An ultra-sensitive strategy for fluorescent detection of uranyl ions based on MoS2 nanosheet and entropy-driven amplification

• A novel biosensor has been developed for the detection of trace amounts of UO 2 2+ ; • The LOD of this strategy is at pM level; • This can be used to detect very small amounts of other substances by substituting DNAzyme; • The strategy achieves signal amplification under the condition of constant temperature without enzyme. An ultra-sensitive method for detection of UO 2 2+ was developed based on MoS 2 nanosheet and the principle of entropy-driven amplification. UO 2 2+ -specific DNAzyme was cleaved to release DNA fragments. The cyclic amplification reaction was initiated by the DNA fragment, and DNA with the fluorophore in the DNA complex is released. MoS 2 has a high affinity for ssDNA, but a low affinity for dsDNA. The ssDNA with fluorophore binds to MoS 2 based on this characteristic, and the fluorescence intensity is greatly reduced. The degree of fluorescence intensity change has a linear relationship with UO 2 2+ in the range of 10-100 pM, and the detection limit is 3.6 pM. This method has been successfully applied to the detection of UO 2 2+ in water samples and has shown certain potential in the prevention and control of environmental pollution.