Na-No Thank You? Exploring the Dangers of Commercial Nanoparticles

Ah, a day at the beach. You find the perfect spot near the water’s edge, spread out your towel, slather on some sunscreen, and settle in with a cool drink. You spot a sparkling white boat bobbing in the distance, full of relaxed passengers tanning in the sun.

While this scene is full of idyllic summer imagery, is it also full of lurking danger? I’m not talking about sharks, but rather something much smaller: both the sunscreen you put on and the paint on the boat contain nanoparticles that provide important benefits but can harm both you and the environment around you. Nanoparticles are spheres made from a wide range of materials and are tiny in size. A nanoparticle is a million times smaller than the grains of sand clinging to your towel, making it about the same size as a single molecule and imperceptible to the naked eye.

white lifeguard nose zinc oxide nanoparticle. Found on pinxav.com

In sunscreen, a chemical called zinc oxide offers protection against UV rays. This chemical can exist either as nanoparticles or as larger, non-nano particles. Have you ever seen a lifeguard in a movie with a white stripe down their nose? They used sunscreen that contains the larger zinc oxide particles, which are opaque. Zinc oxide nanoparticles, on the other hand, are transparent and leave no visible residue when applied to the skin, the advantages of which are pretty clear (pun intended). On the boat, silver nanoparticles in the paint ward off bacteria, preventing the boat from rusting. Silver is anti-bacterial regardless of its size, but only silver nanoparticles are small enough to blend in with the paint.

Thanks to their shrunken size, nanoparticles of a certain material either give that material new properties (like making zinc oxide transparent) or allow its existing properties to be used in a new context (like making silver compatible with paint). Commercial nanoparticles have harnessed and revealed the capabilities of countless materials for applications ranging from batteries to coolant liquids to television displays. But despite the prevalence of nanoparticles in consumer products, we have only recently begun probing the harm they could cause to humans and other organisms. Could nanoparticles be bad for you? What about the sea creatures that become exposed to them when they leach into the water? Scientists are trying to answer these questions by studying the danger, or toxicity, of nanoparticles.  

zinc oxide nanoparticles
A zinc oxide crystal

Unfortunately, the very thing that gives nanoparticles so many desirable properties—their miniscule size—is the same thing that can cause them to be toxic. As an object gets smaller, its surface area increases relative to its volume. For example, think of donut holes and how they taste better than donuts. Because donut holes are smaller, you get more of the yummy donut coating (sprinkles, icing, powdered sugar, etc.) with each bite. Nanoparticles are like donut holes, in that they have a very large surface area compared to their size. And just like how donut holes can become coated with sprinkles or powdered sugar, a nanoparticle that finds itself inside of a human or a fish can become coated with proteins.

Proteins are the components of our bodies that form structures such as muscle, carry out chemical reactions, and perform many other important roles. When proteins cover the surface of the nanoparticle, both the protein and the particle can undergo certain changes that may be harmful to the organism.

For the protein, this is a change in shape. Proteins adopt different shapes that dictate their role in the body. The proteins that make up muscle are long and flexible to allow our muscles to contract. The proteins that carry out chemical reactions have crevices that specific molecules fit into so they can be converted into something else. A protein’s shape is crucial to its function. So, if a protein changes shape, it loses its function.

Scientists have confirmed that certain protein-nanoparticle interactions can alter the shape of the protein, impairing its function and interfering with the important processes this function serves. While the nanoparticles in sunscreen do not penetrate intact skin, they—as well as nanoparticles in all other commercial products—could enter the body through a cut, accidental ingestion, and even inhalation if used in an aerosol. Scientific studies have shown that proteins that store oxygen in muscle cells and transport cholesterol can lose their shape and function if they come into contact with different nanoparticles, increasing the risk of cardiovascular disease and other serious health problems. 

The interaction between the nanoparticle and the protein can also create changes in the particle that affect its toxicity down the line. When the proteins in an organism’s body coat the surface of the nanoparticle, they form what is called a “protein corona.” While nanoparticles can’t get inside of a cell, proteins, like the ones in this corona, can. The corona essentially disguises the nanoparticle as a protein so that the cell will let it in, just like a party crasher dressing up like someone on the list. Upon entering the cell, the nanoparticle gains access to all the proteins that are inside the cell. It then has the opportunity to interrupt the critical functions of these proteins, which include replicating DNA to make new cells and generating life-sustaining energy sources. 

The protein corona also influences the way in which the particles interact with one another. Nanoparticles typically carry an electrical charge at their surface. Like magnets, similar charges repel each other, preventing nanoparticles of the same type from clumping together. But, the protein corona can obscure a nanoparticle’s surface charge, preventing this repulsion and enabling multiple particles to form clumps. Clumping slows down the nanoparticles, affecting their mobility and the locations within the body at which they settle. For example, researchers discovered that inhaled nanoparticles deposit at different parts of the lung depending on how many were clumped together. Nanoparticles’ fate within the body will in turn determine which other proteins they may encounter and impair later on.  

silver nanoparticles
Silver accumulates in the rainbow trout’s gills, causing the fish to suffocate.

Finally, the protein corona can impact a nanoparticle’s toxicity by physically changing the particle itself. When a protein binds to a nanoparticle’s surface, it can trigger a chemical reaction that causes the particle to dissolve. Unfortunately, this can make the nanoparticle even more toxic.For example, the silver nanoparticles in the boat’s paint can dissolve when they become coated by a certain protein found inside an organism’s body. Scientific studies have revealed that dissolved silver can be toxic toward rainbow trout and zebrafish, even at low amounts.

What does all this mean for us and for our oceans? We’re not quite sure yet. It’s important to note that no study conducted in a laboratory can perfectly replicate the conditions of an organism’s body. Additionally, these toxic effects all hinge on initial exposure to nanoparticles, which may or may not actually happen. So, while the answer isn’t entirely straightforward, the potential for nanoparticle toxicity toward humans and marine life is undeniable.

But… we need nanoparticles, right? So we don’t have rusty boats and white lifeguard noses? This is true. Luckily, nanoparticles come in all different types of materials, shapes, sizes and surface charges, and these things can greatly affect the way they behave. For example, the cholesterol-transporting protein only binds to nanoparticles that carry a certain surface charge. Similarly, the protein interaction that causes the silver nanoparticles to dissolve depends on the size of the particle. Thanks to the development of new screening tools that can analyze thousands of nanoparticles at once, scientists can test nanoparticles of all designs for toxicity. This makes it possible to identify a specific nanoparticle that maintains its useful properties but does not hurt people or the environment.

Thanks to the work of foresighted scientists, we now know that nanoparticles can be toxic to living organisms and we have the opportunity to modify commercial particles to minimize their potential for harm. Whether or not manufacturers seize that opportunity is another matter. So, for now, sit back and enjoy the sights and sounds of the ocean. But keep your eyes peeled for danger.

northwestern phd student headshot glioblastoma cancer brainer

Sarah Anderson is a PhD candidate in the chemistry department at Northwestern University.

Artificial Organs? How We Can Get There with 3D Printing

Medical technology is rapidly advancing, with new technologies emerging faster than we can appreciate. Technologies such as liquid biopsies, 3D fluorescence imaging, and heart-in-a-box are just a sampling of the very cool advances we’ve seen in medicine in the past decade. Liquid biopsies can detect cancer in a patient’s blood, giving clinicians a reliable, non-invasive, and informative clinical tool to use to monitor cancer growth over time. Three dimensional imaging makes it easier to see what’s going on in your tissues. And heart-in-a-box allows donor hearts to live longer before transplanting them, giving time for hearts to travel far distances to patients in need. But, a tool that’s not so new yet is still particularly fascinating in its potential medical applications is the 3D printer.

Continue reading “Artificial Organs? How We Can Get There with 3D Printing”

A Tale of Two Speeds: How Planes Stay in the Air

Last spring, my wife and I took a trip to Bali for our honeymoon. While the trip was an absolutely incredible, once-in-a-lifetime adventure, the journey to our destination, as I described previously, was not a walk in the park. After 24 hours in transit through 13 time zones, where daytime accelerated and nighttime shrouded the plane in darkness for the majority of the trip, paired with my inability to sleep on planes, I was starting to regret ever getting a passport in the first place. Continue reading “A Tale of Two Speeds: How Planes Stay in the Air”

Brand-Name Drugs vs. Generics: What’s the Difference?

You’re in the midst of a headache, temples throbbing, and you rush to the drug store for medication only to have your headache intensify because you can’t decide whether you should get Tylenol or its generic form. Does that sound familiar?  Ever dreaded having to pick up an expensive prescription and then been shocked to receive a generic version of it at a lower or no co-pay? (What a nice surprise!) Or, are you wondering why sometimes there is no generic alternative of your medicine available?  Read on and hopefully, by the end of this article, you have all these questions answered.

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Say Goodbye to Trans Fats

Today, you can find hydrogenated butter with canola oil right next to trans fat-free margarine. Partially-hydrogenated soybean oil a few aisles down from Omega-3 fatty acids. Your friends tell you that you can eat fat as long as you avoid sugar, while doctors tell you to avoid some fats because they’ll clog your arteries and cause heart disease. Yes, the world of fats is as complex as it is diverse.  Continue reading “Say Goodbye to Trans Fats”

A Cell’s Search for Identity

All of us have gone through the torment of high school—the growing pains and the mood swings and the cliques. It turns out that during development the cells of your body also go through something similar to high school. Once a new cell is created in the developing embryo, the cell undergoes a process called cellular differentiation, where it responds to varying cues to choose what kind of cell it’s going to be, or rather how it should respond to the incessant “what do you want to be when you grow up” question. The process of cellular differentiation in embryonic development is very similar to school—the cell enters the process naïve and innocent about the world, and leaves with an idea of who and what it wants to be.

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Blood, Sweat, and… Saliva: How Our Bodily Fluids Can Save Us

Picture a fighter pilot commanding a plane as they engage in aerial combat.  When you think of the greatest threats to the pilot’s safety, you probably think of attacks from other aircraft or the risk of crashing the plane as they swiftly maneuver it between various obstacles.  But what about the potential for harm coming from inside the pilot’s own body?  For example, the stress the pilot is feeling might give him or her a heart attack.  Similarly, their severe dehydration could lead to heat stroke.  Both of these conditions would spell disaster for the pilot.  While often overshadowed by the inherent hazards of weapons and machinery, these ailments pose a very serious threat to the safety of military personnel.  But how can we know if someone is dehydrated or enduring dangerous levels of stress while they’re thousands of feet in the air? Continue reading “Blood, Sweat, and… Saliva: How Our Bodily Fluids Can Save Us”

On a Small Island in Indonesia: The Last Dragons on Earth

Halfway across the Earth, nestled deep within the Indonesian archipelago, lie two small, tropical islands unlike any others on the planet. From the United States, it takes at least three planes, a boat, and a couple of days to get there. By the time you dock at the main pier on one of these islands, you realize that you’ve stepped foot into an entirely different world. There is no technology – no cell service, no internet, no cars; not even paved roads. It’s just you, a guide, and the wilderness around you. Continue reading “On a Small Island in Indonesia: The Last Dragons on Earth”

Does Sprinkles McFluffington have Resting Cat Face?

Why is your cat so judgmental?  Sure, you’ve been lounging on the couch stuffing your face and binging on Netflix for like seven hours. But still.  A animal who uses their tongue to shower doesn’t get to judge us, right? Nevertheless, our cats seem to direct a thick layer of skepticism and condescension toward us, even though we prepare their meals, clean their litter boxes, and buy them toys filled with catnip. Continue reading “Does Sprinkles McFluffington have Resting Cat Face?”

Kombucha: the Science Behind the Craze

It seems like every year there’s a new miracle food. First it was kale, then it was açai bowls, and now kombucha (pronounced come-BOOCH-uh) is the new health craze. You may have heard friends or colleagues touting its benefits: “It prevents cancer!” “It fights off colds!” “It’s the fountain of youth!” Maybe you’ve recently hopped on the kombucha train, or have been drinking it for years, or, if you’re honest, maybe you have absolutely no idea what it is. (It’s a fermented tea drink, in case you were wondering).

Well, you’re in the right place! Let’s learn more about the science behind kombucha. We’ll explore how it is made and how it interacts with our bodies. And spoiler alert: while it’s probably not the fountain of youth, evidence suggests it could be really, really good for us.  

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Piping Plovers: Conservation in Action

You may have heard that some little birds, the Piping Plovers, are making big waves at Montrose Beach this summer in Chicago, as well as other beaches around the country. Piping Plovers are federally endangered in the Great Lakes region, with only about 80 nesting pairs. A Jersey Shore concert series was canceled this year to protect a nest that was found in the area, and just the other day, they cancelled the summer music fest Mamby, which was scheduled to happen at Montrose Beach in late August. Why all the fuss over one species of shorebird?  Continue reading “Piping Plovers: Conservation in Action”

The Hunt for the Elusive Neutrino

About 100 trillion neutrinos just passed through your body a second ago. Did you feel them? Neutrinos are one of the most abundant particles in the universe, but they’re also the most elusive. They can pass through just about anything, including your body, without being noticed. Now, imagine if we could harness this power. Imagine the possibilities if you could control a particle that can pass through anything undetected.

While an intriguing idea, it’s this exact characteristic that kept neutrinos from being detected for nearly half a century after physicist James Chadwick first theorized their existence back in 1914. Continue reading “The Hunt for the Elusive Neutrino”

Liquid Rocks and Where to Find Them

Summer in Illinois can feel unbearably hot, but how hot is that exactly?  At 80ºF, Illinoisans can be found enjoying the sunshine and the reprieve from our winters.  At 100ºF, Chicagoans complain incessantly as cautionary heat warnings show up on billboards.  But what about, 200ºF?  Or 1000ºF?  These are the real extreme temperatures, and they are so hot that they literally melt rocks.  Believe it or not, parts of our very own planet heat up to these temperatures.  Continue reading “Liquid Rocks and Where to Find Them”

Stripping, Drugs, Neurosurgery: Living With Epilepsy

Somehow, the first seizure I recall makes me giggle. I was getting changed after sports at school, age 6-ish, when I had a focal seizure, a seizure that starts on one side of the brain. The problem really was that I was still only half-dressed when I started walking down the corridor in only my underwear. It wasn’t until I was about to enter the classroom that I came out of the seizure. Can you imagine how different my life might have been if I had half-flashed my classmates?!  Continue reading “Stripping, Drugs, Neurosurgery: Living With Epilepsy”

How to Take Great Photos: The Three Pillars of Photography

If you ever decide your smartphone camera isn’t cutting it and you want to buy a standalone DSLR camera, you’ll find that you have a lot more control over how your photographs come out. DSLRs come loaded with lots of features and settings that contribute to the overall look of your photographs, all of which are either controlled automatically by your phone or not available at all. Use these features the right way, and you can capture images your phone never could. Continue reading “How to Take Great Photos: The Three Pillars of Photography”

Viva Las Vagus

Chances are, you’ve had a few opportunities to be crippled by symptoms of anxiety in your life. Maybe it was a first day at a new job or a social occasion with no familiar faces. Perhaps it happened right before you needed to perform in front of an audience. These occasions can be few and far between for some or chronically debilitating for others. Any way you experience it, anxiety generally comes with the same set of symptoms—accelerated heart rate, increased blood pressure, an abrupt tightness in your stomach. What’s happening here is your body’s fight-or-flight response, the automatic physiological and psychological behaviors that prepare your body to react to a perceived danger. Continue reading “Viva Las Vagus”