Invisible Remnants of Dead Stuff Hiding in Water

Ready for a little test?  Try to list all of the things you can think of that are found in a river or lake…

NiagaraFalls

Sweet picture of the Niagara River in Niagara Falls, New York.

I’m sure you came up with things like fish, algae, dirt, plants, and many others.  But one thing found in these water bodies that you may not have thought of and that I’m really interested in studying is natural organic matter, or NOM (not to be confused with the sound you make while eating a delicious meal). NOM dissolved in water is hard to detect with the naked eye but can be readily detected using a variety of scientific instruments. A glass of water with and without NOM, for example, would look very similar to the naked eye, with just a slight color change. However, it turns out they differ in some very important ways. Continue reading

Animated Ladybug Super Zoom-In

Here is the underside of a ladybug. Click the image to enlarge. You won’t regret it!

Here

Click to enlarge!!

In this post I hope to help you appreciate just how small “nano” is, using the official ladybug of science!

Before we get there, let me explain how I took this image.

Step 1 – Find a dead ladybug. As I am the bug-loving sort, I generally try not to kill them myself. I found this one hanging out in the glass casing underneath a ceiling light during spring cleaning. Continue reading

How I Study Nanoparticles’ Interactions with Biological Soup

Designing non-toxic nanomaterials requires that we understand how those nanomaterials interact with biological systems. Systems such as you me, and all other organisms, contain a “biological soup” of chemical compounds, known as biomolecules. So the question becomes…how do nanomaterials transform once they come into contact with these biomolecules? This question has become increasingly important, especially as nanomaterials are developed for the biotechnology and medical fields.

Once a nanomaterial enters the body, typically through the bloodstream, the nanomaterial is exposed to a slew of biological matter such as proteins, cells, and minerals. Molecules from this “biological soup” will latch onto the exterior surface of the nanomaterial creating what scientists have started calling a “protein corona.” It is important to understand the protein corona because when these nanomaterials interact with biological systems such as cells, the cells first encounter the protein corona, which coats the surface of the nanomaterial. Therefore, the protein corona is a critical component of the nanomaterial and is essential in understanding how nanomaterials interact with biological systems.

What happens when nanoparticles are exposed to biological systems?

Proteins can coat the surfaces of nanoparticles, completely changing many of their properties.

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The Chemical Story Behind Non-Petroleum-Based Plastics

Every year, millions of tons of plastic are discarded into landfills, where they will take hundreds of years to break down.  New biodegradable plastics offer a potential solution to this problem.

Let’s back up and talk about “traditional” plastics first. In addition to being landfilled, some plastic is disposed of improperly, leading to plastic pollution on land and in lakes and oceans where they persist.  Once in the environment, animals can accidentally eat the plastic but are incapable of digesting it, so the plastic just sits in their stomachs.  Over time, the plastic can block off their digestive system, and the animal will starve.

Luckily, there are plastics that are designed to break down rapidly upon disposal.  These types of plastics are known as biodegradable plastics, meaning that organisms can decompose the plastic in the environment.  When biodegradable plastics are decomposed, they are converted to chemicals found in nature, often carbon dioxide and water.  The organisms that carry out the decomposition are generally microorganisms like bacteria.  Instead of hundreds of years, most biodegradable plastics take only a few months to decompose after they’ve been thrown away.  Many of the biodegradable plastics produced today can be made from renewable resources.  I’m going to talk about a few different biodegradable plastics in use today. Continue reading

Girls-in-STEM Programs & My Single-Sex Education Experience

Attending Spelman College helped me to realize my potential as a scientist and as a scholar. Sitting in a room full of women, the pressure of impressing members of the opposite sex removed, I was able to come into myself, build confidence and explore my role in scientific discourse.

Spelman College Department of Chemistry graduates, class of 2013

Spelman College Department of Chemistry graduates, class of 2013

I did not realize how comfortable I was in a room solely occupied by intelligent and accomplished young women until I experienced nearly the opposite. I recently took a Differential Equations course at Morehouse College, where I was the only woman. Though I performed well in the class, I was more reluctant to share my ideas even though I was confident that they were correct and sound.

I began to wonder if my experience was an isolated case, or if there were people like me that might benefit from single-sex educational experiences particularly in the fields of science, technology, engineering and mathematics (STEM). These experiences prompted me to explore the debate on gender-specific educational experiences. Continue reading

Two Ways to Make Nanoparticles

In Marco’s previous post, you can read how making nanoparticles is like baking – different proportions of ingredients and different processing conditions (time and temperature) can turn your batter into a pancake, bread, a biscuit, etc.  But how do you come up with recipes to make nanoparticles in the first place?

In general, as I see it, there are two main ways to make nanoparticles:

1.  Take a large hunk of material and drill/blast/mechanically process it into tiny nano-sized pieces.  This is the top-down approach. Another way to think about this is “making big stuff smaller.”

2.  Take a molecule, or a simple salt , that has the right atoms, and perform a chemical reaction to build the nanoparticle atom-by-atom. This is the bottom-up approach.  Another way to think about this is “making small stuff bigger.”

No matter which way you do it, though, the trick is to control the nanoparticle size and shape!

Let’s look at examples of these approaches.

Top-Down Approach

The nanodiamond we use in our Center is made via the top-down approach.  Nanodiamond is nearly pure carbon.  Nanodiamond is made by detonation (explosion) or ultrasonication (using sound waves to break up materials) of bulk graphite flakes:

Graphite can be turned into nanodiamonds breaking up graphite's atomic structure using high-energy sound waves. Image adapted from source.

Graphite can be turned into nanodiamonds breaking up graphite’s atomic structure using high-energy sound waves. Image adapted from source.

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Dumping Nanoparticles into a Fjord: How to Think About the Potential Environmental Impacts

Nanoparticles and the Environment Series, Part II  (click here for Part I)

Let’s dive in to a real-world nanotechnology problem raised by one of our readers: should waste composed of nanoparticles, let’s call it “nanowaste”, be disposed of differently than regular waste? There are many types of nanowaste that we could discuss, but today we’ll focus specifically on nanoscale titanium dioxide, which Sam discussed in his recent post, generated as a by-product of mining.

Mining for phosphates. Image source.

Mining for phosphates. Image source.

Our journey into the world of nanoscale titanium dioxide starts in Southwestern Norway, at the Engebø mine. This not-yet-operational mine will extract rutile, the most common structural arrangement of titanium dioxide in nature, from a 2.5 kilometer swath of rock near Engebø Mountain. Extracted material will be sold to producers interested in making pigments and perhaps products that incorporate emerging titanium dioxide nanotechnologies. Most of it will not be nanoscale, but the waste material, also called “tailings”, will contain nanoscale titanium dioxide. Our interest, then, is in how the Engebø mine handles this nanowaste.

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