Floating biodegradable beads remove oil in 60 minutes and stay easy to recover
Floatable beads made from chitosan and cellulose acetate and enhanced with bentonite have been engineered to effectively clean oil from water. The beads showed good oil adsorption capacity while remaining easy to collect from the water surface.
Oil spills, the accidental and uncontrolled release of crude oil into the ocean, are remediated by removing the oil from the environment. Typical approaches include mechanical recovery, a dangerous, labor-intensive, and time-consuming process; in situ burning, which causes severe ecological disruption; bioremediation, an environmentally friendly yet slow process; chemical dispersants, which also cause severe ecological disruption; and sorbent-based approaches, which are promising but currently inadequate.
By sending nanoemulsion formulations on a space flight, scientists are investigating whether chitosan—a material derived from shrimp and wid
By sending nanoemulsion formulations on a space flight, scientists are investigating whether chitosan—a material derived from shrimp and widely used to control the release of medications—performs well in controlling medicine delivery when exposed to zero gravity. Their preliminary results suggest that drugs needed by astronauts can be delivered effectively in space.
A team from the University of Adelaide working with the German Aerospace Center (DLR), Institute of Aerospace Medicine, conducted the StarMed experiment by exposing six small glass vials on a space flight and then analyzing the stability of the emulsion on its return to Earth. The same number of identical control vials were on the ground in both Europe and Adelaide.
Our skin is a deceptively complex material, delicate but strong, protective but permeable. An ideal artificial skin substitute for wound healing must support blood vessel growth, have antibacterial properties, and be sufficiently porous for air and moisture exchange. A new approach has developed a scaffold to grow such tissue-engineered material by incorporating a glass-ceramic onto electrospun nanofibres made of chitosan – a sugar from shellfish outer skeletons – and gelatin (pictured). The scaffold was also laced with silver, which provides antibacterial properties, and was found to be compatible with the body and blood, and promoted cell growth. Connective cells (pink) fully attached and spread over the scaffold, and researchers then treated wounds on mice. The scaffolds showed good vessel and protein growth, and even supported the regeneration of glands and hair follicles, which means this approach may help wounds repair without leaving a scar.
Written by Anthony Lewis
Image from work by Esmaeel Sharifi and colleagues
Cellular and Molecular Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Science; Dept of Emergency Medicine, School of Medicine, Hamadan University of Medical Sciences; School of Chemistry, Damghan University, Iran
Image originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)
Published in Bioengineering & Translational Medicine, July 2022
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Chitin and chitosan from crustacean shells could put a dent in the world’s plastic waste problem.
Lobster bisque and shrimp cocktail make for scrumptious meals, but at a price. The food industry generates 6 million to 8 million metric tons of crab, shrimp and lobster shell waste every year. Depending on the country, those claws and legs largely get dumped back into the ocean or into landfills.
In many of those same landfills, plastic trash relentlessly accumulates. Humans have produced over 8 billion tons of plastic since mass production began in the 1950s. Only 10 percent of plastic packaging gets recycled successfully. Most of the rest sits in landfills for a very long time (a plastic bottle takes about 450 years to break down), or escapes into the environment, perhaps sickening seabirds that swallow tiny pieces or gathering in the Pacific Ocean’s floating garbage patch (SN Online: 3/22/18).
Some scientists think it’s possible to tackle the two problems at once. Crustaceans’ hardy shells contain chitin, a material that, along with its derivative chitosan, offers many of plastic’s desirable properties and takes only weeks or months to biodegrade, rather than centuries.
The challenge is getting enough pure chitin and chitosan from the shells to make bio-based “plastic” in cost-effective ways. “There’s no blueprint or operating manual for what we’re doing,” says John Keyes, CEO of Mari Signum, a start-up company based just outside of Richmond, Va., that is devising ways to make environmentally friendly chitin. But a flurry of advances in green chemistry is providing some guideposts.
Nature’s scaffold
Chitin is one of the most abundant organic materials in the world, after cellulose, which gives woody plants their structure. In addition to crustaceans, chitin is found in insects, fish scales, mollusks and fungi. Like plastic, chitin is a polymer, a molecular chain made from repeating units. The building block in chitin, N-acetyl-D-glucosamine, is a sugar related to glucose. Chitin and chitosan are antibacterial, nontoxic and used in cosmetics, wound dressings and pool-water treatments, among other applications.
This 2-inch square of compostable chitin foam could be used to make surfboards or biodegradable food packaging. CREDIT: CRUZ FOAM
Entrepreneurs are trying to launch new chitin products. Cruz Foam, a company in Santa Cruz, Calif., set out to produce surfboards from chitin, though the company has since pivoted to focus on the much larger market of packaging foam. Polystyrene foam, a common component in both surfboards and food packaging, takes a minimum of 500 years to biodegrade. Company cofounder Marco Rolandi is convinced that his Cruz Foam will biodegrade readily, based on his at-home test. “I put Cruz Foam in my backyard compost and a month later there were worms growing on it,” he says. Eco-friendly surfboards and wound dressings are valuable, but they are niche products — small potatoes that won’t make a dent in the massive amounts of fossil fuel–based plastics. Scientists have proposed large-scale production of chitin or chitosan in the past. But the chemistry for isolating the materials from shell waste has some big drawbacks, so the work didn’t get far.
Making use of seafood shell waste starts with drying the shells. CREDIT: MARI SIGNUM
For one thing, pulling out the chitin traditionally requires corrosive chemicals. A crustacean shell contains 15 to 40 percent chitin. To get to the chitin requires removing the protein along with the minerals, largely calcium carbonate, that make the shells stiff. Hydrochloric acid, a strong acid, removes calcium carbonate while generating carbon dioxide emissions; sodium hydroxide, or lye, is a strong base that removes the protein. Producing a single kilogram of chitin requires 10 kilograms of shells, six kilograms of coal for heating purposes, nine kilograms of hydrochloric acid, eight kilograms of sodium hydroxide and 330 kilograms of freshwater. Washing the chitin to remove residual contaminants can use up to an additional 200 kilograms of water.
Getting the chitosan requires an extra step: adding hot, concentrated sodium hydroxide solution to the chitin. To do this work in a sustainable way, companies must invest in pricey corrosion-resistant reactors, wastewater treatment and carbon dioxide capture technology.
The harsh reactions used today also sever the long polymer chains that make the materials sturdy, limiting chitin’s and chitosan’s versatility. Mari Signum’s chief technology officer, Julia Shamshina, offers a clothing analogy: It’s impossible to make a sweater with a ball of yarn made only of short threads.
Dried seafood waste is put through several chemical steps to extract the chitin. One extra step gets to the derivative, chitosan (shown), which is also being tested as a plastic replacement. CREDIT: COURTESY OF MICHAEL HOFER/FRAUNHOFER INST.
Approaches that reduce or eliminate corrosive reagents, recycle water and keep the polymers strong are in demand, says Pierre-Olivier Morisset of Merinov, a research center in Gaspé, Canada, that helps marine-product companies manage waste and commercialize innovations. “We’re looking for technologies that can produce hundreds of kilograms” of chitin or chitosan with long polymer chains, Morisset says. But developing greener methods is not easy.
Seafood suppliers face economic drawbacks as well. Today, U.S. producers pay landfills to take their shells. But those who want to keep the waste out of the landfill and support chitin production must still pay to dry the shells and transport them to often faraway extraction facilities, like Mari Signum. For its part, Mari Signum is changing the equation by paying the transportation bills for its Gulf Coast suppliers. Once Mari Signum is profitable, the company says it will also pay those suppliers for their shells.
When Keyes was a pro bono consultant for an aquaculture business a few years ago, he faced that same food waste decision. The company planned to haul its shells to regional landfills, Keyes says, “until we … tracked down Robin Rogers.”
Bio-based film matches traditional plastic packaging in blocking moisture and oxygen
Plastic packaging is ubiquitous in our world, with its waste winding up in landfills and polluting oceans, where it can take centuries to degrade.
To ease this environmental burden, industry has worked to adopt renewable biopolymers in place of traditional plastics. However, developers of sustainable packaging have faced hurdles in blocking out moisture and oxygen, a barrier critical for protecting food, pharmaceuticals, and sensitive electronics.
Now, researchers at the Georgia Institute of Technology have developed a biologically-based film made from natural ingredients found in plants, mushrooms, and food waste that can block moisture and oxygen as effectively as conventional plastics. Their findings were recently published in ACS Applied Polymer Materials.
Graphene 'scaffold' recruits bone cells and helps the body regenerate fractures
Experiments conducted in Brazil using laboratory rats have shown that graphene-based structures can act as a powerful ally in bone regeneration. These structures are made of sheets of the chemical element carbon that are just one atom thick. They can help heal fractures or bone loss. In the tests, the biocompatible matrix containing graphene facilitated nearly 90% repair of the damage sustained by the test subjects one month after the fracture was induced in the laboratory—a superior performance to that of other materials used in the research.
The analysis of the performance of the biomaterial was published in the journal Scientific Reports. Daniela Franco Bueno of the Albert Einstein Israeli Faculty of Health Sciences and Guilherme Lenz e Silva of the Engineering School of the University of São Paulo (POLI-USP) coordinated the study.
Chitosan-nickel biomaterial becomes stronger when wet, and could replace plastics
A new study led by the Institute for Bioengineering of Catalonia (IBEC) has unveiled the first biomaterial that is not only waterproof but actually becomes stronger in contact with water. The material is produced by the incorporation of nickel into the structure of chitosan, a chitinous polymer obtained from discarded shrimp shells. The development of this new biomaterial marks a departure from the plastic-age mindset of making materials that must isolate from their environment to perform well. Instead, it shows how sustainable materials can connect and leverage their environment, using their surrounding water to achieve mechanical performance that surpasses common plastics.
