▎ 摘　　要

A hierarchical nanocomposite optosensing probe was designed and fabricated to detect ofloxacin. The nanocomposite probe was fabricated by incorporating graphene quantum dots (GQDs) and hierarchical porous carbon (HPC) into molecularly imprinted polymer (MIP). The synthesized HPC and GQDs, and the composite probe were characterized. The fabrication procedure of the probe and detection conditions were investigated to obtain the best sensitivity and fast detection. In the optimized condition, the developed nanocomposite probe was ultrasensitive and selective toward ofloxacin while remaining unaffected by structural analogue compounds. The probe showed good linear range for ofloxacin from 0.10 to 25 mu g L-1 with a limit of detection of 0.066 mu g L-1. Applied to detect ofloxacin in milks, the probe was accurate, achieving recoveries in the range of 92-99% with an RSD <7%. The analysis results of spiked milk samples agreed well with HPLC analysis. The optosensing system is cost-effective, simple and could be modified and applied as an alternative method to detect trace compounds in various samples.