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polymer material with a biological system to create a living material that can function and respond to stimuli in ways that regular synthetic materials cannot,” said Jon Pokorski, a professor of nanoengineering at UC San Diego who co-led the research.
The work was a collaboration among engineers, materials scientists and biologists at the UCSD Materials Research Science and Engineering Center. Co- principal investigators of the multidisciplinary team include molecular biology professors Susan Golden and James Golden and nanoengineering professor Shaochen Chen.
“This collaboration allowed us to apply our knowledge of the genetics and physiology of cyanobacteria to create a living material,” said Susan Golden. “Now we can think creatively about engineering novel functions into cyanobacteria to make more useful products.”
To create the living bacteria, the researchers used hydrated alginate to make a gel, then mixed it with cyanobacteria before feeding the mixture into a 3D printer. After testing various 3D-printed geometries for their material, the researchers found that a grid-like structure was optimal for keeping the bacteria alive. The chosen shape has a high surface area to volume ratio, which places most of the cyanobacteria near the material’s surface to access nutrients, gases and light. According to UCSD, the increased surface area also makes the materials more effective at decontamination.
As a proof-of-concept experiment, the researchers genetically engineered the cyanobacteria in their material to continually produce laccase, a decontaminating enzyme. Laccase can be used to neutralise organic pollutants, including bisphenol A, antibiotics, pharmaceutical drugs and dyes.
The researchers also developed a way to eliminate the cyanobacteria after the pollutants have been cleared. They genetically engineered the bacteria to respond to theophylline, which triggers the bacteria to produce a protein that destroys their cells.
“The living material can act on the 22
With the increases in flood events, the role SuDS play is more important than ever. Photo - Sheffield City Council
pollutant of interest, then a small molecule can be added afterwards to kill the bacteria,” Pokorski said in a statement. “This way, we can alleviate any concerns about having genetically modified bacteria lingering in the environment.”
The researchers noted that a preferable solution is to have the bacteria destroy themselves without the addition of chemicals and this will be one of the future directions of this research.
“Our goal is to make materials that respond to stimuli that are already present in the environment,” said Pokorski.
A more depressing picture?
In amongst all our attempts to be greener lies the simple fact that we are today sourcing more materials from further away than ever before. Gone are the days of locally supplied parts and metalwork for equipment; although some companies are trying to source locally wherever they can after the recent nightmares of the effects of external events like Covid and Brexit on the established international supply chain. Anna Humphreys of XTI summed it up very well:
“I can’t see how we can ever really be green, as it all comes in heavily packaged
| October 2023 |
www.draintraderltd.com
from so far away – Taiwan, China, Japan, India. Less and less is coming from the UK and the decline in manufacturing means we can source very little from the UK. Even our control unit cases come from Italy, which is slightly closer than some other places.
“Plastics are heavily used in our industry, from drain pipes to the sheathing around push rods, and rare earth materials are increasingly used in electronics. We use bio-degradable bubble-wrap and don’t have vehicles on the road, unlike the actual operators. We use lots of metalwork but the UK steel industry has shrunk too, so these elements are getting less and less green in reality.
“The only thing the Government seems to do anything about is the motorist – an easy target. And the ULEZ expansion in London means many in the drainage industry will be very isolated as jobs more than a couple of miles away become too expensive to price. There is a rush to replace vans with hybrid and electric versions but there are still many other significant costs such as parking in the capital to account for when pricing jobs.
“Everything we eat, wear and use has often travelled thousands of miles to reach us. It’s a bit depressing, really.”
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