DNA as a natural flame retardant

Highly flammable cotton fabrics refuse to burn when they're coated with herring sperm DNA. Could this naturally occurring compound be a non-toxic alternative?

Normally, cotton fabrics are highly flammable, but when coated with herring sperm DNA, the fabric refuses to burn. Wired reports.

“DNA can be considered as a natural flame retardant and suppressant,” says study researcher Giulio Malucelli at Italy’s Politecnico di Torino, Alessandria branch.

Its chemical structure makes it ideal for stopping fires. Remember, DNA is made of an alternating phosphate-and-sugar backbone with nitrogen bases (the A, T, G, C).

  1. When heated, the phosphate-containing backbone produces phosphoric acid, which chemically removes water from cotton fibers. This leaves behind a flame-resistant, carbon-rich residue.
  2. The nitrogen-containing bases release ammonia, which dilutes flammable gases and inhibits combustion reactions. They also help turn the carbon-rich deposits into a slow-burning protective layer.
  3. These ingredients eventually stop combustion by forming a mix of a carbon-rich foam and a protective, glassy carbon coating (called char).

To test these fire-retardant properties, the team dissolved DNA extracted from herring sperm in water, then coated cotton fabrics with it and let them dry. When they tried to light up the cotton, the coating behaved similarly to a flame retardant commonly used with foams, Spandex, and electrical insulation. Watch a video of cotton not burning.

Since it’s a naturally occurring compound, DNA could be a good alternative to conventional flame retardants. “To the best of our knowledge, DNA is not toxic at all,” Malucelli adds. It could also work on synthetic fabrics and plastic films.

But right now, it costs up to five times more than current chemicals. And, the DNA-treatment isn’t water resistant, so the coating rinses off in the wash. The team is looking for a way to bind individual DNA strands to the fabric and to each other, creating a giant, insoluble matrix.

The work was published in Journal of Materials Chemistry A.

[Via Wired]

Image: A. Di Blasio, Politecnico di Torino, Alessandria branch

This post was originally published on Smartplanet.com

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