein molecules . In a study on the dielectrophoretic collection of RNA, Giraud et al found the expected square dependence on voltage starting at a threshold voltage. A detailed theory on the interplay between DEP and Brownian motion has been developed by Ramos et al .…”

Floating-electrode enhanced constriction dielectrophoresis for biomolecular trapping in physiological media of high conductivity

“…20 However, DEP trapping within media of high conductivity for enhancement of DNA hybridization kinetics poses distinct challenges. The enhanced current flow under applied fields within media of high conductivity (1 S/m) causes Joule heating.…”

Information processing tools for extracting the electrical properties of nanoparticles

“…0 f MHz and the probe frequencies spanning the range, 4 1 f MHz. Time dependent collection profiles for each of the control and probe cycles were quantified by linear fitting (fourteen data points) that approximates an exponential series for sufficiently short time intervals [4,[8][9][10][11][12][13][14][15][16]. The initial collection rate ratio of …”

“…The initial collection rate is approximately proportional to the small-time averaged DEP force [4,[8][9][10][11][12][13][14][15][16] [5,7] and all other symbols have their usual meanings. Usually the DEP force is switched on for a limited time (up to a minute) then switched off.…”

“…Pulsed DEP has been used to characterize the electrical properties of cells and their constituents, e.g. DNA, RNA, viruses, and colloidal bioparticles [4,[8][9][10][11][12][13][14][15][16]21], whereby initial collection rates were measured and fitted to the real part of CM [1, 19,20]. A newly developed, fast alternative to traditional methods for characterizing electrical properties, e.g.…”