Gold nanoparticles and nitrogen-doped carbon dots based fluorescent nanosensor for ultrasensitive detection of thiram in hawthorn

•A signal “on–off-on” fluorescent nanosensor was developed for ultrasensitive detection of thiram.•The nanosensor was based on AuNPs and biomass N-CDs through inner filter effect.•N-CDs with excellent optical properties was prepared by one-step microwave strategy.•The nanosensor exhibited high selectivity and sensitivity with LOD of 4.7 ng/mL for thiram.•The fluorescent nanosensor succeeded in real hawthorn sample with good recoveries.