This sandcastle worm lives in the laboratory where scientists can study it. The worm built its house in the lab from small white beads instead of bits of shell and sand. Scientists have created a glue similar to the worm’s glue that may one day be us

Scientists often look to the natural world for inspiration and ideas. Now, we may be able to thank an unusual worm for a new kind of superglue.

At the University of Utah in Salt Lake City, scientists have created a powerful adhesive that works underwater and hardens quickly, which means it may be useful inside the human body. Most glues don’t work well inside the body, where everything is wet. When surgeons operate on a person to repair broken bones, for example, they may be able to use the new glue to hold the bones together.

The Utah scientists were inspired to make the new glue by a little sea animal called the sandcastle worm. It lives on the coast in an area between the water levels for high and low tides. During high tide, their homes are underwater; when the tide goes out, their homes are left high and dry.

This sea creature gets its name from its house. A sandcastle worm builds its own house by collecting grains of sand, broken shells and other debris and stacking these bits all around. The worm also produces a glue that is used to stick all these pieces together, forming a solid tube. The worm’s glue hardens underwater in less than 30 seconds, and within a few hours the glue gets tough like leather.

Russell Stewart, one of the scientists who worked on the new glue, says that in the same way the sandcastle worm glues together grains of sand, surgeons may be able to glue together broken bones. The worm “literally glues skeletons together underwater, so we thought it would be a good model for wet surgery,” he says.

Stewart, who is a bioengineer at the University of Utah in Salt Lake City, and his colleagues set out to understand the worm’s adhesive, so they could then make their own. First, they studied the sandcastle worm’s glue in the laboratory. They found many proteins, which are tiny molecules that are the construction material of most living things. The researchers learned which proteins give the glue its super-sticking power by studying the proteins’ structures. Half the proteins had strong positive or negative electric charges. Positive and negative charges are attracted to each other and stick together, and this helped make the glue extra sticky.

Once they identified and understood the proteins, the scientists made their own version of the glue in the laboratory. They tested their creation and found that it worked underwater—and was about twice as strong as the worm glue. Further tests showed that the glue isn’t poisonous to human cells.

At the end of the experiment, the scientists had invented a new superstrong glue that worked underwater and was not toxic, which means it didn’t cause harm. These three qualities—strong, working underwater, nontoxic—could make the glue an important part of surgeries in the future. Plus, researchers are now looking at ways to make the glue able to dissolve, which means that over time, as the bones healed, the glue would disappear.

Stewart and his team may have found a new way to help bones heal—all because of a funny little worm on the beach.

Going Deeper:

Factories, cars, and other machines spit out lots of a gas called carbon dioxide. Carbon dioxide (CO₂) is known as a greenhouse gas because it traps heat in the atmosphere. More and more of the gas has been accumulating in the air in recent years.

CO₂ has also been dissolving in seawater, and that’s been changing the water’s chemical composition. As a result, seawater at the surface of the world’s oceans has become more acidic. That shift could eventually make life tougher for a type of snail called the common periwinkle, say researchers from the University of Plymouth in England.

Common periwinkles, like this one, are able to grow thicker shells when predators are near, unless the seawater becomes too acidic.

Simon Rundle

The common periwinkle lives along coastlines throughout much of Europe. One of its main predators is the common shore crab. The hungry crabs grab the snails “like ice cream cones,” says lead researcher Simon Rundle. Snails with thin shells are most likely to get crushed and eaten.

Scientists already knew that snails grow thicker shells to protect themselves when predators live nearby. The British researchers wanted to know if an increase in the acidity of the water would affect this thickening process.

The scientists grew more than 100 periwinkles in tanks. They put half of the snails in tanks filled with normal seawater. They added CO₂ bubbles to the water in the other snails’ tanks to make it acidic. The researchers then put a crab in some of the tanks with both types of water.

In the tanks with normal seawater, the periwinkle shells grew substantially thicker when a crab was living at the bottom. In the tanks with acidic water, the snail shells did not get thicker. These results suggest that snails living in acidic water have a harder time defending themselves from predators.

Scientists measure acidity on what’s called the pH scale. A liquid with a pH of 7, such as distilled water, is considered neutral. A pH measurement of less than 7 indicates acidity. Lemon juice and stomach acid are examples of acidic substances. A pH of greater than 7 is the opposite of acidic, often called basic or alkaline. Bleach is one example.

Overall, the oceans are slightly alkaline, with a pH of 8.2. But studies show that the pH of ocean water has dropped by about 0.1 unit in the past few hundred years. And computer models suggest that ocean pH could drop another 0.3 to 0.4 unit by 2100.

That change could be a problem for all sorts of underwater organisms. As seawater becomes more acidic, these creatures have an increasingly difficult time producing a mineral called calcium carbonate. This material makes up coral reefs, sea urchin teeth, and snail shells, among other structures.

Until now, studies of seawater acidity have mostly looked at its effects on individual species. The new study shows that changes in the oceans are influencing interactions between species, too.—Emily Sohn

Going Deeper:

Milius, Susan. 2007. Bad acid: Ocean’s pH drop threatens snail defense. Science News 172(Oct. 20):245-246. Available at http://www.sciencenews.org/articles/20071020/fob7.asp .

Now, scientists have found a way to copy what oysters have been doing all along. They’ve made a pearl-like material that could some day be useful for replacing weak bones and making machines. What’s more, the method promises to be easy, cheap, and kind to the environment.

Oysters have a strong layer of armor called nacre (or mother-of-pearl). The substance is made up of tiny crystals pieced together like the bricks and mortar of a brick wall, as seen in this micrograph.

© Science

Oysters, abalone, and some other mollusks have a strong layer of armor called nacre (or mother-of-pearl). The substance is made out of tiny crystals and proteins, pieced together like the bricks and mortar of a brick wall.

Their structure makes these natural materials sturdier than any human-made ceramics (a category that includes clay, cement, and glass). Scientists have long tried to mimic the architecture of these creatures’ shells, with little success.

Researchers at the Lawrence Berkeley National Laboratory came up with a new approach. First, they mixed water with a ceramic powder and some glue-like molecules, called polymer binders. Then, they poured the concoction into a little chamber that measured a few centimeters across.

The scientists carefully controlled chilly temperatures at the top and bottom of the chamber, until an icy structure formed. The ice was similar to the ice that sometimes forms in frozen seawater.

New materials made from microplates of ceramic such as alumina joined by metal mortar have a layered structure like that of natural mother-of-pearl (inset). The two micrographs are at different scales. The artificial plates are actually about 10 times as

© Science

A closer look at the ice structure showed that it contained vertical sheets made of tiny, hexagonal (six-sided) ice crystals. As those crystals grew, the ceramic powder and polymers gathered between the ice sheets.

The scientists put this entire structure through freeze-drying to remove the ice. Heating the material to high temperatures then fused the remaining powder and polymers into solid sheets. Finally, they added a filling between the ceramic sheets to act like the protein mortar that’s found in nacre.

One potential application of the technique is to make a strong framework for growing new human bones to replace ones that are broken or weak from disease. Tough, pearl-like mixtures of aluminum, silicon, and titanium, on the other hand, could be useful for engineers who construct machines and work with electronics.

Glamorous pearl necklaces will probably never go out of style. Now, however, they hint at a suite of new technologies to come.—E. Sohn

Going Deeper:

Weiss, Peter. 2006. Mother-of-pearl on ice: New ceramics might serve in bones and machines. Science News 169(Jan. 28):51-52. Available at http://www.sciencenews.org/articles/20060128/fob2.asp .

You can learn more about mother-of-pearl (or nacre) at en.wikipedia.org/wiki/Mother_of_pearl (Wikipedia).

Sohn, Emily. 2004. Inspired by nature. Science News for Kids (Nov. 3). Available at http://www.sciencenewsforkids.org/articles/20041103/Feature1.asp .