Sulfadimethoxine

Song K. M, et al. Biosensors and Bioelectronics, 2012, 33(1), 113-119.

A coordination polymer nanobelt (CPNB)-based fluorescent aptasensor was developed for the sensitive detection of sulfadimethoxine residues. The sensor employed a fluorescein amidite (FAM)-labeled single-stranded DNA aptamer (Su13: 5'-GAGGGCAACGAGTGTTTATAGA-3'), selected via magnetic bead-assisted SELEX. Sulfadimethoxine was immobilized on tosylactivated magnetic beads by incubation with 0.1 M borate buffer containing 0.67 M (NH₄)₂SO₄ at 37 °C for 20 hours, followed by PBS washing. UV absorbance at 270 nm was used to quantify the immobilization efficiency. The quenching element, CPNBs, was synthesized through coordination of AgNO₃ and 4,4'-bipyridine. In the sensing assay, fluorescence from the FAM-labeled aptamer was quenched by CPNBs, but recovered upon target binding to sulfadimethoxine. This fluorescence response enabled a sensitive detection with a limit of 10 ng/mL.