First Direct Imaging of Protein Complexes Using in-situ Liquid STEM
April 2012
Researchers at UC Davis and Pacific Northwest National Laboratory utilized a continuous flow in-situ liquid stage developed by Hummingbird Scientific to capture direct images of individual proteins and macromolecular complexes in a fully hydrated environment without freezing or chemical fixation. They were able to capture images of both static (b, white arrow) and moving (b, white arrowhead) ferritin proteins with a spatial resolution better than 2nm. Using this technology, researchers were able to distinguish between the inner, iron-oxide core (~7.5nm diameter), and less-dense outer protein layer (c). Nanolipoprotein discs (NLP's) were also imaged for the first time in a fully-hydrated and non-frozen state. These images indicate that NLP stacking (d, arrowhead) occurs in a buffered solution and is not solely an artifact caused by other TEM sample preparation processes, as previously thought. These experiments demonstrate that individual proteins and macromolecules can be imaged at high resolution using in-situ liquid TEM and represent a vital first step towards developing new methods for imaging complex molecular interactions in real-time at nanometer-scales. Scale bars represent 20nm (a, b and d) and 10nm (c).
Reference: Evans, J.E., et al., Visualizing macromolecular complexes with in situ liquid scanning transmission electron microscopy. Micron (2012), doi:10.1016/j.micron.2012.01.018. Images copyright © 2012, Elsevier.
In-situ TEM Changes in Magnetic Structure
December 2011
Researchers at Carnegie Mellon University and Argonne National Laboratory have used the Hummingbird Scientific in-situ TEM magnetizing holder to investigate the changes in magnetic domain structure with respect to the applied magnetic field in a Fe-Pd-Co magnetic shape memory alloy. They have shown that the magnetic domain boundaries break away from the twin boundaries at higher magnetic field values. The individual frames in the figure (a-f) show Fresnel out-of-focus images of a twinned structure in a Ni-Mn-Ga magnetic shape memory alloy. Twins are running downwards from the top left corner of the images. The magnetic domain walls (MDWs) appear as bright or dark linear features. In frame (a), a pair of MDWs have been indicated by white and black arrows. Broken domain walls are visible in image (c) at locations 1 and 2.
Reference: A. Budruk, C. Phatak, A.K. Petford-Long, and M. De Graef, "In-situ Lorentz magnetization study of a Ni-Mn-Ga ferromagnetic shape memory alloy," Acta Materialia, vol. 59, pp. 4895-4906 (2011). Images copyright © 2011 Acta Metallurgica, Inc. Published by Elsevier Ltd. All rights reserved.
High Resolution TEM Imaging in Liquid
August 2011
Researchers at UC Davis and Lawrence Livermore National Laboratory have used Hummingbird Scientific in-situ TEM liquid stages to study lead-sulfide (PbS) nanoparticles growth. Images with resolution down to the atomic scale showed that the Pb:S ratio in the solution controls the growth mechanisms and final morphology. By using both a laser or the condensed electron beam to initiate growth, they were able to repeatedly control growth and morphology by using different Pb:S ratios in solution. Image shows two different types of PdS nanoparticles (Top left: BF TEM of one type particle - scale bar 25 nm; Other images: BF TEM, DF TEM and FFT of other type particle - scale bar 2.5 nm).
Images and article source: "Controlled Growth of Nanoparticles from Solution with In Situ Liquid Transmission Electron Microscopy", J. E. Evans, K. L. Jungjohann, N. D. Browning and I. Arslan, Nano Letters, 2011, 11 (7), pp 2809-2813, Copyright © 2011 American Chemical Society. Full Abstract
Atmospheric Pressure TEM
November 2010
Atomic scale imaging of gold nanoparticles in 1.1 atmosphere nitrogen gas, imaged using a 300kV FEI Titan in BFTEM mode using Hummingbird Scientific's recently launched atmospheric pressure gas holder. The Fast Fourier Transform (FFT) of the particle on top right shows the 2.04 Aring; lattice spots.
Unpublished results courtesy of Eric Stach and Daan Hein Alsem, Hummingbird Scientific.
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