Dual amplifying fluorescence anisotropy for detection of respiratory syncytial virus DNA fragments with size-control synthesized metal-organic framework MIL-101

In order to eliminate the scattered light induced by the signal amplifier in fluorescence anisotropy (FA) assays, a nanosized metal-organic framework MIL-101, ranging from 80-500 nm, has been synthesized through a hydrothermal method with the addition of glycerol. We chose the 100 nm MIL-101 to enhance FA for label-free detection of the respiratory syncytial virus (RSV) gene sequence and the DNA-intercalating dye SYBR Green I (SGI) as the fluorophore, based on the different affinities of MIL-101 toward ssDNA and dsDNA. The nanosized MIL-101 has a negligible scattering effect owing to its smaller particle size, so all of the experimental data of FA values were smaller than the maximum initial anisotropy of 0.4. As a specific advantage, a dual amplification result of not only an increase in the FA value of SGI/ssDNA (r(1)) but also a decrease in the FA value of SGI/dsDNA (r(2)) was presented at the same time. Consequently, a larger FA value change Delta r (Delta r, Delta r = r(1) -r(2)) was obtained and contributed to improve the sensitivity. In addition, the quantitative detection of the target DNA (T) was achieved according to the relationship between Delta r and the concentration of T. In the presence of MIL-101, the Delta r is 7-fold higher than that without MIL-101 and achieved the sensitive and selective detection of RSV DNA.