Chemistry breakthrough could transform both cancer care and recycling

A simple chemistry breakthrough is setting off a chain reaction with enormous potential - from making cancer treatments more effective to turning plastic into something we can reuse again and again. Scientists say the discovery could quietly reshape medicine, manufacturing and everyday life.

After years of research, international experts have confirmed the discovery of a new chemical reaction, launching new opportunities for rapid advances in a range of fields – from recycled plastics to pharmaceuticals.

“It is rare to discover an entirely new reaction, and even more rare for it to be useful in so many fields and applications,” says senior author Professor Justin Chalker, from Flinders University, who began pioneering work on more environmentally friendly sulfur polymers more than a decade ago.

“Understanding the new reaction allowed us to use it in several high-value applications – including selective modification of an anti-tumour drug and production of a novel plastic that can be moulded, used and then ‘unmade’ when recycling is required.”

Sulfur–sulfur (S-S) bonds are found in many important places, including proteins in the human body, some medicines, and everyday materials like rubber. Until now, scientists have struggled to work with these bonds in a precise way without using extra chemicals or applying heat or light.

In contrast, a new approach called the ‘trisulfide metathesis reaction’ can make and break the S-S bonds without extra chemicals or energy. The result is a clean, efficient reaction and in some cases, the reaction is complete within seconds.

What makes this reaction stand out is how fast and precise it is. It can be used to tweak a powerful anti‑tumour drug called calicheamicin, which contains these sulfur bonds. This opens the door to developing future medicines that are more targeted, more effective, and potentially have fewer side effects.

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First author Dr Harshal Patel, from the Chalker Lab at Flinders University, says the new reaction has already been used to modify anti‑cancer drugs, as well as a wide range of chemicals that could help scientists develop future medicines.

“I’m excited to see how this chemistry is adopted, expanded and applied in ways not yet imagined. Encountering a new reaction is exciting, and we already have demonstrated several meaningful applications in biomolecular and materials chemistry,” says Dr Patel.

The research began with exploratory work by Professor Chalker and Liverpool University collaborator Dr Tom Hasell – supported by Australian Research Council (ARC) Discovery Grant funding – who found surprising behaviour of S-S bonds in certain solvents.

With further exploration at Flinders University, led by Matthew Flinders Professor in Chemistry Michelle Coote, Associate Professor Zhongfan Jia and 13 other chemistry researchers in Australian and UK universities, a mechanistic model was developed to account for this new and unusual chemistry.

The model explains how the bonds break and reform, and under what conditions it might be useful.

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By understanding exactly how this new reaction works, researchers were able to explore how it could be used in practice. This includes precisely changing natural compounds and drug molecules, quickly creating large collections of chemical compounds for medical research, and making plastics that can be fully recycled.

It's use in recyclable plastics could have major benefits for global sustainability. The study shows how this chemistry can be used to create fully recyclable versions of materials similar to polyethylene. A new ARC Discovery Grant will now expand this work to develop recyclable plastics, as well as rubber, foams and fibres.

Co-author Dr Hasell from the School of Physical Sciences at the University of Liverpool, says the trisulfide metathesis is a really versatile way to make reversible changes in both molecular and materials chemistry.

“I think the examples we’ve shown of what can be done with this chemistry are only the tip of the iceberg,” says Dr Hasell, a Royal Society University Research Fellow.