In Situ Incorporation of Fluorophores in Zeolitic Imidazolate Framework-8 (ZIF-8) for Ratio-Dependent Detecting a Biomarker of Anthrax Spores

Abstract

Monitoring and early warning of spores germination is of great significance in avoiding their potential pathogenicity. Thus, effective monitoring of markers during spore germination is of great value. A ratio-dependent fluorescent probe based on in situ incorporation of fluorophores in a metal–organic framework (MOF) was designed to monitor a main component of bacterial spores, 2,6-pyridinedicarboxylic acid (DPA), with high sensitivity and specificity. The fluorescence of CdS quantum dots loaded on zeolitic imidazolate framework-8 (ZIF-8) nanocrystals is initially quenched by europium ions. The europium ions, however, can be seized by DPA, leading to restoring the fluorescence of quantum dots. Simultaneously, the fluorescence of another dye molecule, rhodamine 6G, loaded on the ZIF-8 is not affected by DPA and can serve as a stable internal fluorescence reference signal. On this basis, a ratio-dependent fluorescence method for rapid detection of DPA was established. The linear calibration ranged from 0.1 to 150 μM with a detection limit of 67 nM, which is much lower than the amount of DPA (60 μM) released by the contagious number of spores needed to cause anthrax. This analysis platform exhibits good anti-interference ability for monitoring spore germination. The practicable application of the method was verified by monitoring and imaging the release of DPA in the course of spore germination.

Metal‐Organic Frameworks‐Based Fluorescent Nanocomposites for Bioimaging in Living Cells and in vivo†

“…Yang and co‐workers designed a fluorescent probe which encapsulated CdS QDs in situ during the synthesis of ZIF‐8. [ 83 ] Fluorescence imaging was finally achieved through the “off‐on” effect of CdS quantum dots. Moreover, Shi and co‐workers integrated porphyrinic MOFs with CuS NPs via a simple post‐synthesis strategy to achieve fluorescence and photothermal imaging.…”

Fluorescent Assay of FEN1 Activity with Nicking Enzyme-Assisted Signal Amplification Based on ZIF-8 for Imaging in Living Cells

“…To take advantage of these ingenious characteristics of the nicking enzyme in our designed biosensor, it is a challenge to deliver enzymes into living cells since proteins have poor cell membrane permeability, easy degradation, and denaturation . Fortunately, metal–organic framework nanoparticles (MOFs), composed of metal clusters and organic ligands with high porosity, remarkably tunable pore size, excellent biocompatibility, and simply tailored functionality, have been extensively applied in various fields, including catalysis, adsorption and separation, drug delivery, and biosensors . Among different types of MOFs, zeolitic imidazolate framework-8 (ZIF-8), built with metal nodes (Zn 2+ ) and organic ligands (2-methylimidazole) which possess excellent pH-responsive biodegradability, is an emerging star tool for delivery of different materials into living cells including photosensitizers, drugs, antibodies, proteins, and nucleic acids .…”

Eu(III)–DO3A and BODIPY dyad as a chemosensor for anthrax biomarker

“…Assorted chemical and biological techniques including high‐performance liquid chromatography (HPLC), [ 43 ] surface‐enhanced Raman scattering, [ 44 ] luminescence detection, [ 40,45–53 ] electrochemical detection, [ 54 ] immunoassays, [ 34 ] and polymerase chain reaction (PCR), [ 55 ] can be used for the determination of bacterial spores. In particular, lanthanide luminescence has become a powerful tool for sensing DPA due to its selectivity, sensitivity, straightforward and quick detection, and low cost [for europium (Eu) based sensors see references [ 40,48,50,51,56–72 ] ; for other lanthanide based DPA sensors see references [ 41,45,47,54,73–87 ] ; for other DPA sensors see references. [ 88–92 ]…”