A tiny change in a tiny particle can mean the difference between treatment and toxicity, federal researchers found in the first observations of its kind.
Researchers at the Los Alamos National Laboratory in New Mexico originally set out to study the interactions of carbon fullerenes – soccer-ball shaped molecules more commonly known as “buckyballs” – and cell membranes, said Rashi Iyer, a toxicologist at Los Alamos and principal research lead on the study, which was recently published in the journal Toxicology and Applied Pharmacology. As research progressed, she said that she and her colleagues began to observe an unexpected reaction that could either be dangerous or desirable.
Researchers found that exposure to a certain type of fullerene known as the “tris” configuration, referring to a certain configuration of molecular branches on the nanoparticle, produced a toxic reaction in human tissue.
Iyer said that cells from skin and lungs were among those studied, since those would be likely points of exposure to nanoparticles. Cells exposed to the tris fullerenes went into a state that could be described as suspended animation, she said. Cells’ normal life cycle halted, meaning that they stopped growing, dividing and dying.
Typically, this effect would pose a risk to human organs by inhibiting normal development or immune responses. The same effect could also delay the onset of degenerative diseases such as Alzheimer’s or prevent the spread of cancerous cells, giving doctors more time to treat abnormal cells, said the press release.
Iyer noted that the discovery of the senescence effect highlighted the importance of identifying health risks as nanoscience continues to develop. Studies like this can “guide material science,” she said, demonstrating, in this case, that application matters when dealing with particles that may have a toxic potential. In a targeted scenario, this particle could lead to new medical treatments. If it had been inadvertently employed in a commercial product, there could be a health crisis.
Currently, nanomaterials face few federal regulations. Lynn Bergeson, a Washington, D.C. lawyer who counsels companies on nanotechnology innovation, said that it is a misconception that there are no regulations – while no laws address nanotechnology alone, many nanomaterials do fall under broader rules such as sections of the Environmental Protection Agency’s Toxic Substances Control Act. “The EPA is doing a ton of work on nanoscale materials,” said Bergeson, and there are several new rules on the horizon.
Iyer said that she thinks that regulations have been slow to appear because agencies “don’t want to press the panic button” on a growing field with the potential to address many day-to-day problems.
“[Nanomaterials] need to be exploited for what they can offer us,” said Iyer, “but we need to be cautious.”
To that end, she said that her future research will entail efforts to broadly classify nanomaterials and assess their risks. With researchers in 40 countries creating new nanoparticles every day, she said that it would be difficult to assess each particle individually. By using physical and chemical characteristics to classify particles, scientists will be able to better predict responses to particles and the effects of modifying them.
Bergeson said that regulatory agencies face “a steep learning curve” in assessing the risks and benefits of nanotechnology. “The EPA is doing, I think, a very good job in obtaining information,” she said, adding that there is a “steady increase in the sophistication and work devoted by regulatory agencies” to nanomaterials.
Establishing standards, said Iyer, “should be the universal effort” in nanomaterials research.
What's a buckyball?
Fullerenes are molecules composed of carbon in a cage-like arrangement that resembles a soccer ball. They are commonly referred to as “buckyballs,” since their shape resembles the geodesic dome popularized by the late engineer and architect Buckminster Fuller.
Los Alamos National Laboratory toxicologist Rashi Iyer said buckyballs were one of the first nanomaterials created, dating to 1985, and were “launched into the limelight” after its discoverers won the Nobel prize in 1996.
Buckyballs are now one of the few types of nanomaterials able to be synthesized in large amounts. The hollow particles are also highly configurable – Iyer described them as “so easy to play with.” Their shape may make them a good candidate for drug delivery systems in the future, researchers have suggested.
In the Los Alamos study, one-nanometer buckyballs consisting of 60 carbon atoms were used. In comparison, a virus is about 100 nanometers in size.
Researchers studied both a plain buckyball as well as two modified versions: the “tris” configuration with three molecular branches extending from one hemisphere of the ball and the “hexa” configuration with six branches extending from the main structure in a rougly symmetrical manner. The tris configuration produced the toxic effect observed in the study, while the hexa configuration did not cause damage to cells in the study.