When larger pieces of plastic are broken down, nanoparticles can be formed. These nanoparticles have the potential to wind up in the soil as well as the water. It is possible that less people are aware of the fact that they are able to float in the air. Although it’s unknown how nanoplastics affect human health, research on animals suggests they could be dangerous. Researchers have created a sensor that detects these particles and uses vibrant carbon dot films to identify the types, quantities, and sizes of the plastics in order to better understand the prevalence of airborne nanoplastics.
The researchers will report their findings today at the American Chemical Society’s fall meeting (ACS).
Raz Jelinek, Ph.D., the project’s lead researcher, argues that nanoplastics are a serious worry if they are present in the air you breathe and enter your lungs, where they may cause health issues. “A straightforward, low-cost detector like ours might have profound effects and one day warn people of the presence of nanoplastics in the air, enabling them to take appropriate action.”
Millions of tons of plastic are manufactured and dumped every year. Some plastic materials slowly deteriorate during use or after disposal, releasing micro- and nanosized particles into the environment. Since they are typically less than 1 m across and extremely light, nanoplastics can even float in the air, where people may accidentally breathe them in. According to research on animals, breathing and eating these nanoparticles could be harmful. Knowing the extent of airborne nanoplastic pollution in the environment may therefore be useful.
In the past, Jelinek’s research group at Ben-Gurion University of the Negev created a “e-nose”—an electronic nose—to detect the presence of bacteria by adsorbing and sensing the distinct combination of gas vapor molecules that each type of bacterium releases. To construct a sensitive nanoplastic sensor for ongoing environmental monitoring, the researchers wanted to test if the same carbon-dot-based technology might be modified.
According to Jelinek, carbon dots are created when a starting substance with a high carbon content, like sugar or other organic materials, is cooked at a moderate temperature for several hours. You might even carry out this procedure using a regular microwave. The carbon-containing substance transforms into “carbon dots,” or colored, frequently fluorescent nanometer-sized particles, after heating. The surface characteristics of the carbon dots can alter depending on the initial substance, which can attract a variety of molecules.
The team coated tiny electrodes, each the size of a fingernail, with thin layers of various carbon dots to produce the bacterial e-nose. Interdigitated electrodes, which have two sides with spaced-apart comb-like features, were employed. An electric field forms between the two sides, and the stored charge is known as capacitance. We can simply detect the change in capacitance that occurs when the carbon dots undergo a change, for as when they adsorb gas molecules or nanoplastic particles.
The scientists next tested a proof-of-concept sensor for nanoplastics in the air, using carbon dots that would adsorb common forms of plastic, such as polystyrene, polypropylene, and polyethylene (methyl methacrylate). In trials, aerosolized nanoscale plastic particles were made to float in the air. And the team noticed distinct signals for each type of material when electrodes covered in carbon-dot films were exposed to the airborne nanoplastics, according to Jelinek. Jelinek continues, “At the moment, the sensor can indicate the amount of particles from a particular plastic type either above or below a predefined concentration threshold because the number of nanoplastics in the air impacts the intensity of the signal created.” Additionally, the sensor’s signal intensity was proportional to the size of the aerosolized polystyrene particles, which were 100 nm, 200 nm, and 300 nm broad.
The team’s next step is to test if their method can identify different kinds of plastic in nanoparticle combinations. According to Jelinek, it’s likely that they might modify the nanoplastic sensor to discern between additional types and sizes of nanoplastics, just as the combination of carbon dot films in the bacterial e-nose distinguished between gases with different polarity. Nanoplastic sensors would be beneficial for locating tiny particles in classrooms, offices, residences, and the outdoors if they could identify various plastics based on their surface characteristics.
The researchers thank the Israel Innovation Authority for its assistance.
