In Vivo Manipulation of Single Biological Cells With an Optical Tweezers-Based Manipulator and a Disturbance Compensation Controller

2017 ◽  
Vol 33 (5) ◽  
pp. 1200-1212 ◽  
Author(s):  
Xiaojian Li ◽  
Chichi Liu ◽  
Shuxun Chen ◽  
Yong Wang ◽  
Shuk Han Cheng ◽  
...  
Keyword(s):  
Optical Tweezers ◽  
Biological Cells ◽  
Disturbance Compensation

scholarly journals Force generation by protein–DNA co-condensation

2021 ◽  
Author(s):  
Thomas Quail ◽  
Stefan Golfier ◽  
Maria Elsner ◽  
Keisuke Ishihara ◽  
Vasanthanarayan Murugesan ◽  
...  
Keyword(s):  
Optical Tweezers ◽  
Self Assembly ◽  
Spider Silk ◽  
Regulatory Elements ◽  
Heterochromatin Formation ◽  
First Order Phase Transition ◽  
Dna Strand ◽  
First Order Phase

AbstractInteractions between liquids and surfaces generate forces1,2 that are crucial for many processes in biology, physics and engineering, including the motion of insects on the surface of water3, modulation of the material properties of spider silk4 and self-assembly of microstructures5. Recent studies have shown that cells assemble biomolecular condensates via phase separation6. In the nucleus, these condensates are thought to drive transcription7, heterochromatin formation8, nucleolus assembly9 and DNA repair10. Here we show that the interaction between liquid-like condensates and DNA generates forces that might play a role in bringing distant regulatory elements of DNA together, a key step in transcriptional regulation. We combine quantitative microscopy, in vitro reconstitution, optical tweezers and theory to show that the transcription factor FoxA1 mediates the condensation of a protein–DNA phase via a mesoscopic first-order phase transition. After nucleation, co-condensation forces drive growth of this phase by pulling non-condensed DNA. Altering the tension on the DNA strand enlarges or dissolves the condensates, revealing their mechanosensitive nature. These findings show that DNA condensation mediated by transcription factors could bring distant regions of DNA into close proximity, suggesting that this physical mechanism is a possible general regulatory principle for chromatin organization that may be relevant in vivo.

Large Deformation of Biological Cells by Optical Tweezers

2003 ◽  
Author(s):  
S. Suresh ◽  
C. T. Lim ◽  
M. Dao
Keyword(s):  
Optical Tweezers ◽  
Mechanical Test ◽  
Living Cells ◽  
Test Methods ◽  
Mechanical Forces ◽  
Deformation Characteristics ◽  
Biological Cells ◽  
Whole Cells ◽  
Aspiration Technique ◽  
Stress States

The chemical and biological functions of living cells are known to be influenced strongly by mechanical forces and deformation, and the ability of cells to detect and support forces, in turn, is also affected by chemical and biological factors. Furthermore, the progression of a number of inherited and infectious diseases have also been identified to have a strong correlation with the mechanical deformation characteristics of biological cells. Consequently, the deformation characteristics of whole cells and cell membranes have long been investigated using a variety of experimental methods, such as the micropipette aspiration technique, and by computational modeling (see, for example, refs. [1, 2]). Recent advances in experimental techniques capable of probing mechanical forces and displacements to a resolution of picoNewton and nanometer, respectively, have facilitated use of mechanical test methods for living cells whereby precise measurements of response under different stress states could be investigated.

scholarly journals Hemodynamic forces can be accurately measured in vivo with optical tweezers

2017 ◽  
Author(s):  
Sébastien Harlepp ◽  
Fabrice Thalmann ◽  
Gautier Follain ◽  
Jacky G. Goetz
Keyword(s):  
Optical Tweezers ◽  
Cell Biology ◽  
Accurate Determination ◽  
Force Measurements ◽  
Hemodynamic Forces ◽  
Non Invasive ◽  
Drag Forces ◽  
Measured Flow ◽  
Living Organisms

AbstractForce sensing and generation at the tissular and cellular scale is central to many biological events. There is a growing interest in modern cell biology for methods enabling force measurements in vivo. Optical trapping allows non-invasive probing of pico-Newton forces and thus emerged as a promising mean for assessing biomechanics in vivo. Nevertheless, the main obstacles rely in the accurate determination of the trap stiffness in heterogeneous living organisms, at any position where the trap is used. A proper calibration of the trap stiffness is thus required for performing accurate and reliable force measurements in vivo. Here, we introduce a method that overcomes these difficulties by accurately measuring hemodynamic profiles in order to calibrate the trap stiffness. Doing so, and using numerical methods to assess the accuracy of the experimental data, we measured flow profiles and drag forces imposed to trapped red blood cells of living zebrafish embryos. Using treatments enabling blood flow tuning, we demonstrated that such method is powerful in measuring hemodynamic forces in vivo with accuracy and confidence. Altogether, this study demonstrates the power of optical tweezing in measuring low range hemodynamic forces in vivo and offers an unprecedented tool in both cell and developmental biology.

scholarly journals Bio-Molecular Applications of Recent Developments in Optical Tweezers

Biomolecules ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 23 ◽  
Author(s):  
Dhawal Choudhary ◽  
Alessandro Mossa ◽  
Milind Jadhav ◽  
Ciro Cecconi
Keyword(s):  
Photonic Crystal ◽  
Optical Tweezers ◽  
Single Molecule ◽  
Continuous Wave ◽  
Imaging Techniques ◽  
Resolving Power ◽  
Optical Traps ◽  
Laser Source ◽  
One Dimensional

In the past three decades, the ability to optically manipulate biomolecules has spurred a new era of medical and biophysical research. Optical tweezers (OT) have enabled experimenters to trap, sort, and probe cells, as well as discern the structural dynamics of proteins and nucleic acids at single molecule level. The steady improvement in OT’s resolving power has progressively pushed the envelope of their applications; there are, however, some inherent limitations that are prompting researchers to look for alternatives to the conventional techniques. To begin with, OT are restricted by their one-dimensional approach, which makes it difficult to conjure an exhaustive three-dimensional picture of biological systems. The high-intensity trapping laser can damage biological samples, a fact that restricts the feasibility of in vivo applications. Finally, direct manipulation of biological matter at nanometer scale remains a significant challenge for conventional OT. A significant amount of literature has been dedicated in the last 10 years to address the aforementioned shortcomings. Innovations in laser technology and advances in various other spheres of applied physics have been capitalized upon to evolve the next generation OT systems. In this review, we elucidate a few of these developments, with particular focus on their biological applications. The manipulation of nanoscopic objects has been achieved by means of plasmonic optical tweezers (POT), which utilize localized surface plasmons to generate optical traps with enhanced trapping potential, and photonic crystal optical tweezers (PhC OT), which attain the same goal by employing different photonic crystal geometries. Femtosecond optical tweezers (fs OT), constructed by replacing the continuous wave (cw) laser source with a femtosecond laser, promise to greatly reduce the damage to living samples. Finally, one way to transcend the one-dimensional nature of the data gained by OT is to couple them to the other large family of single molecule tools, i.e., fluorescence-based imaging techniques. We discuss the distinct advantages of the aforementioned techniques as well as the alternative experimental perspective they provide in comparison to conventional OT.

Measuring stall forces in vivo with optical tweezers through light momentum changes

2011 ◽  
Author(s):  
J. Mas ◽  
A. Farré ◽  
C. López-Quesada ◽  
X. Fernández ◽  
E. Martín-Badosa ◽  
...  
Keyword(s):  
Optical Tweezers

Bio-Resorbable Nanoceramics for Gene and Drug Delivery

MRS Bulletin ◽  
2004 ◽  
Vol 29 (1) ◽  
pp. 33-37 ◽  
Author(s):  
Waltraud M. Kriven ◽  
Seo-Young Kwak ◽  
Matthew A. Wallig ◽  
Jin-Ho Choy
Keyword(s):  
Drug Delivery ◽  
Controlled Release ◽  
Layered Double Hydroxides ◽  
Negative Charge ◽  
Acidic Environment ◽  
Biological Cells ◽  
Double Hydroxides ◽  
Or Genes

AbstractNanoscale ceramic particles, such as layered double hydroxides (LDHs), have been developed to deliver drugs or genes into biological cells. In this article, we describe the controlled-release properties of LDHs as drug delivery carriers, the formation of bio-LDH nanohybrids, theirin vivoandin vitrocytotoxicity tests, and their potential as anticancer gene delivery carriers. Unstable biomolecules can be intercalated into LDHs, displacing the interlayer anions; the drug or gene's negative charge is thus shielded, enabling penetration into the cell. In the slightly acidic environment of the cell, ceramic nanoplatelets of ∼100 nm diameter dissolve, thus releasing the intercalates in a controlled manner.

scholarly journals Mechanically switching single-molecule fluorescence of GFP by unfolding and refolding

2017 ◽  
Vol 114 (42) ◽  
pp. 11052-11056 ◽  
Author(s):  
Ziad Ganim ◽  
Matthias Rief
Keyword(s):  
Optical Tweezers ◽  
Single Molecule ◽  
Optical Sensors ◽  
Structural Integrity ◽  
Fluorescent Protein ◽  
Single Molecule Fluorescence ◽  
Extended States ◽  
Green Fluorescent ◽  
Ensemble Experiments

Green fluorescent protein (GFP) variants are widely used as genetically encoded fluorescent fusion tags, and there is an increasing interest in engineering their structure to develop in vivo optical sensors, such as for optogenetics and force transduction. Ensemble experiments have shown that the fluorescence of GFP is quenched upon denaturation. Here we study the dependence of fluorescence on protein structure by driving single molecules of GFP into different conformational states with optical tweezers and simultaneously probing the chromophore with fluorescence. Our results show that fluorescence is lost during the earliest events in unfolding, 3.5 ms before secondary structure is disrupted. No fluorescence is observed from the unfolding intermediates or the ensemble of compact and extended states populated during refolding. We further demonstrate that GFP can be mechanically switched between emissive and dark states. These data definitively establish that complete structural integrity is necessary to observe single-molecule fluorescence of GFP.

In vivo vascular flow profiling combined with optical tweezers based blood routing

2017 ◽  
Author(s):  
Robert Meissner ◽  
Wade W. Sugden ◽  
Arndt F. Siekmann ◽  
Cornelia Denz
Keyword(s):  
Optical Tweezers ◽  
Vascular Flow
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