Template and skeleton-co-confinement pyrolysis to synthesize two-dimensional N-doped carbon nanoflakes for profiling...

Antibiotics residues have attracted substantial concerns given their hazards to food safety, good health and national economy. Developing sensitive and reliable antibiotics sensors remains highly desirable, whereas confronts an enormous challenge, attributable to scarcity of ideal quenchers with high efficiency and functionality. Here, we report the design of two-dimensional N-doped carbon nanoflakes (2D-N@CNFs) as quenchers for developing a fluorescence sensor for kanamycin (Kana) via target-aptamer recognition-promoted Exonuclease III (Exo III)-mediated digestion. 2D-N@CNFs were prepared using flake-stacked polypyrrole from interfacial polymerization as precursors via template and skeleton-co-confinement pyrolysis, and showed preferred absorption to ssDNA with high quenching efficiency, making carboxyfluorescein-tagged ssDNA (FAM-ssDNA) be immobilized onto 2D-N@CNFs' surface in quenched state via resonance energy transfer (RET). The recognition of ON1 by Kana switched Exo III's digestion of FAM-ssDNA into FAM-mNs, departing from quenchers to weaken RET. Thus, a significantly improved fluorescence was determined, contributing to quantitative detection of Kana against other antibiotics with detection limit down to 15.8 pM. Finally, dynamic Kana degradation in fish was demonstrated to evaluate the practicality of 2D-N@CNFs-based sensor. It is expected the sensor will find more useful application in monitoring antibiotics residues in animals, showing a great promise for advanced precision breeding industry.