Recent Advances in Optical Tweezers

Department of Physics, University of California, Berkeley, CA 94720, USA.
Annual Review of Biochemistry (Impact Factor: 30.28). 08/2008; 77(1):205-28. DOI: 10.1146/annurev.biochem.77.043007.090225
Source: PubMed


It has been over 20 years since the pioneering work of Arthur Ashkin, and in the intervening years, the field of optical tweezers has grown tremendously. Optical tweezers are now being used in the investigation of an increasing number of biochemical and biophysical processes, from the basic mechanical properties of biological polymers to the multitude of molecular machines that drive the internal dynamics of the cell. Innovation, however, continues in all areas of instrumentation and technique, with much of this work focusing on the refinement of established methods and on the integration of this tool with other forms of single-molecule manipulation or detection. Although technical in nature, these developments have important implications for the expanded use of optical tweezers in biochemical research and thus should be of general interest. In this review, we address these recent advances and speculate on possible future developments.

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Available from: Jeffrey R Moffitt, Apr 18, 2014
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    • "These methods generally probe large ensembles of cells and molecules, and do not provide information on molecular interaction forces. By contrast, several force-measuring techniques have been developed to measure molecular forces on cell surfaces, including optical and magnetic tweezers, and atomic force microscopy (AFM) (Tanase et al., 2007; Moffitt et al., 2008; Neuman and Nagy, 2008). Among these tools, AFM is the only method that can simultaneously quantify and localize specific forces on cells, at a resolution of a few nanometers. "
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    ABSTRACT: Staphylococcus epidermidis and Staphylococcus aureus are two important nosocomial pathogens that form biofilms on indwelling medical devices. Biofilm infections are difficult to fight as cells within the biofilm show increased resistance to antibiotics. Our understanding of the molecular interactions driving bacterial adhesion, the first stage of biofilm formation, has long been hampered by the paucity of appropriate force-measuring techniques. In this minireview, we discuss how atomic force microscopy techniques have enabled to shed light into the molecular forces at play during staphylococcal adhesion. Specific highlights include the study of the binding mechanisms of adhesion molecules by means of single-molecule force spectroscopy, the measurement of the forces involved in whole cell interactions using single-cell force spectroscopy, and the probing of the nanobiophysical properties of living bacteria via multiparametric imaging. Collectively, these findings emphasize the notion that force and function are tightly connected in staphylococcal adhesion.
    Full-text · Article · Dec 2015 · Journal of Structural Biology
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    • "al . , 1986 ) , which allow micromanipulation of cells and molecules using forces and displacements in the piconewton ( pN ) and nanometer ( nm ) ranges respectively , corresponding to the scales of important physical and biological events . Thus , OT represents an ideal technique to study biological phenomena in detail ( Neuman and Block , 2004 ; Moffitt et al . , 2008 ) . OT applications range from the study of molecular motors at single - molecule level ( Veigel and Schmidt , 2011 ; Elting and Spudich , 2012 ) , to the determination of the mechanical properties of biopolymers ( Greenleaf et al . , 2007 ) , and cellular structures ( Pontes et al . , 2008 , 2011 , 2013 ) . An OT is formed by focusing "
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    Full-text · Article · Jun 2015 · Frontiers in Microbiology
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    • "This approach does not permit easy adjustment of the amount of torque or independent measurement and application of force and torque, and so more complicated designs using electromagnets and multiple coils around inverted microscopes have been built.[32] [33] Magnetic tweezers alone struggle to manipulate DNA torque and end-to-end extension independently in 3D; for this, optical tweezers represent a promising tool.[34] Systems with both optical and magnetic tweezers have been built before[35] [36] but the movement of the proteins and DNA investigated with such systems was inferred from bead position rather than the molecules directly. "
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    ABSTRACT: DNA-interacting proteins have roles multiple processes, many operating as molecular machines which undergo dynamic metastable transitions to bring about their biological function. To fully understand this molecular heterogeneity, DNA and the proteins that bind to it must ideally be interrogated at a single molecule level in their native in vivo environments, in a time-resolved manner fast to sample the molecular transitions across the free energy landscape. Progress has been made over the past decade in utilising cutting-edge tools of the physical sciences to address challenging biological questions concerning the function and modes of action of several different proteins which bind to DNA. These physiologically relevant assays are technically challenging, but can be complemented by powerful and often more tractable in vitro experiments which confer advantages of the chemical environment with enhanced detection single-to-noise of molecular signatures and transition events. Here, we discuss a range of techniques we have developed to monitor DNA-protein interactions in vivo, in vitro and in silico. These include bespoke single-molecule fluorescence microscopy techniques to elucidate the architecture and dynamics of the bacterial replisome and the structural maintenance of bacterial chromosomes, as well as new computational tools to extract single-molecule molecular signatures from live cells to monitor stoichiometry, spatial localization and mobility in living cells. We also discuss recent developments from our lab made in vitro, complementing these in vivo studies, which combine optical and magnetic tweezers to manipulate and image single molecules of DNA, with and without bound protein, in a new superresolution fluorescence microscope.
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