co-written by Claire Alford

People love to categorize themselves by personality type, whether it’s describing what kind of baked potato we are, or which character we have most in common with from Stranger Things. But have you ever wondered what kind of nanoparticle you would be? We thought it would be fun to create a Buzzfeed quiz to relate science-based nanoparticle properties to non-scientific personality traits. Given that there is so much variation across types of nanoparticles, we created a type of nanoparticle zodiac. After you’ve answered the questions, the quiz will tell you the nanoparticle that you are most similar to. We only picked ten nanoparticles for this quiz, and hopefully it goes without saying that although the nanoparticle descriptions are based on science, the personality part of this is purely for entertainment. Go take the quiz (it is short and fun!), then come back to learn more about your nanoparticle (and the others too)!

Disclaimer: In a scenario where you are equally two or more nanoparticles, Buzzfeed automatically assigns you as the first nanoparticle from the list.

Visual example of carbon dot fluorescence color complexity. Much like this diversity we see in carbon dot color, nanoparticles are also diverse in terms of properties, applications, and attributable personality types. (Image by *Bo Zhi* )

The Nanoparticles

Silver Nanoparticles (Ag)^1,2,3

When it comes to silver nanoparticles (Ag NPs), you may have heard that they are found in laundry detergent, silverware, and clothing. Ag NPs are used in these applications because they are known to exhibit antibacterial, antiviral, and antifungal properties. Ag NPs can be considered a “jack-of-all-trades” in that they have the abovementioned properties as well as anti-inflammatory and anticancer uses. Because of Ag NPs’ unique properties (i.e., optical, electrical, thermal, and biological), they also have potential use in the biomedical, food, and industrial sectors. Interestingly, researchers have found that Ag NPs can be synthesized by ordinary life forms like bacteria. This is one of the ways that researchers can get Ag NPs more efficiently via green synthesis methods as opposed to conventional chemical routes that are more costly and produce hazardous byproducts. These nanoparticles exhibit localized surface plasmon resonance (LSPR), which is a small-scale version of surface plasmon resonance (SPR; discussed below). Scientists can use LSPR to learn about the shape of Ag NPs and their surrounding environments.

If you are a silver NP:

You are a protector: these nanoparticles are used in detergents, silverware, and clothing for protection against pathogens
You are a jack-of-all trades: these particles have lots of different properties
You are environmentally friendly: scientists use “green chemistry” to synthesize silver NPs
You’re great at leading small groups, and may have short-lived energy: LSPR suggests that you are better at leading small groups of people, not larger groups like SPR. You may also have short-lived bursts of energy during the day
You are a reflective person: Ag NPs can be used to coat glass for making mirrors and, given our Moon’s associated esoteric beliefs to be a symbol of inner reflection (i.e., a mirror), Ag NPs are associated with the Moon

Left: close-up photo of two forks and a spoon. Right: assortment of black dots on a gray background, with a 100 nm scale bar — Ag NPs are used in silverware, among many other applications. Image on the right is showing an electron microscope view of Ag NPs obtained from silverware on the left. (Image reproduced from Sam Lohse)

Aluminum Oxide Nanoparticles (Al₂O₃)^4,5

Aluminum oxide nanoparticles (Al₂O₃ NPs), also known as alumina, are very hardy due to their ability to withstand high temperatures and physically wearing environments. This makes sense given that they are the starting material for making rubies and sapphires. In addition, they are poor electrical conductors, which makes them different from other metal oxide nanoparticles. Some researchers have investigated the use of Al₂O₃ NPs for treating asthma, while others use them to prevent proteins from folding incorrectly (folding errors can cause problems with protein function). One variety of Al₂O₃ NPs was shown to reduce the concentration of antibiotics in hospital wastewater. Such promising results indicate that Al₂O₃ NPs might be useful for preventing antibiotic resistance in pathogens.

If you are an Al₂O₃ NP:

You are a lifesaver: these NPs are used to treat asthma and provide soothing energy
You are resilient: these NPs are hardy and have learned important life lessons from hardship
You guide others toward solutions during times of conflict: Al₂O₃ NPs prevent protein misfolding/aggregation which helps the protein take on its correct form
Your environment does not bring you down: Al₂O₃NPs can push through difficult conditions
You work best under pressure: Al₂O₃ NPs can withstand high temperatures and wearing environments, they are akin to people that thrive in high-pressure environments

cartoon of an Al2O3 nanoparticle (blue circle) with arrows pointing into it from squiggly line labeled Mis/un-folded protein and out of it toward another squiggly line labeled correctly folded protein — *Al₂O₃ NPs have been shown to be able to refold mis/un-folded proteins back into correct confirmation. (Image adapted courtesy of open access from Kavetskyy et al. 2018*)

Gold Nanoparticles (Au)^6,7,8

Despite gold having been one of the first metals ever discovered, gold nanoparticles (Au NPs) were not studied by modern scientists until 1971. Au NPs have a very wide range of biomedical applications ranging from biosensors and bioimaging to targeted delivery of drugs to cancer cells. Given gold’s inert nature, it is helpful for delivering payloads of medicine in the body because the gold itself won’t harm living tissues (it is biocompatible). Another property of Au NPs is surface plasmon resonance (SPR), which is discussed in detail in this blog post; basically it describes that the electrons of Au NPs can be vibrated using specific wavelengths of light. This SPR property of Au NPs allows them to be used for disrupting tumor cells and essentially killing them in a process known as photothermal therapy. Because of all of this, Au NPs have already had a major impact on medicine.

Au NPs have also demonstrated promise for applications in other fields, such as in energy harvesting and water purification. As Au NPs get smaller and smaller, their properties change, which opens up opportunities for even more technological uses. For example, if a Au NP’s diameter is within the range of 1-2 nm, particles that were generally inert now become a great catalyst for converting carbon monoxide into carbon dioxide, much like the catalytic converter of a car. Also, as the diameter of Au NPs change, they absorb slightly different wavelengths of light. Due to this property, Au NPs hold potential in improving current solar cell technology by absorbing a greater array of light wavelengths. These slight changes in diameter also contribute to the color that is observed, from red to magenta, in colloidally stable solutions of Au NPs.

If you are a gold nanoparticle:

You are great at leading large groups: the SPR quality of Au NPs correlates to a person who can lead a large group in concerted action
You de-escalate conflicts to decrease tension in difficult situations: gold NPs can work as catalysts that convert CO to CO₂
You are a confidant: gold NPs quench fluorescence, which is similar to a friend who can listen to your emotions and act as a shoulder to cry on
You enjoy photography: Au NPs are known to be used in bioimaging

three vials of bright colored liquid: purple, maroon, and red — *Each vial contains Au NPs of different sizes. This nano-scaled difference in size causes the observed color difference. (image by Nikonianman)*

Carbon Dots^9,10

Carbon dots (CDs) can be prepared from a plethora of organic (carbon-based) materials such as honey, coffee, orange peel, and tree bark – the list goes on and on. Given CDs’ “green” starting reagents, it is no surprise that CDs have great biocompatibility and are generally considered eco-friendly. Another trait of CDs is their unique optical properties. They exhibit photoluminescence, which means these nanoparticles absorb a specific wavelength in the visible region and emit light at a different wavelength. This property of CDs, along with their biocompatibility, has made them a very important NP for bioimaging purposes. When comparing synthesis to other nanoparticles, CDs take the cake when it comes to affordability. Also, synthesis processes using different types of material or reaction conditions yield CDs with unique behaviors for absorbing and emitting light, so there is lots of variability in what they can do! (Researchers in the CSN even published a guide for how high school and college teachers can make carbon dots in a regular microwave!¹¹

If you are a carbon dot:

You enjoy painting as a hobby: CDs come in an array of colors and can be compared to a palette with multiple colors
You are a minimalist: CDs can be made from simple and affordable starting materials
You are a resourceful person: CDs are made from a range of super simple materials and can be used for lots of different things
You value the time spent on meal prepping: Starting reagents of CDs are organic materials such as orange peels and coffee grounds

Schematic showing the process of making carbon dots out of orange peel. Clockwise from top left, with simple images and arrows connecting each step: orange peel to drying to milling to ethylene glycol to microwave to purifying to carbon dot to a glowing green dot with Excitation 420 nm energy going in and Emission 522 nm coming out. — *Schematic protocol for making CDs out of orange peel. (figure adapted from Li et al. 2021, with images by OpenCage, Jon Ross, LoveIntheWinter, biologycorner, JustinMarx, Jo Zimny Photos, & fdecomite)*

Carbon Nanotubes¹²

Carbon nanotubes (CNTs) are generally made of a single sheet of graphene, a famous nanomaterial comprising a 2-dimensional array of carbon atoms. The graphene sheet is exposed to a chemical process that closes it into a CNT. Among all the NPs on this list, the cylindrical structure of CNTs is unique. The diameter of the cylinders are what make CNTs “nano”: they range between 1-10 nm wide, while their lengths are in the micrometer range. Characteristics of CNTs include high thermal and electrical conductivity, along with high tensile strength and elasticity. Because of these properties, CNTs have been used to make bullet proof jackets and durable sporting goods. Bare CNTs are chemically neutral. However, when adorned with functional groups of molecules, they can work as catalysts. These surface modifications can also optimize their solubility and dispersion in liquids.

If you are a CNT:

You are level headed: CNTs are generally known to be inert
You spend most of your free time exercising: CNTs have been used to make sports equipment
You stay more focused on your long term goals than short term: CNTs’ cylindrical structure is like a long tunnel that blocks out distractions as you work toward your long term goals
You like the excitement of living life on the edge: CNTs’ long, thin structure is like a tightrope

cartoon of a carbon nanotube: interconnected black balls representing carbon atoms — *CNTs have a unique cylindrical structure which provides them unique characteristics, such as elasticity and conductivity. (Image* by Eric Weiser)

Cerium Oxide Nanoparticles (CeO₂/Ce₂O₃)^{13, 14, 15, 16}

Cerium Oxide NPs (CeO₂ NPs), also known as nanoceria, are composed of the most common rare earth element, cerium. These rare earth elements are essential for the functionality of electronic devices such as laptops and cellphones. CeO₂ NPs have the unique ability to gain or lose electrons to switch Ce oxidation states from +3 to +4 charge, which gives these NPs catalytic activity. An example of nanoceria’s catalytic activity is in its antioxidant properties; they break down harmful reactive oxygen species such as hydrogen peroxide. On the other hand, nanoceria has also been shown to produce reactive oxygen through its oxidase activity (this essentially adds an oxygen to biological molecules, which can ultimately become reactive oxygen species). Researchers have also observed that CeO₂ NPs possess anticancer activity and are effective antibacterial agents against bacteria. Depending on how they are made, CeO₂ NPs have different effects on cells. Cells exposed to CeO₂ NPs that were synthesized in pure water were less able to survive compared to cells exposed to CeO₂ NPs that were made in polyethylene glycol (similar to the liquid used for making carbon dots, see image above). So controlling the way we make nanoceria can help us control its biocompatibility.

If you are a CeO₂ NP:

You are protective of your friends: CeO₂ NPs have antioxidant activity that can protect organisms from the effects of harmful reactive oxygen species
You prioritize self-improvement and personal growth from within: CeO₂ NPs can change oxidation states
You are a self-starter: CeO₂ NPs are great catalysts that can initiate reactions between other materials
You spend your free time working on your car: CeO₂ is the most commonly used material for making catalytic converters

*Ceres is a dwarf planet (it’s the largest object in our asteroid belt). It was named after the Roman god of agriculture, and the same namesake as the element cerium.*15 (Image by Nasa Visualization Technology Applications and Development)

Copper Oxide Nanoparticles (CuO)^{17, 18, 19}

Scientists have found that copper oxide nanoparticles (CuO NPs) can help deliver copper to plants as a micronutrient, and can also protect plants against fungus. One theory is that CuO NPs elicit this antifungal property in plants by boosting the plant’s natural defenses. CuO NPs have major potential for improving current agricultural practices as well as alleviating crop loss due to harmful fungus. Another area where CuO NPs are showing potential is in making antimicrobial fabrics in the biomedical field. In addition, researchers have been able to use different levels of acidity in synthesis to make different shapes of CuO NPs, including flat and/or spike-like. Unlike some other nanoparticles like gold or carbon dots, CuO NPs can be hazardous to human white blood cells at high concentrations, so they are not used in medical applications.

If you are a CuO NP:

You enjoy gardening: CuO NPs can be used to deliver nutrients to plants
You enjoy spending time with friends, but you value your alone time: CuO NPs are generally safe at low concentrations but can be toxic at high concentrations
You want to leave a big impact on the world: CuO NPs have potential to alleviate food scarcity by increasing crop production
Your environment sets your mood for the day: depending on the synthesis conditions, CuO NPs can have different morphologies (shapes)

*Some hospital bed sheets are made with CuO NPs due to the antifungal properties of these NPs.¹⁹ (Image by US Navy Medicine )*

Iron Oxide Nanoparticles (Fe₃O₄)^20-24

How cool would it be to see nanoparticle properties with your own eyes? With iron oxide nanoparticles (Fe₃O₄ NPs), you can! Fe₃O₄ NPs actually have a property that is visibly discernible to the human eye: superparamagnetism. Superparamagnetism means the Fe₃O₄ NPs move toward magnets but aren’t magnetic if there’s no other magnet around. This property is significant to researchers because it makes these NPs easy to retrieve with a magnetic field, which is not possible with some other nanoparticles.

Left: black fluid in a har forms smooth, rounded peaks suspended between two magnets. Right: spiky gray iron filings form two mounds on a tan surface — One way to see the difference between nano iron and “bulk” iron is by suspending the nanoparticles in liquid, called “ferrofluid.” This image on the left shows how the nanoparticles react to the two magnets outside the jar (image by Nickynada); regular micro-scale iron filings on the right look much more spiky instead of smooth (image by Andrew Ballantyne)

In the medical field, scientists are making strides in the “theranostic” use of Fe₃O₄ NPs. Theranostics is a field that combines therapy and diagnostics to achieve diagnosis and therapeutic aid at the same time. Fe₃O₄ NPs can be used to guide therapeutic payloads to specific tissues or cells while also highlighting the targeted cells in MRI imaging. Hyperthermia is another therapeutic technique involving the use of Fe₃O₄ NPs, and it is used to treat cancer. This process involves targeting Fe₃O₄ NPs toward the cancerous tissues, and then exposing them to an alternating magnetic field. This magnetic activity causes the NPs to heat up and kill the cancer cells while leaving normal cells intact. You can also find these nanoparticles rocking out to Mick Jagger on the weekends (just kidding).

If you are an Fe₃O₄ NP:

You are a rolling stone: Fe₃O₄ NPs are superparamagnetic, so they are moved by outside magnetic fields
You side with your closest friend amidst conflict in your friend group: Fe₃O₄ NPs stick with magnetic materials that attract them, like someone might stick with their best friend through thick and thin
You naturally gravitate towards the right people for you when making new friends, like Fe₃O₄ NPs are drawn to magnets
You are easily affected by your environment- Fe₃O₄(magnetite) is easily oxidized to Fe₂O₃ (maghemite)

Left: Brown liquid in a vial labeled Fe3O4@CA NPs suspension. Right: translucent yellow liquid in a vial with a dark brown blob on the side, close to a magnet on the outside, labeled Magnetic attraction of Fe3O4@CA NPs — Visual display of Fe₃O₄ NPs fully dispersed in aqueous medium (a) and the magnetic attraction of Fe₃O₄ NPs to a magnet (b). In this case, citric acid (@CA) was used to prevent agglomeration of Fe₃O₄ NPs. (Image from Mehrdel et al. 2020 courtesy of open access)

Silica Nanoparticles (SiO₂)^25,26

Sílice, or silicon dioxide, nanoparticles (SiO₂ NPs) are the most widely produced nanomaterial, with a yearly global production of approximately 185-1,400 kilotons. To give some perspective, the annual global production of aluminum is about 6,230 kilotons. Certain forms of SiO₂ NPs are used throughout society to improve health or make life more convenient. For example, in medicine they can be used to help carry drugs, and can even deliver their payloads specifically to cancer cells. Many of these medical applications utilize mesoporous SiO₂ NPs, which are spheres with pores distributed across the nanoparticle surface – to visualize this shape, think of a golf ball or a whiffle ball. Powdered foods like pancake mix or powdered milk and soups may use SiO₂ NP complexes to prevent the product from forming clumps. Who knew you could find nanoparticles in your favorite Sunday morning breakfast?

Black and white microscopy image showing small white and gray spheres against a dark gray background, with a 1 micrometer scale bar — *Mesoporous silica nanoparticles can carry payloads such as medicine, and are not harmful to the body (Image by Monique Tso)*

If you are a SiO₂ NP:

You absorb outside energies easily and bottle up your emotions: SiO₂ NP have a mesoporous form that can absorb things easily and/or carry other substances inside
You enjoy watching or playing golf: mesoporous SiO₂ NPs resemble the shape of a golf ball
You are most productive when things are orderly: SiO₂ NPs can be used for separating mixtures into pure forms
You are a very important person: SiO₂ NPs are the most produced NP in society

*A stack of pancakes with banana slices. Silica NPs may be used in prepackaged pancake mixes to prevent clumps from forming in the powder. (Image* by *Brandon Martin-Anderson)*

Titanium Dioxide Nanoparticles (TiO₂)²⁷

Both everyday and futuristic applications are possible for titanium dioxide nanoparticles (TiO₂ NPs). These biocompatible NPs are used as a pigment in paper because they reflect light so well they actually increase how bright the paper looks. TiO₂ NPs are also reaction catalysts that boost chemical reactions in many technological and energy applications. For example, TiO₂ NPs can catalyze the creation of hydrogen gas by splitting water molecules. As a result, these NPs hold much promise for creating hydrogen fuel for sustainable technologies. Also, TiO₂ NPs can be used in solar panels, another form of sustainable energy. Scientists are also working on using them in lithium ion batteries. The applications of TiO₂ NPs are centered on technologies and energy forms that will make the world more sustainable.

If you are a TiO₂NP:

You have a bright and cheery personality: TiO₂ NPs are used as a white pigment in paper making
You like to play video games in your free time and are tech savvy: TiO₂ NPs are used for technological applications
You have a sweet tooth for candy and sweets: TiO₂ NPs are used to enhance the bright white color of some candies and sweets*You get organized using electronic methods, such as digital calendars and reminders: TiO₂ are being investigated for possible use in lithium ion batteries, which are currently used to power laptops and phones

*Solar cells on a roof with trees in the background. Some researchers hope to use TiO2 NPs in solar cells, which might allow society to use more renewable energy. (Image from Rawpixel)*

Now that you’ve learned about all ten different kinds of nanoparticles, why not use your new insights to go back and take our quiz again?

REFERENCES

alicehuang2000. “Comparing LSPR and SPR for Diagnostics – LamdaGen.” YouTube, YouTube, 13 Nov. 2015, https://www.youtube.com/watch?v=QLT1vrnJXWI
Klaus T, et al. Silver-based crystalline nanoparticles, microbially fabricated. Proceedings of the National Academy of Sciences of the USA. 1999, 96(24):13611-4. doi: 10.1073/pnas.96.24.13611.
Zhang XF, et al. Silver Nanoparticles: Synthesis, Characterization, Properties, Applications, and Therapeutic Approaches. International Journal of Molecular Science. 2016, 17(9): 1534. doi: 10.3390/ijms17091534.
Dao TH, et al. Adsorption Characteristics of Synthesized Polyelectrolytes onto Alumina Nanoparticles and their Application in Antibiotic Removal. Langmuir. 2020, 36: 13001-13011. doi: 10.1021/acs.langmuir.0c02352.
Hassanpour, P. et al. Biomedical applications of aluminum oxide nanoparticles. Micro Nano Letters, 2018, 13: 1227-1231. https://doi.org/10.1049/mnl.2018.5070
Dykman LA, Khlebtsov NG. Gold nanoparticles in biology and medicine: recent advances and prospects. Acta Naturae. 2011, 3:34-55. PMID: 22649683.
NatureVideoChannel. “Tiny Treasure: The Future of Nano-Gold.” YouTube, 28 Jan. 2015, https://www.youtube.com/watch?v=QorK2X7GsVU
Yeh YC, Creran B, Rotello VM. Gold nanoparticles: preparation, properties, and applications in bionanotechnology. Nanoscale. 2012 4:1871-80. doi: 10.1039/c1nr11188d.
Liu J, Li R, Yang B. Carbon Dots: A New Type of Carbon-Based Nanomaterial with Wide Applications. ACS Central Science. 2020, 6:2179-2195. doi: 10.1021/acscentsci.0c01306
Yao B, Huang H, Liu Y, Kang Z. Carbon Dots: A Small Conundrum. Trends in Chemistry. 2019, 1:235-246. doi: 10.1016/j.trechm.2019.02.003
Pham S. et al. Carbon Dots: A Modular Activity To Teach Fluorescence and Nanotechnology at Multiple Levels. Journal of Chemical Education, 2017 94 (8), 1143-1149 DOI: 10.1021/acs.jchemed.6b00995
Cheap Tubes Inc. “Applications of Carbon Nanotubes.” AZoNano.com, 9 Aug. 2019, https://www.azonano.com/article.aspx?ArticleID=4842
Biomedical Applications of Nanoceria,” YouTube, 25 Jan. 2022, https://www.youtube.com/watch?v=7BFdTvF8qnE
Dutta D, et al. Green synthesized cerium oxide nanoparticle: A prospective drug against oxidative harm. Colloids and Surfaces B: Biointerfaces. 2016, 147: 45-53. doi: 10.1016/j.colsurfb.2016.07.045
Johnson I. “Cerium.” Royal Australian Chemical Institute, 2011. https://raci.imiscloud.com/common/Uploaded%20files/Periodic%20files/409.pdf
Karakoti AS, et al. Nanoceria as Antioxidant: Synthesis and Biomedical Applications. The Journal of The Minerals, Metals & Materials Society, 2008, 60(3):33-37. doi: 10.1007/s11837-008-0029-8 .
Assadian E, et al. Toxicity of Copper Oxide (CuO) Nanoparticles on Human Blood Lymphocytes. Biological Trace Element Research. 2018, 184(2): 350-357. doi: 10.1007/s12011-017-1170-4
Borgatta J, et al. Biomolecular corona formation on CuO nanoparticles in plant xylem fluid. Environmental Science: Nano. 2021, 8: 1067-1080. doi: 10.1039/D1EN00140J
Grigore ME, et al. Methods of Synthesis, Properties and Biomedical Applications of CuO Nanoparticles. Pharmaceuticals. 2016, 9(4): 75. doi: 10.3390/ph9040075
Ali A, et al. Synthesis, characterization, applications, and challenges of iron oxide nanoparticles. Nanotechnology, Science, & Applications. 2016, 9: 49-67. doi: 10.2147/NSA.S99986
Liu G, Gao J, Ai H, Chen X. Applications and potential toxicity of magnetic iron oxide nanoparticles. Small. 2013, 9: 1533-45. doi: 10.1002/smll.201201531
American Chemical Society. “Sopping up Sunblock from Oceans to Save Coral Reefs (Video).” American Chemical Society, 21 Aug. 2017, http://bit.ly/acssunblock
Wahajuddin, Arora S. Superparamagnetic iron oxide nanoparticles: magnetic nanoplatforms as drug carriers. International Journal of Nanomedicine. 2012, 7: 3445-71. doi: 10.2147/IJN.S30320
Dheyab M, et al. Simple rapid stabilization method through citric acid modification for magnetite nanoparticles. Scientific Reports, 2020, 10: 10793. doi: 10.1038/s41598-020-67869-8
Mebert AM, et al. Nanoengineered silica: Properties, applications and toxicity. Food and Chemical Toxicology. 2017, 109(Pt 1) :753-770. doi: 10.1016/j.fct.2017.05.054
Yang X, et al. Distinguishing the sources of silica nanoparticles by dual isotopic fingerprinting and machine learning. Nature Communications, 2019, 10, 1620: . doi: 10.1038/s41467-019-09629-5
Ali I, Suhail M, Alothman ZA, Alwarthan A. Recent advances in syntheses, properties and applications of TiO2 nanostructures. RSC Advances. 2018, 8(53): 30125-30147. doi: 10.1039/c8ra06517a