Microbe-killing polymer made from PET shows promise

By Jeremy Pafford

HOUSTON (ICIS)–An IBM synthetic organic chemist who has spent much of his research career making materials for semiconductors is now applying his know-how on making things smaller and better to help create nanopolymers at the forefront of medical research.

James Hedrick and others from IBM’s Almaden Research Center in California have collaborated with researchers from the Institute of Bioengineering and Nanotechnology in Singapore as well as from Yamagata University in Japan and Zhejiang University in China on using chemistry on polyethylene terephthalate (PET) flakes to produce a tiny “super plastic” capable fighting microbial infections.

Their findings were recently published in the journal Nature.

The nanopolymer the researchers created showed in laboratory tests to successfully kill the bacterial infection Staphylococcus aureus (MRSA) by effectively popping the membrane “like a balloon with a pin”, Hedrick said in a telephone interview this week.

The nanopolymer Hedrick helped create is amphiphilic – consisting of molecules having a polar water-soluble group attached to a water-insoluble hydrocarbon chain – as well as cationic in that it carries a positive ionic charge.

That positive charge is engineered to seek out the oppositely charged MRSA.

“On the surface of the microbe is a slightly negative charge, so we designed the polymers to be positive,” Hedrick said.

A typical antibiotic drug will enter the microbe’s membrane and attack a specific part of it in an effort to kill it, the researcher said. But the fact that it does not attack the entire microbe allows the organism to adapt and build resistance to the drug, he said.

By simply popping the membrane, the new super plastic does not give MRSA that chance.

“MRSA doesn’t have time to think,” Hedrick said. “It’s dead – 100% dead.”

Lab tests show that the nanopolymer completes its work in about 24 hours of being introduced to the body, he said. After its job is done, the non-toxic substance will then pass out of the body in the urine stream.

The super plastic is created by depolymerising PET through “simple green chemistry”, Hedrick said.

Researchers developed some strong catalysts to depolymerise the PET and then some gentle catalysts to rework the created chemical into the antimicrobial nanopolymer that has “accurate and specific” behaviour, the researcher said.

The research is still ongoing but holds promise amid a health care landscape in which microbes are becoming more resistant to antibacterial and antifungal drugs. Researchers also are venturing into using nanopolymers to go after viruses and tuberculosis, which are much more difficult to fight, Hedrick said.

Someday in the future, the PET used to bottle gallons upon gallons of drinks could save thousands upon thousands of lives, thanks in part to an IBM chemical engineer who originally worked on semiconductors.

 “Everyone kept telling me, ‘You are working in the wrong field,’” Hedrick said.