Say hello to biodegradable microplastics

Microplastics are tiny, nearly indestructible fragments shed from everyday plastic products. As we learn more about microplastics, the news keeps getting worse. Already well-documented in our oceans and soil, we're now discovering them in the unlikeliest of places: our arteries, lungs and even placentas. Microplastics can take anywhere from 100 to 1,000 years to break down and, in the meantime, our planet and bodies are becoming more polluted with these materials every day.

Finding viable alternatives to traditional petroleum-based plastics and microplastics has never been more important. New research from scientists at the University of California San Diego and materials-science company Algenesis shows that their plant-based polymers biodegrade -- even at the microplastic level -- in under seven months. The paper, whose authors are all UC San Diego professors, alumni or former research scientists, appears in Nature Scientific Reports.

"We're just starting to understand the implications of microplastics. We've only scratched the surface of knowing the environmental and health impacts," stated Professor of Chemistry and Biochemistry Michael Burkart, one of the paper's authors and an Algenesis co-founder. "We're trying to find replacements for materials that already exist, and make sure these replacements will biodegrade at the end of their useful life instead of collecting in the environment. That's not easy."

"When we first created these algae-based polymers about six years ago, our intention was always that it be completely biodegradable," said another of the paper's authors, Robert Pomeroy, who is also a professor of chemistry and biochemistry and an Algenesis co-founder. "We had plenty of data to suggest that our material was disappearing in the compost, but this is the first time we've measured it at the microparticle level."

Putting it to the test

To test its biodegradability, the team ground their product into fine microparticles, and used three different measurement tools to confirm that, when placed in a compost, the material was being digested by microbes.

The first tool was a respirometer. When the microbes break down compost material, they release carbon dioxide (CO2), which the respirometer measures. These results were compared to the breakdown of cellulose, which is considered the industry standard of 100% biodegradability. The plant-based polymer matched the cellulose at almost one hundred percent.

Next the team used water flotation. Since plastics are not water soluble and they float, they can easily be scooped off the surface of water. At intervals of 90 and 200 days, almost 100% of the petroleum-based microplastics were recovered, meaning none of it had biodegraded. On the other hand, after 90 days, only 32% of the algae-based microplastics were recovered, showing that more than two thirds of it had biodegraded. After 200 days, only 3% was recovered indicating that 97% of it had disappeared.

The last measurement involved chemical analysis via gas chromatography/mass spectrometry (GCMS), which detected the presence of the monomers used to make the plastic, indicating that the polymer was being broken to its starting plant materials. Scanning-electron microscopy further showed how microorganisms colonize the biodegradable microplastics during composting.

"This material is the first plastic demonstrated to not create microplastics as we use it," said Stephen Mayfield, a paper coauthor, School of Biological Sciences professor and co-founder of Algenesis. "This is more than just a sustainable solution for the end-of-product life cycle and our crowded landfills. This is actually plastic that is not going to make us sick."

Creating an eco-friendly alternative to petroleum-based plastics is only one part of the long road to viability. The ongoing challenge is to be able to use the new material on pre-existing manufacturing equipment that was originally built for traditional plastic, and here Algenesis is making progress. They have partnered with several companies to make products that use the plant-based polymers developed at UC San Diego, including Trelleborg for use in coated fabrics and RhinoShield for use in the production of cell phone cases.

"When we started this work, we were told it was impossible," stated Burkart. "Now we see a different reality. There's a lot of work to be done, but we want to give people hope. It is possible."

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Advanced artificial photosynthesis catalyst uses CO2 more efficiently to create biodegradable plastics

A research team from Osaka Metropolitan University that had previously succeeded in synthesizing fumaric acid using bicarbonate and pyruvic acid, and carbon dioxide collected directly from the gas phase as one of the raw materials, has now created a new photosensitizer and developed a new artificial photosynthesis technology, effectively doubling the yield of fumaric acid production compared to the previous method. The results of this research are expected to reduce carbon dioxide emissions and provide an innovative way to produce biodegradable plastics while reusing waste resources.

Amid growing global concern over climate change and plastic pollution, researchers at Osaka Metropolitan University are making great strides in the sustainable production of fumaric acid -- a component of biodegradable plastics such as polybutylene succinate, which is commonly used for food packaging.

The researchers have managed to efficiently produce fumaric acid, which is traditionally derived from petroleum, using renewable resources, carbon dioxide, and biomass-derived compounds.

In a previous study, a research team led by Professor Yutaka Amao of the Research Center for Artificial Photosynthesis at Osaka Metropolitan University demonstrated the synthesis of fumaric acid from bicarbonate and pyruvic acid, a biomass-derived compound, using solar energy.

They also succeeded in producing fumaric acid using carbon dioxide obtained directly from the gas phase as a raw material.

However, the yield in the production of fumaric acid remained low.

In their latest research, published in Dalton Transactions, the researchers have now developed a new photosensitizer and further advanced an artificial photosynthesis technique that doubles the yield of fumaric acid compared to conventional methods.

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Self-healing plastic becomes biodegradable

Imagine a plastic like this: harder than common plastics, non-flammable, and even with self-healing properties. But that is not all! It can be produced at room temperature in water, which is very energy-efficient and does not require toxic solvents. Before hardening, you can shape the plastic in any way you want -- like chewing gum. By adding water, it can also be converted back to its "chewing gum" form at any time, reshaped and thus recycled as often as desired.

Is that impossible? No, it is not! In 2016, the research team around Konstanz chemist Helmut Cölfen presented just such a material -- a mineral plastic. However, even though the plastic, with its novel manufacturing process and outstanding material properties, has since attracted great interest from industry, it still had a crucial shortcoming from the Konstanz chemists' point of view: due to its chemical composition, it was difficult to biodegrade.

A new ingredient for greater environmental compatibility

"Previously, we used polyacrylic acid to produce our mineral plastic. Chemically, this acid has the same backbone as polyethylene, which is known to cause major problems in the environment because it is hardly biodegradable," explains Cölfen. The research team led by Cölfen and Ilesha Avasthi, a postdoc in Cölfen's lab, therefore set to work looking for an alternative basic building block to develop an environmentally compatible mineral plastic that retains the intriguing properties of the original material. And they found what they were looking for.

In their current publication in the journal Small Methods, the Konstanz chemists present the next generation of their mineral plastic. Instead of petroleum-based ingredients such as polyacrylic acid, they now use polyglutamic acid. This natural biopolymer is readily available in large quantities and can even be obtained sustainably, for example from biotechnological production using microorganisms. A variety of microorganisms that already exist in the environment can degrade polyglutamic acid.

"Our new mineral plastic has the same positive properties as the previous one, but has the decisive advantage that its basic building block -- polyglutamic acid -- can be produced with the help of microorganisms and is completely biodegradable," says Helmut Cölfen.

Support from biologists

In order to prove that this biodegradability also applies to the new mineral plastic itself and not just to its individual components, the chemists enlisted the support of David Schleheck and postdoc Harry Lerner from the Department of Biology at the University of Konstanz. "Helmut Cölfen has created a new type of mineral plastic in his laboratory, and our task now was to make it disappear again with the help of microorganisms," says Schleheck with a smile.

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System to create bioplastics

A team of Texas A&M AgriLife Research scientists has developed a system that uses carbon dioxide, CO2, to produce biodegradable plastics, or bioplastics, that could replace the nondegradable plastics used today. The research addresses two challenges: the accumulation of nondegradable plastics and the remediation of greenhouse gas emissions.

Published Sept. 28 in Chem, the research was a collaboration of Susie Dai, Ph.D., associate professor in the Texas A&M Department of Plant Pathology and Microbiology, and Joshua Yuan, Ph.D., formerly with the Texas A&M Department of Plant Pathology and Microbiology as chair for synthetic biology and renewable products and now Lopata professor and chair in the Washington University in St. Louis Department of Energy, Environmental and Chemical Engineering.

The research was made possible by the John '90 and Sally '92 Hood Fund for Sustainability and Renewable Products, Texas A&M AgriLife and Texas A&M University.

Creating bioplastics

Dai said today's petroleum-based plastics do not degrade easily and create a massive issue in the ecosystems and, ultimately, oceans.

To address these issues, the Texas A&M College of Agriculture and Life Sciences researchers and their teams worked for almost two years to develop an integrated system that uses CO2 as a feedstock for bacteria to grow in a nutrient solution and produce bioplastics. Peng Zhang, Ph.D., postdoctoral research associate, and Kainan Chen, doctoral student, both in the Texas A&M Department of Plant Pathology and Microbiology, contributed to the work. The Texas A&M University System has filed a patent application for the integrated system.

"Carbon dioxide has been used in concert with bacteria to produce many chemicals, including bioplastics, but this design produces a highly efficient, smooth flow through our carbon dioxide-to-bioplastics pipeline," Dai said.

"In theory, it is kind of like a train with units connected to each other," Dai said. "The first unit uses electricity to convert the carbon dioxide to ethanol and other two-carbon molecules -- a process called electrocatalysis. In the second unit, the bacteria consume the ethanol and carbon molecules to become a machine to produce bioplastics, which are different from petroleum-based plastic polymers that are harder to degrade."

Capturing and re-using CO2 waste

Using CO2 in the process could also help reduce greenhouse gas emissions. Many manufacturing processes emit CO2 as a waste product.

"If we can capture the waste carbon dioxide, we reduce greenhouse gas emission and can use it as a feedstock to produce something," Dai said. "This new platform has great potential to address sustainability challenges and transform the future design of carbon dioxide reduction."

The major strength of the new platform is a much faster reaction rate than photosynthesis and higher energy efficiency.

"We are expanding the capacity of this platform to broad product areas such as fuels, commodity chemicals and diverse materials," Dai said. "The study demonstrated the blueprint for 'decarbonized biomanufacturing' that could transform our manufacturing sector."

Expanding future impacts

Dai said currently, bioplastics are more expensive than petroleum-based plastics. But if the technology is successful enough to produce bioplastics at an economic scale, industries could replace traditional plastic products with ones that have fewer negative environmental impacts. In addition, mitigating CO2 emissions from energy sectors such as gas and electric facilities would also be a benefit.

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A sea change for plastic pollution: New material biodegrades in ocean water

Plastics, now ubiquitous in the modern world, have become a rising threat to human and environmental health. Around the planet, evidence of plastic pollution stretches from grocery bags in the deep sea to microplastics in our food supplies and even in our blood.

Seeking solutions to counteract the rise in plastic trash, scientists at the University of California San Diego have developed new biodegradable materials that are designed to replace conventionally used plastic. After proving their polyurethane foams biodegrade in land-based composts, an interdisciplinary team of scientists including UC San Diego biologist Stephen Mayfield and chemists Michael Burkart and Robert "Skip" Pomeroy have now shown that the material biodegrades in seawater. The results are published in the journalScience of the Total Environment.

The researchers are working to address a plastic pollution problem now described as a global environmental crisis. In 2010, researchers estimated that 8 billion kilograms of plastic enter the ocean in a single year, with a steep escalation predicted by 2025. Upon entering the ocean, plastic waste disrupts marine ecosystems, migrates to central locations and forms trash gyres such as the Great Pacific Garbage Patch, which covers an area more than 1.6 million square kilometers. These plastics never degrade, but rather break up into ever-smaller particles, eventually becoming microplastics that persist in the environment for centuries.

Working with study coauthor Samantha Clements, a marine biologist and scientific diver at Scripps Institution of Oceanography, the UC San Diego researchers conducted a series of tests of their biodegradable polyurethane materials -- currently used as foams in the first commercially available biodegradable shoes (sold by a spinoff company called Blueview) -- at Scripps' Ellen Browning Scripps Memorial Pier and Experimental Aquarium. The pier's location provided scientists the access and a unique opportunity to test materials in the natural nearshore ecosystem, which is the exact environment where rogue plastics are most likely to end up.

The team found that an assortment of marine organisms colonizes on the polyurethane foam and biodegrades the material back to their starting chemicals, which are consumed as nutrients by these microorganisms, in the ocean environment. Data from the study suggest that the microorganisms, a mix of bacteria and fungi, live throughout the natural marine environment.

"Improper disposal of plastic in the ocean breaks down into microplastics and has become an enormous environmental problem," said Mayfield, a professor in the School of Biological Sciences and director of the California Center for Algae Biotechnology. "We've shown that it's absolutely possible to make high performance plastic products that also can degrade in the ocean. Plastics should not be going into the ocean in the first place, but if they do, this material becomes food for microorganisms and not plastic trash and microplastics that harm aquatic life."

Shoes, including flip-flops, the world's most popular shoe, make up a large percentage of plastic waste that ends up in the world's oceans and landfills. To fully test and analyze their polyurethane materials, developed at UC San Diego over the last eight years, the study joined experts in biology, polymer and synthetic chemistry and marine science. Foam samples were exposed to tidal and wave dynamics and tracked for molecular and physical changes using Fourier-transform infrared spectroscopy and scanning electron microscopy. The results showed that the material started to degraded in as little as four weeks. The researchers then identified microorganisms from six marine sites around San Diego that are capable of breaking down and consuming the polyurethane material.

"No single discipline can address these universal environmental problems but we've developed an integrated solution that works on land -- and now we know also biodegrades in the ocean," said Mayfield. "I was surprised to see just how many organisms colonize on these foams in the ocean. It becomes something like a microbial reef."

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