DopaShield: a bioinspired flame-retardant spray nanocoating for versatile surface protection.

As wildfires intensify due to climate change and expanding development in fire-prone areas of the world, there is a critical need for scalable, bioinspired flame-retardant technologies that can be applied across diverse substrates and environments. Here, we introduce DopaShield, a sprayable, bioinspired flame-retardant nanocoating composed of core-shell silica-polydopamine (SiO2@PDA) colloids. Applied via pneumatic spraying, DopaShield forms a conformal coating on flammable materials such as cotton and polyurethane (PU) foam without the need for curing or solvents. Upon flame exposure, it rapidly forms a cohesive char layer that suppresses ignition, prevents melt dripping, and insulates against heat transfer. Vertical flame tests reveal self-extinguishing behavior, while mechanical testing confirms that substrate integrity is maintained. Halogen-free, and metal-free, DopaShield offers a platform for fire protection in textiles, insulation, infrastructure, and vegetation. Its field-deployable, substrate-independent design makes it a promising solution for mitigating fire risks in wildfire-prone communities.