GR5 DNAzyme and difunctional carbon dots-encapsulated zeolitic imidazolate framework for ratiometric fluorescence...

Accurate and rapid detection of lead ions in food and environment is urgently needed for human health. Herein, we have developed a ratiometric fluorescence system grounded in GR5 DNAzyme and carbon dots-embedded ZIF-8 nanocomposite (CDs@ZIF-8) to achieve the self-calibration detection of lead ions (Pb²⁺). GR5 DNAzyme, which acts as a molecular recognition element, is adsorbed onto the surface belonging to CDs@ZIF-8. Pb²⁺-induced cleavage of DNAzyme results in the desorption of short FAM-labeled single-stranded DNA, which triggers a detectable change in the FAM fluorescence. Meanwhile, CDs@ZIF-8 provides an unchanging reference signal through the self-luminescence of encapsulated blue-emitting CDs. The ratiometric fluorescence signal blocks the environmental interference. This method achieves a hypersensitized and specific monitoring method of Pb²⁺ in 60 min through a simple mixing process, with a minimum detectable limit of 0.1 nM. The use of self-calibrating multifunctional nanomaterials is expected to enable the development of more reliable and accurate sensors compared to single-functional nanomaterials, with the resulting sensors having broader application prospects.