Gwyneth K. Shaw Photo
UNH Professor Shannon Ciston and student Nicole Reardon in the lab where they’ll add nanoparticles to water from the Long Island Sound.
You might find the slimy stuff that collects at the bottom of your birdbath or the hull of your boat a bother, or just plain gross. But for Shannon Ciston and Nicole Reardon, the tiny ecosystems embedded in the goo offer a way to study how nanoparticles interact with our environment — and, ultimately, us.
Ciston, an assistant professor at the University of New Haven’s Tagliatela College of Engineering, has been working with the growths, formally known as biofilms, for several years. Since this summer, she’s been collaborating with Reardon (pictured, with Ciston), a student, to collect and study biofilms from Long Island Sound.
Over the next several months they plan to begin introducing nanoparticles — specifically, titanium dioxide and carbon nanotubes — into the Sound water to see how the biofilms react to the new substances. They hope to get a better sense of what happens when these tiny particles turn up in our water.
Ciston and Reardon are among a growing group of researchers investigating how nanoparticles, which gain amazing properties from their super-small size, affect people, animals and the environment. As more and more products incorporate nanomaterials, concern is growing that traditional detection and protection methods aren’t adequate to protect us from known and unknown risks.
Now that they’ve studied the biofilms that are growing in the Sound, Ciston and Reardon want to expose the organisms to two commonly-used nanoparticles to see what happens. Ciston is focused mostly on nano-sized titanium dioxide, which is increasingly turning up in sunscreens—and therefore, potentially, in water used for swimming or in public wastewater.
Ciston said they also chose carbon nanotubes because they’re widely used and widely studied. The tubes are also one of the nanosubstances that most worry experts, since research shows that the material can cause problems in animals.
Ciston said they’re expecting to find that the nanoparticles and the biofilms will have an effect on one another. Some possibilities are that the biofilms will retard the growth of the titanium dioxide particles or that the particles will make it harder for the biofilms to adhere to surfaces — which would be a major disruption.
Since some research shows that titanium dioxide nanoparticles in sunscreen don’t penetrate the skin very deeply, Cison said it would make sense that the particles would essentially wash off when people swim or take showers. That could have implications for the Sound as well as wastewater treatment, she said.
“Things that are so small, like nanoparticles, our water treatment system is not designed to screen for them,” Ciston said.
The researchers also are interested in whether the biofilms would help break down these types of materials. Ciston said it’s clear that small concentrations can have a big impact, and these studies aim to follow that trail.
Biofilms are “pretty robust,” Ciston said, and can survive a lot.
“But it’s a question of, what makes up the biofilm?” she said.
The films can adapt, but those changes could cause problems if the biofilms stop doing something important for a particular aquatic environment, she said.
A slide showing dried biofilm.
What, exactly, are biofilms, and why do they matter?
“Biofilms are sort of a community of microorganisms,” Ciston explained, adding that they can be found in lots of places.
They’re not exactly like the oil-eating bacteria that helped the Gulf of Mexico recover from last summer’s oil spill, Ciston said, but they do perform similar filtering and cleaning functions. They can also adjust to conditions to perform the job that’s most needed.
“They send out signals, kind of like synapses in the brain,” Reardon said.
To collect the biofilms, Reardon built a collection device out of basic materials: she took a length of PVC pipe and cut slots in it for standard glass sample slides, then secured them with aquarium sealant. She hangs the pipe vertically from a pier, low enough that it’s always covered with water no matter what the tide level.
Nicole Reardon shows off the tool she developed for collecting biofilm samples.
Over the summer the pipe hung off a pier in Port Jefferson, N.Y. Now, Ciston and Reardon want to use water and biofilms from the Connecticut side.
Generally, the pipe stays in place for about three weeks — longer than that, and it’s overrun with barnacles. Reardon takes samples about twice a week over that time frame. Over the summer, the biofilms grew fast, although the pace will be slower now that the weather is cooler.
In the initial study, designed to provide a baseline for the Sound biofilms, Ciston and Reardon tested the slime for reaction to different types of carbon. That helped them determine what was in the biofilm they collected.
For the upcoming research using the nanoparticles, they’ll use a system that basically puts the water and the particles into a jar that’s then spun to simulate the flow the biofilms would experience in a larger body of water.
Just as they did with the baseline samples, once the experiment is complete they’ll run a number of tests, including different kinds of microscopes and tests to determine the makeup of the films. Some of that work can be done at UNH. Most will require side trips to the Brookhaven National Laboratory. Ciston and Reardon have been able to work there through a collaboration with a researcher at Stony Brook University.
Ciston’s funding has so far come from internal research money from UNH, and Reardon got university money, too, through a Summer Undergraduate Research Fellowship, or SURF. They plan to seek outside grant funding for their work, and to get a formal affiliation with Brookhaven.
They hope to begin the nanoparticle experiments during the university’s semester break in December, and to have results they can work with by the end of the academic year.
They’ve got time: Reardon’s target date for graduation is 2012, leaving open lots of possibilities.
“I definitely want to see what happens,” she said.