Shellfish And Inkjet Printers May Hold Key To Faster Healing From Surgeries

Using the natural glue that marine mussels use to stick to rocks, and a variation on the inkjet printer, a team of researchers led by North Carolina State University has devised a new way of making medical adhesives that could replace traditional sutures and result in less scarring, faster recovery times and increased precision for exacting operations such as eye surgery.

Traditionally, there have been two ways to join tissue together in the wake of a surgery: sutures and synthetic adhesives. Sutures work well, but require enormous skill and longer operating times. Additionally, the use of sutures is associated with a number of surgical complications, including discomfort, infection and inflammation. Synthetic adhesives are also widely used, but they are the source of increasing concerns over their toxicological and environmental effects. One such concern with some synthetic medical adhesives is that – because they are not biodegradable – they do not break down in the body and therefore may cause inflammation, tissue damage, or other problems.
But new research shows that adhesive proteins found in the "glue" produced by marine mussels may be used in place of the synthetic adhesives without these concerns, because they are non-toxic and biodegradable, according to study co-author Dr. Roger Narayan. In addition, the mussel proteins can be placed in solution and applied using inkjet technology to create customized medical adhesives, which may have a host of applications. For example, Narayan says this technique may "significantly improve wound repair in eye surgery, wound closure and fracture fixation." Narayan is an associate professor in the joint biomedical engineering department of NC State and the University of North Carolina at Chapel Hill.
"This is an improved way of joining tissues," Narayan says, "because the use of the inkjet technology gives you greater control over the placement of the adhesive. This helps ensure that the tissues are joined together in just the right spot, forming a better bond that leads to improved healing and less scarring." This increased control would be a boon for surgery that relies on extreme precision, such as eye repair, Narayan explains.
The study was performed in collaboration with Professor Jon Wilker in the Department of Chemistry at Purdue University. The National Science Foundation, the National Institutes of Health and the Office of Naval Research funded the research.
Journal reference:
Doraiswamy et al. Inkjet printing of bioadhesives. Journal of Biomedical Materials Research Part B Applied Biomaterials, 2009; 89b (1): 28 DOI: 10.1002/jbm.b.31183
Adapted from materials provided by North Carolina State University.

Sticky Mussels Inspire Biomedical Engineer Yet Again

Mussels are delicious when cooked in a white wine broth, but they also have two other well-known qualities before they're put in a pot: they stick to virtually all inorganic and organic surfaces, and they stick with amazing tenacity।

Northwestern University biomedical engineer Phillip B. Messersmith already has developed a material that mimics the strength of the bonds; now he has produced a versatile coating method that mimics the mussels' ability to attach to a wide variety of objects.
Messersmith and his research team, in a study to be published in the Oct. 19 issue of the journal Science, report that a broad variety of materials can be coated and functionalized through the application of a surface layer of polydopamine.
Potential applications of the simple and inexpensive method include flexible electronics, such as bendable and flexible displays, biosensors, medical devices, marine anti-fouling coatings, and water processing and treatment, such as removing heavy metals from contaminated water.
Key to the coating method is the small molecule dopamine, commonly known as a neurotransmitter. Dopamine, it turns out, is a good mimic of the essential components of mussel adhesive proteins, and the researchers use it as a building block for polymer coatings. (Dopamine itself is not found in mussels.) So, like a mussel, Messersmith's coating sticks to anything.
"This is an astonishingly simple and versatile approach to functional surface modification of materials," said Messersmith, professor of biomedical engineering at Northwestern's McCormick School of Engineering and Applied Science, who led the research। "We dissolve dopamine, which we buy at low cost, in a beaker of water exposed to air. We adjust the water's pH to marine pH, about 8.5, put in an object and several hours later it's coated with a thin film of polydopamine. That's it."

Solid objects of any size and shape can be immersed in the solution. (The dopamine solution is very dilute -- only two milligrams of dopamine per one milliliter of water.) At marine pH, there are chemical changes in the dopamine molecule that result in polymerization of the molecules together to form a polymer, polydopamine, which coats the object. The polymer is fairly similar to what is found in the mussel adhesive protein.
And to make things more interesting, the polydopamine coating, in turn, provides a very chemically reactive surface onto which the researchers can deposit a second coating. And because the surface is so reactive in so many different ways, a wide variety of second coatings can be applied.
"We take advantage of that reactivity to apply the second layer," said Messersmith. "As a simple example, I could put an iPod in the dopamine solution, and a thin polydopamine coating would form. Then I could take it out and put it in a metal salt solution and form a coating of copper or silver."
This second coating, depending on what it is, promises to take researchers and industry in multiple directions as far as applications go. In addition to cladding objects with metal coatings, this includes inhibiting biofouling of materials (such as for medical devices), engineering surfaces to support biospecific interactions with cells (such as for culture and expansion of stem cells) and applying self-assembled monolayers to nonmetal surfaces (such as for biosensors).
Messersmith and his colleagues tested the two-step process on 25 different substrate materials (but not an iPod) with a wide range of characteristics representing all major classes of materials, from hydrophobic to hydrophilic, from inorganic to organic, as well as the traditionally difficult material Teflon, all with positive results. They then demonstrated deposition of metal and organic coatings and self-assembled monolayers onto the polydopamine coating.
"Existing methods for modifying material surfaces are fairly restricted to specific materials -- what works well on glass would not work well on gold," said Messersmith. "Our method is a much more general strategy for a variety of surfaces. We haven't found a material to which we can't apply polydopamine."
In addition to Messersmith, other authors of the paper, titled "Mussel-Inspired Surface Chemistry for Multifunctional Coatings," are Haeshin Lee (lead author) and Shara M. Dellatore, both graduate students, and William M. Miller, professor of chemical and biological engineering, all from Northwestern.
Adapted from materials provided by Northwestern University.

Study Reveals Details Of Mussels' Tenacious Bonds

When it comes to sticking power, marine mussels are hard to beat। They can adhere to virtually all inorganic and organic surfaces, sustaining their tenacious bonds in saltwater, including turbulent tidal environments. Little is known, however, about exactly how the bivalves achieve this amazing feat.

In a paper to be published online the week of Aug. 14 by the Proceedings of the National Academy of Sciences, a Northwestern University research team sheds new light on the adhesive strategies of mussels, information that could be used to develop adherents or repellants for use in medical implants.
This is the first-ever single molecule study to focus on the key amino acid 3,4-L-dihydroxyphenylalanine (DOPA), a tyrosine derivative that is found in high concentration in the "glue" proteins of mussels.
The researchers, led by Phillip B. Messersmith, associate professor of biomedical engineering in the McCormick School of Engineering and Applied Science, attached single DOPA amino acids to an atomic force microscope tip and measured the strength of interaction between DOPA and inorganic and organic surfaces.
They found that on an inorganic metal oxide surface DOPA interacts with the substrate by a coordinated noncovalent interaction, which is over an order of magnitude stronger than hydrogen bonding but still completely reversible.
On an organic substrate, DOPA can form even stronger, and irreversible, covalent bonds when it is oxidized by seawater। This helps to explain the remarkable versatility of mussels to adhere strongly to many different materials.

On neither substrate could tyrosine alone mimic such a strong binding interaction, which highlights that the modification of tyrosine residues to form DOPA during mussel glue processing is critical.
"Our results point the way toward new applications for our mussel mimetic polymers," said Messersmith, who has designed a versatile two-sided coating that sticks securely to a surface and prevents cell, protein and bacterial buildup. "For example, we may be able to take advantage of the reactivity of oxidized DOPA to form covalent bonds between adhesive DOPA-containing polymers and human tissue surfaces."
Other authors on the paper are lead author Haeshin Lee, a graduate student at Northwestern, and Norbert F. Scherer, professor of chemistry at the University of Chicago.
Adapted from materials provided by Northwestern University.

The Bivalves World

Before the worst mass extinction of life in Earth's history -- 252 million years ago -- ocean life was diverse and clam-like organisms called brachiopods dominated। After the calamity, when little else existed, a different kind of clam-like organism, called a bivalve, took over.

What can the separate fates of these two invertebrates tell scientists about surviving an extinction event?
A lot, says UWM paleoecologist Margaret Fraiser। Her research into this particular issue not only answers the question; it also supports a relatively new theory for the cause of the massive extinctions that occurred as the Permian period ended and the Triassic period began: toxic oceans created by too much atmospheric carbon dioxide (C02).

The theory is important because it could help scientists predict what would happen in the oceans during a modern "C02 event." And it could give them an idea of what recovery time would be.
Studying the recovering ecology is equally significant, says Fraiser. The evolution of surviving species in the aftermath of the mass extinction set the stage for dinosaurs to evolve later in the Triassic.
From air to water Fossil records suggest that trauma in the oceans actually began in the air.
"Estimates of the C02 in the atmosphere then were between six and 10 times greater than they are today," says Fraiser, an assistant professor of geosciences। It makes sense, she says. The largest continuous volcanic eruption on Earth -- known as the "Siberian Traps" -- had been pumping out C02 for about a million years prior to the Permian-Triassic mass extinction.

The Permian-Triassic extinction wiped out 70 percent of life on land and close to 95 percent in the ocean -- nearly everything except for bivalves and a fewer number of gastropods (snails).
C02 is a greenhouse gas that influences global temperatures. But, says Fraiser, according to the fossil record, high levels of C02 and the correspondingly low levels of oxygen do much more than that.
The hypothesis unfolds like this: High C02 levels would have increased temperatures, resulting in global warming on a large scale. With no cold water at the poles, ocean circulation would have stagnated. The oceans would have become low in oxygen, killing off life in deeper waters where there was no opportunity for water to mix with the little oxygen in the atmosphere.
More carbon dioxide would have been created as life forms died and microbes broke them down, which also would have created poisonous hydrogen sulfide. The oceans would have become an inhabitable chemical cocktail.
Follow the CO2 In fact, there have been many CO2 events in geologic time, and they've literally left their mark।

"You can see where the rock turned dark," says Fraiser, pointing out different-colored layers in a fossil samples from the period. "That is an indicator of low oxygen at the time. These are from sites that were underwater at the beginning of the Triassic period."
Fraiser, who has just finished her first year at UWM, is one of several new faculty in geosciences and its emerging paleobiology program.
She has collected fossil samples of the marine survivors from the period in what today are China, Japan, Italy and the western United States. The similarities of the fossils from all these locations have been surprising.
"It is unexpected to see that," says Fraiser. "It appears that these bivalves and gastropods were the only survivors worldwide."
They had all the right characteristics to tolerate the lack of oxygen, she says. They were tiny, shallow-water dwellers, with a high metabolism and flat shape that allowed them to spread out to extract more of the limited oxygen when feeding.
Toxic conditions also inhibited marine life from producing a shell. Size suddenly mattered for mollusks, and only the very small survived, eroding the balance of the marine food chain.
Ultra-slow rebound As she sorts through the rock record from just after the Permian-Triassic extinction, Fraiser also has unearthed evidence that explains why it took so long for life to recover. The answer appears to be more of the same: C02 levels remained high long after the initial die-off.
"After other extinction events on Earth, life bounced back within 100,000 to a million years," she says. "But with the Permian-Triassic extinction, we don't see a recovery for 5 million years. There is very low ecological complexity and diversity for all of that time."
Another intriguing aspect of this interval in Earth's history, says Fraiser, is that, according to the rock record from the Triassic, it was bounded by two C02 events.
The first was the disappearance of coral reefs. "That gap sounded the alarm," she says. "That's what indicated that C02 levels were elevated."
On the back end, large communities of bivalves prevailed in such large numbers that they formed their own reefs.
Fraiser's charting of the C02 "domino effect" on Early Triassic marine life is valuable as scientists study climate change today, says UWM Geology Professor John Isbell.
"The Earth's system doesn't care where the C02 comes from," Isbell says. "It's going to respond the same way."
Note: This story has been adapted from a news release issued by University of Wisconsin - Milwaukee.

New Mollusks Found in Western Cuba

The discovery of 27 new mollusks in the sea bed of Guanahacabibes peninsula,
Pinar del Rio, Cuba, enlarges its current stock to 627.

An expedition found the presumed endemic mollusks at nine locations within
the UNESCO Biosphere Reserve, namely at Maria La Gorda, Las Tumbas, Cabo de
San Antonio and Ensenada de Bolondron.

Jose Espinosa, from the Cuban Oceanology Institute, runs this project in
coordination with Oviedo University, Spain, and the Office for the
Comprehensive Development of Guanahacabibes.

Among the new species Espinosa mentioned gasteropods, bivalves, cephalopods
and more, all of great scientific significance for Cuba and the Caribbean.

They are very rare in sea beds and are significant diversity indicators for
this area, currently considered the most complete in Cuba, 166 miles west of
Havana.

Guanahacabibes concentrates Cuba's largest bio-speleological wealth and the
area is site of in-depth study.

Full story at