Novel sandwich-type electrochemiluminescence aptasensor based on luminol functionalized aptamer as signal probe for...

A novel sandwich electrochemiluminescence (ECL) aptasensor was developed for highly sensitive detection of kanamycin using luminol-functionalized aptamer as a signal probe. The aptasensor used polyethyleneimine (PAMAM), molybdenum disulfide, and multi-walled carbon nanotubes as the substrate, which provided enough binding sites for aptamer1 (the aptamer which modified NH₂) coupling. We found that kanamycin could be detected using the aptamer1 containing the same base sequence as aptamer2 (the aptamer which modified SH) on the electrode self-assembly. In addition, PAMAM nanocomposites can be used to effectively improve the ECL intensity by loading a high volume of luminol molecules and silver nanoparticles. In the presence of kanamycin, the sandwiched aptasensor was formed between aptamer1 and the probe of aptamer2 connecting silver nanoparticles, luminol, and PAMAM, resulting in a proportional increase of ECL intensity. Since the significantly enhanced loading of luminol by PAMAM accelerated the electron transfer, the sensitive aptasensor exhibited a wide linear range of detection from 1 × 10^-3 to 1 × 10³ ng/mL and a low detection limit of 0.21 pg/mL (S/N) for kanamycin. The fabricated aptasensor was successfully applied in quantitative analysis of kanamycin in milk samples.