Metal-organic framework-based molecular beacons for multiplexed DNA detection by synchronous fluorescence analysis

We report a new sensor combined two dimensional metal-organic framework (MOF), N,N-bis(2-hydroxyethyl)dithiooxamidato copper(II) (H2dtoaCu), with the hairpin-structured oligonucleotides and demonstrate its feasibility in detecting multiplexed sequence-specific DNA. The key component of this sensor (MOF-MBs) is the hairpin-structured fluorescent oligonucleotide that allows the MOFs to function as both a nanoscaffold for the oligonucleotide and a nanoquencher of the fluorophore. An oligonucleotide sequence fragment of wild-type HBV (T-1) and a reverse-transcription oligonucleotide sequence of RNA fragment of HIV (T-2) were used as model systems. While in the presence of the targets, the fluorescence of dyes was recovered by forming a double strand structure. Multiplex DNA detection can be realized by synchronous scanning fluorescence spectrometry, and there was no cross reaction between the two probes. Under the optimum conditions, the fluorescence intensities of two dyes all exhibit good linear dependence on their target DNA concentration in the range of 1-10 nM with the detection limit of 0.87 nM and 0.22 nM for T-1 and T-2, respectively. As a proof of concept, the MOF-MBs have been successfully used as a potential sensing platform for simultaneous detection of multiplexed DNA.