Chemist Honored for Studies on Biological Activities of Titanium

Some people love gold; others are crazy about platinum. For Ann Valentine, it’s titanium.

As a young scientist, she heard about a certain type of sea squirts - soft, tubular-shaped marine creatures that attach themselves to rocks and coral - that filters titanium from the surrounding seawater into its bloodstream in massive concentrations. She was hooked.

Years later, the Yale bioinorganic chemist has been honored for her “outstanding contributions to the field of metals in biology” with the Paul D. Saltman Memorial Award, given annually by the Gordon Research Conferences. For Valentine, the recognition is welcome validation for research that, at times, was considered to be somewhat niche.

“We’ve known for a long time that metals are important for biological processes, such as the iron in our blood, but conventional wisdom in chemistry is that biology doesn’t use titanium for any native process,” the Yale bioinorganic chemist says. “I find that really surprising, because there’s lots of titanium all around us and humans use it for all kinds of applications: in catalysts, in pigments, in paints. I just don’t believe that humans are better chemists than nature.”

So while other chemists were studying the biological activity of some of the more obvious metals out there, Valentine wondered whether titanium — for which at least one species had found a use — didn’t deserve more attention.

The research coming out of Valentine’s lab is proving just how valuable that second glance may be. It turns out titanium dioxide, a sort of titanium “rust” that forms the basis of commercial paints, has photoactive properties. But in order for the substance to convert sunlight into energy, it needs to bind to other molecules that help absorb the light.

Creating those chemical bonds has proven difficult, but now Valentine and her team are studying how a particular type of bacteria seems capable of doing just that, which could help in the design of more efficient solar cell technology.

In another application, Valentine is working to understand the mechanisms that make titanium medicinally active. Decades ago scientists discovered two titanium compounds that appeared to have promising cancer-fighting properties, but which ultimately failed as drugs because of their toxicity. “We really hope we can rescue that hope by doing better chemistry,” she says.

Valentine was selected for the Saltman Award for her “groundbreaking work on the structures and reactions of complexes containing titanium,” notes Harry Gray, the Arnold O. Beckman Professor of Chemistry at the California Institute of Technology and a member of the awards selection ­committee.

“I was very honored,” Valentine says. “I never had the chance to meet Paul Saltman, but his ethic of encouraging young scientists is something that I greatly admire. I’ve really benefitted from the atmosphere he helped to foster.”

— By Suzanne Taylor Muzzin