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Scientists have developed a new synthetic substance that has the potential to be used to improve drug delivery

6 April 2023

6

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.

Dr Farah El Mohtadi, University of Portsmouth’s School of Pharmacy & Biomedical Sciences

Lead author, Dr Farah El Mohtadi from the University of Portsmouth’s School of Medicine, Pharmacy and 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.

16th & 17th January 2019
Centre for Enzyme Innovation Bid

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, Centre for Enzyme Innovation Director

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.”