The nanowrinkled 'mouth' of the pitcher plant inspired the engineered nanomaterial. Source: Sydney NanoThe nanowrinkled 'mouth' of the pitcher plant inspired the engineered nanomaterial. Source: Sydney Nano

The carnivorous pitcher plant is the inspiration for a new nanostructure surface coating developed to fight biofouling in Australia. The phenomenon, a build-up of damaging biological material on a wet surface, is a huge issue for aquaculture and shipping. Annual costs for maintenance and extra fuel usage are in the billions of dollars. The issue has been further complicated by the banning of tributyltin, a toxic anti-fouling agent.

As published in the American Chemical Society's Applied Materials & Interfaces, a team of chemistry researchers from the University of Sydney Nano Institute has incorporated "nanowrinkles" into their coating, inspired by the way the plants of the genus Nepenthes trap a layer of water on the tiny structures around the rim of their pitcher-like openings. The water causes insects to aquaplane on the surface, before falling into the pitcher to be digested.

The coating also produces a slippery surface that stops the initial adhesion of bacteria, inhibiting the formation of a biofilm from which larger marine fouling organisms can grow. In the lab, coated surfaces resisted almost all fouling from a common species of marine bacteria, while control samples of Teflon without the lubricating layer became completely fouled. The team also tested their surfaces in the much harsher marine environment of the ocean, attaching them to shark nets at Watsons Bay baths in Sydney Harbour for a period of seven weeks.

"We are keen to understand how these surfaces work and also push the boundaries of their application, especially for energy efficiency," said Prof. Chiara Neto, leader of the research team. "Slippery coatings are expected to be drag-reducing, which means that objects, such as ships, could move through water with much less energy required."

The new coating uses no toxic components, and is also moldable and transparent — making it ideal for underwater camera and sensor applications.