While swimmers and boaters along any shore consider the slimy green film that coats everything from rocks to docks as a nuisance, University of New Haven (UNH) chemical engineering student Nicole Reardon and Assistant Professor Shannon Ciston, Ph.D. think otherwise.

They view the slime, or biofilm, as a complex community that may hold the key to informing humanity of the true environmental impact of the chemical nanoparticles that find their way from area kitchens, baths and garages into Long Island Sound. One such controversial compound is titanium dioxide, which is used to whiten and brighten a multitude of products, including candy, cosmetics, toothpaste and paint.

The underlying premise for testing the effects of titanium dioxide nanoparticles on biofilms is simple: when some chemicals are in nanoparticle form—ranging in size from 1/100th to 1/1000th of a human hair—they become bioactive, degrading and passing through cell membranes. Noting that “large” particles of titanium dioxide are considered safe by the FDA, Ciston and Reardon are interested in how nanoparticles of titanium dioxode affect marine ecosystems, particularly in terms of the humble biofilm. Reardon explains that while marine biofilms can be a bother, they are critical players in the oceanic environment. In addition to transforming nitrogen and carbon in ways that positively impact the greater food web, biofilms

Reardon and Ciston “dose” the samples with a composite material made of carbon nanotubes and titanium dioxide nanoparticles. Ultimately, they will compare the dosed biofilm with the untreated samples, determine how the microorganisms were affected and look at the greater implications for Long Island Sound.

As a chemical engineer with an environmental engineering background, Ciston notes she is fascinated by titanium dioxide and has been studying it, and its effects on organisms, for several years. She notes that titanium oxide is included in many cosmetic preparations to reflect light away from the skin and, as a pigment, is used to enhance the white color of certain foods, including dairy products and candy. It also brightens toothpaste and some medications, is used as a food additive and flavor enhancer, and used in paints for cars, boats, and airplanes.