Preparation of ofloxacin molecularly imprinted polymer Raman sensor based on magnetic graphene oxide

Ofloxacin is a commonly used quinolone antibiotic that is also used as a feed supplement in livestock production and in plant disease prevention and treatment. However, the excessive use and abuse of ofloxacin will accumulate along the food chain and endanger human health. Therefore, the development of a simple, rapid, and sensitive detection method for the determination of ofloxacin is critical. Herein, a detection method combining molecularly imprinted magnetic solid-phase extraction (MISPE) and surface-enhanced Raman spectroscopy (SERS) was developed for the detection of ofloxacin. Graphene oxide supported by magnetic beads was synthesized by a one-pot method, producing what was subsequently referred to as magnetic graphene oxide (MGO), and a molecularly imprinted membrane was synthesized on its surface by exploiting the ability of dopamine to self-polymerize under alkaline conditions. MGO@MIPs were obtained as the adsorbent for magnetic solid-phase extraction, which was used for the extraction and enrichment of ofloxacin in complex sample matrix, and then quantitative analysis was conducted by SERS. The developed method exhibited an excellent linear relationship with respect to ofloxacin concentration (10^-5 to 10² μg mL^-1), with a detection limit of 9.7 × 10^-6 μg mL^-1 in ultrapure water. Blank honey, milk, and pork samples spiked with ofloxacin at concentrations of 0.005, 0.1, 1, and 10 μg mL^-1 were extracted and determined using the developed method, with recoveries ranging from 93.1% to 105.6%. The results support the strong application prospects for the method, demonstrating simple and time-efficient operation and high accuracy.