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

ABSTRACT

A novel fluorescence platform was fabricated for enrofloxacin determination by using cDNA-modified dipeptide fluorescence nanoparticles (FDNP-cDNA) and aptamer-modified magnetic Fe3O4 nanoparticles (Fe3O4-Apt). The FDNP were prepared via tryptophan-phenylalanine self-assembling. When magnetic Fe3O4-Apt incubated with standard solution or sample extracts, the target enrofloxacin was selectively captured by the aptamer on the surface of the Fe3O4 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 Fe3O4 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 Fe3O4 nanoparticles, and the more the FDNP-cDNA can be observed in the supernatant. Fluorescence intensity (Ex/Em = 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).