Shedding Light on Nanoplastics: Research Team Develops New Detection Methods

Scientists at ASU BIOS turn their attention to a threat we cannot see: nanoplastics 
 

After people throw away trash like plastic bags and bottles, this human-generated plastic waste continues to break down into smaller pieces, eventually forming nanoplastics, tiny plastic particles that threaten ecosystems and human health. Nanoplastics are so small (ranging from 2 to 20 μm in size) that they can cross cell membranes and have been detected in human blood, lungs, placenta, and even brain tissue, with potential links to adverse human health outcomes. 

As scientists race to determine the impacts of this invisible pollutant, recent research from the Microbial Ecology Laboratory at ASU BIOS will prove instrumental in understanding how ocean currents carry these microscopic plastics to some of the most remote places on Earth. 

Led by microbiologist Rachel Parsons, the Microbial Ecology Laboratory has developed techniques to quantify nanoplastics, tracking their movement throughout Bermuda’s waters to prove that plastic is now pervasive across the globe. 

“Last year, we sampled a transect going down to Puerto Rico,” Parsons said. “We found nanoplastics mostly along the surface, but we also found nanoplastics in the Puerto Rico Trench, over 6,000 meters below the ocean’s surface.”

These findings inspired the team to optimize a new method to detect nanoplastics in the water column, staining filtered seawater with a red dye typically used to stain lipids. Under the microscope, the dye makes the plastic particles fluoresce, allowing researchers to quickly quantify nanoplastic samples. 

ASU-BIOS Research Experiences for Undergraduates (REU) student, Madeleine Rugella, developed the method in 2023, validating it the following year. Since then, Zoe Skinner, a former Bermuda Program intern and current laboratory technician, has taken the project in stride, refining the protocol to cut processing time in half, allowing the lab to analyze plastic samples at an unprecedented rate. 

 “We're confident that the counts we are getting are the plastics that are present,” said Skinner. “Now we are just in the stage of demonstrating this method is repeatable, which is exciting, especially because [the new protocol] is quick and easy to do, and a lot less expensive than other methods.”

Building on the Bermuda Time-series Backbone

In early July, R/V Atlantic Explorer returned to Bermuda from Puerto Rico as part of the Bermuda Atlantic Time-series Study Validation (BVAL) Cruise. While the cruises’ primary goal was to look at the chemical and physical properties of the ocean, this year the team had a secondary focus: nanoplastics.

At 16 stations located from Bermuda to Puerto Rico, researchers collected seawater at 15 different depths, from the ocean surface down to 6,000+ meters, totaling 240 water samples, which will head straight to Parsons’ lab for analysis. 

The success of the nanoplastics project relies on the strong infrastructure of the Bermuda Atlantic Time-series Study (BATS), where ASU BIOS researchers have been monitoring the physical health of the ocean, once a month, for the past 40 years. Researchers have added nanoplastic sampling to the past two years of BATS and BVAL cruises, compiling a comprehensive dataset of nanoplastic abundance from Bermuda to Puerto Rico.

Rugella will be returning to process these samples along with Bermuda Program student, Shavon Nesbitt, who participated on the cruise. “Most of the papers I’ve looked at focus on nanoplastics in humans or freshwater. There is some research in marine environments but the focus is on the surface or one or two profiles. I don't think anyone has done an offshore time series like this, especially not one looking at [nanoplastics] suspended in the water column and at depth,” said Parsons.

The 240 new samples from BVAL will move the project into its next phase. Using their refined sampling protocol, the team hopes to validate the data collected and build a detailed depth profile of nanoplastics in Bermuda’s waters and beyond. The team hopes to show how these harmful plastics are transported across the ocean, from inshore waters to deep-sea trenches, impacting both marine ecosystems and human health. 

“I mean, it’s scary,” said Parsons. “We know that plastic is everywhere, but now we’re seeing that it's also suspended in the water column, small creatures are eating it, and it is getting into our food system and our bodies. So [research like this] is important.”

By shedding light on what was once invisible, ASU BIOS scientists add to the growing body of nanoplastics research, helping to confront a global pollution problem, one microscopic piece at a time.