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 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”

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?”

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”

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”

Is the Measles Really That Bad?

It’s official. In 2019, the United States (U.S.) is experiencing the nation’s largest outbreak of measles since 1994.

As the pairing of “measles” and “outbreak” screams across the headlines of countless news outlets, the majority of us experience an internal and instinctive shrinking back. But why? Is this learned response necessary, or is it simply the result of scare tactics and media hype? Continue reading “Is the Measles Really That Bad?”

The Truth about Cannabidiol (As Far as We Know)

“CBD.” Perhaps you’ve seen these letters shining bright, in green neon, on a store window in a seedy part of the city, fronting a shop with glass vials and trinkets lining the shelves and creepy men behind the counter. Or, maybe you took a stroll downtown on a sunny day and walked into CVS or Walgreens, only to see these same letters on small boxes lining the shelves next to the vitamins. You might be wondering what’s going on – how could the same compound be proudly sold in shady hemp shops and mainstream convenience stores at the same time? What is this confounded chemical? Continue reading “The Truth about Cannabidiol (As Far as We Know)”

The Moving Cells that Make Our Pups the Pups They Are Today

What makes dogs so doggy? You might have noticed that your dog has traits, like floppy ears, a curly tail, speckles or patches, or a cute, short nose,  that make it look pretty different from the wolf it’s descended from. For more than a century, scientists have wondered why so many domesticated animals, ranging from cows to pigs to mice, share traits like these that don’t exist in the wild animals they’re related to. Continue reading “The Moving Cells that Make Our Pups the Pups They Are Today”

Redrawing the Battle Plan Against Antibiotic Resistant Bacteria

Emily Collins has spent her life under the shadow of recurring bacterial infections. She spent a significant part of her childhood in the hospital, taking time off from her studies at her university, which cause her to lose her dream job of being a nurse. Emily suffers from chronic ESBL infections. ESBLs, or Extended-Spectrum-Beta-Lactamases, are bacterial chemicals that can break down a range of antibiotics, helping certain bacteria resist a large fraction of antibiotic treatments. As a result, these antibiotic-resistant infections are notoriously difficult to treat and can cause chronic, life-long infections.

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Immunity: How Vaccines Keep You Healthy

“It’s just like riding a bike!”

We usually say this when we’re trying out a task or a skill that we may have learned long ago, and have not used for a while, but can still execute like no time has passed. Think back for a moment to that time when you were learning this persistent skill. What exactly did you need to learn that stuck with you all this time? Your brain and muscles learned how to stay balanced, how to pedal and how to steer, and how to do all of those things at once. It was a pretty complicated task to learn. Continue reading “Immunity: How Vaccines Keep You Healthy”

What Your 23andMe Results Mean for Your Health

Last year, the genetic testing company 23andMe announced they will start testing for mutations in the BRCA genes, the ones that predict whether a woman will develop breast cancer, with surprising accuracy. A year prior, the FDA approved 23andMe genetic tests for other complex conditions such as Late-Onset Alzheimer’s Disease, Parkinson’s Disease, and Celiac disease. Continue reading “What Your 23andMe Results Mean for Your Health”

Glioblastoma: This Cancer is Not a No-Brainer

In the summer of 2018, you probably heard the word “glioblastoma” popping up quite frequently in news reports upon the decline and death of American politician John McCain.  McCain was diagnosed with the aggressive class of brain cancer in July 2017, stopped treatment on August 24, 2018 and passed away the very next day. While this timeline might seem exceptional, the unfortunate reality is that McCain’s experience with glioblastoma is a very accurate representation of the rapid progression of the disease.  In fact, those afflicted by glioblastoma survive on average just over one year upon diagnosis.  Let’s explore what makes glioblastoma so evasive in nature and what scientists are doing to try to increase patients’ lifespans.   Continue reading “Glioblastoma: This Cancer is Not a No-Brainer”

A Spoonful of Insulin Makes the Blood Sugar Go Down

Imagine drinking ten glasses of sugar water. What would you do after? Wash out your mouth? Eat something salty? You’d probably eat or drink whatever it takes to get rid of the extremely sweet taste. In the same way, when your body encounters high blood sugar, it tries to lower your glucose back to normal levels. Insulin, meaning island in Latin, is a hormone that is made in your pancreas.  Its primary role is to reduce your blood sugar. Defective insulin secretion, which is the hallmark of diabetes, can have adverse consequences in the body, such as unintended weight loss, increased thirst, increased urination, vision problems, and skin problems. Continue reading “A Spoonful of Insulin Makes the Blood Sugar Go Down”

How Genetic Mutations Cause — And Prevent — Disease

Stephen Crohn, an artist from New York, lost a lot to the AIDS epidemic of the 1980s. For more than a decade, he watched his boyfriend, Jerry Green, as well as nearly all of his friends slowly grow sicker and perish from this mysterious illness. His passion for his art dried up, and survivors’ guilt consumed him.

But the one thing he didn’t lose during this scourge was his own life. The reason he survived was not luck, however. Rather, he made it through because he carried a rare genetic mutation that made him virtually immune to HIV. Continue reading “How Genetic Mutations Cause — And Prevent — Disease”

Why Jet Lag Sucks: Your Body Clock and You

One weekend in early May, I endured one of the most confusing experiences in my life: a two-legged, 24-hour flight across 13 time zones. I took off from Chicago on Saturday evening, and 24 hours later, I arrived in Bali on Monday morning. In that 24 hour period, I ate two dinners and two breakfasts, while lunchtime didn’t exist. I couldn’t tell when I was supposed to be hungry or go to sleep, so I ate when food was placed in front of me and I tried to sleep when I got tired. Continue reading “Why Jet Lag Sucks: Your Body Clock and You”

Diabetes in Low-Income Communities: Its Causes and Its Solutions

According to the Center for Disease Control, in 2014, over 29 million people had diabetes in the United States – a disease that is more common among the poor, the less educated, and racial and ethnic minorities. While some people inherit genetic susceptibility to Type 2 diabetes, the onset of this disease can be exacerbated by factors that are all common to underserved neighborhoods, such as poor diet, lack of exercise, and limited access to quality healthcare. This is a complex problem that requires a multifaceted solution. Continue reading “Diabetes in Low-Income Communities: Its Causes and Its Solutions”