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Optical Tweezers (0):
Recent article
Optical Tweezers
FEBS Journal (278)19 2011
Abstract
Through its capability to transiently pack and unpack our genome, chromatin is a key player in the regulation of gene expression. Single-molecule approaches have recently complemented conventional biochemical and biophysical techniques to decipher the complex mechanisms ruling chroma...
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PMID: 21810177
PDF is available here.
PDF is available here.
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Abstract
We created two mutant constructs with extended neck-linkers and measured their properties using single-molecule optical trapping and ensemble fluorescence techniques. Owing to a reduction in the inter-head tension, the constructs access an otherwise rarely populated conformational state in which bot...
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PMID: 21841789
PDF is available here.
PDF is available here.
Abstract
We propose to use a robot-tweezer manipulation system to solve the problem of automatic transportation of biological cells, where optical tweezers function as special robot end effectors. Dynamics equation of the cell in optical tweezers is analyzed. A closed-loop controller is designed for transpor...
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PMID: 21764021
PDF is available here.
PDF is available here.
Abstract
We propose a general Bayesian framework to model diffusion processes with nonlinear drift based on incomplete observations as generated by various types of experiments. A maximum penalized likelihood estimator is given as well as a Gibbs sampling method that allows to estimate the trajectories that...
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PMID: 21517623
PDF is available here.
PDF is available here.
Biopolymers (95)5 2011
Abstract
Mechanical tension plays a large role in cell development ranging from morphology to gene expression. On the molecular level, the effects of tension can be seen in the dynamic arrangement of membrane proteins as well as the recruitment and activation of intracellular proteins. Forces applied to biopo...
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PMID: 21267988
PDF is available here.
PDF is available here.
Abstract
We use optical trapping as a non-invasive, non-destructive, but fast and effective method to position cells in culture. Optical traps, or optical tweezers, are increasingly utilized in biological research to capture and physically manipulate cells and other micron-sized particles in three dimensions...
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PMID: 21841755
PDF is available here.
PDF is available here.
Lab On a Chip (10)23 2010
Abstract
We review the electro-physical basis for how live and dead human spermatozoa respond to OET. The maximal velocity that non-motile spermatozoa could be induced to move by attraction or repulsion to a moving OET field was measured. Viable sperm are attracted to OET fields and can be induced to move at...
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PMID: 20835428
PDF is available here.
PDF is available here.
Optics Express (18)20 2010
Abstract
We have studied optical trapping and propulsion of red blood cells in the evanescent field of optical waveguides. Cell propulsion is found to be highly dependent on the biological medium and serum proteins the cells are submerged in. Waveguides made of tantalum pentoxide are shown to be efficient fo...
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PMID: 20941001
PDF is available here.
PDF is available here.
Biophysical Journal (99)4 2010
Abstract
We investigated physical and analytical optimization procedures that can be used to improve the range over which forces can be reliably measured. To systematically probe the limitations of magnetic tweezers spectral analysis, we have developed a magnetic tweezers simulator, whose outcome was validat...
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PMID: 20713015
PDF is available here.
PDF is available here.
Applied Optics (49)22 2010
Abstract
We present a highly integrated optofluidic system made of polydimethylsiloxane (PDMS). The system is replicated in a single-step process from a micromilled polymethyl methacrylate master mold. It already includes the reservoirs, the channel system, as well as the optical interconnect surfaces for hi...
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PMID: 20676190
PDF is available here.
PDF is available here.
Optics Letters (35)14 2010
Abstract
Our results show that the optical tweezers may serve as a unique tool for the measurement of DEP forces in various applications....
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PMID: 20634874
PDF is available here.
PDF is available here.
Abstract
We describe the development of a calibrated biosensor that measures forces across specific proteins in cells with piconewton (pN) sensitivity, as demonstrated by single molecule fluorescence force spectroscopy. The method is applied to vinculin, a protein that connects integrins to actin filaments a...
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PMID: 20613844
PDF is available here.
PDF is available here.
Nanotechnology (21)24 2010
Abstract
A modified optical tweezers set-up has been used to generate microbubbles in flowing, biologically relevant fluids and human whole blood that contains carbon nanotubes (CNTs) using low power (< or =5 mW), infrared (1064 nm wavelength), continuous wave laser light. Temperature driven effects at the t...
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PMID: 20484785
PDF is available here.
PDF is available here.
Abstract
We uncover a previously undescribed force-induced quaternary structure of the N. gonorrhoeae Tfp. By using a combination of optical and magnetic tweezers, atomic force microscopy, and molecular combing to apply forces on purified Tfp, we demonstrate that Tfp subjected to approximately 100 pN of forc...
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PMID: 20534431
PDF is available here.
PDF is available here.
Optics Letters (35)12 2010
Abstract
We develop light-driven optoelectronic tweezers based on the organic photoconductive material titanium oxide phthalocyanine. These tweezers function based on negative dielectrophoresis (nDEP). The dynamic manipulation of a single microparticle and cell patterning are demonstrated by using this light...
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PMID: 20548352
PDF is available here.
PDF is available here.
Abstract
We use a single-molecule optical tweezers approach to induce the selective unfolding of particular regions of T4 lysozyme and monitor the effect on other regions not directly acted on by force. We investigate how the topological organization of a protein (the order of structural elements along the s...
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PMID: 20495548
PDF is available here.
PDF is available here.
Optics Express (18)11 2010
Abstract
We present a study of the optical force on a small particle with both electric and magnetic response, immersed in an arbitrary non-absorbing medium, due to a generic incident electromagnetic field. Expressions for the gradient force, radiation pressure and curl components are obtained for the force...
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PMID: 20589003
PDF is available here.
PDF is available here.
Optics Express (18)11 2010
Abstract
We show the feasibility of a single-beam gradient-trap system working with a force detection technique based on this same principle....
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PMID: 20589058
PDF is available here.
PDF is available here.
Optics Express (18)11 2010
Abstract
We present an optical system capable of generating stereoscopic images to track trapped particles in three dimensions. Two-dimensional particle tracking on each image yields three dimensional position information. Our approach allows the use of a high numerical aperture (NA=1.3) objective and large...
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PMID: 20589039
PDF is available here.
PDF is available here.
Optics Express (18)11 2010
Abstract
We present a method for reducing intensity fluctuations that typically occur when a spatial light modulator is updated between consecutive computer generated holograms. The method is applicable to most iterative hologram generating algorithms and minimizes the average phase difference between consec...
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PMID: 20588985
PDF is available here.
PDF is available here.
Abstract
We used an optical trap to measure the bending rigidity of live Escherichia coli cells. We find that the actin-homolog MreB contributes nearly as much to the stiffness of a cell as the peptidoglycan cell wall. By quantitatively modeling these measurements, our data indicate that the MreB is rigidly...
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PMID: 20439764
PDF is available here.
PDF is available here.
Optics Express (18)10 2010
Abstract
These results are consistent with numerical predictions.
(c) 2010 Optical Society of America....
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PMID: 20588937
PDF is available here.
PDF is available here.
Optics Express (18)10 2010
Abstract
We compute the stress re-distribution on the deformed cell and its subsequent deformations recursively until a final equilibrium state solution is achieved. The experiment is done with the red blood cells in suspension swollen to spherical shape. The cell membrane elasticity coefficient is obtained...
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PMID: 20588900
PDF is available here.
PDF is available here.
Abstract
We use the three bead dumbbell assay to show for the first time, that cytoplasmic dynein is a non-processive motor at low ATP concentrations. Processivity can be restored even in the absence of dynactin by increasing the ATP concentration to 100muM. We propose that an altered occupancy of the differ...
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PMID: 19961937
PDF is available here.
PDF is available here.
Biophysical Journal (98)8 2010
Abstract
We stretched VWF multimers and a poly-protein (A1A2A3)3 that contains three repeats of the triplet A1A2A3 domains at constant speeds of 2000 nm/s and 400 nm/s, respectively, which yielded corresponding average force loading rates of 90 and 22 pN/s. We found that VWF multimers became stiffer when the...
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PMID: 20409490
PDF is available here.
PDF is available here.
Journal of Plant Research (123)2 2010
Abstract
An intriguing feature of most eukaryotes is that chloroplast (cp) and mitochondrial (mt) genomes are inherited almost exclusively from one parent. Uniparental inheritance of cp/mt genomes was long thought to be a passive outcome, based on the fact that eggs contain multiple numbers of organelles, wh...
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PMID: 20196233
PDF is available here.
PDF is available here.
Optics Express (18)5 2010
Abstract
We report on the fabrication by a femtosecond laser of an optofluidic device for optical trapping and stretching of single cells. Versatility and three-dimensional capabilities of this fabrication technology provide straightforward and extremely accurate alignment between the optical and fluidic com...
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PMID: 20389480
PDF is available here.
PDF is available here.
Abstract
We directly extract the full free energy landscape of a single molecule of the GCN4 leucine zipper using dual beam optical tweezers. To this end, we use deconvolution force spectroscopy to follow an individual molecule's trajectory with high temporal and spatial resolution. We find a heterogeneous e...
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PMID: 20133846
PDF is available here.
PDF is available here.
Abstract
We consider realistic discrete models in terms of energy functionals defined on networks/lattices. Using concepts of Gamma-convergence, convergence results as well as explicit homogenisation formulae are derived. Based on a characterisation via energy functionals, appropriate macroscopic stress-stra...
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PMID: 19440743
PDF is available here.
PDF is available here.
Abstract
We consider realistic discrete models in terms of energy functionals defined on networks/lattices. Using concepts of Gamma-convergence, convergence results as well as explicit homogenisation formulae are derived. Based on a characterisation via energy functionals, appropriate macroscopic stress-stra...
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PMID: 19440743
PDF is available here.
PDF is available here.
Abstract
We consider realistic discrete models in terms of energy functionals defined on networks/lattices. Using concepts of Gamma-convergence, convergence results as well as explicit homogenisation formulae are derived. Based on a characterisation via energy functionals, appropriate macroscopic stress-stra...
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PMID: 19440743
PDF is available here.
PDF is available here.
Biophysical Journal (98)2 2010
Abstract
We investigate the effect of force on individual single headed myosin-V constructs bound to actin in the absence of ATP. If pulled forward, the myosin-V head dissociates at forces twice as high than if pulled backward. Moreover, backward but not forward distances to the unbinding barrier are depende...
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PMID: 20338849
PDF is available here.
PDF is available here.
Optics Express (18)2 2010
Abstract
We present comprehensive case studies on trapping of light in plasmonic waveguides, including the metal-insulator-metal (MIM) and insulator-metal-insulator (IMI) waveguides. Due to the geometrical symmetry, the guided modes are classified into the anti-symmetric and symmetric modes. For the lossless...
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PMID: 20173880
PDF is available here.
PDF is available here.
Optics Express (18)2 2010
Abstract
An image-patterned molecular delivery system for mammalian cells is demonstrated by pulsed laser irradiation of gold particles immobilized on a substrate below a cell monolayer. Patterned cavitation bubble nucleation was captured using a time-resolved imaging system and molecular delivery verified b...
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PMID: 20173916
PDF is available here.
PDF is available here.
Optics Express (18)2 2010
Abstract
We have shown that a few tens of milli-Watts of laser power can produce pico-Newton range forces....
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PMID: 20173874
PDF is available here.
PDF is available here.
Optics Express (18)2 2010
Abstract
We report on the experimental evidence of tilted polymer nanofiber rotation, using a highly focused linear polarized Gaussian beam. Torque is controlled by varying trapping power or fiber tilt angle. This suggests an alternative strategy to previously reported approaches for the rotation of nano-obj...
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PMID: 20173904
PDF is available here.
PDF is available here.
Abstract
We describe an assay in which one end of an MT abuts a barrier, and MT length changes are coupled to the movement of an optically trapped bead, the motion of which is tracked with high resolution. We detail assay execution, including preparation of the experimental chamber and orientation of the MT...
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PMID: 20466137
PDF is available here.
PDF is available here.
Abstract
We focus on two main optical manipulation techniques: optical trapping and laser ablation. We illustrate with selected applications in fission yeast how in vivo optical manipulation can be used to study organelle positioning and the force balance in the microtubule cytoskeleton.
2010 Elsevier Inc. A...
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PMID: 20719271
PDF is available here.
PDF is available here.
Methods in Enzymology (475) 2010
Abstract
We present details of the design, construction, and testing of a single-beam optical tweezers apparatus capable of measuring and exerting torque, as well as force, on microfabricated, optically anisotropic particles (an "optical torque wrench"). The control of angular orientation is achieved by rota...
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PMID: 20627165
PDF is available here.
PDF is available here.
Abstract
We developed a high-spatial resolution optical-trapping assay for RecBCD. The RecBCD is anchored to the surface via a genetically engineered biotin. This RecBCD-bio exhibited native activity, as measured by biochemical assays. Motion is continuous down to a detection limit of 2 nm, implying a unitar...
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PMID: 20225148
PDF is available here.
PDF is available here.
Abstract
We developed a protocol to measure the bending rigidity of filamentous rod-shaped bacteria. Forces are applied with an optical trap, a microscopic three-dimensional spring made of light that is formed when a high-intensity laser beam is focused to a very small spot by a microscope's objective lens....
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PMID: 20421864
PDF is available here.
PDF is available here.
Abstract
We present a review of optical manipulation, emphasizing its impact on the areas of single-molecule studies and single-cell biology, and indicating some of the key experiments in the fields....
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PMID: 20799781
PDF is available here.
PDF is available here.
Abstract
We induce shape changes in RBCs by altering the properties of the suspension medium in which live cells float. We find that certain shape anisotropies result in the rotation of optically trapped cells. Indeed, even normal (healthy) RBCs can be made to rotate using linearly polarized trapping light b...
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PMID: 20799782
PDF is available here.
PDF is available here.
Abstract
We demonstrate a single-beam, high-throughput method where optical forces are applied anisotropically to stretch swollen erythrocytes in microfluidic flow. We also present numerical simulations of model spherical elastic cells subjected to optical forces and show that dual, opposing optical traps ar...
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PMID: 20799841
PDF is available here.
PDF is available here.
Abstract
The detection and trapping of single fluorescent molecules in solution within a nanochannel is studied using numerical simulations. As optical forces are insufficient for trapping molecules much smaller than the optical wavelength, a means for sensing a molecule's position along the nanochannel and...
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PMID: 20799801
PDF is available here.
PDF is available here.
Optics Letters (34)23 2009
Abstract
We show that, in the liquid-filled hollow core of a single-mode photonic crystal fiber, a micrometer-sized particle can be held stably against a fluidic counterflow using radiation pressure and can be moved to and fro (over tens of centimeters) by ramping the laser power up and down. Accurate studie...
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PMID: 19953158
PDF is available here.
PDF is available here.
Optics Express (17)24 2009
Abstract
We present a new kind of vortex lenses in which the radial phase distribution is characterized by the "devil's staircase" function. The focusing properties of these fractal DOEs coined Devil's vortex-lenses are analytically studied and the influence of the topological charge is investigated. It is s...
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PMID: 19997433
PDF is available here.
PDF is available here.
Optics Express (17)24 2009
Abstract
The capabilities of optical tweezers to trap DNG (double negative) spherical particles, with both negative permittivity and permeability, are explored in detail by analyzing some interesting theoretical features not seeing in conventional DPS (double positive) particles possessing positive refractiv...
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PMID: 19997436
PDF is available here.
PDF is available here.
Optics Express (17)24 2009
Abstract
We created multiple optical traps with an inclined dual-fiber optical tweezers setup. One 3D trap and two 2D traps were formed at different vertical levels with adjustable separations and positions. We demonstrated that this fiber-based trapping system can be used as a simple block to perform multip...
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PMID: 19997409
PDF is available here.
PDF is available here.
Optics Express (17)22 2009
Abstract
We analytically investigate the forces due to Surface Plasmon Polariton (SPP) modes between finite and infinitely thick metal slabs separated by an air gap. Using the Drude model and experimentally determined values of the dielectric functions of gold and silver, we study how frequency dispersion an...
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PMID: 19997224
PDF is available here.
PDF is available here.
Optics Express (17)22 2009
Abstract
We experimentally investigate an optical mirror trap that is created after reflection of two holographically shaped collinear beams on a mirror. This approach combines a large field of view and a large working distance with the possibility to manipulate particles in a large size range, since it allo...
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PMID: 19997161
PDF is available here.
PDF is available here.
Optics Express (17)22 2009
Abstract
We applied oscillatory optical tweezers to measure the differential stiffness of dsDNA molecules, interacting with RecA, as a function of time at a constant stretching force of 33.6pN. The values of the differential stiffness of DNA (for stretching force in the range of 20.0pN to 33.6pN) measured by...
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PMID: 19997266
PDF is available here.
PDF is available here.
Abstract
We discuss what entails a quiet environment--what sources of noise are relevant and how they affect the instrument--and provide guidelines for choosing an appropriate location for a high-resolution instrument....
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PMID: 20147037
PDF is available here.
PDF is available here.
Abstract
We present the design of a high-resolution optical tweezers, which is designed to minimize sensitivity to environmental noise. When the tether is attached to a stage, resolution is typically limited by drift and fluctuations in the relative position of the stage and trap-forming objective, cued by e...
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PMID: 20147038
PDF is available here.
PDF is available here.
Abstract
We focus on the ways in which the design and implementation of an experiment--the choice of bead size, tether length, and even the method in which the motions of the beads are monitored--can have a large impact on the fundamental resolution of the measurement. By investigating how the Brownian fluct...
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PMID: 20147040
PDF is available here.
PDF is available here.
Abstract
We describe methods of data detection and calibration for our dual-trap design....
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PMID: 20147039
PDF is available here.
PDF is available here.
Abstract
We can detect length changes to a DNA molecule tethering the trapped beads of 1 bp. By forming two traps from the same laser and maximizing the common optical paths of the two trapping beams, we decouple the instrument from many sources of environmental and instrumental noise that typically limit sp...
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PMID: 20147041
PDF is available here.
PDF is available here.
Abstract
We briefly review the basic concepts and components of optical traps and the single-molecule experiments in which they are used....
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PMID: 20147062
PDF is available here.
PDF is available here.
Optics Express (17)20 2009
Abstract
We demonstrate the benefits of using various lengths of In(2)O(3) nanowires by using non-contact mechanisms, such as scanning optical tweezers, to place them on designated targets during the fabrication process. Furthermore, these nanowires can be stabilized at both ends of the conducting wires usin...
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PMID: 19907533
PDF is available here.
PDF is available here.
Optics Letters (34)15 2009
Abstract
We show how both ways can be combined on an optofluidic chip in a fully planar geometry utilizing counterpropagating liquid-core waveguide modes to form a loss-based optical trap. This all-optical concentrator can increase the concentration of particles by more than 2 orders of magnitude and also pr...
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PMID: 19649079
PDF is available here.
PDF is available here.