How can you calculate how many atoms are in a nanoparticle?

Two years ago, I wrote a blog post called Two Ways to Make Nanoparticles, describing the difference between top-down and bottom-up methods for making nanoparticles. In the post I commented, “we can estimate, knowing how gold atoms pack into crystals, that there are about 2000 gold atoms in one 4 nm diameter gold nanoparticle.” Recently, a Sustainable Nano reader wrote in to ask about how this calculation is done. It’s a great question!

In order to estimate how many atoms are in a gold nanoparticle, we have to talk a little about crystal structure. Crystals form when atoms (or molecules) arrange themselves in an ordered way in three dimensions. The smallest unit of that structure is called a unit cell. The example below shows a simple cubic structure where there is one atom at each corner of a cube, and the cubes stack together to make the crystal structure.

cubic crystal

A simple cubic crystal built from 27 unit cells. (image by Miriam Krause)

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Fluorescence is Awesome: New CSN Videos!

Fluorescence is a favorite topic here at Sustainable Nano – we’ve written about quantum dotsfluorescein in the Chicago River, glowing bacteria, and many other topics, but one of our most popular blog posts of all time is about how highlighters and blacklights work.

Well, now our colleagues at ACS Reactions have made two amazing new videos inspired by that post! The first one is all about highlighters and fluorescence, including some cool nanotechnology applications; the second is a how-to guide for making flowers glow under blacklight.



Update July 27: Our video was featured on Gizmodo! Regarding their headline, though, it’s important to note that highlighters glow under UV light, not in the dark:)

It’s time for the 2016 Reader Survey!

Who are you, dear Sustainable Nano readers? We’d like to learn a little bit about you and what you think of our blog!

Instead of reading a new blog post this week, please take a few minutes to fill out our second annual Sustainable Nano Reader Survey.


When you’re done, you may enjoy celebrating last weekend’s Fourth of July holiday in the U.S. by re-reading our post about nanomaterials making their way into fireworks; or check out this ACS Reactions video about the chemistry of fireworks:

Thanks so much for reading Sustainable Nano – we look forward to hearing from you!

Field Trip to the Minnesota Nano Center

Ever wondered what it’s like to go into a “clean room”? A couple weeks ago a group of students from the Center for Sustainable Nanotechnology (CSN) got to find out during a tour at the Minnesota Nano Center.

MNC group

Dressed for the Minnesota Nano Center clean room! Personally, I think we look like Oompa-Loompas. (photo by Miriam Krause)

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Bacteria in the Shell: A Nano-bio Hybrid for Solar Energy Capture

As a fan of sci-fi, I recently watched two classic movies: the original Star Wars (which you’re probably familiar with) and Ghost in the Shell (a post-cyberpunk Japanese animation). Both movies had a very interesting commonality: human-machine hybrids. But what does this have to do with nanotechnology?


The most famous human-machine hybrid in pop culture?  (image from The Empire Strikes Back, adapted from

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How to search for a needle in a haystack: Spotting really tiny signals from the edge of the universe

As a chemistry graduate student I don’t normally take classes outside of the chemistry building, but this semester I happened to have an optics course in the physics department. So a few months ago when scientists at the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO for short) found gravitational waves,1 I got an inside look at just how excited physicists can get! Everyone in the department was walking around with smiles on their faces and talking animatedly to each other in the hallways. They were like kids at Christmas. Well, like kids who know a lot of math and like to talk about physics.

gravity waves

Gravity waves! (image by NASA/Ames Research Center/C. Henze)

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How to Survive Your First Professional Conference

Now that spring semester is coming to an end, a lot of scientists are getting ready to go to scientific conferences over the summer. During spring break I had the opportunity to participate in the American Chemical Society conference held in San Diego. This national conference attracts thousands of chemists from all over the country to spend five days learning about the latest information in their areas of professional interest and networking with colleagues. Moreover, this conference was particularly interesting to me as an undergrad student because it provides an opportunity for undergrads to present an oral or poster presentation on their research. Here’s a picture of me presenting the work that I did last summer with Dr. Vivian Feng as part of the Center for Sustainable Nanotechnology.


Figure 1: I had a pleasure to be part of a poster presentation at 251st ACS national meeting! (Photo by Vivian Feng)

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