Selection and truncation of aptamers as fluorescence sensing platforms for selective and sensitive detection of nitrofurazone

Nitrofurazone (NFZ) is an antibiotic banned in many countries, as its residue seriously harms the human body. Herein, anti-NFZ aptamers were selected and identified based on the magnetic bead SELEX technique using a ssDNA library with a full length of 90 nucleotides (nt). Five full sequence candidate aptamers (NFZ8, NFZ24, NFZ28, NFZ34, and NFZ70) were obtained by secondary structure analysis. We optimized the entire sequence to obtain a truncated aptamer, a 16 nt sequence (NFZ8-1:5′-GTTCTATTGAAAAAAC-3′) that showed the highest affinity for NFZ (Kd = 76.11 nM). The binding site of NFZ and aptamer NFZ8-1 was found to be "GAA" by molecular docking. In addition, utilizing the most special truncated aptamer NFZ8-1 as the identification probe, a graphene oxide fluorescent aptasensor is an innovative for the detection of NFZ residue that showed a wide linear reach from 1.25 to 160 ng/mL and a low limit of detection of 1.13 ng/mL. In the actual water environment sample detection, the recovery rate ranged from 95.21 to 113.66%, and the coefficient of variation ranged from 3.53 to 11.24%. These results demonstrate that the NFZ-truncated aptamer applied to the aptasensor provides a novel methodology for recognizing NFZ residues. Schematic illustration of fluorescent aptasensor based on aptamer/graphene oxide complex detection of NFZ (see below). [Display omitted] •This is the first report the screened of NFZ-specific aptamers using magnetic bead SELEX.•A truncated aptamer NFZ8-1 was obtained with a Kd value of 76.11 nM.•The recognition site “GAA” was identified by molecular docking simulations.•The GO-based fluorescent aptasensor was established showed high sensitivity and good stability.