Dual-mode sensing platform for the detection of multiple metal ions based on amine-functionalized MIL-101 (Fe) Y-shaped DNAzyme-assisted fluorescence and colorimetric analysis

Our environment is being polluted by numerous sources of heavy metals, which are discharged by various industries, and hence, monitoring of heavy metals in environment and other fields is very essential. Herein, an amine-functionalized metal organic framework (NH₂-MIL-101(Fe)) was prepared via a hydrothermal method. DNA sequences with enzyme and substrate strands were annealed to form a Y-shaped DNAzyme and used as the recognition element. Subsequently, we developed a fluorescence/colorimetric dual channel for the sensitive detection of Pb²⁺, Hg²⁺ and Cu²⁺ using NH₂-MIL-101(Fe) and Y-shaped DNAzyme with the ability to be magnetically separated. A good linear response and detection limit were observed by fluorescence method like 0.21 nM for Pb²⁺, 0.23 nM for Hg²⁺ and 0.37 nM for Cu²⁺ and by colorimetric method such as 0.43 nM for Pb²⁺, 0.57 nM for Hg²⁺ and 0.99 nM for Cu²⁺. Therefore, we employed the conventional method for the dual-mode detection of Pb²⁺, Hg²⁺ and Cu²⁺ ions and obtained high specificity, high accuracy and satisfactory results in real sample analyses.