Two-phase systems in which one is uniformly dispersed in another as particles small enough so they cannot be filtered or will not settle out. The dispersing or continuous phase or medium envelops the particles of the discontinuous phase. All three states of matter can form colloids among each other.
1Chemical and Biomolecular Engineering Department, University of Houston
Confocal microscopy is used to image quiescent and flowing colloid-polymer mixtures, which are studied as model systems for attractive suspensions. Image analysis algorithms are used to calculate structural and dynamic metrics for the colloidal particles that measure changes due to geometric confinement.
Published May 20, 2014. Keywords: Chemistry, confocal microscopy, particle tracking, colloids, suspensions, confinement, gelation, microfluidics, image correlation, dynamics, suspension flow
1Department of Chemistry, Wright State University, 2Department of Neuroscience, Cell Biology, and Physiology, Wright State University
Tangential flow ultrafiltration (TFU) is a recirculation method used for the weight-based separation of biosamples. TFU was adapted to size-select (1-20 nm diameter) and highly concentrate a large volume of polydisperse silver nanoparticles (4 L of 15.2 μg ml-1 down to 4 ml of 8,539.9 μg ml-1) with minimal aggregation.
Published October 4, 2012. Keywords: Chemistry, Biomedical Engineering, Chemical Engineering, Nanotechnology, silver nanoparticles, size selection, concentration, tangential flow ultrafiltration
1Jülich Supercomputing Centre, Forschungszentrum Jülich, 2Materials Science and Technology of Polymer, MESA+ Institute for Nanotechnology, University of Twente, 3Department of Materials Science and Engineering, Universität des Saarlandes
The methodology to perform friction force microscopy experiments for contacting brushes is presented: Two polymer brushes that are grafted from (a) substrates and (b) colloidal probes are slid to show that, by using two contacting immiscible brush systems, friction in sliding contacts is reduced compared to miscible brush systems.
Published December 24, 2014. Keywords: Physics, Atomic force microscopy, polymers, polymer brush, colloid probe, colloid probe chemical modification, surface initiated atom-transfer radical polymerization, friction, molecular dynamics
1Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign
Traditional techniques for fabricating polyacrylamide (PA) gels containing fluorescent probes involve sandwiching a gel between an adherent surface and a glass slide. Here, we show that coating this slide with poly-D-lysine (PDL) and fluorescent probes localizes the probes to within 1.6 µm from the gel surface.
Published September 16, 2014. Keywords: Bioengineering, cell mechanics, polyacrylamide (PA) gel, traction force microscopy, fluorescent beads, poly-D-lysine (PDL), cell culture surface
1Marcoule Institute for Separative Chemistry, UMR 5257 CEA-CNRS-UM2-ENSCM
Acoustic cavitation in liquids submitted to power ultrasound creates transient extreme conditions inside the collapsing bubbles, which are the origin of unusual chemical reactivity and light emission, known as sonoluminescence. In the presence of noble gases, nonequilibrium plasma is formed. The "hot" particles and the photons generated by collapsing bubbles are able to excite species in solution.
Published April 11, 2014. Keywords: Chemistry, Sonochemistry, sonoluminescence, ultrasound, cavitation, nanoparticles, actinides, colloids, nanocolloids
1School of Ecology and Environmental Studies, Nalanda University, 2Department of Earth Sciences, Uppsala University
Surface properties of a nanoparticle are important for their interaction with the surrounding medium. Therefore the surface modification of carbon nanotubes can be critical for their transport and retention through porous media. Here, lab scale column experiments are used to understand the possible transport and retention of these nanoparticles.
Published April 2, 2015. Keywords: Chemistry, Carbon nanotubes, functionalization of carbon nanotubes, solution chemistry, flow rate, porous media
1Department of Physics and Astronomy, The University of Texas at San Antonio, 2Centro de Investigaciones en Optica A. C., 3Department of Biology and Neurosciences Institute, The University of Texas at San Antonio
We synthesized star shaped gold nanostars using a silver seed mediated growth method. The diameter of the nanostars ranges from 200 to 300 nm and the number of tips vary from 7 to 10. The nanoparticles have a broad surface plasmon resonance mode centered in the near infrared.
Published January 15, 2012. Keywords: Bioengineering, thermal ablation, surface plasmon resonance, nanoparticle, nanotechnology, silver seeds
1Oak Ridge Institute for Science and Education, 2Air Force Research Laboratory, Airbase Technology Division, 3School of Materials Science and Engineering, Clemson University
Silica nanoparticles were prepared using acid-catalysis of a siloxane precursor and microwave-assisted synthetic techniques resulting in the controlled growth of nanomaterials ranging from 30-250 nm in diameter. The growth dynamics can be controlled by varying the initial silicic acid concentration, time of the reaction, and temperature of reaction.
Published December 16, 2013. Keywords: Chemistry, Chemistry, chemical manufacturing, chemistry (general), materials (general), nanocomposites, catalysts (chemical), chemistry of compounds, Chemistry and Materials (General), Composite Materials, Inorganic, Organic and Physical Chemistry, Engineering (General), Microwave, nanoparticle, silica, silicic acid, NP, SiO2, synthesis
1Faculty of Pharmacy, University of Sydney, 2Department of Nanobiomedical Science & BK21 PLUS NBM Global Research Center for Regenerative Medicine, Dankook University
Colloidal probe nanoscopy can be used within a variety of fields to gain insight into the physical stability and coagulation kinetics of colloidal systems and aid in drug discovery and formulation sciences using biological systems. The method described within provides a quantitative and qualitative means to study such systems.
Published July 18, 2014. Keywords: Chemistry, Colloidal Probe, Nanoscopy, Suspension Stability, Adhesion Mapping, Force, Particle Interaction, Particle Kinetics
JoVE Immunology and Infection
1Department of Microbiology and Immunology, Louisiana State University Health Sciences Center, 2Center for Molecular and Tumor Virology, Louisiana State University Health Sciences Center, 3Department of Microbiology and Immunology, SUNY Upstate Medical University, 4Feist-Weiller Cancer Center, Louisiana State University Health Sciences Center
The phagokinetic motility track assay is a method used to assess the movement of cells. Specifically, the assay measures chemokinesis (random cell motility) over time in a quantitative manner. The assay takes advantage of the ability of cells to create a measurable track of their movement on colloidal gold-coated coverslips.
Published December 4, 2012. Keywords: Immunology, Microbiology, Cellular Biology, Molecular Biology, gold nanoparticles, coverslips, cell migration, quantitative cell movement, microscopy, motility, assay
1Division of Pulmonary and Critical Care Medicine, State University of New York, Buffalo, 2Interventional Pulmonology Section, Division of Medicine, Roswell Park Cancer Institute, State University of New York, Buffalo
Substernal thyroid lesions are common, and need to be differentiated from malignancy. Obtaining percutaneous fine needle biopsy is not possible due to its retrosternal location. This article proposes a protocol for biopsy of substernal thyroid lesions using Endobronchial Ultrasound-guided Transbronchial Needle Aspiration (EBUS-TBNA).
Published November 10, 2014. Keywords: Medicine, substernal thyroid, retrosternal thyroid, intra-thoracic thyroid, goiter, endobronchial ultrasound, EBUS, transbronchial needle aspiration, TBNA, biopsy, needle biopsy
1Department of Surgical Oncology, University of Texas M.D. Anderson Cancer Center, 2Department of Chemistry, Rice University, 3Mechanical Engineering and Materials Science, Rice University
We describe the protocols used to investigate the interactions of 13.56 MHz radiofrequency (RF) electric-fields with gold nanoparticle colloids in both non-biological and biological systems (in vitro/vivo). These interactions are being investigated for applications in cancer therapy.
Published August 28, 2013. Keywords: Medicine, Electronics and Electrical Engineering, Life Sciences (General), Radiofrequency, Cancer, Nanoparticles, Hyperthermia, Gold
JoVE Immunology and Infection
1Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 2The Medical Research Council Mitochondrial Biology Unit, University of Cambridge, 3National Library of Medicine, National Institutes of Health, 4Massachusetts Institute of Technology, 5William Fremd High School, 6University of Virginia, 7Duke University, 8Yale University, 9University of Notre Dame, 10Washington University in St. Louis, 11Bioinformatics and Computational Biosciences Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 12Thomas Jefferson High School for Science and Technology
The protocol describes a high-throughput approach to determining structures of membrane proteins using cryo-electron tomography and 3D image processing. It covers the details of specimen preparation, data collection, data processing and interpretation, and concludes with the production of a representative target for the approach, the HIV-1 Envelope glycoprotein. These computational procedures are designed in a way that enables researchers and students to work remotely and contribute to data processing and structural analysis.
Published December 1, 2011. Keywords: Immunology, HIV, Envelope glycoprotein, membrane protein, vaccine design, cryo-electron tomography, transmission electron microscopy, structural biology, high school science, scientific outreach, scientific visualization, National Institutes of Health, National Cancer Institute, National Library of Medicine
1School of Biological Sciences, Nanyang Technological University
Sedimentation equilibrium (SE) can be used to study protein-protein interactions in a physiological environment. This manuscript describes the use of this technique to determine the effect of pH on the stability of a homo-pentamer formed by the small hydrophobic (SH) protein encoded by the human syncytial respiratory virus (hRSV).
Published April 2, 2015. Keywords: Chemistry, Analytical ultracentrifugation, sedimentation equilibrium, molecular weight, membrane proteins, small hydrophobic, respiratory syncytial virus, detergent, density matching, oligomeric size, histidine protonation, oligomer stability
1Department of Biomedical Engineering, The University of Akron, 2Saint Vincent Saint Mary's High School
This work describes the formation of poly(ethylene glycol) (PEG) microgels via a photopolymerized precipitation reaction. Increasing the PEG molecular weight increased microgel diameter and swelling ratio. Simple adaptations to the PEG microgel precipitation reaction are explored for future applications of microgels as drug delivery vehicles and tissue engineering scaffolds.
Published December 23, 2013. Keywords: Bioengineering, hydrogels, microgels, polyethylene glycol, molecuar weight, photopolymerized precipitation reaction, polymers, polydispersity index
1Department of Physics, University of Massachusetts Boston
Particle-tracking microrheology can be used to non-destructively quantify and spatially map changes in extracellular matrix mechanical properties in 3D tumor models.
Published June 10, 2014. Keywords: Bioengineering, viscoelasticity, mechanobiology, extracellular matrix (ECM), matrix remodeling, 3D tumor models, tumor microenvironment, stroma, matrix metalloprotease (MMP), epithelial-mesenchymal transition (EMT)
1Institute of Chemistry, The Hebrew University of Jerusalem, 2Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem
A detailed procedure for surface doping of Silicon interfaces is provided. The ultra-shallow surface doping is demonstrated by using phosphorus containing monolayers and rapid annealing process. The method can be used for doping of macroscopic area surfaces as well as nanostructures.
Published December 2, 2013. Keywords: Basic Protocol, nanotechnology, chemistry, monolayer contact doping (MLCD), nanowire, silicon substrate, chemical vapor deposition (CVD),
1Department of Chemistry, Gottwald Center for the Sciences, University of Richmond, 2Department of Biochemistry and Molecular Biology, Gottwald Center for the Sciences, University of Richmond
Alkanethiolate stabilized gold colloids known as monolayer protected clusters (MPCs) are synthesized, characterized, and assembled into thin films as an adsorption interface for protein monolayer electrochemistry of simple redox protein like Pseudomonas aeruginosa azurin (AZ) and cytochrome c (cyt c).
Published October 4, 2011. Keywords: Bioengineering, Monolayer protected clusters, film assemblies, protein monolayer electrochemistry, azurin, self-assembled monolayers
JoVE Immunology and Infection
1Plant Sciences Institute, Agricultural Research Service, United States Department of Agriculture, 2Molecular Plant Pathology Laboratory, Agricultural Research Service, United States Department of Agriculture
A method to analyze the solvent accessibility of the thiol group of cysteine residues of Maize rayado fino virus (MRFV)-virus-like particles (VLPs) followed by a peptide cross-linking reaction is described. The method takes advantage of the availability of several chemical groups on the surface of the VLPs that can be targets for specific reactions.
Published February 14, 2013. Keywords: Virology, Plant Biology, Infection, Molecular Biology, Biochemistry, Proteins, Chemicals and Drugs, Analytical, Diagnostic and Therapeutic Techniques and Equipment, Technology, Industry, Agriculture, Chemistry and materials, Virus-like particles (VLPs), VLP, sulfhydryl-reactive chemistries, labeling, cross-linking, multivalent display, Maize rayado fino virus, mosaic virus, virus, nanoparticle, drug delivery, peptides, Nicotiana benthamiana, plant model
1Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute
The demonstration of the small and wide angle X-ray scattering (SWAXS) procedure has become instrumental in the study of biological macromolecules. Through the use of the instrumentation and procedures of specific angle methods and preparation, the experimental data from the SWAXS displays the atomic and nano-scale characterization of macromolecules.
Published January 8, 2013. Keywords: Bioengineering, Biophysics, Structural Biology, Physics, Molecular Biology, Mechanical Engineering, Nanotechnology, Small angle X-ray scattering, wide angle X-ray scattering, X-ray, biological macromolecules
1Institut Curie, Centre de Recherche, CNRS, UMR 168, PhysicoChimie Curie, Université Pierre et Marie Curie, 2Kavli Institute for Brain and Mind, University of California, San Diego, 3Molecular Physiology and Biophysics Section, National Institute for Neurological Disorders and Stroke, National Institute of Health
The reconstitution of the transmembrane protein, KvAP, into giant unilamellar vesicles (GUVs) is demonstrated for two dehydration-rehydration methods — electroformation, and gel-assisted swelling. In both methods, small unilamellar vesicles containing the protein are fused together to form GUVs that can then be studied by fluorescence microscopy and patch-clamp electrophysiology.
Published January 22, 2015. Keywords: Biochemistry, Biomimetic model system, Giant Unilamellar Vesicle, reconstitution, ion channel, transmembrane protein, KvAP, electroformation, gel assisted swelling, agarose, inside-out patch clamp, electrophysiology, fluorescence microscopy
1MESA+ Institute for Nanotechnology, University of Twente
Procedures are outlined to prepare segmented and coaxial nanowires via templated electrodeposition in nanopores. As examples, segmented nanowires consisting of Ag and ZnO segments, and coaxial nanowires consisting of a TiO2 shell and a Ag core were made. The nanowires were used in photocatalytic hydrogen formation experiments.
Published May 2, 2014. Keywords: Physics, Multicomponent nanowires, electrochemistry, sol-gel processes, photocatalysis, photochemistry, H2 evolution
1Department of Biological Regulation, Weizmann Institute of Science, 2Unit of Biological Services, Weizmann Institute of Science, 3Department of Diagnostic Imaging, Meir Medical Center, 4Pathology Department, Meir Medical Center
We describe how to obtain parametric and vector maps of the diffusion tensor of the breast using magnetic resonance imaging. The protocol and final output following imaging processing are tailored for tracking breast architectural features and detecting breast malignancy.
Published December 15, 2014. Keywords: Medicine, Magnetic Resonance Imaging, breast, breast cancer, diagnosis, water diffusion, diffusion tensor imaging
1Institute for Critical Technology and Applied Science, Virginia Tech, 2Macromolecules and Interfaces Institute, Virginia Tech, 3Institute for Food Safety and Health, Illinois Institute of Technology- Moffett Campus, 4Wood, Cellulose, and Paper Research Department, University of Guadalajara, 5Department of Sustainable Biomaterials, Virginia Tech, 6Sustainable Nanotechnology Interdisciplinary Graduate Education Program, Virginia Tech
The objective of this research was to form synthetic plant cell wall tissue using layer-by-layer assembly of nanocellulose fibrils and isolated lignin assembled from dilute aqueous suspensions. Surface measurement techniques of quartz crystal microbalance and atomic force microscopy were used to monitor the formation of the polymer-polymer nanocomposite material.
Published June 17, 2014. Keywords: Plant Biology, nanocellulose, thin films, quartz crystal microbalance, layer-by-layer, LbL
1Laboratoire Interdisciplinaire Carnot de Bourgogne CNRS-UMR 6303, Université de Bourgogne, 2Department of Optics and Optical Engineering, University of Science and Technology of China, 3CEMES, CNRS-UPR 8011
Silver nanowires can simultaneously transport electrons and optical information in the form of surface plasmons. A procedure is described here to realize such a shared circuitry and the limitations at propagating both information carriers are evaluated.
Published December 11, 2013. Keywords: Physics, light transmission, optical waveguides, photonics, plasma oscillations, plasma waves, electron motion in conductors, nanofabrication, Information Transport, plasmonics, Silver Nanowires, Leakage radiation microscopy, Electromigration
1Department of Chemical Engineering, UC Berkeley, 2Department of Materials Science and Engineering, UC Berkeley, 3Department of Chemistry, UC Berkeley, 4Materials Sciences Division, Lawrence Berkeley National Laboratory, 5Department of Chemistry, University of Chicago, 6Center for Nanoscale Materials, Argonne National Laboratory
A protocol for the seeded synthesis of rod-shaped and tetrapod-shaped multicomponent nanostructures consisting of CdS and CdSe is presented.
Published December 11, 2013. Keywords: Chemistry, nanostructures, synthesis, nanocrystals, seeded rods, tetrapods, nanoheterostructures
JoVE Immunology and Infection
1Microbiology Unit, Department of Biochemistry, University of Oxford, 2Biological Physics Research Group, Clarendon Laboratory, Department of Physics, University of Oxford
Photoactivated localization microscopy (PALM) combined with single-molecule tracking allows direct observation and quantification of protein-DNA interactions in live Escherichia coli cells.
Published March 10, 2014. Keywords: Immunology, Super-resolution microscopy, single-particle tracking, Live-cell imaging, DNA-binding proteins, DNA repair, molecular diffusion
1Department of Surgery, Duke University Medical Center, 2Department of Cardiothoracic Surgery, University Hospital of South Manchester
Most studies involving the Langendorff apparatus use small animal models due to the increased complexity of systems for larger mammals. We describe a Langendorff system for large animal models that allows for use across a range of species, including humans, and relatively easy data acquisition.
Published June 11, 2014. Keywords: Medicine, cardiac physiology, surgery, transplantation, large animal models, isolated working heart, cardiac disease
1Lasers, Optics, & Targets for the National Ignition Facility, Lawrence Livermore National Laboratory
A novel optical polishing process, called “Convergent Polishing”, which enables faster, lower cost polishing, is described. Unlike conventional polishing processes, Convergent Polishing allows a glass workpiece to be polished in a single iteration and with high surface quality to its final surface figure without requiring changes to polishing parameters.
Published December 1, 2014. Keywords: Physics, optical fabrication, pad polishing, fused silica glass, optical flats, optical spheres, ceria slurry, pitch button blocking, HF etching, scratches
1Electrical Engineering Department, Polytechnique Montreal
In this article we describe different techniques for microfluidic rapid prototyping platforms. The proposed techniques are based on ultraviolet (UV) sensitive and temperature curing epoxies, polydimethylsiloxane (PDMS) based tubing, wire-bonding, and anisotropic adhesive films. The assembling procedures presented are developed for both one-time use devices as well as reusable microfluidic systems.
Published December 23, 2013. Keywords: Bioengineering, Microfluidics, PDMS, Lab-on-chip, Rapid-Prototyping, Microfabrication
JoVE Immunology and Infection
1London Centre for Nanotechnology and Departments of Medicine, University College London
Acquired resistance to antibiotics is a major public healthcare problem and is presently ranked by the WHO as one of the greatest threats to human life. Here we describe the use of cantilever technology to quantify antibacterial resistance, critical to the discovery of novel and powerful agents against multidrug resistant bacteria.
Published October 25, 2013. Keywords: Immunology, Engineering, Technology, Diagnostic Techniques and Procedures, Early Diagnosis, Bacterial Infections and Mycoses, Lipids, Amino Acids, Peptides, and Proteins, Chemical Actions and Uses, Diagnosis, Therapeutics, Surface stress, vancomycin, mucopeptides, cantilever sensor
1Fischell Department of Bioengineering, University of Maryland, 2Institute for Bioscience and Biotechnology Research, University of Maryland, 3Department of Materials Science and Engineering, University of Maryland
This article describes a biofabrication approach: deposition of stimuli-responsive polysaccharides in the presence of biased electrodes to create biocompatible films which can be functionalized with cells or proteins. We demonstrate a bench-top strategy for the generation of the films as well as their basic uses for creating interactive biofunctionalized surfaces for lab-on-a-chip applications.
Published June 6, 2012. Keywords: Bioengineering, Biomedical Engineering, electrodeposition, biofabrication, chitosan, alginate, lab-on-a-chip, microfluidic, DTRA
1Department of Electrical and Computer Engineering, University of Minnesota, 2Department of Biomedical Engineering, University of Minnesota, 3Department of Neurology, Mayo Clinic College of Medicine, 4Department of Immunology, Mayo Clinic College of Medicine
Supported lipid bilayers and natural membrane particles are convenient systems that can approximate the properties of cell membranes and be incorporated in a variety of analytical strategies. Here we demonstrate a method for preparing microarrays composed of supported lipid bilayer-coated SiO2 beads, phospholipid vesicles or natural membrane particles.
Published May 8, 2014. Keywords: Bioengineering, supported lipid bilayer, beads, microarray, fluorescence, microfabrication, nanofabrication, atomic layer deposition, myelin, lipid rafts
1Department of Mechanical Engineering, University of British Columbia
Two experimental devices for examining liquid jet impingement on a high-speed moving surface are described: an air cannon device and a spinning disk device. The apparatuses are used to determine optimal approaches to the application of liquid friction modifier (LFM) onto rail tracks for top-of-rail friction control.
Published April 17, 2015. Keywords: Engineering, Liquid jet impingement, high-speed moving surface, spray nozzle, liquid friction modifier (LFM), air cannon, spinning disk, rail track lubrication, fluid mechanics
1Department of Mechanical Engineering, Vanderbilt University
Combining monodisperse drop generation with inertial ordering of cells and particles, we describe a method to encapsulate a desired number of cells or particles in a single drop at kHz rates. We demonstrate efficiencies twice exceeding those of unordered encapsulation for single- and double-particle drops.
Published June 15, 2012. Keywords: Bioengineering, Drop-based microfluidics, inertial microfluidics, ordering, focusing, cell encapsulation, single-cell biology, cell signaling
JoVE Immunology and Infection
1Department of Health Science & Technology, Cartilage Engineering & Regeneration, 2Biomaterials Department, Innovent e.V.
A bioprinter was used to create patterned hydrogels based on a sacrificial mold. The poloxamer mold was backfilled with a second hydrogel and then eluted, leaving voids which were filled with a third hydrogel. This method uses fast elution and good printability of poloxamer to generate complex architectures from biopolymers.
Published July 10, 2013. Keywords: Bioengineering, Immunology, Cellular Biology, Biomedical Engineering, Biophysics, Molecular Biology, Materials Science, Tissue Engineering, Biomaterials, Hydrogel, Biopolymers, Structured/Patterned Hydrogels, Bioprinter, Sacrificial Mold, Thermoresponsive Polymers, Poloxamer, tissue, polymer, matrix, cell, cell culture
1Department of Chemical Engineering, Michigan Technological University, 2Department of Mechanical Engineering, Michigan Technological University, 3XG Sciences, Inc.
A microdevice with high throughput potential is used to demonstrate three-dimensional (3D) dielectrophoresis (DEP) with novel materials. Graphene nanoplatelet paper and double sided tape were alternately stacked; a 700 μm micro-well was drilled transverse to the layers. DEP behavior of polystyrene beads was demonstrated in the micro-well.
Published June 22, 2014. Keywords: Physics, graphene paper, dielectrophoresis, graphene electrodes, 3D laminated microdevice, polystyrene beads, cell diagnostics
1Center for Advanced Microstructures and Devices (CAMD), Louisiana State University, 2Center for Atomic-Level Catalyst Design, Cain Department of Chemical Engineering, Louisiana State University, 3Department of Biological and Agricultural Engineering, Louisiana State University, 4Argonne National Laboratory
Millifluidic devices are utilized for controlled synthesis of nanomaterials, time-resolved analysis of reaction mechanisms and continuous flow catalysis.
Published November 27, 2013. Keywords: Bioengineering, Millifluidics, Millifluidic Device, Time-resolved Kinetics, Synthesis, Catalysis, Nanomaterials, Lab-on-a-Chip
1The Rowland Institute, Harvard University, 2Faculdade de Ciências e Letras de Assis, Universidade Estadual Paulista
The three-dimensional locations of weakly-scattering objects can be uniquely identified using digital inline holographic microscopy (DIHM), which involves a minor modification to a standard microscope. Our software uses a simple imaging heuristic coupled with Rayleigh-Sommerfeld back-propagation to yield the three-dimensional position and geometry of a microscopic phase object.
Published February 8, 2014. Keywords: Basic Protocol, holography, digital inline holographic microscopy (DIHM), Microbiology, microscopy, 3D imaging, Streptococcus bacteria
1Photonics and Optoelectronics Group, Ludwig-Maximilians-Universität
We use optical tracking of plasmonic nanoparticles to probe and characterize the frequency movements of aquatic organisms.
Published July 15, 2014. Keywords: Biophysics, optical tweezers, particle tracking, plasmonic nanoparticles, Nauplius, bioindicator, water sample analysis
1Department of Physiology and Biophysics, University of Washington
Reconstituting functional membrane proteins into giant liposomes of defined composition is a powerful approach when combined with patch-clamp electrophysiology. However, conventional giant liposome production may be incompatible with protein stability. We describe protocols for producing giant liposomes from pure lipids or small liposomes containing ion channels.
Published June 21, 2013. Keywords: Physiology, Biophysics, Molecular Biology, Biochemistry, Genetics, Cellular Biology, Proteins, Membranes, Artificial, Lipid Bilayers, Liposomes, Phospholipids, biochemistry, Lipids, Giant Unilamellar Vesicles, liposome, electrophysiology, electroformation, reconstitution, patch clamp
1Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, 2Department of Chemistry, The Johns Hopkins University
We describe experimental details of the synthesis of patterned and reconfigurable particles from two dimensional (2D) precursors. This methodology can be used to create particles in a variety of shapes including polyhedra and grasping devices at length scales ranging from the micro to centimeter scale.
Published February 4, 2013. Keywords: Chemistry, Chemical Engineering, Biomolecular Engineering, Materials Science, Physics, Nanotechnology, Molecular Self-assembly, Electrochemistry, Folding, three dimensional, lithography, colloid, patchy particles, particles, nanoparticles, robotics, drug delivery, microfabrication, nanofabrication, nano, assembly, synthesis, reaction, origami
1Institute of Nanoengineering and Microsystems, National Tsing Hua University, 2Taichung Veterans General Hospital
This protocol details a method to isolate extracellular vesicles (EVs), small membranous particles released from cells, from as little as 10 μl serum samples. This approach circumvents the need for ultracentrifugation, requires only a few minutes of assay time, and enables the isolation of EVs from samples of limited volumes.
Published April 3, 2015. Keywords: Bioengineering, extracellular vesicles, exosomes, cellulose paper, microfluidics, paper ELISA, aqueous humor, chemical conjugation
1Department of Mechanical Engineering, University of Michigan, 2Department of Biomedical Engineering, University of Michigan, 3Department of Biomedical Engineering, Institute for Cellular and Molecular Biology, The University of Texas at Austin, 4Department of Bioengineering, University of California, Berkeley, 5Physical Biosciences Division, Lawrence Berkeley National Laboratory
Microfluidic jetting against a droplet interface lipid bilayer provides a reliable way to generate vesicles with control over membrane asymmetry, incorporation of transmembrane proteins, and encapsulation of material. This technique can be applied to study a variety of biological systems where compartmentalized biomolecules are desired.
Published February 21, 2014. Keywords: Bioengineering, Microfluidic jetting, synthetic biology, vesicle encapsulation, lipid bilayer, biochemical reconstitution, giant unilamellar vesicles
1Division of Biology, California Institute of Technology - Caltech, 2Howard Hughes Medical Institute, California Institute of Technology - Caltech
We illustrate here how to use electron cryotomography (ECT) to study the ultrastructure of bacterial cells in near-native states, to "macromolecular" (~4 nm) resolution.
Published May 6, 2010. Keywords: Cellular Biology, Electron cryotomography, microbiology, bacteria, electron microscopy
1Biomedical Technology, CFD Research Corporation
Flow chambers used in adhesion experiments typically consist of linear flow paths and require multiple experiments at different flow rates to generate a shear adhesion map. SynVivo-SMN enables the generation of shear adhesion map using a single experiment utilizing microliter volumes resulting in significant savings in time and consumables.
Published May 25, 2014. Keywords: Bioengineering, particle, adhesion, shear, microfluidics, vasculature, networks
1Department of Pharmacology, Rush University, 2Pulmonary and Critical Care Department, Rush University
Repeated retro-orbital injections of cationic liposomes/siRNA/ITSN-1s complexes in mice, every 72 hours for 24 days, efficiently deliver the siRNA duplex to the mouse lung microvasculature reducing ITSN-1s mRNA and protein expression by 75%. This technique is highly reproducible in an animal model, has no adverse effects and avoids fatalities.
Published June 21, 2013. Keywords: Bioengineering, Biomedical Engineering, Biochemistry, Genetics, Molecular Biology, Cellular Biology, Anatomy, Physiology, Medicine, Immunology, Pharmacology, animal models, Cardiovascular Diseases, intersectin-1s, siRNA, liposomes, retro-orbital injection, acute and chronic ITSN-1s knockdown, transgenic mice, liposome, endothelial cells, tissue, lung, perfusion, electron microscopy, animal model
1Aerospace and Mechanical Engineering, University of Arizona, 2Biomedical Engineering IDP and BIO5 Institute, University of Arizona
A versatile plasma lithography technique has been developed to generate stable surface patterns for guiding cellular attachment. This technique can be applied to create cell networks including those that mimic natural tissues and has been used for studying several, distinct cell types.
Published June 14, 2011. Keywords: Bioengineering, Cell Network, Surface Patterning, Self-Organization, Developmental Biology, Tissue Engineering, Nanopattern, Micropattern, Self-Assembly, Cell Guidance, Neuron
1Department of Surgery, Division of Surgical Oncology, University Medical Center Groningen, 2Helmholtz Zentrum, Technical University Munich, 3Department of Obstetrics and Gynaecology, University Medical Center Groningen
Fluorescence imaging is a promising innovative modality for image-guided surgery in surgical oncology. In this video we describe the technical procedure for detection of the sentinel lymph node using fluorescence imaging as showcased in gynecologic oncologicy. A multispectral fluorescence camera system, together with the fluorescent agent indocyanine green, is applied.
Published October 20, 2010. Keywords: Medicine, Image-guided surgery, multispectral fluorescence, sentinel lymph node, gynecologic oncology
1Vanderbilt Institute for Integrative Biosystems Research and Education, Vanderbilt University, 2Department of Biomedical Engineering, Vanderbilt University, 3Department of Molecular Physiology and Biophysics, Vanderbilt University, 4Department of Physics and Astronomy, Vanderbilt University, 5Department of Chemical, Materials and Biomolecular Engineering, University of Connecticut, 6Center for Environmental Sciences and Engineering, University of Connecticut
Microfluidic devices can be used to visualize complex natural processes in real time and at the appropriate physical scales. We have developed a simple microfluidic device that mimics key features of natural porous media for studying growth and transport of bacteria in the subsurface.
Published May 3, 2010. Keywords: Microbiology, Microfluidic device, bacterial transport, porous media, colloid, biofilm, filtration theory, artificial habitat, micromodel, PDMS, GFP