Dipeptide nanoparticle and aptamer-based hybrid fluorescence platform for enrofloxacin determination

A novel fluorescence platform was fabricated for enrofloxacin determination by using cDNA-modified dipeptide fluorescence nanoparticles (FDNP-cDNA) and aptamer-modified magnetic Fe 3 O 4 nanoparticles (Fe 3 O 4 -Apt). The FDNP were prepared via tryptophan-phenylalanine self-assembling. When magnetic Fe 3 O 4 -Apt incubated with standard solution or sample extracts, the target enrofloxacin was selectively captured by the aptamer on the surface of the Fe 3 O 4 nanoparticles. After removing interference by washing with phosphate-buffered saline, the FDNP-cDNA was added, which can bind to the aptamer on the surface of the Fe 3 O 4 nanoparticles not occupied by the analyte. The higher the concentration of the target enrofloxacin in the standard or sample solution is, the less the FDNP-cDNA can be bound with the Fe 3 O 4 nanoparticles, and the more the FDNP-cDNA can be observed in the supernatant. Fluorescence intensity (E x /E m  = 310/380 nm) increased linearly in the enrofloxacin concentration range 0.70 to 10.0 ng/mL with a detection limit of 0.26 ng/mL (S/N = 3). Good recoveries (88.17–99.30%) were obtained in spiked lake water, chicken, and eel samples with relative standard deviation of 2.7–6.2% ( n  = 3). Graphical abstract