Three-dimensional magneto-optic trap for micro-object manipulation

Sacconi, Leonardo; Romano, G.; Ballerini, R.; Capitanio, Marco; Pas, Marco De; Giuntini, M.; Dunlap, David; Finzi, Laura; Pavone, Francesco S.

doi:10.1364/ol.26.001359

Cited by 64 publications

(37 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Discussion A large part of the results described here was obtained by the use of an apparatus that combines optical and magnetic tweezers. Although the building of a similar experimental configuration has been reported in previous studies (24,25), our work constitutes its application to the study of a biologically relevant problem. This setup unites two features that are essential for studying the intrinsic dynamics of supercoiled DNA: first, the ability to twist DNA, provided by the magnetic tweezers, and second, the possibility to apply a sudden force switch.…”

Section: Resultsmentioning

confidence: 93%

Fast dynamics of supercoiled DNA revealed by single-molecule experiments

Crut

Köster²,

Seidel³

et al. 2007

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

View full text Add to dashboard Cite

The dynamics of supercoiled DNA play an important role in various cellular processes such as transcription and replication that involve DNA supercoiling. We present experiments that enhance our understanding of these dynamics by measuring the intrinsic response of single DNA molecules to sudden changes in tension or torsion. The observed dynamics can be accurately described by quasistatic models, independent of the degree of supercoiling initially present in the molecules. In particular, the dynamics are not affected by the continuous removal of the plectonemes. These results set an upper bound on the hydrodynamic drag opposing plectoneme removal, and thus provide a quantitative baseline for the dynamics of bare DNA.magnetic tweezers ͉ optical tweezers ͉ polymer dynamics T he degree of DNA supercoiling affects a number of important cellular processes, such as gene expression (1), initiation of DNA replication (2), binding kinetics of sequence-specific proteins to their targets (3), and site-specific recombination (4, 5). A strict regulation of DNA supercoiling is therefore essential for cell survival. This regulation results from a complex interplay between the occurrence of processes that generate local supercoiling of DNA, such as replication and transcription, and the action of topoisomerases, which are able to modify the global linking number (Lk) of DNA molecules via a mechanism of transient DNA strand breakage and religation (for reviews, see refs. 6 and 7).DNA supercoiling dynamics, i.e., the rate at which supercoils are created, propagated and removed on a DNA molecule, represent an important aspect of the regulation process. This can be clearly illustrated by the example of transcription-induced supercoiling. As initially proposed by Liu and Wang (8) and confirmed by later experiments in vitro (9) and in vivo (10, 11), the inability of a transcription complex of increasing molecular weight to rotate around helical DNA results in the supercoiling of DNA in its immediate vicinity: positively supercoiled domains are generated ahead of the transcription complex, whereas negatively supercoiled domains are generated behind it. In the simple case of a single transcription complex bound to a circular DNA molecule, these supercoiled domains of opposite sign can be relaxed in one of two ways, either by the action of topoisomerases or by their mutual annihilation following their propagation along the connecting DNA segment. These two processes can have very different consequences for DNA topology: the action of topoisomerases induces a modification of Lk unless these enzymes relax positive and negative supercoils in a perfectly balanced way, whereas the merging of oppositely supercoiled domains does not influence the global Lk. Thus, the relative kinetics of these two processes appears as a major determinant of the degree of supercoiling of DNA in steady state. Within this context, DNA internal dynamics play an important role because they determine the rate at which oppositely supercoiled domains propagate and mer...

show abstract

Section: Resultsmentioning

confidence: 93%

Fast dynamics of supercoiled DNA revealed by single-molecule experiments

Crut

Köster²,

Seidel³

et al. 2007

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

View full text Add to dashboard Cite

show abstract

“…This force cannot produce a three-dimensional potential well, but has anyway been used to manipulate biomolecules (Gosse and Croquette, 2002). Sacconi et al (2001) built a magneto-optic manipulator that combines optical tweezers with a magnetic wrench. Superparamagnetic beads can be trapped in three dimensions by the optical tweezers and contemporaneously rotated around the three axes by the magnetic wrench.…”

Section: Twisting Biomolecules With Magnetic and Optical Wrenchesmentioning

confidence: 99%

Exploring molecular motors and switches at the single‐molecule level

Capitanio

Vanzi

Broggio

et al. 2004

Microscopy Res & Technique

Self Cite

View full text Add to dashboard Cite

Single-molecule techniques have propelled an impressive number of biophysical studies during the last decade. From relatively simple video-microscopy techniques, to sophisticated manipulation and detection apparata, single-molecule techniques are capable of tracking the movements and the reaction trajectories of single enzymatic units. By observing microspheres attached to biomolecules it is possible to follow the motion of molecular motors, or to detect conformational "switching" induced by regulatory proteins. Micromanipulation tools like optical tweezers have been widely applied to understand the mechanisms of linear molecular motors, and have allowed the measurement of the elementary steps and the forces produced by several motor proteins, including myosin, kinesin, and dynein. New experimental assays based on magnetic or optical "wrenches," which are able to apply and detect torques on rotary motors and biopolymers, are opening new possibilities in this field. Here, established and emerging magneto-optical manipulation and video-tracking techniques are reviewed, in the perspective of single molecular motors and regulatory proteins studies.

show abstract

“…Various operational methods for particle and/or cell manipulation have been developed, such as ultrasonic (Harris et al 2005), thermal (Gramotnev et al 2007), optical (Ashkin 1997), dielectrophoretic (Taff and Voldman 2005;Rosenthal et al 2006), magnetic (Lee et al 2004), magneto-optic (Sacconi et al 2001), and hydrodynamic tweezer (Lutz and Meldrum 2005) techniques. Dielectrophoresis (DEP) and magnetic traps consisting of two-dimensional electrodes are recognized as the most powerful methods for fast, robust, and selective manipulation of target particles and/or cells in biological applications, but difficulties can be encountered with magnetic traps due to the increasing cell temperature caused by the magnetic field.…”

Section: Introductionmentioning

confidence: 99%

Experimental study on a single particle trap with a pneumatic vibrator matrix

Jeong

Konishi

2008

Microfluid Nanofluid

View full text Add to dashboard Cite

This paper describes a fundamental study on a pneumatic particle trap with a vibrator matrix. The particle trap device consisted of pneumatic vibrators and a trap chamber used to trap a particle. The entire structure was fabricated from polydimethylsiloxane (PDMS). The particle in the trap chamber was manipulated and trapped in the equilibrium region by exploiting the geometrical symmetry of the vibrators. The x-axial velocity of the viscous fluid induced by the deformation of the flexible diaphragms was eliminated or minimized at the center of two vibrators. Therefore, a particle could be trapped in the central capturing region by two or four vibrators. The trapping of static and dynamic single particles was observed to verify the proposed operational method.

show abstract

Three-dimensional magneto-optic trap for micro-object manipulation

Cited by 64 publications

References 19 publications

Fast dynamics of supercoiled DNA revealed by single-molecule experiments

Fast dynamics of supercoiled DNA revealed by single-molecule experiments

Exploring molecular motors and switches at the single‐molecule level

Experimental study on a single particle trap with a pneumatic vibrator matrix

Contact Info

Product

Resources

About