Partial carbonization of quercetin boosts the antiviral activity against H1N1 influenza A virus

•One-step pyrolytic synthesis of highly water-soluble quercetin carbonized nanogels (CNGQur).•The CNGQur exhibits superior antiviral activity and biocompatibility compared to quercetin.•The selectivity index of antiviral CNGsQur is much higher than quercetin and other clinical antiviral drugs.•Aerosol inhalation of CNGsQur exhibited a significant protective effect against influenza A virus.