Publication Summary: Dark Field Microscopy Makes Nanoparticles Light Up

This post is part of our ongoing series of public-friendly summaries describing research articles that have been published by members of the Center for Sustainable Nanotechnology. Katie Hurley and Nathan Klein, a doctoral mentor/undergraduate mentee team at the University of Minnesota, were co-first authors on this paper. Katie says, “In this post I want to point out how important it can be to have a fresh perspective. Because he had just been introduced to an instrument we use routinely, Nathan had the creativity and inspiration to see how dark field microscopy could be used to help solve a big imaging problem.”

 The article was first published online in April 2015 in Analytical Chemistry1

An illustration showing how nanoparticles are much easier to see using dark field TEM. Reprinted from Klein, Hurley, Feng, & Haynes (2015).1

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How Can You See an Atom? – ACS Reactions Video

Here at Sustainable Nano, we’ve published several posts talking about the instrumentation used by researchers in the Center for Sustainable Nanotechnology to visualize nanoparticles and cell membranes, such as atomic force microscopy and super-resolution fluorescence microscopy.

For this week’s post, we’re sharing a video produced by the American Chemical Society‘s Reactions series, called “How Can You See an Atom?” The video includes really nice explanations of tools such as x-ray crystallography and tunneling electron microscopy that allow scientists to “see” at even smaller than nano-scale. (Check out the 0.5 nm scale bar in the image at 5:05 in the video!)

Nano-Crystalline Metals and Sustainability

You’ve read a lot on this blog about how nanoparticles provide amazing opportunities for developing new materials. Over the next few years, we will have incredible advances in sustainable energy, biology, and more based on these new substances that never existed before. But what about the old, structural materials used in our buildings and cars?  Well, nano is going to play a big role in the sustainability of those too!

First, a bit of a background on what makes materials good for these applications: that is, what makes them strong and stand the test of time? For metals, their strength comes from the way their atoms fit together. They’re held together by a strong “metallic bond”. Unlike the other types of bonds, in metallic bonds all of the atoms share their electrons with each other. This allows for some of the properties you probably identify with metals – conduction of heat and electricity. The bonds also lack any directionality requirements, and this lets the atoms fit together in very space efficient ways like you could see in a grocery store aisle’s oranges or the bubbles that form on the top of some sudsy water. Space efficiency in this case means that the objects fit together in a way that minimizes the empty space around each of them.

Oranges and bubbles also like to fill up space efficiently if given the chance! image source

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Publication Summary: Designing a Simple, Easy-to-Build Reactor for Making Nanoparticles

This post is part of our ongoing series of public-friendly summaries describing research articles that have been published by members of the Center for Sustainable NanotechnologySam Lohse, the first author on this paper, was a post-doctoral student at the University of Illinois and is now an assistant professor at Colorado Mesa University in Grand Junction, CO.

He says, “Everyone (researchers, industry, etc.) wants nanomaterials, in order to test their fantastic applications and their implications for human health. Unfortunately, it can be difficult and frustrating even for experienced nanotechnology researchers to synthesize high-quality nanomaterials in meaningful quantities. We were hoping to come up with a simple and accessible approach to make nanomaterials in quantities of more than a gram at a time.”

The article was published in May 2013 in the journal ACS Nano.1


The new reactor system (left) and some of the gold nanorods that it helped us produce (right). Image reprinted with permission from Lohse et al. 1

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The Atomic Force Microscope – Probing to “See” at the Nanoscale

Take a look around – do you see a surface that looks a little bumpy?  Now close your eyes, reach out your hand, and feel that surface. Got an idea of what it feels like? Great! Now, could you use what you’ve learned with your sense of touch to draw a picture of this bumpy surface? Probably not. Creating three-dimensional images of surfaces like the one you just touched is a difficult task for a human, but is the specialty of one of the instruments I use, the atomic force microscope!


Figure 1. Here’s a picture of the AFM I work on. Here it’s set up to analyze samples containing flowing fluids, so that we can mimic environmental conditions.

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Celebrating St. Patrick’s Day with Fluorescence

Our last blog post featured lighting technology powered by algae, and this week is all about a different example of green-colored water: the Chicago River.

Every year since 1962, the Chicago River has been dyed green for the downtown St. Patrick’s Day parade. So how does this amazing color transformation relate to the Center for Sustainable Nanotechnology?

The Chicago River dyed green for St. Patrick’s Day, 2009        image by Mike Boehmer

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Sustainable Lamps Powered by Algae

Have you ever thought about lighting up the streets using algae? I know I certainly hadn’t before researching for this post, but there are some scientists who have been working on the idea for a long time. There is even a prototype street lamp that’s been built using algae as its power source! This streetlamp currently helps light up a parking lot in Bordeaux, France.1

Figure 1. Green algae, like the ones shown here, are very abundant and obtain their energy from photosynthesis.   image source

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