Optical Manipulation of Objects in Microfluidic Devices

2002 ◽  
Vol 729 ◽  
Author(s):  
Erhan Ata ◽  
Aaron L. Birkbeck ◽  
Mihrimah Ozkan ◽  
Cengiz S. Ozkan ◽  
Richard Flynn ◽  
...  
Keyword(s):  
Optical Tweezers ◽  
Cell Biology ◽  
Optical Power ◽  
Microfluidic Devices ◽  
Live Cells ◽  
Optical Manipulation ◽  
Polystyrene Spheres ◽  
Pdms Elastomer ◽  
Photon Interactions ◽  
Vcsel Arrays

AbstractIn this paper, we present object manipulation methodologies in microfluidic devices based on object-photon interactions. Devices were fabricated by polydimethylsiloxane (PDMS) elastomer molding of channel structures over photolithographically defined patterns using a thick negative photoresist. Inorganic objects including polystyrene spheres and organic objects including live cells were transferred into fluidic channels using a syringe pump. The objects were trapped and manipulated within the fluidic channels using optical tweezers formed by VCSEL arrays, with only a few mW of optical power. We have also shown that it is possible to manipulate multiple objects as a whole assemble by using an optically-trapped particle as a handle, or an “optical handle”. Optical manipulation will have applications in biomedical devices for drug discovery, cytometry and cell biology research.

Optical Manipulation of Inorganic and Organic Objects in Soft Microfluidic Devices

2000 ◽  
Vol 657 ◽  
Author(s):  
Cengiz S. Ozkan ◽  
Erhan Ata ◽  
Mihrimah Ozkan ◽  
Sadik C. Esener
Keyword(s):  
Optical Tweezers ◽  
Cell Sorting ◽  
Cell Biology ◽  
Microfluidic Devices ◽  
Optical Manipulation ◽  
Microfluidic Channels ◽  
Negative Photoresist ◽  
Pdms Elastomer ◽  
Biology Research ◽  
Inorganic And Organic

ABSTRACTWe describe a technique for trapping and manipulation of inorganic and organic objects in microfluidic channels, based on photonic momentum transfer using an optical tweezers arrangement. Microfluidic devices have been fabricated by polydimethylsiloxane (PDMS) elastomer molding of patterns lithographically defined on a thick negative photoresist. Polystyrene microspheres dispersed in water were transferred into the fluidic channels using a syringe pump. Microspheres and live biological cells are trapped and redirected by optical manipulation within the fluidic channels. Optical trapping and patterning will have applications in creation of active cellular arrays for cell biology research, tissue engineering, cell sorting and drug discovery.

scholarly journals Cell Biology of Conidial Anastomosis Tubes in Neurospora crassa

2005 ◽  
Vol 4 (5) ◽  
pp. 911-919 ◽  
Author(s):  
M. Gabriela Roca ◽  
Jochen Arlt ◽  
Chris E. Jeffree ◽  
Nick D. Read
Keyword(s):  
Neurospora Crassa ◽  
Optical Tweezers ◽  
Cell Biology ◽  
Transmembrane Protein ◽  
Mitogen Activated Protein Kinase ◽  
Cellular Element ◽  
Hyphal Fusion ◽  
Self Recognition ◽  
Mitogen Activated Protein ◽  
Germ Tubes

ABSTRACT Although hyphal fusion has been well documented in mature colonies of filamentous fungi, it has been little studied during colony establishment. Here we show that specialized hyphae, called conidial anastomosis tubes (CATs), are produced by all types of conidia and by conidial germ tubes of Neurospora crassa. The CAT is shown to be a cellular element that is morphologically and physiologically distinct from a germ tube and under separate genetic control. In contrast to germ tubes, CATs are thinner, shorter, lack branches, exhibit determinate growth, and home toward each other. Evidence for an extracellular CAT inducer derived from conidia was obtained because CAT formation was reduced at low conidial concentrations. A cr-1 mutant lacking cyclic AMP (cAMP) produced CATs, indicating that the inducer is not cAMP. Evidence that the transduction of the CAT inducer signal involves a putative transmembrane protein (HAM-2) and the MAK-2 and NRC-1 proteins of a mitogen-activated protein kinase signaling pathway was obtained because ham-2, mak-2, and nrc-1 mutants lacked CATs. Optical tweezers were used in a novel experimental assay to micromanipulate whole conidia and germlings to analyze chemoattraction between CATs during homing. Strains of the same and opposite mating type were shown to home toward each other. The cr-1 mutant also underwent normal homing, indicating that cAMP is not the chemoattractant. ham-2, mak-2, and nrc-1 macroconidia did not attract CATs of the wild type. Fusion between CATs of opposite mating types was partially inhibited, providing evidence of non-self-recognition prior to fusion. Microtubules and nuclei passed through fused CATs.

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.

Tomographic phase microscopy with 180° rotation of live cells in suspension by holographic optical tweezers

2015 ◽  
Vol 40 (8) ◽  
pp. 1881 ◽  
Author(s):  
Mor Habaza ◽  
Barak Gilboa ◽  
Yael Roichman ◽  
Natan T. Shaked
Keyword(s):  
Optical Tweezers ◽  
Live Cells ◽  
Phase Microscopy ◽  
Holographic Optical Tweezers

Hydrodynamically-Confined Microflows for Cell Adhesion Strength Measurement

2010 ◽  
Author(s):  
Kevin V. Christ ◽  
Kevin T. Turner
Keyword(s):  
Cell Adhesion ◽  
Adhesion Strength ◽  
Cell Biology ◽  
Microfluidic Devices ◽  
Cell Behavior ◽  
Shear Stresses ◽  
Strength Measurement ◽  
Coated Surfaces ◽  
Biology Research ◽  
Standard Techniques

Cell adhesion plays a fundamental role in numerous physiological and pathological processes, and measurements of the adhesion strength are important in fields ranging from basic cell biology research to the development of implantable biomaterials. Our group and others have recently demonstrated that microfluidic devices offer advantages for characterizing the adhesion of cells to protein-coated surfaces [1,2]. Microfluidic devices offer many advantages over conventional assays, including the ability to apply high shear stresses in the laminar regime and the opportunity to directly observe cell behavior during testing. However, a key disadvantage is that such assays require cells to be cultured inside closed microchannels. Assays based on closed channels restrict the types of surfaces that can be examined and are not compatible with many standard techniques in cell biology research. Furthermore, while techniques for cell culture in microchannels have become common, maintaining the viability of certain types of cells in channels remains a challenge.

Integration of optical manipulation in 3D printed microfluidic devices (Conference Presentation)

2020 ◽  
Author(s):  
Haoran Wang ◽  
Anton Enders ◽  
Alexander Heisterkamp ◽  
Janina Bahnemann ◽  
Maria Leilani Torres-Mapa
Keyword(s):  
Microfluidic Devices ◽  
Optical Manipulation ◽  
3D Printed

SU-8 bonding protocol for the fabrication of microfluidic devices dedicated to FTIR microspectroscopy of live cells

Lab on a Chip ◽  
2014 ◽  
Vol 14 (1) ◽  
pp. 210-218 ◽  
Author(s):  
Elisa Mitri ◽  
Giovanni Birarda ◽  
Lisa Vaccari ◽  
Saša Kenig ◽  
Massimo Tormen ◽  
...  
Keyword(s):  
Microfluidic Devices ◽  
Live Cells ◽  
Ftir Microspectroscopy

Photoactivation in Fluorescence Microscopy

2009 ◽  
Vol 17 (4) ◽  
pp. 8-13 ◽  
Author(s):  
David W. Piston ◽  
Gert-Jan Kremers ◽  
Richard K.P. Benninger ◽  
Michael W. Davidson
Keyword(s):  
Cell Biology ◽  
Fluorescent Proteins ◽  
Photophysical Properties ◽  
Live Cells ◽  
General Description ◽  
Caged Compounds ◽  
Introductory Overview ◽  
Photoactivatable Gfp ◽  
Genetic Labeling ◽  
New Applications

The use of photoactive compounds in microscopy has a long history. Caged compounds have been used for almost forty years, not only to elicit chemical reactions in cells, but also to mark specific cells or regions within cells by photoactivation of fluorescence. During the last seven years, the advent of photoactivatable GFP (PA-GFP) and its successors has opened up a myriad of new applications. All of this work has, of course, been greatly facilitated in live cells through the possibility of genetic labeling that is given by the fluorescent proteins. However, even as more photo-activatable and photo-switchable proteins are discovered, they are still limited in terms of wavelength ranges and photophysical properties. Thus, there has been a resurgence of interest in small organic photoactive molecules for cell biology experiments. In this short introductory overview, we will present the basic concepts of photoactivation and discuss many of the strengths and limitations of various approaches. We will also provide a general description of the kinds of applications for which these probes can be used.

Well Plate—Coupled Microfluidic Devices Designed for Facile Image-Based Cell Adhesion and Transmigration Assays

2009 ◽  
Vol 15 (1) ◽  
pp. 102-106 ◽  
Author(s):  
Carolyn G. Conant ◽  
Michael A. Schwartz ◽  
Cristian Ionescu-Zanetti
Keyword(s):  
Cell Adhesion ◽  
Shear Flow ◽  
Cell Biology ◽  
Mononuclear Cells ◽  
Biological Significance ◽  
Microfluidic Devices ◽  
Response Curves ◽  
Single Experiment ◽  
Cell Monolayers ◽  
Biological Phenomena

Microfluidic devices have become invaluable tools in recent years to model biological phenomena. Here, the authors present a well plate microfluidic (WPM) device for conducting cell biology assays under shear flow. Physiological shear flow conditions of cell-cell and cell-ligand adhesion within this device produce results with higher biological significance than conventional well plates. The WPM format also produced significant work flow advantages such as faster liquid handling compared to static well plate assays. The authors used the VLA-4—VCAM-1 cell adhesion model as the basis for a rapid, higher throughput adhesion inhibition screen of monoclonal antibodies against VLA-4. Using the WPM device, they generated IC50 dose-response curves 96 times faster than conventional flow cells. The WPM device was also used to study transmigration of mononuclear cells through endothelial cell monolayers. Twenty-four channels of transmigration data were generated in a single experiment.

scholarly journals Nanog fluctuations in ES cells highlight the problem of measurement in cell biology

2016 ◽  
Author(s):  
Rosanna C G Smith ◽  
Patrick S Stumpf ◽  
Sonya J Ridden ◽  
Aaron Sim ◽  
Sarah Filippi ◽  
...  
Keyword(s):  
Cell Lines ◽  
Cell Biology ◽  
Measurement Problem ◽  
Es Cells ◽  
Expression Patterns ◽  
Embryonic Stem ◽  
Genetically Engineered ◽  
Live Cells ◽  
Reporter Cell ◽  
Nanog Expression

A number of important pluripotency regulators, including the transcription factor Nanog, are observed to fluctuate stochastically in individual embryonic stem (ES) cells. By transiently priming cells for commitment to different lineages, these fluctuations are thought to be important to the maintenance of, and exit from, pluripotency. However, since temporal changes in intracellular protein abundances cannot be measured directly in live cells, these fluctuations are typically assessed using genetically engineered reporter cell lines that produce a fluorescent signal as a proxy for protein expression. Here, using a combination of mathematical modeling and experiment, we show that there are unforeseen ways in which widely used reporter strategies can systemically disturb the dynamics they are intended to monitor, sometimes giving profoundly misleading results. In the case of Nanog we show how genetic reporters can compromise the behavior of important pluripotency-sustaining positive feedback loops, and induce a bifurcation in the underlying dynamics that gives rise to heterogeneous Nanog expression patterns in reporter cell lines that are not representative of the wild-type. These findings help explain the range of published observations of Nanog variability and highlight a fundamental measurement problem in cell biology.

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