DNA-Modified Graphene Oxide Supported on a Fire-Resistant Hydroxyapatite Paper for Timely and Reliable Fire Warning

The traditional fire alarm sensors suffer from sluggish fire warnings. Recently, graphene oxide (GO)-based sensors have attracted much attention due to their ultrafast fire warning. There are two major challenges: (i) the duration time of fire warning is short due to poor flame retardancy of GO and (ii) the response temperature of the GO sensor is high due to the abundant oxygen-containing groups. This work reports the single-stranded deoxyribonucleic acid (ssDNA)-modified GO supported on the hydroxyapatite (HA) nanowire paper. The ssDNA molecules have an action of intumescent flame retardancy, which effectively improves the flame retardancy of GO. Moreover, the thermal degradation of nitrogenous base of ssDNA causes nitrogen doping in GO. Concomitantly, the thermal reduction of GO is promoted, and some oxidative groups are removed. As a result, the period of fire warning of GO increases up to 180 s, and the response temperature decreases to as low as 159 °C. Besides, the HA paper with intrinsic fire resistance ensures the structural integrity of ssDNA–DNA in the flame, contributing to the steady working of the composite paper. This work highlights the critical roles of biomolecules and inorganic materials in synergistically regulating fire warning performance of GO.