Ratiometric fluorescence assay for sulfide ions with fluorescent MOF-based nanozyme.

A novel ratiometric fluorescence strategy for sulfide ions (S) analysis has been developed using metal-organic framework (MOF)-based nanozyme. NH-Cu-MOF displays blue fluorescence (λem = 435 nm) originating from 2-amino-1,4-benzenedicarboxylic acid ligand. Besides, it possesses oxidase-like activity due to Cu node, which can trigger chromogenic reaction.

Ratiometric fluorescence sensing of formaldehyde in food samples based on bifunctional MOF.

A new fluorescence strategy was described for ratiometric sensing of formaldehyde (FA) with bifunctional MOF, which acted as a fluorescence reporter as well as biomimetic peroxidase. With the assistance of HO, NH-MIL-101 (Fe) catalyzes the oxidation of non-luminescent substrate o-phenylenediamine (OPD) to produce fluorescent product (oxOPD) with the maximum emission at 570 nm. Besides, intrinsic fluorescence of MOF (λem = 445 nm) was quenched by oxOPD through inner filter effect (IFE).

Enhanced detection of ascorbic acid with cascaded fluorescence recovery of a dual-nanoquencher system.

An innovative strategy with target-triggered cascade fluorescence recovery of a dual-nanoquencher system was developed to detect ascorbic acid (AA). Herein, manganese dioxide (MnO) nanosheets and gold nanoparticles (AuNPs) were used as nanoquenchers simultaneously. Owing to their synergistic effects, the fluorescence of 2,3-diaminophenazine (DAP) was decreased efficiently, thus minimizing the background fluorescence.

Cascade amplification strategy combined with analyte-triggered fluorescence switching of dual-quenching system for highly sensitive detection of isoniazide.

A sensitive fluorescence sensing platform consisting of manganese dioxide nanosheets (MnO) and gold nanoparticles (AuNPs) as dual nanoquenchers has been constructed to detect isoniazid combined with analyte-triggered cascade reactions. The fluorescence of 2,3-diaminophenazine (DAP) is quenched simultaneously by MnO and AuNPs via inner filter effect. MnO is decomposed by isoniazid to generate Mn, which makes AuNPs aggregated.

Colorimetric determination of the activities of tyrosinase and catalase via substrate-triggered decomposition of MnO nanosheets.

The authors describe novel colorimetric assays for tyrosinase (TYR) and catalase (CAT) based on the substrate-triggered decomposition of MnO nanosheets (NSs). The MnO NSs can act as oxidase mimics that catalyze the oxidation of the substrate tetramethylbenzidine (TMB) to form a blue dye with an absorption maximum at 652 nm. The oxidase-mimicking activity of the MnO NSs is inhibited by dopamine (DA)/hydrogen peroxide (HO) due to their decomposition of the MnO NSs.

Molecular beacon-templated silver nanoclusters as a fluorescent probe for determination of bleomycin via DNA scission.

The authors describe a molecular beacon-based fluorescent probe for the determination of the cancer drug bleomycin (BLM). The probe was tagged with DNA-templated silver nanoclusters (DNA-AgNCs) and guanine-rich sequences (GRSs) at two terminals serving as signal reporter with a loop. In the absence of the BLM-iron(II) complex [BLM-Fe(II)], the probe has a hairpin shape and displays strong fluorescence because the AgNCs are close to the GRSs.