Selection of Brownian particles

Faucheux, Luc P.; Libchaber, Albert

doi:10.1039/ft9959103163

Cited by 51 publications

(30 citation statements)

References 6 publications

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“…Previously, a pulsed, one-dimensional asymmetric potential has been used to propel colloidal particles at different speeds (13)(14)(15). Compared with this technique and with traditional methods such as gel electrophoresis, our approach has the advantage of accomplishing sorting continuously.…”

Section: Discussionmentioning

confidence: 99%

Sorting by diffusion: An asymmetric obstacle course for continuous molecular separation

Chou

Bakajin

Turner

et al. 1999

Proc. Natl. Acad. Sci. U.S.A.

197

150

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A separation technique employing a microfabricated sieve has been demonstrated by observing the motion of DNA molecules of different size. The sieve consists of a two-dimensional lattice of obstacles whose asymmetric disposition rectifies the Brownian motion of molecules driven through the device, causing them to follow paths that depend on their diffusion coefficient. A nominal 6% resolution by length of DNA molecules in the size range 15-30 kbp may be achieved in a 4-inch (10-cm) silicon wafer. The advantage of this method is that samples can be loaded and sorted continuously, in contrast to the batch mode commonly used in gel electrophoresis.DNA fractionation ͉ Brownian motion ͉ microfabricated array T he separation of DNA fragments from restriction enzyme digests plays a central role in molecular biology (1), and there is a growing realization that new and faster methods are needed to accelerate and simplify genomic analysis. One route to this goal is the exploitation of technologies in the microfabrication industry to create miniature silicon-based devices in which sample preparation, separation, and analysis are integrated in a single microenvironment (2-5). The task is complicated by the fact that, when forced to move by a flow or by the application of an electric field, DNA molecules of different sizes all migrate at the same speed. Traditionally, a sieving medium such as a gel or a solution of polymers has been used to alter the mobility. Recently, however, Duke and Austin (6) and Ertas (7) proposed an alternative approach that takes advantage of the fact that, as the molecules migrate, they also diffuse-and this they do at a size-dependent rate. On theoretical grounds, they showed how a two-dimensional obstacle course could be constructed to sort the swift diffusers from the slow. The basic concept is to use a regular lattice of asymmetric obstacles to rectify the lateral Brownian motion of the molecules so that species of different sizes follow different trajectories through the device. A mixture of molecules injected in a fine stream would be sorted continuously.We have implemented this idea by using a microfabricated silicon array. That such a device works in principle has been demonstrated by making microscopic observations of the dynamics of fluorescently labeled latex beads and DNA molecules † † and also by the recent work of van Oudenaarden and Boxer (8) with lipids. The experiments are technically demanding, however, and the resolution of different species has not yet been achieved. Progression from a demonstration of principle to practical continuous stream sorting of molecules requires perfection of the technology. In the work reported here, our aim has been to conduct a systematic, quantitative study of the separation process, using molecules of a well-defined size and experimental conditions that are close to optimal. The close correspondence of the results with theoretical predictions permits us to predict, with some confidence, how to construct a device that will work well in practice. Ma...

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Section: Discussionmentioning

confidence: 99%

Sorting by diffusion: An asymmetric obstacle course for continuous molecular separation

Chou

Bakajin

Turner

et al. 1999

Proc. Natl. Acad. Sci. U.S.A.

197

150

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“…Dielectrophoresis is the induced motion of polarisable particles in non-uniform fields [14][15][16], which generates a force proportional to the gradient of the electric field squared. The application of dielectrophoresis for ratcheting was demonstrated by Rousselet et al [17] and subsequently Faucheux and Libchaper [18] and Gorre-Talini et al [19] to manipulate colloidal particles in dielectrophoretic ratchet structures. Similar electrode structures have been used for quantum tunnelling ratchets by Linke et al [20] and for vortex reduction in superconductors [21].…”

Section: Introductionmentioning

confidence: 99%

Numerical simulation of dielectrophoretic ratchet structures

Hughes¹

2004

J. Phys. D: Appl. Phys.

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SummaryAsymmetrical periodic ("ratchet") potential energy structures have a number of applications, including the dielectrophoretic rectification of Brownian motion, the implementation of quantum tunnelling devices, and as a model of the action of molecular motors such as muscles. The effectiveness of such devices is dependent on the asymmetry of the potential energy, not that of the potential energy generating structures. Using empirical analysis of simulations of electric field ratchets, this paper derives empirical expressions describing, and optimising, electric field ratchets in terms of the electrode dimensions.

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“…In these cases motor proteins (dynein, kinesin and myosin) convert the chemical energy stored in ATP molecules into mechanical work while moving along polymeric filaments (dynein and kinesin along microtubules, and myosin along actin filaments) [14]. A transport mechanism of this kind has also been experimentally demonstrated in simple physical systems [15][16][17] and can lead to new technological ideas such as constructing nano-scale devices or novel type of particle separators.…”

Section: Introductionmentioning

confidence: 99%

Realistic models of biological motion

Derényi

Vicsek

1998

Physica A: Statistical Mechanics and its Applications

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The origin of biological motion can be traced back to the function of molecular motor proteins. Cytoplasmic dynein and kinesin transport organelles within our cells moving along a polymeric filament, the microtubule. The motion of the myosin molecules along the actin filaments is responsible for the contraction of our muscles. Recent experiments have been able to reveal some important features of the motion of individual motor proteins, and a new statistical physical descriptionoften referred to as "thermal ratchets" -has been developed for the description of motion of these molecules. In this approach the motors are considered as Brownian particles moving along one-dimensional periodic structures due to the effect of nonequilibrium fluctuations. Assuming specific types of interaction between the particles the models can be made more realistic. We have been able to give analytic solutions for our model of kinesin with elastically coupled Brownian heads and for the motion of the myosin filament where the motors are connected through a rigid backbone. Our theoretical predictions are in a very good agreement with the various experimental results. In addition, we have considered the effects arising as a result of interaction among a large number of molecular motors, leading to a number of novel cooperative transport phenomena.

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Selection of Brownian particles

Cited by 51 publications

References 6 publications

Sorting by diffusion: An asymmetric obstacle course for continuous molecular separation

Sorting by diffusion: An asymmetric obstacle course for continuous molecular separation

Numerical simulation of dielectrophoretic ratchet structures

Realistic models of biological motion

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