Bloodworm fangs hold drug delivery promise

A marine worm's gruesome method of feeding may provide a key to making lightweight but durable materials, according to researchers at the University of California's Santa Barbara site.

The team has been studying the bloodworm, a venomous creature that lives in sediment at the bottom of the sea, and has found that its teeth are made from a material which contains copper.

The finding is unusual, the team explains in a paper in the journal Science, because the copper is present at levels which would normally be extremely toxic. The metal occurs in two forms - in a mineral form, at the tip of the worm's hollow fangs, and a non-mineral form, where it seems to act as a cross-linker between fibrous protein chains.

'Most other organisms mineralise with calcium phosphate or calcium carbonate,' says Herbert Waite, one of the paper's authors. 'And in all these structures, the mineral to protein ratio is more like 10 to 1. But this worm makes a structure that is 10 parts protein and one part mineral and exploits that structure for wear resistance. If you want to make something hard, how do you do it with a preponderance of protein? We think the worm does it by adding copper.'

The discovery raises the possibility of a new class of hard, durable materials, made from simple proteins cross-linked with copper, the researchers say. They also suggest a use for these materials. The worm stores its venom in a harmless form, and the copper in its jaws seems to act as a catalyst, activating the poison as it is injected into the prey.

A similar strategy could be used as a drug delivery device, especially for drugs whose structures are inherently unstable. 'We may be able to synthesise the drug in a precursor form, and have that last important step done as part of delivery,' Waite says.