Scientists have developed a new synthetic substance that has the potential to be used to improve drug delivery
Researchers have developed a novel synthetic substance that has the potential to be a more effective and safer way of delivering drugs around the body.
Currently, Polyethylene glycol (PEG) is the most commonly used polymer for biomedical applications due to its non-toxicity and high solubility. It has many applications, including coating nanocarriers which ferry pharmaceuticals in a patient’s bloodstream.
While PEGs have a vast number of benefits, there are also significant shortcomings. Currently, researchers have concerns over PEG’s own immunogenicity, so their tendency to trigger an unwanted immune response against themselves. The widespread use of PEG in Covid-19 vaccines and boosters has led to significantly higher levels of PEG-antibodies found in vaccinated people.
A team of scientists has created a new ‘active stealth’ polymer, called Polythio Glycidyl glycerol (PTGG), which initial data suggests is safer and more effective in drug-delivery.
The study, published in the Journal of the American Chemical Society (JACS), found PTGG was less likely to be detected by immune systems when travelling around a body compared to PEG. It also enhanced physical stability and protected tissue from oxidative and inflammatory damage.
PTGG's 'active-stealth' character makes it a highly promising alternative to PEG for delivering drugs, and therapeutic proteins.
Lead author, Dr Farah El Mohtadi from the University of Portsmouth’s School of Pharmacy & Biomedical Sciences, said: “PTGG's 'active-stealth' character makes it a highly promising alternative to PEG for delivering drugs, and therapeutic proteins.
“Not only can it effectively avoid detection in the bloodstream, the polymer’s advantageous properties can also significantly reduce the need for expensive substances to prevent freeze-damage during storage.”
The study's findings have significant implications for the development of more effective and safer drugs and nanocarriers. Further research will be conducted to explore the potential applications of PTGG in clinical settings.
“On top of the medical application, we also want to explore PTGG’s potential use in other areas,” added Dr El Mohtadi.
“These include temporarily uniting the polymer to enzymes and exploring whether they are more effective at breaking down man-made materials, including plastics.”
The potential for utilising the polymer to stabilise nylon-degrading enzymes will be explored as part of an Aquapak-funded PhD studentship at the University’s Centre for Enzyme Innovation (CEI), a project supervised by Professor Andy Pickford (the CEI Director), Dr El Mohtadi and Dr Bruce Lichtenstein.
CEI scientists have already developed enzyme technology to reduce single use plastics, including PET, to their chemical building blocks, leading to safe and energy efficient recycling. Now they have set their sights on creating a similar process for polyester textiles, and for this project targeting nylon.
In an industrial setting, plastic-degrading enzymes must operate under challenging conditions such as high temperature, so we are excited to see whether attaching PTGG to them can enhance their performance.
Professor Andy Pickford said: “In an industrial setting, plastic-degrading enzymes must operate under challenging conditions such as high temperature, so we are excited to see whether attaching PTGG to them can enhance their performance.”
‘Plastic-eating’ enzymes help recycle clothing
Scientists from the University of Portsmouth say the search is on for a ‘plastic-eating’ enzyme that can help recycle polyester clothing to stop millions of tons of waste ending up in landfill or being burned every year.
Imagine being able to turn this polyester T-shirt back into its raw material building blocks. UK scientists at the University of Portsmouth are doing just that, with the help of ‘plastic-eating enzymes.'
“What we want to do is to see whether the enzymes that can break down these plastic bottles are also able to break down the polyester in fabrics such as this.”
Researchers say the enzymes can help recycle polyester clothing and stop millions of tons of waste ending up in landfill or being burned every year.
So how exactly is it done?
First, scientists take the item of clothing and cut it up. After it's been dipped in liquid nitrogen, it’s milled down into small particles. These are then placed in a water-based solution in a bioreactor containing the enzymes. These then 'digest' the plastic back into its raw materials.
Senior Research Fellow Victoria Bremmer explains: “So we can think of an enzyme as like, almost like a pair of scissors. So when we take our plastics, they're just a very long string of different molecules. And then we use our enzymes to cut that string in specific places. So when we do that, at the end of the reaction, we have like a soup of different parts of the plastic which we can then sort of separate off into different things and then we can react to those to either make a new plastic or they can be used in other chemical industries."
Polyester is the most widely-used clothing fibre in the world. It accounts for 60% of what we wear, but it’s not sustainable, especially when it’s dyed and treated with chemicals.
The team at University of Portsmouth have already identified more than 70 enzymes that can break down plastic, with varying success. Now they're looking for the best one.
“Obviously we're looking for the enzyme that's the fastest, that's gonna break this down as quickly as possible. And we're looking for enzymes that are sort of stable at the temperatures that we want to react, work out in industry which is usually around sort of 70 degrees. We have a lot of people within the CEI that I kind of engineering these enzymes to make them either faster or more stable.”
It is already possible to turn some oil-based textiles into carpets and other products, but current recycling methods are highly energy intensive.
Director of the Centre for Enzyme Innovation Professor Andy Pickford hopes the enzymes will help create an environmentally-friendly circular economy for plastic based clothing.
“Although we have reasonably good recycling rates for plastics at end of life, plastic packaging end of life, the recycling rates for textiles when they reach their end of life is very, very poor, typically less than 10%. So we have a major challenge here that we're trying to tackle.”
“There's greater and greater pressure on the fashion industry to tackle some of the sustainability issues around their fabrics and so having a nature-inspired solution to re-utilise the polymers that are in our clothing at end of life could be a real game changer.”