Antibodies made entirely from plastic have saved the lives of mice injected with bee venom – the first time such a strategy has worked in live animals.
Researchers developing the antibodies say it is the first step towards customised antibodies for a host of other medical applications, from treating people who have been poisoned to combating infection.
Natural antibodies are made by the body's immune system to lock onto a specific "antigen". Likewise, the plastic antibodies contain cavities moulded in exactly the right shape to capture target molecules, in this case, melittin – the active agent in bee venom.
Kenneth Shea of the University of California at Irvine led the team which made melittin antibodies through a process called molecular imprinting. They used a catalyst to stimulate polymers to form around molecules of bee venom, then dissolved away the venom itself, leaving empty cavities with the exact shape to trap melittin.
Shea injected these tiny plastic nanoparticles into mice 20 seconds after they'd been injected with bee venom, 60 per cent survived whereas all the untreated mice died. The plastic antibodies were then destroyed by the liver.
"We conclude that imprinted polymer nanoparticles efficiently capture melittin in the bloodstream," say Shea and his colleagues in the paper.
"We see this as a very significant paper, and the first demonstration in living things of these materials, effectively using them as a drug," says Mike Whitcombe, whose lab at Cranfield University in the UK develops imprinted polymers and runs a database of the polymers available.
Philipp Holliger of the Laboratory of Molecular Biology in Cambridge, UK, said that the plastic antibodies do perform some of the functions of natural antibodies – capturing toxins and sending them to the liver for destruction. "These properties should make them attractive alternatives to antibodies in antidote anti-toxin treatments," he says.
However, Holliger doubts whether they could perform other important functions of natural antibodies, such as priming the body's immune system to fight future infections. Unlike natural antibodies, they are not equipped to communicate with other cells and components of the immune system.
Journal reference: Journal of the American Chemical Society, DOI: 10.1021/ja102148f
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