Great hopes for curious teeth of the chiton

Shellfish with surprisingly strong teeth could hold the key to a new era of smarter, stronger materials, including for use in building construction and surgical implants, Kate McGrath says.

Associate Prof McGrath, of Victoria University of Wellington, who is a former senior lecturer at the University of Otago chemistry department, was back in Dunedin yesterday to give the latest talk in the national Marie Curie Lecture Series, organised by the Royal Society of New Zealand.

When it had been discovered, in the 1960s, that the humble chiton, a member of the mollusc family, could produce chemicals in its teeth strong enough to leave marks in rocks, the study of "biomineralisation" was born, Prof McGrath said.

In her talk, "From Minerals to Miracles", she said that the biomineral within chiton teeth was similar to the mineral that gave lodestones their magnetic power.

"But what intrigued scientists is that the magnetite of chiton teeth is tougher than that of geologically formed magnetite, despite being essentially the same material."

Chitons, which are also found in New Zealand waters, use their teeth to cut into rock to gain access to algae, a food supply living inside porous rocks on coastlines.

The two forms of magnetite were "essentially the same material", but the magnetite produced biologically by the chiton differed in its three-dimensional shape and structure, which greatly added to the strength, she said in an interview.

She noted that the calcium carbonate structure found in paua shells was about 3000 times stronger than in its geological form.

Scientists studying "biomineralisation" did not want to mimic the biological processes involved in creating the materials, but wanted to achieve "the same outcomes" by developing materials with some of the same properties.

There was "huge potential" in this new approach, which had already been used to create a new form of cement which was more elastic than the traditional form, and less prone to cracking.

The new approach would generate many benefits, including ceramics that retained their known favourable characteristics, but were less prone to breaking.

Traditional manufacture of ceramics was energy intensive, requiring great heat, but new approaches could result in cheaper, room temperature manufacture.

New hybrid materials that were very strong but relatively light could also contribute to the building industry in future.

Other materials that were also strong and were also biocompatible would prove useful for dental and surgical implants, she predicted.

• The Curie series is a year-long tour of talks by female New Zealand chemists in honour of Curie's Nobel Prize in Chemistry, awarded 100 years ago for her studies in radium and polonium.