Embedding carbon dots in Eu³⁺‐doped metal‐organic framework for label‐free ratiometric fluorescence detection of Fe³⁺ ions

Abstract

Fluorescent detection is a new spectroscopic measurement for ions sensing due to the advantages of real-time determination with high selectivity, accuracy, and low cost. However, chemosensors based on fluorescent detection are usually determined by absolute intensity from a monochromatic emission signal, which is easy to be fluctuated by the external environment, especially for Fe 3+ detection in complex fluids. Herein, we rationally design a dual-emission Eu 3+ : CDs@ZIF-8 to construct a ratiometric fluorescent sensor with self-calibrating ability for Fe 3+ determination. High efficient carbon dots (CDs) are embedded in europium ions (Eu 3+)-doped MOF by simple stirring preparation at room temperature. The label-free ratiometric fluorescent probe (I CDs@ZIF-8 /I Eu) exhibits simultaneous blue and red emission under the same excitation at 365 nm. Remarkably, Eu 3+ : CDs@ZIF-8 displays the superiority of high selectivity to Fe 3+ , which shows ratiometric fluorescence characteristics (I 0 /I) in a range of 0-6 μmol\L with a low limit of detection (LOD) of 0.897 μmol\L. Besides, the CDs-MOF nanocomposite holds good aqueous dispersibility and low cytotoxicity, which shows great potential applications in medical aid including biological detection and clinical diagnosis. K E Y W O R D S carbon dots, Fe 3+ detection, metal-organic framework, ratiometric fluorescent probe | 887 GUO et al.

Recent Progress in Luminous Particle‐Encapsulated Host–Guest Metal‐Organic Frameworks for Optical Applications

“…Guo et al construct a ratiometric fluorescent sensor for Fe 3+ by loading CDs into a Eu 3+ -doped MOF through a simple stirring method. [223] Under excitation at 365 nm, the Eu 3+ /CDs@ZIF-8 presents simultaneous blue and red emission from CDs and Eu 3+ ions, respectively. When the concentration of Fe 3+ increased from 1 to 10 m, the fluorescence intensity of CDs in Eu 3+ /CDs@ZIF-8 decreased rapidly while the emission of Eu 3+ ions changed relatively little, attributed to the easy chelation of Fe 3+ with N and O atoms of CDs and fast electrons-transfer from blue emission CDs to the d-orbital of Fe 3+ (Figure 4d).…”

“…Reproduced with permission. [223] Copyright 2020, Wiley-VCH. e) Schematic diagram of explosive molecules detection based on DSM@bio-MOF-1 composite.…”

“…d) Schematic diagram of the preparation of Eu 3+ /CDs@ZIF-8 composite and its ratio sensing for Fe 3+ . Reproduced with permission [223]. Copyright 2020, Wiley-VCH.…”

Applications of Carbon Dots for the Photocatalytic and Electrocatalytic Reduction of CO2

“…Sun et al confined CDs within a SiO 2 matrix, constructing an effective multi-confinement effect which lead to ultralong room temperature phosphorescence lifetime and exceptional stability [ 146 ]. Guo et al embedded CDs in europium ions (Eu 3+ )-doped Metal Organic Framework (MOF) by simple stirring the preparation at room temperature for label-free ratiometric fluorescence detection of Fe 3+ ions [ 147 ]. Sun et al dispersed CDs into a cross-linked silica network on the surface of SiO 2 nanoparticles to produce an efficient full-color emitting composite [ 148 ].…”

A Selective Fluorescent Probe for Ferric Ion Based on Rhodamine 6G

“…[4][5][6] In recent years, numerous promising fluorescence probes for fast detection of Fe 3+ have been developed. [7][8][9] Fluorescent probes can provide a direct visualization mode, which is a powerful tool for optical imaging and analytical sensing. [10][11][12] Rhodamine is one of the widely used fluorescent materials due to its excellent photophysical properties, such as high fluorescence quantum yield, high molar absorption coefficient, large rigid plane structure, great chemical, optical and thermal stability.…”