A fullerene is a molecule made entirely of carbon atoms arranged in a hollow, cage-like structure of pentagons and hexagons. The most common and most stable fullerene, C60, contains 60 carbon atoms arranged in the exact same pattern as a soccer ball: 20 hexagons and 12 pentagons forming a closed sphere. Fullerenes are one of three pure forms of carbon, alongside diamond and graphite, and they range in size from C20 (the smallest theoretically possible) up through C70, C84, C96, and beyond.
Structure and Shape
Every fullerene follows a strict geometric rule: the cage is built from only five-membered and six-membered carbon rings, and the total number of carbon atoms is always even. C60, often called a “buckyball,” is the smallest stable version. Its 60 carbon atoms sit at the vertices of a shape mathematicians call a truncated icosahedron. If you’ve ever looked closely at a soccer ball, you’ve seen the pattern.
The next stable size up is C70, which stretches into more of a rugby ball shape. From there, larger fullerenes like C76, C78, C80, and C84 become increasingly complex, though C60 and C70 dominate commercial production. When fullerene-containing soot is processed, the extract is roughly 75% C60, with C70 making up most of the remainder and higher fullerenes accounting for less than 1%.
How Fullerenes Were Discovered
In 1985, Harry Kroto, Robert Curl, Rick Smalley, and colleagues Jim Heath and Sean O’Brien detected C60 while vaporizing graphite with a laser. They proposed the soccer ball structure based on the data, though they couldn’t confirm it directly at the time. The discovery earned Kroto, Curl, and Smalley the Nobel Prize in Chemistry in 1996. The name “buckminsterfullerene” comes from architect Buckminster Fuller, whose geodesic domes share the same geometric pattern.
Types of Fullerenes
Beyond the classic hollow ball, fullerenes come in modified forms that expand their usefulness. Endohedral fullerenes have an atom or small molecule trapped inside the carbon cage. Exohedral fullerenes have atoms or chemical groups attached to the outside surface. The distinction matters because whether an atom sits inside or outside the cage significantly changes how electrons are distributed across the molecule, which in turn affects how it behaves in applications like solar cells.
There are also cylindrical fullerenes, better known as carbon nanotubes, which extend the same pentagon-and-hexagon framework into a tube shape rather than a sphere.
Physical and Chemical Properties
C60 is essentially nonpolar, which means it dissolves well in organic solvents and oils but not in water. Solubility studies show it behaves more like a chain of carbon-carbon double bonds than like a traditional aromatic compound such as benzene. It is highly lipophilic, meaning it has a strong affinity for fats and can cross biological membranes, including the barrier between blood and brain tissue.
One of C60’s most notable chemical properties is its ability to react with free radicals by attaching them to its many double bonds. This radical-scavenging capacity has earned fullerenes the nickname “radical sponges.” Research into the mechanism suggests C60 can also absorb protons and carry them into mitochondria (the energy-producing structures inside cells), which reduces the production of damaging reactive oxygen species at the source rather than simply neutralizing them after they form. This dual action gives fullerenes a protective effect that exceeds many conventional antioxidants.
How Fullerenes Are Made
Most fullerene production starts with vaporizing carbon in an oxygen-free environment. The oldest and most common technique uses an electric arc between two graphite rods in a helium atmosphere. The intense heat turns graphite into a soot that contains fullerenes, which are then extracted with solvents. The downside is low yield: ultraviolet radiation from the arc destroys many fullerene molecules as they form, so only 5 to 10% of the collected soot is usable fullerene.
Laser ablation of graphite can achieve higher yields, but it’s too expensive to scale up for commercial quantities. A more practical alternative is combustion of hydrocarbons. Frontier Carbon Corporation, a Mitsubishi subsidiary, built the first large-scale fullerene production facility using a combustion-based process capable of producing 40,000 kilograms per year. More recently, researchers have explored using concentrated solar energy to vaporize carbon, which avoids the UV destruction problem and pushes yields up to around 20%, potentially cutting costs to a quarter of what arc-based production requires.
Medical and Biological Research
Fullerenes are being studied for cancer treatment through a mechanism called photodynamic therapy. When exposed to ultraviolet or visible light, C60 absorbs the energy and converts it into reactive oxygen species and singlet oxygen with near-perfect efficiency (close to 100% conversion). These reactive molecules can kill tumor cells while the fullerene’s antioxidant properties help protect surrounding healthy tissue. Fullerenes also show good photostability, meaning they don’t break down quickly under repeated light exposure.
A particularly promising line of research involves glucose-coated fullerenes, nicknamed “sweet-C60.” Because many aggressive cancers, especially pancreatic cancer, consume enormous amounts of glucose, these modified fullerenes act as bait. Tumor cells with high numbers of glucose receptors pull the fullerene inside, delivering whatever therapeutic payload is attached. Early findings suggest sweet-C60 could become a targeted drug delivery vehicle for cancers that are difficult to treat with conventional chemotherapy.
Skincare and Cosmetics
Fullerenes have entered the cosmetics industry as an anti-aging and skin-brightening ingredient. Their radical-scavenging ability translates into protection against oxidative stress in skin cells, and they’ve been incorporated into serums, facial masks, and anti-wrinkle formulations. One practical advantage over ingredients like vitamin C (ascorbic acid) is stability: fullerenes don’t degrade as easily in formulation, which is a persistent challenge with vitamin C products. Recent 2025 research has also explored pairing C60 with curcumin (a compound from turmeric), finding that the combination eliminates free radicals more effectively than either ingredient alone.
Solar Cells and Electronics
Fullerene derivatives are a key component in organic solar cells, where they serve as electron acceptors, catching electrons that have been knocked loose by sunlight. Whether the fullerene is endohedral or exohedral changes how quickly those captured electrons lose energy, so researchers can tune performance by choosing the right configuration. The latest results from 2024 show organic solar cells using functional fullerene derivatives reaching 19.44% power conversion efficiency, among the highest values recorded for this type of cell. That number still trails silicon panels, but organic solar cells are flexible, lightweight, and cheaper to manufacture, which makes them attractive for applications where rigid panels won’t work.
Safety Profile
Toxicity data on fullerenes is mixed and depends heavily on the form, dose, and route of exposure. In rat studies, water-soluble C60 injected directly into the abdomen at doses up to 2 grams per kilogram of body weight caused no observable signs of acute or subacute toxicity. That’s a remarkably high dose with no apparent harm. On the other hand, inhaling C60 nanoparticles at concentrations of about 2.2 milligrams per cubic meter increased protein levels in lung fluid in rats, a marker of mild lung irritation. And when a water-soluble C60 suspension was delivered directly into the lungs of mice, it triggered an inflammatory immune response at doses as low as 0.5 milligrams per kilogram.
The takeaway is that fullerenes appear to be well tolerated when ingested or absorbed through the skin, but inhaling them as fine particles can irritate lung tissue, consistent with what we know about other nanoparticles. The safety picture for cosmetic and oral supplement use looks more favorable than for occupational inhalation exposure during manufacturing.