New technology allows scientists to watch cancer cells in action at unprecedented resolution

Diana Peckys and Niels de Jonge have developed a new approach for the study of nanoparticle (NP) and cell interactions. The traditional method for EM imaging of NPs involves dehydrating, embedding and sectioning the sample into multiple thin sections (<100 nm). Such processing can lead to extraction or loss of NPs from the sample, particularly in membrane regions. In addition, thin sections may cut through three-dimensional structures, such as vesicles that contain high densities of NPs. In this study the Poseidon™ liquid TEM holder and E-Chips™ were utilized to eliminate these disadvantages.

The microfluidic chamber was comprised of two Poseidon™ E-Chips™, both with a 50 nm thin silicon nitride membrane in their center to provide a transparent window for photons and electrons. The E-Chips™ are used in combination to enclose the liquid and seal the cells from the EM vacuum. One E-Chip™ had a flat surface and served as the substrate on which adherent cells were cultured. The second E-Chip™ contained two, 6mm thick, integrated spacers that formed a flow channel. These spacers prevent compression of the cells when the E-Chips™ are assembled into the microfluidic chamber, and allow the introduction of buffer to maintain the cell’s hydrated state during imaging.

A resolution of 3 nm was obtained on fully hydrated, intact COS7 fibroblast cells that were living at the onset of imaging. EM images were collected in STEM mode using a Philips CM200 microscope. An average electron dose of 3 e^-/Ų, a factor 10 below cryo-TEM dose limits, was used to produce the initial image. Because the STEM image contains signals from the full three-dimensional space of the cell, this technique can be used for quantitative studies of NP uptake and spatial distribution without sectioning sample. Citing the absence of signs of radiation damage in the recorded images, and the low electron dose, Peckys and de Jonge hypothesize that the first image recorded on a cell can be used to assess the distribution of NPs inside a live cell.

Serum-protein coated gold-NPs were observed sequestered intracellular vesicles, likely lysozomes. Analysis of these vesicles indicated that the NPs were primarily localized on the vesicle membranes, rather than filling the entire intravesicular space.  The distributions of these NPs were analyzed further, and found to occupy 67±11% of the available membrane area. Thus, Liquid STEM is an efficient and robust technique for whole cell analysis of uptake and distribution NPs

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The fast Fourier transform shows that 0.7 Å resolution was obtained at 600 °C. The resolution is close to the resolution limit of the TEM, 0.5 Å, and indicates that the Aduro™ system, even at this temperature, is not limiting the resolution of the TEM. As the temperature was ramped from room temperature to 600 °C during the experiment, the nanoparticles became increasingly dynamic. They started to coalesce, facets changed and defects in the material became mobile. The stability of Aduro™ made imaging, including real time movies, and analysis of these events possible at the atomic scale with unparalleled clarity.

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Protochips (http://www.protochips.com), a company specializing in revolutionary products for in situ electron microscopy, today announced JoeXray as the new distributor for the Aduro^TM and Poseidon^TM systems in the states of Kentucky, Indiana, Ohio, Michigan, West Virginia, and western Pennsylvania.

This is a natural partnership that opens new sales channels for Protochips. The Aduro^TM and Poseidon^TM platforms will be powerful additions to the JoeXray line of microscopy products. This partnership will allow clients to:

Design and implement unique and custom experiments

Produce and image low drift thermal samples

Obtain nanometer resolution of liquid samples

The Aduro™ system has revolutionized the capabilities of in situ electron microscopy. Researchers can now complete real time, dynamic thermal studies in high resolution. The Aduro™ E-chip™ consumables are customized to meet the exact needs of an experiment. E-chip™ sample supports replace the traditional TEM grid while providing electrical, thermal, or electro-thermal stimulus to the supported specimen.

The Poseidon™ system is a liquid based system that allows for the imaging of both material and biological samples. Samples that previously required freezing or were unable to be imaged live can now be studied directly in their native environment in real time. The Poseidon E-chip™ consumables increase flexibility by allowing customization of volume and flow path on a per-experiment basis.

Steve Shannon, Protochips’ Vice President of Sales, says, “Joe Ullmer has been in the EM/EDX industry since 1984, understands our technology and the applications, and has an extensive network in our target markets.  We anticipate Joe having a very strong impact on our business and know he can provide outstanding service to our mutual customers.”

Protochips, located in Raleigh, NC, is a company providing revolutionary products and technologies for the in situ electron microscopy market for more than eight years. Through their innovative E-Chip™ consumable technology, Protochips is fundamentally changing the way in situ microscopy is performed. The E-Chip™ platform is the engine that drives Protochips Aduro™ and Poseidon™ in situ solution, providing temperature and electrical in situ capabilities and the Poseidon™ for liquid in situ capabilities. More information can be found at http://www.protochips.com.

CONTACT: Protochips, Inc.

Steve Shannon, 919-349-7785

Vice President of Sales

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CONTACT: JoeXray

Joe Ullmer, 937-554-2628

Founder

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