Determination of Lipid Raft Partitioning of Fluorescently-tagged Probes in Living Cells by Fluorescence Correlation Spectroscopy (FCS)
1Centre de Recherche de l’Institut du Cerveau et de la Moelle Épinière, Hôpital de la Pitié-Salpêtrière, 2Institut des Sciences Moléculaires d'Orsay, Université Paris-Sud, 3Centre de Photonique Biomédicale du Centre Laser, Université Paris-Sud
A technique to probe the lipid raft partitioning of fluorescent proteins at the plasma membrane of living cells is described. It takes advantage of the disparity in diffusion times of proteins located inside or outside of lipid rafts. Acquisition can be performed dynamically in control conditions or after drug addition.
1Department of Ophthalmology, Massachusetts Eye and Ear, 2JoVE Content Production
Here are some highlights from the March 2013 issue of Journal of Visualized Experiments (JoVE).
We present a high-throughput flow cytometric assay to determine the phagocytic activity of antigen-specific antibodies from clinical samples, utilizing fluorescent antigen-coated beads and a monocytic cell line expressing multiple Fc receptors—providing receptor usage and phagocytic activity determinations in a standardized and reproducible fashion for any antigen of interest.
1Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, 2Lab. PALM, Université de Caen Basse-Normandie, 3Fetal-Neonatal Neuroimaging and Developmental Science Center, Boston Children's Hospital, Harvard Medical School, 4ISS, INC.
We combined frequency-domain near-infrared spectroscopy measures of cerebral hemoglobin oxygenation with diffuse correlation spectroscopy measures of cerebral blood flow index to estimate an index of oxygen metabolism. We tested the utility of this measure as a bedside screening tool to evaluate the health and development of the newborn brain.
Microwave-assisted Intramolecular Dehydrogenative Diels-Alder Reactions for the Synthesis of Functionalized Naphthalenes/Solvatochromic Dyes
Microwave-assisted intramolecular dehydrogenative Diels-Alder (DA) reactions provide concise access to functionalized cyclopenta[b]naphthalene building blocks. The utility of this methodology is demonstrated by one-step conversion of the dehydrogenative DA cycloadducts into novel solvatochromic fluorescent dyes via Buchwald-Hartwig palladium-catalyzed cross-coupling reactions.
We discuss the construction and operation of a complex nonlinear optical system that uses ultrafast all-optical switching to isolate Raman from fluorescence signals. Using this system we are able to successfully separate Raman and fluorescence signals utilizing pulse energies and average powers that remain biologically safe.
This technique provides a method to harvest, normalize and quantify intracellular growth of bacterial pathogens that are pre-cultivated in natural protozoan host cells prior to infections of mammalian cells. This method can be modified to accommodate a wide variety of host cells for the priming stage as well as target cell types.
1NMR Surgical Laboratory, Department of Surgery, Massachusetts General Hospital, Harvard Medical School, 2Shriners Burn Institute, 3Department of Radiology, Athinoula A. Martinos Center of Biomedical Imaging, Harvard Medical School, 4Molecular Surgery Laboratory, Department of Surgery, Massachusetts General Hospital, Harvard Medical School
This technique enables the use of high-resolution magic angle spinning proton MR spectroscopy (HRMAS 1H-MRS) for molecular characterization of live Drosophila melanogaster with a conventional 14.1 tesla spectrometer equipped with an HRMAS probe.
In this video we will demonstrate measuring and calculating absolute quantum yield and chromaticity coordinates directly in powder samples using the Hitachi F-7000 Quantum Yield Measuring System.
This article intends to describe in stepwise fashion the commonly used in vitro assays used in studying Schwann cell-asrtocyte interactions.
Cell transplantation is an essential technique for studying tissue regeneration and for developing cell-based therapies of disease. We demonstrate here a microsurgical technique that permits the transplantation of genetically labeled cells directly into the kidney of adult zebrafish fish.
1Department of Ophthalmology, Massachusetts Eye and Ear, 2JoVE Content Production
Here's a look at some of the milestones and highlights of the year 2012 in Journal of Visualized Experiments (JoVE).
This protocol describes a rapid technique to quantify the translocation of GLUT4 from the cytoplasm to the plasma membrane of cells by flow cytometry.
The biarsenical dyes FlAsH and ReAsH bind specifically to tetracysteine motifs in proteins and can selectively label proteins in live cells. Recently this labeling strategy has been used to develop sensors for different protein conformations or oligomeric states. We describe the labeling approach and methods to quantitatively analyze binding.
1Department of Ophthalmology, Massachusetts Eye and Ear, 2JoVE Content Production
Here are some highlights from the October 2012 Issue of Journal of Visualized Experiments (JoVE).
We demonstrate the utility of multicolor flow cytometry for detailed phenotypic and functional characterization of total as well as memory subsets of CD4+ and CD8+ T cells in rhesus macaques, the ideal model for HIV/AIDS vaccine studies.
Cancer stem cells (CSCs) have been identified in a number of malignancies. In this protocol we describe a flow cytometric method utilizing aldehyde dehydrogenase activity and CD44 and CD24 expression to isolate CSCs from human pancreatic adenocarcinoma xenografts. These viable cells can then be used in functional and analytical studies.
1Department of Thoracic and Cardiovascular Surgery and Inter-University Centre for Medical Technology Stuttgart-Tübingen (IZST), Eberhard Karls University, Tübingen, 2Department of Cell and Tissue Engineering, Fraunhofer Institute of Interfacial Engineering and Biotechnology (IGB) Stuttgart, Germany, 3Department for Medical Interfacial Engineering (IGVT), University of Stuttgart, Germany, 4Institute of Tissue Engineering and Regenerative Medicine, Julius-Maximillians University, Würzburg, Germany
Raman spectroscopy is a suitable technique for the non-contact, label-free analysis of living cells, tissue-engineered constructs and native tissues. Source-specific spectral fingerprints can be generated and analyzed using multivariate analysis.
1Department of Biomedical Engineering, The Ohio State University, 2Department of Biomedical Informatics, The Ohio State University, 3Comprehensive Wound Center, The Ohio State University, 4Department of Surgery, The Ohio State University
A dual-mode imaging system was developed for non-contact assessment of cutaneous tissue oxygenation and vascular function.
For many scientific studies requiring a biological and chemical analysis of cell populations the cells must be in a high state of purity. Fluorescence activated cell sorting (FACS) is a superior method in which to obtain pure cell populations.
We demonstrate FRET between conjugated polymer polydiacetylene (PDA) and fluorophore attached to the surface of PDA liposomes for the sensing of biomolecules. PDA liposomes also contained receptor molecules on their surfaces for biomolecules to be used as probes. Ligand-receptor interactions lead to changes in the FRET efficiency between the fluorophore and PDA which is the basis of the sensing mechanism.
1Department of Biotechnology & Bioinformatics, California State University Channel Islands, 2Department of Diabetes, Endocrinology and Metabolism, Beckman Research Institute of City of Hope, 3The Irell & Manella Graduate School of Biological Sciences, Beckman Research Institute of City of Hope
A three-dimensional clonogenic assay that allows pancreatic-like progenitors to differentiate into insulin-expressing colonies is described. This method takes advantage of semi-solid media containing methylcellulose, Matrigel and growth factors, in which single progenitors proliferate and differentiate in vitro, permitting quantification of the number of functional progenitors in a population.
1Department of Physiology, University of Maryland School of Medicine, 2Department of Orthopaedics, University of Maryland School of Medicine, 3Department of Diagnostic Radiology, University of Maryland School of Medicine
An in vivo animal model of injury is described. The method takes advantage of the subcutaneous position of the fibular nerve. Velocity, timing of muscle activation, and arc of motion are all pre-determined and synchronized using commercial software. Post injury changes are monitored in vivo using MR imaging/spectroscopy.
We describe the preparation of colloidal quantum dots with minimized hydrodynamic size for single-molecule fluorescence imaging. Compared to conventional quantum dots, these nanoparticles are similar in size to globular proteins and are optimized for single-molecule brightness, stability against photodegradation, and resistance to nonspecific binding to proteins and cells.
The Use of Carboxyfluorescein Diacetate Succinimidyl Ester (CFSE) to Monitor Lymphocyte Proliferation
CFSE covalently labels long-lived intracellular molecules with the fluorescent dye, carboxyfluorescein. As such, when a CFSE-labeled cell divides, its progeny have half the amount of fluorescence, which can thereby be used to assess cell division. This article describes the procedures typically used for labeling mouse lymphocytes with CFSE.
The following setup approach details low power optical trapping of dielectric nanoparticles using a double-nanohole in metal film.
We demonstrate the fabrication of a low-cost cryogenic stage designed to fit most reflected light microscopes. This lab-built cryogenic stage enables efficient and reliable correlative imaging between cryo-light and cryo-electron microscopy.
1Laboratory of Biophysics and Surface Analysis, University of Nottingham, 2School of Molecular Medical Sciences, University of Nottingham, 3David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology
A description of the formation of a polymer microarray using an on-chip photopolymerization technique. The high throughput surface characterization using atomic force microscopy, water contact angle measurements, X-ray photoelectron spectroscopy and time of flight secondary ion mass spectrometry and a cell attachment assay is also described.
Carcinoma-associated fibroblasts (CAFs) rich in myofibroblasts present within the tumour stroma, play a major role in driving tumour progression. We developed a coimplantation tumour xengraft model for experimentally generating CAFs from human mammary fibroblasts. The protocol describes how to establish CAF myofibroblasts that acquire an ability to promote tumourigenesis.
Therapeutic Gene Delivery and Transfection in Human Pancreatic Cancer Cells using Epidermal Growth Factor Receptor-targeted Gelatin Nanoparticles
Type B gelatin-based engineered nanovectors system (GENS) was developed for systemic gene delivery and transfection in the treatment of pancreatic cancer. By modification with epidermal growth factor receptor (EGFR) specific peptide on the surface of nanparticles, they could target on EGFR receptor and release plasmid under reducing environment, such as high intracellular glutathione concentrations.
The Neuroblast Assay: An Assay for the Generation and Enrichment of Neuronal Progenitor Cells from Differentiating Neural Stem Cell Progeny Using Flow Cytometry
This video protocol demonstrates a novel method for the generation and subsequent purification of neuronal progenitor cells from a renewable source of neural stem cells (NSCs) based on their physical (size and internal granularity) and fluorescent properties using flow cytometry technology.
Bioimaging methods used to assess cell biodistribution of nanoparticles are applicable for therapeutic and diagnostic monitoring of nanoformulated compounds. The methods described herein are sensitive and specific when assessed by histological coregistration. The methodologies provide a translational pathway from rodent to human applications.
Infection of mice with an Adenovirus expressing the major human autoantigen cytochrome P450 2D6 (hCYP2D6) recognized by sera of patients suffering from type 2 autoimmune hepatitis results in a persistent form of autoimmune-mediated liver disease characterized by extensive hepatitis, fibrosis and generation of a CYP2D6-specific immune response.
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.
There are technical obstacles to measuring current flux through multiple ion channels simultaneously, and later discerning what portion of the transmembrane current is due to each channel type. To address this need, this method presents a way to generate the IV curve of individual channel types using specific frequency components.
In this article we describe how we obtain FRET traces from individual DNA molecules immobilized to a surface using an automated scanning confocal microscope.
Intravital microscopy to follow temporal and spatial hemodynamic and inflammatory events in the pial microcirculation.
Dry Oxidation and Vacuum Annealing Treatments for Tuning the Wetting Properties of Carbon Nanotube Arrays
This article describes a simple method to fabricate vertically aligned carbon nanotube arrays by CVD and to subsequently tune their wetting properties by exposing them to vacuum annealing or dry oxidation treatment.
Use of Cerenkov Luminescence Imaging (CLI) for monitoring preclinical cancer treatment is described here. This method takes advantage of Cerenkov Radiation (CR) and optical imaging (OI) to visualize radiolabeled probes and thus provides an alternative to PET in preclinical therapeutic monitoring and drug screening.
This article describes a method for the isolation and purification of intact Legionella-containing vacuoles (LCVs) from amoeba and macrophages. The two-step protocol comprises LCV enrichment by immuno-magnetic separation using an antibody against a bacterial LCV marker and further purification by density gradient centrifugation.
Quantitative FRET (Förster Resonance Energy Transfer) Analysis for SENP1 Protease Kinetics Determination
A novel method involving quantitative analysis of FRET (Förster Resonance Energy Transfer) signals is described for studying enzyme kinetics. KM and kcat were obtained for the hydrolysis of the catalytic domain of SENP1 (SUMO/Sentrin specific protease 1) to pre-SUMO1 (Small Ubiquitin-like MOdifier). The general principles of this quantitative-FRET-based protease kinetic study can be applied to other proteases.
We present a novel and powerful integration of nanophotonics (QD-FRET) and microfluidics to investigate the formation of polyelectrolyte polyplexes, which is expected to provide better control and synthesis of uniform and customizable polyplexes for future nucleic acid-based therapeutics.
This video article details the experimental procedure for obtaining the Gibbs free energy of membrane protein folding by tryptophan fluorescence.
Nanodiscs are small discoid particles that incorporate membrane proteins into a small patch of phospholipid bilayer. We provide a visual protocol that shows the step-by-step incorporation of the MalFGK2 transporter into a disc.
Plant viral nanoparticles (VNPs) are promising platforms for applications in biomedicine. Here, we describe the procedures for plant VNP propagation, purification, characterization, and bioconjugation. Finally, we show the application of VNPs for tumor homing and imaging using a mouse xenograft model and fluorescence imaging.
1Center for Innovative Fuel Cells and Battery Technologies, School of Materials Science and Engineering, Georgia Institute of Technology, 2School of Chemistry and Biochemistry, Georgia Institute of Technology
We present a unique platform for characterizing electrode surfaces in solid oxide fuel cells (SOFCs) that allows simultaneous performance of multiple characterization techniques (e.g. in situ Raman spectroscopy and scanning probe microscopy alongside electrochemical measurements). Complementary information from these analyses may help to advance toward a more profound understanding of electrode reaction and degradation mechanisms, providing insights into rational design of better materials for SOFCs.
Fluorescence Lifetime Imaging (FLIM) has emerged as a key technique to image the environment and interaction of specific proteins and dyes in living cells. FLIM of fluorescent molecular rotors allows mapping of viscosity in living cells.
Evaluation of Polymeric Gene Delivery Nanoparticles by Nanoparticle Tracking Analysis and High-throughput Flow Cytometry
1Biomedical Engineering Department, Johns Hopkins University School of Medicine, 2Translational Tissue Engineering Center, Johns Hopkins University School of Medicine, 3Wilmer Eye Institute, Johns Hopkins University School of Medicine, 4Institute for Nanobiotechnology, Johns Hopkins University School of Medicine
A protocol for nanoparticle tracking analysis (NTA) and high-throughput flow cytometry to evaluate polymeric gene delivery nanoparticles is described. NTA is utilized to characterize the nanoparticle particle size distribution and the plasmid per particle distribution. High-throughput flow cytometry enables quantitative transfection efficacy evaluation for a library of gene delivery biomaterials.
A recently developed novel particle agglutination (PA) assay utilizing virus receptor molecule allowed a rapid and easy identification of poliovirus (PV). In this article, we will show the procedure for the PA assay for PV identification.