LAUSR

Multicolor fluorescence probes can show fluorescence of different colors when detecting different targets, and the excellent feature can create a highly differentiated multicolor sensing platform. However, most of the previously reported multicolor luminescent materials usually suffer from high toxicity and photo bleaching, complex preparation procedures and poor water solubility may not be conducive to bioanalytical applications. Two dimensional metal organic frameworks (2D MOFs) which own large specific surface area with long-range fluorescence quenching coupled with biomolecular recognition events have encouraged innovation in biomolecular probing. Here, we propose a 2D MOFs-based multicolor fluorescent aptamer nanoprobe using a double stirring bar assisted target replacement (DSBTR) system for enzyme-free signal amplification. It utilizes the interaction between 2D MOFs and DNA molecules to detect multiple antibiotics quickly, sensitively and selectively. Since 2D MOFs have excellent quenching efficiency for luminescence of fluorescent dye-labeled single-strand DNA (ssDNA), the background fluorescence can be largely reduced and the signal-to-noise ratio be improved. When the adsorbed ssDNA formed double helix double-stranded DNA (dsDNA) with its complementary ssDNA, its fluorescence can be almost fully recovered. The assay was tested by detecting chloramphenicol (CAP), oxytocin (OTC) and kanamycin (KANA) in biological samples. The developed aptasensor was sufficiently sensitive to detect the antibiotic residues as low as 1.5 pM CAP, 2.4 pM OTC and 1 pM KANA (S/N=3), respectively. It has been preliminarily used for multicolor image of three different antibiotics in fish tissue slices with satisfying results.