Sulfo-modified MIL-101 with immobilized carbon quantum dots as a fluorescence sensing platform for highly sensitive detection of DNP

Metal-organic framework-based composites can help overcome the functional shortcomings of single materials by virtue of the synergetic properties of their components. The new functionalities introduced in the resulting material allow for their use in a wide range of applications. Herein, we prepared a fluorescent amino-CQDs@MIL-101-SO 3 H composite sensor by immobilizing amino-functionalized carbon quantum dots (amino-CQDs) on sulfo-modified MIL-101 nanoparticles. MIL-101-SO 3 H was not only used as a carrier to encapsulate the amino-CQDs in the pore cavity by hydrogen bonding interactions between the free -SO 3 H groups of MIL-101-SO 3 H and the –NH 2 group of the amino-CQDs, but also as an adsorbent to selectively adsorb and capture the target analyte, i.e. 2,4-dinitrophenol (DNP), via hydrogen bonding interactions between the free -SO 3 H groups of MIL-101-SO 3 H and the –NO 2 group of DNP. The amino-CQDs were used as a probe to sense the target molecules with high selectivity. The amino-CQDs@MIL-101-SO 3 H composite sensor displayed excellent selectivity and sensitivity toward DNP, with a detection limit of 0.041 μM. This is the first study to demonstrate the immobilization of fluorescent amino-CQDs in mesostructured MIL-101-SO 3 H. The selective fluorescence detection demonstrated herein will provide a new platform for sensing hazardous pollutants.