Optical surfaces coated with a thin layer to improve light transmission are ubiquitous in everyday optical applications as well industrial and scientific instruments. Discovered first 1817 by Fraunhofer, the coating of lenses became standard practice 1930s. In spite intensive research, broad-band antireflection coatings still limited lack materials low refractive indices. A method based on phase separation macromolecular liquid generate nanoporous polymer films is demonstrated that creates...

The development of synthetic nanomotors for technological applications in particular life science and nanomedicine is a key focus current basic research. However, it has been challenging to make active nanosystems based on biocompatible materials consuming nontoxic fuels providing self-propulsion. Here, we fabricate self-propelled Janus hollow mesoporous silica nanoparticles (HMSNPs), which are powered by biocatalytic reactions three different enzymes: catalase, urease, glucose oxidase...

During unequal cell divisions a mitotic spindle is eccentrically positioned before cleavage. To determine the basis of net force imbalance that causes displacement in one-cell Caenorhabditis elegans embryos, we fragmented centrosomes with an ultraviolet laser. Analysis mean and variance fragment speeds suggests due to larger number generators pulling on astral microtubules posterior aster relative anterior aster. Moreover, activation heterotrimeric guanine nucleotide- binding protein...

We explain and demonstrate a new method of force position calibrations for optical tweezers with back-focal-plane photodetection. The combines power spectral measurements thermal motion the response to sinusoidal translation stage. It consequently does not use drag coefficient trapped object as an input. Thus, neither viscosity, nor size object, its distance nearby surfaces needs be known. requires only low level instrumentation can applied in situ all spatial dimensions. is both accurate...

The use of enzyme catalysis to power micro- and nanomachines offers unique features such as biocompatibility, versatility, fuel bioavailability. Yet, the key parameters underlying motion behavior enzyme-powered motors are not completely understood. Here, we investigate role distribution quantity on generation active motion. Two different micromotor architectures based either polystyrene (PS) or coated with a rough silicon dioxide shell (PS@SiO2) were explored. A directional propulsion higher...

Biocatalytic micro- and nanomotors have emerged as a new class of active matter self-propelled through enzymatic reactions. The incorporation functional nanotools could enable the rational design multifunctional micromotors for simultaneous real-time monitoring their environment activity. Herein, we report combination DNA nanotechnology urease-powered tools able to swim, simultaneously sense pH surrounding environment, monitor intrinsic With this purpose, FRET-labeled triplex nanoswitch...

We have studied the influence of electric fields on highly viscous polymer films. An electrohydrodynamic (EHD) instability causes a wave pattern with characteristic wavelength λ, leading to an array columns which span gap capacitor device. When represented as master curve, data is quantitatively described by EHD model, without any adjustable parameters. Our results suggest that experiments using films are well suited study non-equilibrium formation in quasi-two-dimensional systems.

Optical tweezers are widely used to measure molecular forces in biology. Such measurements often influenced by a nearby surface that can perturb both the calibration of as well hydrodynamic acting on microspheres which biomolecules attached. In this study, we have very stable optical setup employing recently developed method (Tolić-Nørrelykke, S. F.; Schäffer, E.; Howard, J.; Pavone, F. S.; Jülicher, Flyvbjerg, H. Rev. Sci. Instrum. 2006, 77 (10), 103101) determine how and depend height...

Friction limits the operation of macroscopic engines and is critical to performance micromechanical devices. We report measurements friction in a biological nanomachine. Using optical tweezers, we characterized frictional drag force individual kinesin-8 motor proteins interacting with their microtubule tracks. At low speeds no energy source, was related diffusion coefficient by Einstein relation. higher speeds, increased nonlinearly, consistent jumping 8 nanometers between adjacent tubulin...

Kinesin motors are essential for the transport of cellular cargo along microtubules. How step, detach, and cooperate with each other is still unclear. To dissect molecular motion kinesin-1, we developed germanium nanospheres as ultraresolution optical trapping probes. We found that single took 4-nanometer center-of-mass steps. Furthermore, kinesin-1 never detached from microtubules under hindering load conditions. Instead, it slipped on in microsecond-long, 8-nanometer steps remained this...

Significance Given the importance of cytoskeletal motor proteins, we asked whether translational motors rotate while walking along their tracks. Using an optical tweezers-based approach, simultaneously measured translation, force, rotation, and torque a kinesin with molecular resolution. We found that gait followed rotary stepping mechanism generates spins cargo. Thus, during walking, “tail (and organelle) will tend to wind up like rubber band toy airplane,” as Joe Howard hypothesized in...

External electric fields were used to amplify thermal fluctuations at the interface between two thin liquid films. Similar results shown previously for enhancement of polymer/air interface, interfacial having a well-defined wavelength enhanced with characteristic growth rate. A simple theoretical framework describe experimental observations is presented. Both experiment and model calculation show substantial reduction in feature size as result change surface/interfacial energy when going...

Subjecting a liquid/liquid interface to an electrohydrodynamic pressure enhances fluctuations with characteristic wavelength leading instability and the formation of well-defined columnar structures. An extension linear stability analysis for single fluid bilayer case produced general arguments applicable any interface. Countering is Laplace pressure, which films dictated by surface energy; whereas bilayer, it given in terms interfacial energy. Consequently, length scale reduced bilayers....

When studying microtubules in vitro, label free imaging of single is necessary when the quantity purified tubulin too low for efficient fluorescent labelling or there concern that will disrupt function. Commonly used techniques observing unlabelled microtubules, such as video enhanced differential interference contrast, dark-field and more recently laser-based interferometric scattering microscopy, suffer from a number drawbacks. The contrast images depends on orientation highly sensitive to...

Genome maintenance and stability rely on the repair of DNA double-strand breaks. Breaks can be repaired via single-strand-annealing pathway mediated by protein RAD52. RAD52 oligomerizes to rings that are thought promote annealing. However, have only been observed at micromolar concentrations which annealing activity is impaired. Thus, it unclear oligomeric form responsible for We combined single-molecule mass photometry with biochemical assays determine in vitro states human found was mostly...

We used video microscopy to study the pinning dynamics of air/water contact lines in vertical glass capillaries. Stick-slip behavior and avalanches are observed tubes with rough interior walls strong forces. In smooth walls, we find that receding falling water columns show no evidence pinning, but advancing rising exhibit algebraic slow down. The measured value critical exponent beta varies from run run, it is always larger than unity. Furthermore, rise waiting time preceding experiments....

External electric fields were used to amplify interfacial fluctuations in the air/polymer/polymer system where one polymer dewets other. Two different hydrodynamic regimes found as a function of field strength. If heterogeneous nucleation leads formation holes before electrostatically driven instability sets in, dewetting kinetics is not influenced by field. Stronger lead spinodal electrohydrodynamic which causes columns on top second polymer. The rapid column substantial deformation lower...

The use of optical traps to measure or apply forces on the molecular level requires a precise knowledge trapping force field. Close trap center, this field is typically approximated as linear in displacement trapped microsphere. However, applications demanding high at low laser intensities can probe light-microsphere interaction beyond regime. Here, we measured full nonlinear and response an two dimensions using dual-beam setup with back-focal-plane photodetection. We observed substantial...