Written by Jalia Carlton-Carew
Engineered nanomaterials (ENMs) are among the most remarkable innovations in science. Sized from 1 to 100 nanometers in mass, these chemical materials can capture and transmit light through electromagnetic fields. ENMs can also manipulate the chemical and physical properties of the objects they are used upon making their capabilities infinite. Dr. Hunter Lenihan, a professor at the Bren School of Environmental Science & Management, conducts research on ecological issues. For fifteen years, Lenihan has taught and mentored students at the Bren School. There Lenihan “uses tools from ecology and applies them to solving environmental problems,” he says. Through ecology, Lenihan conducts experiments that determine whether nanomaterials are toxic or beneficial for the environment.
Lenihan, along with several other researchers, performed experiments on marine phytoplankton with engineered nanoparticles (ENPs). Nanoparticles are nanomaterials with “mechanical, optical and electromagnetic properties.” The phytoplankton were exposed to ENPs like zinc oxide (ZnO), silver (Ag), cerium oxide (CeO2) and copper oxide (CuO). After being exposed to the chemicals for 72 hours, the phytoplankton reacted negatively to the ENPs and their populations deteriorated — proving the nanoparticles to be toxic. By studying how organisms are affected by nanomaterials scientists can better understand how toxic ENMs could be to humans or to their supplies of food.
Though in some scenarios ENMs act as harmful pollutants there are other scenarios where nanomaterials are beneficial. When someone is diagnosed with a disease they take drugs that travel throughout their system. “The drug targets the disease and kills it but the rest of the body has to deal with the toxic medicine in their body causing the patient to feel sick,” Lenihan says. This class of drugs is known as “nanomedicine”, and is a rapidly developing field of medical research, especially in the fight against cancer. Like other pharmaceuticals, nanomedicines are released through wastewater into the environment, especially soils, estuaries, and the coastal ocean. Lenihan’s work, as well as his colleagues at UCSB, Patricia Holden, Arturo Keller, Bob Miller, and Roger Nisbet, is focused on understanding the environmental implications and impacts of nanomedicines and materials. To do this, they are categorizing nanomaterials into chemically similar groups to examine their toxicity before they are released into the environment. If the ENMs are found to be toxic they either need to be changed or prevented from being released. Fortunately, nanomaterials can be altered to become harmless. Scientists can “take nanomaterials and coat them with other chemicals that will make them less toxic” Lenihan says.
Lenihan creates opportunities for students to conduct their own research on marine life. In “The Coastal Marine Resource Management” a marine emphasis that Lenihan started, students are trained to solve problems in marine ecosystems. Seven of the program’s PhD students are currently working on topics that range from eco-toxicology, fisheries, restoration to applied ecology.