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A new plastic made from DNA is renewable, requires little energy to make and is easy to recycle or break down.

Traditional plastics are bad for the environment because they are made from non-renewable petrochemicals, require intense heating and toxic chemicals to make, and take hundreds of years to break down. Only a small fraction of them are recycled, with the rest ending up in landfill, being incinerated or polluting the environment.

Alternative plastics derived from plant sources like corn starch and seaweed are becoming increasingly popular because they are renewable and biodegradable. However, they are also energy-intensive to make and hard to recycle.

at Tianjin University in China and his colleagues have developed a plastic that overcomes these problems. It is made by linking short strands of DNA with a chemical derived from vegetable oil, which produces a soft, gel-like material. The gel can be shaped into moulds and then solidified using a freeze-drying process that sucks water out of the gel at cold temperatures.

The researchers have made several items using this technique, including a cup (pictured above), a triangular prism, puzzle pieces, a model of a DNA molecule (pictured below) and a dumb-bell shape. They then recycled these items by immersing them in water to convert them back to a gel that could be remoulded into new shapes.

鈥淲hat I really like about this plastic is that you can break it down and start again,鈥� says at Murdoch University in Australia. 鈥淢ost research has focused on developing bioplastics that biodegrade, but if we鈥檙e serious about going towards a circular economy, we should be able to recycle them too, so they don鈥檛 go to waste.鈥�

Another advantage of the new plastic is the widespread availability of the starting material, since an estimated 50 billion tonnes of DNA exist on Earth. Yang and his colleagues used DNA from salmon sperm, but it could also be extracted from renewable sources like crop waste, algae or bacteria, he says.

Because the production of the DNA plastic doesn鈥檛 require hot temperatures, it results in 97 per cent less carbon emissions than polystyrene plastic, and it can be broken down using DNA-digesting enzymes if it is no longer needed, says Yang.

鈥淭o the best of our knowledge, our reported DNA plastics are the most environmentally sustainable materials of any other known plastics,鈥� he says.

The two main downsides of the plastic are that it isn鈥檛 as strong as traditional petrochemical plastics and it has to stay dry to stop it from turning back into a gel. As a result, it is probably best suited to applications like packaging materials and electronic devices, says Yang.

Alternatively, the DNA plastic could be made waterproof by coating it in water-resistant chemicals as we do with paper cups, says at Deakin University in Australia.

Yang says his team plans to make commercial goods out of the plastic. 鈥淭his is just the beginning,鈥� he says.