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Kishimoto T, Masui K, Minoshima W, Hosokawa C. Recent advances in optical manipulation of cells and molecules for biological science. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY C: PHOTOCHEMISTRY REVIEWS 2022. [DOI: 10.1016/j.jphotochemrev.2022.100554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Optimized cutting laser trajectory for laser capture microdissection. Biologia (Bratisl) 2019. [DOI: 10.2478/s11756-019-00234-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Sakuta H, Seo S, Kimura S, Hörning M, Sadakane K, Kenmotsu T, Tanaka M, Yoshikawa K. Optical Fluid Pump: Generation of Directional Flow via Microphase Segregation/Homogenization. J Phys Chem Lett 2018; 9:5792-5796. [PMID: 30222363 DOI: 10.1021/acs.jpclett.8b01876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We report the successful generation of directional liquid-flow under stationary laser irradiation at a fixed position in a chamber. We adopt a homogeneous solution consisting of a mixture of water and triethylamine (TEA), with a composition near the critical point for phase segregation. When geometrical asymmetry is introduced around the laser focus in the chamber, continuous directional flow is generated, accompanied by the emergence of water-rich microdroplets at the laser focus. The emerging microdroplets tend to escape toward the surrounding bulk solution and then merge/annihilate into the homogeneous solution. The essential features of the directional flow are reproduced through a simple numerical simulation using fluid dynamic equations.
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Affiliation(s)
- Hiroki Sakuta
- Faculty of Life and Medical Sciences , Doshisha University , Kyotanabe 610-0394 , Japan
| | - Shunsuke Seo
- Faculty of Life and Medical Sciences , Doshisha University , Kyotanabe 610-0394 , Japan
| | - Shuto Kimura
- Faculty of Life and Medical Sciences , Doshisha University , Kyotanabe 610-0394 , Japan
| | - Marcel Hörning
- Institute of Biomaterials and Biomolecular Systems , University of Stuttgart , Stuttgart 70569 , Germany
- Institute for Integrated Cell-Material Sciences , Kyoto University , Kyoto 606-8501 , Japan
| | - Koichiro Sadakane
- Faculty of Life and Medical Sciences , Doshisha University , Kyotanabe 610-0394 , Japan
| | - Takahiro Kenmotsu
- Faculty of Life and Medical Sciences , Doshisha University , Kyotanabe 610-0394 , Japan
| | - Motomu Tanaka
- Institute for Integrated Cell-Material Sciences , Kyoto University , Kyoto 606-8501 , Japan
- Institute of Physical Chemistry , University of Heidelberg , Heidelberg 69120 , Germany
- Center for Integrative Medicine and Physics Institute for Advanced Study , Kyoto University , Kyoto 606-8501 , Japan
| | - Kenichi Yoshikawa
- Faculty of Life and Medical Sciences , Doshisha University , Kyotanabe 610-0394 , Japan
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Jin Q, Wang L, Yan S, Wei H, Huang Y. Plasmonic nano-tweezer based on square nanoplate tetramers. APPLIED OPTICS 2018; 57:5328-5332. [PMID: 30117824 DOI: 10.1364/ao.57.005328] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The research fields of trapping nanoparticles have experienced a huge development in recent years, which mainly benefits from the unique field enhancement in plasmonic nanomaterials. Since the large field enhancement originates from the excited localized surface plasmon at the metal surface, exploring novel metal nanostructures with high trapping efficiency is always the main goal in this field. In this work, the plasmonic trapping of nanoparticles based on the gold periodic square tetramers (PST) was investigated through full-wave simulations using the finite-difference time-domain (FDTD) method. The electric field and surface charge distributions on the surface of PST indicate that both the trapping position and efficiency are influenced by orientations of the square nanoplates. The maximum electromagnetic enhancement is achieved when all square nanoplates rotate 45° along the z axis. Therefore, the gradient force and trapping potential of this PST with optimal orientation were further studied, and the results indicate that a dielectric nanoparticle of 15 nm radius can be stably captured. Furthermore, the calculation results show that the plasmonic trapping with this PST exhibits strong polarization dependence. It is easy to change the trapping position and the field intensity by tuning the polarization of the incident wave. Our work enables a deeper understanding of this kind of plasmonic trapping and could have potential applications in biomedical research and life science.
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Pollari R, Milstein JN. Accounting for polarization in the calibration of a donut beam axial optical tweezers. PLoS One 2018; 13:e0193402. [PMID: 29474494 PMCID: PMC5825067 DOI: 10.1371/journal.pone.0193402] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Accepted: 02/09/2018] [Indexed: 11/18/2022] Open
Abstract
Advances in light shaping techniques are leading to new tools for optical trapping and micromanipulation. For example, optical tweezers made from Laguerre-Gaussian or donut beams display an increased axial trap strength and can impart angular momentum to rotate a specimen. However, the application of donut beam optical tweezers to precision, biophysical measurements remains limited due to a lack of methods for calibrating such devices sufficiently. For instance, one notable complication, not present when trapping with a Gaussian beam, is that the polarization of the trap light can significantly affect the tweezers’ strength as well as the location of the trap. In this article, we show how to precisely calibrate the axial trap strength as a function of height above the coverslip surface while accounting for focal shifts in the trap position arising from radiation pressure, mismatches in the index of refraction, and polarization induced intensity variations. This provides a foundation for implementing a donut beam optical tweezers capable of applying precise axial forces.
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Affiliation(s)
- Russell Pollari
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, ON, Canada
- Department of Physics, University of Toronto, Toronto, ON, Canada
| | - Joshua N. Milstein
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, ON, Canada
- Department of Physics, University of Toronto, Toronto, ON, Canada
- * E-mail:
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Ishii S, Kawai M, Ishiwata S, Suzuki M. Estimation of actomyosin active force maintained by tropomyosin and troponin complex under vertical forces in the in vitro motility assay system. PLoS One 2018; 13:e0192558. [PMID: 29420610 PMCID: PMC5805308 DOI: 10.1371/journal.pone.0192558] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Accepted: 01/25/2018] [Indexed: 12/02/2022] Open
Abstract
The interaction between actin filaments and myosin molecular motors is a power source of a variety of cellular functions including cell division, cell motility, and muscular contraction. In vitro motility assay examines actin filaments interacting with myosin molecules that are adhered to a substrate (e.g., glass surface). This assay has been the standard method of studying the molecular mechanisms of contraction under an optical microscope. While the force generation has been measured through an optically trapped bead to which an actin filament is attached, a force vector vertical to the glass surface has been largely ignored with the in vitro motility assay. The vertical vector is created by the gap (distance) between the trapped bead and the glass surface. In this report, we propose a method to estimate the angle between the actin filament and the glass surface by optically determining the gap size. This determination requires a motorized stage in a standard epi-fluorescence microscope equipped with optical tweezers. This facile method is applied to force measurements using both pure actin filaments, and thin filaments reconstituted from actin, tropomyosin and troponin. We find that the angle-corrected force per unit filament length in the active condition (pCa = 5.0) decreases as the angle between the filament and the glass surface increases; i.e. as the force in the vertical direction increases. At the same time, we demonstrate that the force on reconstituted thin filaments is approximately 1.5 times larger than that on pure actin filaments. The range of angles we tested was between 11° and 36° with the estimated measurement error less than 6°. These results suggest the ability of cytoplasmic tropomyosin isoforms maintaining actomyosin active force to stabilize cytoskeletal architecture.
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Affiliation(s)
- Shuya Ishii
- Department of Physics, Faculty of Science and Engineering, Waseda University, Tokyo, Japan
| | - Masataka Kawai
- Department of Anatomy and Cell Biology, College of Medicine, University of Iowa, Iowa City, IA, United States of America
| | - Shin'ichi Ishiwata
- Department of Physics, Faculty of Science and Engineering, Waseda University, Tokyo, Japan
| | - Madoka Suzuki
- PRESTO, Japan Science and Technology Agency (JST), Saitama, Kawaguchi, Japan
- Research Institute for Science and Engineering, Waseda University, Tokyo, Japan
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Leartprapun N, Iyer RR, Adie SG. Depth-resolved measurement of optical radiation-pressure forces with optical coherence tomography. OPTICS EXPRESS 2018; 26:2410-2426. [PMID: 29401781 PMCID: PMC5901099 DOI: 10.1364/oe.26.002410] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
A weakly focused laser beam can exert sufficient radiation pressure to manipulate microscopic particles over a large depth range. However, depth-resolved continuous measurement of radiation-pressure force profiles over an extended range about the focal plane has not been demonstrated despite decades of research on optical manipulation. Here, we present a method for continuous measurement of axial radiation-pressure forces from a weakly focused beam on polystyrene micro-beads suspended in viscous fluids over a depth range of 400 μm, based on real-time monitoring of particle dynamics using optical coherence tomography (OCT). Measurements of radiation-pressure forces as a function of beam power, wavelength, bead size, and refractive index are consistent with theoretical trends. However, our continuous measurements also reveal localized depth-dependent features in the radiation-pressure force profiles that deviate from theoretical predictions based on an aberration-free Gaussian beam. The combination of long-range radiation pressure and OCT offers a new mode of quantitative optical manipulation and detection with extended spatial coverage. This may find applications in the characterization of optical tractor beams, or volumetric optical manipulation and interrogation of beads in viscoelastic media.
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Pollari R, Milstein JN. Improved axial trapping with holographic optical tweezers. OPTICS EXPRESS 2015; 23:28857-28867. [PMID: 26561154 DOI: 10.1364/oe.23.028857] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Conventional optical tweezers suffer from several complications when applying axial forces to surface-tethered molecules. Aberrations from the refractive-index mismatch between an oil-immersion objective's medium and the aqueous trapping environment both shift the trap centre and degrade the trapping strength with focal depth. Furthermore, interference effects from back-scattered light make it difficult to use back-focal-plane interferometry for high-bandwidth position detection. Holographic optical tweezers were employed to correct for aberrations to achieve a constant axial stiffness and modulate artifacts from backscattered light. Once the aberrations are corrected for, the trap height can be precisely determined from either the back-scattered light or Brenner's formula.
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