To Study Biological Molecules and Structures

August 31, 2009

Researchers in the United States and Spain have discovered that a tool widely used in nanoscale imaging works differently in watery environments, a step toward better using the instrument to study biological molecules and structures.

The researchers demonstrated their new understanding of how the instrument – the atomic force microscope – works in water to show detailed properties of a bacterial membrane and a virus called Phi29, said Arvind Raman, a Purdue professor of mechanical engineering. An atomic force microscope uses a tiny vibrating probe to yield information about materials and surfaces on the scale of nanometers, or billionths of a meter. Because the instrument enables scientists to „see“ objects far smaller than possible using light microscopes, it could be ideal for studying molecules, cell membranes and other biological structures. The best way to study such structures is in their wet, natural environments. However, the researchers have now discovered that in some respects the vibrating probe’s tip behaves the opposite in water as it does in air, said Purdue mechanical engineering doctoral student John Melcher. The probe is caused to oscillate by a vibrating source at its base. However, the tip of the probe oscillates slightly out of synch with the oscillations at the base. This difference in oscillation is referred to as a „phase contrast,“ and the tip is said to be out of phase with the base.

Although these differences in phase contrast reveal information about the composition of the material being studied, data can’t be properly interpreted unless researchers understand precisely how the phase changes in water as well as in air, Raman said.

If the instrument is operating in air, the tip’s phase lags slightly when interacting with a viscous material and advances slightly when scanning over a hard surface. Now researchers have learned the tip operates in the opposite manner when used in water: it lags while passing over a hard object and advances when scanning the gelatinous surface of a biological membrane.

Researchers deposited the membrane and viruses on a sheet of mica. Tests showed the differing properties of the inner and outer sides of the membrane and details about the latticelike protein structure of the membrane. Findings also showed the different properties of the balloonlike head, stiff collar and hollow tail of the Phi29 virus, called a bacteriophage because it infects bacteria.

Original Publication:

Melcher J, Carrasco C, Xu X, Carrascosa JL, Gómez-Herrero J, José de Pablo P, Raman A. (2009): Origins of phase contrast in the atomic force microscope in liquids. Proc Natl Acad Sci U S A. 2009 Aug 18;106(33):13655-60. Epub 2009 Aug 5.

Researchers in the United States and Spain have discovered that an atomic force microscope - a tool widely used in nanoscale imaging - works differently in watery environments, a step toward better using the instrument to study biological molecules and structures. The researchers demonstrated their new understanding of how the instrument works in water to show details of the mechanical properties of a virus called Phi29. The images in "a" and "c" show the topography, and the image in "b" shows the different stiffness properties of the balloonlike head, stiff collar and hollow tail of the Phi29 virus, called a bacteriophage because it infects bacteria. (C. Carrasco-Pulido, P. J. de Pablo, J. Gomez-Herrero, Universidad Autonoma de Madrid, Spain)

Researchers in the United States and Spain have discovered that an atomic force microscope - a tool widely used in nanoscale imaging - works differently in watery environments, a step toward better using the instrument to study biological molecules and structures. The researchers demonstrated their new understanding of how the instrument works in water to show details of the mechanical properties of a virus called Phi29. The images in "a" and "c" show the topography, and the image in "b" shows the different stiffness properties of the balloonlike head, stiff collar and hollow tail of the Phi29 virus, called a bacteriophage because it infects bacteria. (C. Carrasco-Pulido, P. J. de Pablo, J. Gomez-Herrero, Universidad Autonoma de Madrid, Spain)

http://news.uns.purdue.edu


Real-Time Observation of Nanocrystal Growth

August 21, 2009

Interim Berkeley Lab Director Paul Alivisatos and Ulrich Dahmen, director of Berkeley Lab’s National Center for Electron Microscopy (NCEM), led a team of experts in nanocrystal growth and electron microscopy who combined their skills to observe the dynamic growth of colloidal platinum nanocrystals in solution with subnanometer resolution. Their results showed that while some crystals in solution grow steadily in size via classical nucleation and aggregation – meaning molecules collide and join together – others grow in fits and spurts, driven by “coalescence events,” in which small crystals randomly collide and fuse together into larger crystals. Despite their distinctly different growth trajectories, these two processes ultimately yield a nearly monodisperse distribution of nanocrystals, meaning the crystals are all approximately the same size and shape.

A new technique known as “liquid cell in situ transmission electron microscopy,” in which the powerful resolution capabilities of a transmission electron microscope (TEM) are brought to bear on a liquid cell that allows liquids to be observed inside a vacuum, enables the visualization of single nanoparticles in solution. The Berkeley researchers deployed this technique on NCEM’s JEOL 3010 In-Situ microscope. Utilizing an electron beam operating at 300 kilovolts of energy, the JEOL 3010 provides outstanding specimen penetration and spatial resolution of about 8 angstroms through the thick liquid cell sample.

Original publication:

Zheng H, Smith RK, Jun YW, Kisielowski C, Dahmen U, Alivisatos AP (2009): Observation of Single Colloidal Platinum Nanocrystal Growth Trajectories. Science Jun 5;324(5932):1309-12.

http://newscenter.lbl.gov


Grant from NIH to Develop AFM Probes

August 19, 2009

Carbon Design Innovations has announced that it has grant in the amount of $390,000 from the National Institutes of Health (NIH) Small Business Innovation Research (SBIR) Program. The grant will fund the development and commercialization of Carbon Nanotube (CNT) Atomic Force Microscope (AFM) probes for bioimaging and investigations in cellular biology. Carbon Design Innovations will collaborate with the University of California at Davis, US on the development of the probes.
www.carbondesigninnovations.com


Methods and Applications of Fluorescence

August 14, 2009

The 11th International Conference on Methods and Applications of Fluorescence: Spectroscopy, Imaging and Probes will be held in Budapest, Hungary, from September 6-9, 2009. The venue of the Conference is the Congress Center of the oldest Hungarian University, the Eötvös Loránd University.
The meeting will cover the following scientific topics:

– Fluorescence Spectroscopy (Theory and Applications)
– Fluorescence Correlation and Single Molecule Spectroscopy
– Fluorescence in Biology/Medicine: Bioassays, Biophysics
– Special Fluorescent Imaging Techniques: Multi-Photon, Live Cell and Single Molecule Imaging
– Novel Fluorescent Probes, Sensors, Fluorescent Proteins, Quantum Dots, Nanomaterials and their Applications
– Special Fluorescence Techniques: Upconversion, Delayed Fluorescence, Fast Fluorescence Kinetics FRET, etc.
– Fluorescence Microscopy: Towards Higher Spatial and Temporal Resolution
– Fluorescence in Systems Biology High Throughput Screening Assays, Arrays, Micro-chip

www.maf11.hu

Budapest, Hungary

Budapest, Hungary


New Bioimaging Method for Observing HPCs

August 13, 2009

timm_schroeder_hpcs

The research team led by Dr. Timm Schroeder, stem cell researcher at Helmholtz Center Munich, Germany has developed a new bioimaging method for observing the differentiation of hematopoietic progenitor cells (HPC) at the single-cell level. With this method the researchers were able to prove for the first time that not only cell-intrinsic mechanisms, but also external environmental factors such as growth factors can control HPC lineage choice directly. The findings, published in Science, provide an essential building block for understanding the molecular mechanisms of hematopoiesis and are an important prerequisite for optimizing therapeutic stem cell applications.

With the new bioimaging techniques developed by Dr. Schroeder’s team, progenitor cells could be observed for a longer period and on the single-cell level. Depending on the kind of cytokines present, after a few days the HPC cultures contained only one cell type. The question remained unanswered whether this was a consequence of direct cytokine regulation or merely the result of sorting out “erroneously differentiated” cells by cell death. Using the new bioimaging techniques for continuous single-cell observation, Dr. Michael Rieger and students in Dr. Schroeder’s research group showed for the first time that no cell death could be detected during the entire cell differentiation process. This proves unambiguously that HPC lineage choices can be steered by external environmental factors such as in this case by cytokines. The hematopoietic progenitor cells are “instructed” by cytokines.
www.helmholtz-muenchen.de

Original publication:
Rieger MA, Hoppe PS, Smejkal BM, Eitelhuber AC & Schroeder T (2009): Hematopoietic cytokines can instruct lineage choice. Science 325:217-218


Aspects of Electron Microscopy and Microanalysis

August 11, 2009

Senior Metallurgical Engineer and Engineering Manager Dr. John Tartaglia of Stork Climax Research Services will be presenting a seminar titled „Aspects of Electron Microscopy and Microanalysis,“ on August 21, 2009 at Stork CRS in Wixom, Michigan, US.  The seminar will be offered in either a morning (9:00 AM to 12:00 PM) or afternoon (1:30 PM to 4:30 PM) session. Both sessions will be followed by optional tours of the laboratory facilities. There is no cost to attend this presentation. For reservations see:
www.storksmt.com


High-Speed X-ray Imaging

August 5, 2009

Scientists from the European Synchrotron Radiation Facility (France) the Forschungszentrum Karlsruhe, the Technische Universität Berlin and the Helmholtz Zentrum Berlin (all Germany) were able to make fast processes inside opaque objects visible, by using white synchrotron radiation to perform hard X-ray radioscopy with high spatio-temporal resolution. The required imaging detector was constructed out of a standard indirect detector in combination with a Photron SA1 CMOS-based camera. Thus, it was possible to investigate pore coalescence and individual cell wall collapse in an expanding liquid metal foam: the rupture of a film and the subsequent merger of two neighbouring bubbles could be recorded with a time sampling rate of 40000 frames per second (25 micorseconds exposure time). The results as published in the Journal of Synchrotron Radiation (http://journals.iucr.org/s/issues/2009/03/00/kv5057/ – open access) allowed to determine that the pore stability in a liquid metal foam is driven by intertia and not the viscosity of the melt. This knowledge is crucial in order to adapt metal foaming process for industrial production.

View videos at:
http://journals.iucr.org/s/issues/2009/03/00/kv5057/kv5057sup1.avi
http://www.alexanderrack.eu/ieee_movie.avi

www.esrf.eu
www.fzk.de
www.tu-berlin.de
www.helmholtz-berlin.de