A hierarchically porous MOF confined CsPbBr3 quantum dots: Fluorescence switching probe for detecting Cu (II) and melamine in food samples

The hypersensitivity of Perovskite quantum dots (PeQDs) towards external environmental conditions and the water quenching of their fluorescence have limited their practical analytical applications. In this work highly luminescent CsPbBr3 was confined into a hierarchically porous ZIF-8 metal organic framework (HZIF-8) through a simple two step in situ growth method. XRD, FTIR, SEM, TEM, and XPS investigations confirmed the successful synthesis of the CsPbBr3/HZIF-8 nanocomposite. CsPbBr3 PeQDs are uniformly distributed within the HZIF-8 MOF matrix and exhibited intense green emission at 510 nm with a FWHM value of 25 nm in ambient conditions. The nanocomposite showed enhanced stability against moisture and UV light. The intense PL emission of the nanocomposite was well maintained in an aqueous solution also, with no noticeable change in fluorescence characteristics for 15 days of storage in aqueous solution. The CsPbBr3/HZIF-8 composite was then utilized as an on–off-on luminescent probe for the detection of Cu2+ metal ions and melamine in real samples. Because of the porous nature of the MOF, the target analytes can be quickly located and this nanosensor is found to be very sensitive toward Cu2+ and melamine detection. A linear relationship from 3 to 500 nM and 30–1500 nM was found for melamine and Cu2+ under an optimal experimental condition, with a limit of detection value of around 4.66 nM and 2.64 nM for Cu2+ and melamine respectively.