DNA can be considered as a natural flame retardant and suppressant

Q: Is DNA fire-proof?

Krishna: Research has shown that DNA is flame retardant (1). Yes, DNA can be considered as a natural flame retardant and suppressant.

NORMALLY, COTTON FABRICS are highly flammable. But when scientists tried to set fire to cotton coated with herring sperm DNA, the fabric refused to burn, the team reported in Journal of Materials Chemistry A.

Abstract: DNA could be considered an intrinsically intumescent flame retardant as it contains the three main components that are usually present in an intumescent formulation, namely: the phosphate groups, able to produce phosphoric acid, the deoxyribose units acting as a carbon source and blowing agents (upon heating a (poly)saccharide dehydrates forming char and releasing water) and the nitrogen-containing bases (guanine, adenine, thymine, and cytosine) that may release ammonia. The flammability tests in horizontal configuration have clearly shown that after two applications of a methane flame for 3 s, the DNA-treated cotton fabrics do not burn at all. Furthermore, when exposed to an irradiative heat flux of 35 kW m⁻², no ignition has been observed.

Explanation: DNA’s chemical structure makes it ideal for the flame-stopping job. When heated, its phosphate-containing backbone produces phosphoric acid, which chemically removes water from cotton fibers while leaving behind a flame-resistant, carbon-rich residue. The nitrogen-containing bases release ammonia — which dilutes flammable gases and inhibits combustion reactions — and can act as “blowing agents,” which help turn the carbon-rich deposits into a slow-burning protective layer. Ultimately, these ingredients stop combustion by forming either a carbon-rich foam, or a protective, glassy carbon coating called char.

So scientists have tried to use it as fabric coating. DNA is not toxic at all. “Its application as flame retardant should not be harmful.”

It is a simple process: process was simple and straightforward—they extracted DNA from herring sperm, dissolved it in water, applied it to a sample piece of cotton, let it dry, then tried to get the sample to burn using a methane flame for several seconds. Their tests showed that the sample would not ignite and that the cotton fabric was not burned as a result of the application of the flame. The coating works because when DNA is heated the phosphate in it gives off phosphoric acid, which pulls water from cotton fiber and in the process leaves behind a residue rich in carbon, which is of course resistant to burning. The nitrogen in DNA also releases ammonia causing a dilution of flammable gasses. Together the materials that make up DNA, when subjected to heat, cause the buildup of a foam rich in carbon and the formation of a glassy outer coating that is also rich in carbon.

However,  most problematically, for the time being, you can’t wash a DNA-coated nerd-shirt. The coating is not yet water resistant and will rinse off in the wash. So far, scientists haven’t yet worked out how to make the treatment more permanent (2).

Also it must be determined that such a coating would not allow for DNA fragments to make their way into the person's body that was wearing material treated with it. There's also the cost—using current methods would make it three to five times more expensive to manufacture than conventional flame retardants. Also, unfortunately, its biodegradable desirability factor which would make it a good "green" alternative to current chemicals used in flame retardant coatings, is also its downfall—it doesn't survive washing (3).

Footnotes:

1. https://pubs.rsc.org/en/content/articlelanding/2013/ta/c3ta00107e#:...(upon%20heating%20a

2. J. Alongi, R.A. Carletto, A. Di Blasio, F. Carosio, F. Bosco and G. Malucelli. DNA: A novel, green, natura flame retardant and suppressant for cotton. Journal of Materials Chemistry A. doi: 1.1039/c3ta00107e

3. DNA: a novel, green, natural flame retardant and suppressant for cotton, J. Mater. Chem. A, 2013, Advance Article, DOI: 10.1039/C3TA00107E