Abstract
This study developed an aptamer-based fluorescence strategy that used oxidized single-walled carbon nanohorns (ox-SWCNHs) for kanamycin sulfate (KAM). Through the oxidation process, single-walled carbon nanohorns were functionalized to produce ox-SWCNHs exhibiting enhanced hydrophilicity, which were subsequently used as fluorescence quenchers within the assay. When kanamycin sulfate was added, it bound to the aptamer and formed a quadruplex structure that detached from the ox-SWCNHs surface and retained the fluorescent dye. During this process, Deoxyribonuclease I (DNase I) was introduced and the G-quadruplex structure was cleaved, resulting in the release of kanamycin sulfate from the complex. This structural rearrangement facilitated the release of the kanamycin sulfate, which was then free to bind additional aptamers on the surface of ox-SWCNHs. This initiated a cyclic mechanism that significantly amplified the fluorescence signal. The detection limit of the KAM was 0.6 nM. This probe exhibited high selectivity which was used for the determination of KAM with satisfied recoveries (81.2 to 101.7%) and good precision (0.4 to 8.9%) in lake water samples. Moreover, the technique was specific to KAM and did not interfere with other antibiotics. This sensor demonstrated significant potential for the environmental monitoring of KAM in aquatic systems and offered a versatile platform for the detection of a variety of other substances by simply altering the aptamer sequence.