One-pot doping platinum porphyrin recognition centers in Zr-based MOFs for ratiometric luminescent monitoring of nitric oxide in living cells.

A new kind of nanoscale MOFs probe for nitric oxide (NO) sensing has been successfully constructed by a one-pot strategy, in which the chemically stable UiO-66 crystal structure was achieved using platinum meso-tetra(4-carboxyphenyl)porphyrin (Pt-TCPP), 1,1,2,2-Tetra(4-carboxylphenyl)ethylene (H4TCPE) and 1,4-dicarboxybenzene (BDC) as co-linkers (Pt-TCPP/H4TCPE@UiO-66). Pt-TCPP was verified to serve as a signal reporter in NO sensing fields for the first time while H4TCPE worked as a luminescence reference to build a ratiometric sensor. The integration of luminescent dyes in nanoscale MOFs effectively avoided their aggregation-caused quenching effect and poor aqueous dispersibility to rationalize NO detection in the aqueous phase. The obtained Pt-TCPP/H4TCPE@UiO-66 nanoparticles (NPs) exhibited an excellent sensing property toward NO with an ultrahigh linear correlation of the Stern-Volmer equation and a rapid response time as short as 2 min. Moreover, the elaborated sensor could work under a wide pH window (7.4, 5.6 and 0) and the limit of detection (LOD) reached as low as 0.1420 µg mL-1. The specificity of the obtained Pt-TCPP/H4TCPE@UiO-66 NPs toward NO sensing was scarcely affected by other possibly coexistent species in biological system. The in vitro monitoring for NO in living cells was also testified with these Pt-TCPP/H4TCPE@UiO-66 NPs.

Specific detection of hypochlorite based on the size-selective effect of luminophore integrated MOF-801 synthesized by a one-pot strategy.

Hypochlorous acid (HClO), as one of the reactive oxygen species, plays a key role in a variety of physiological and pathological processes, while its accurate and specific in vitro monitoring remains a profound challenge. Herein, a novel luminescent metal-organic framework with high chemical stability has been designed for the specific detection of intracellular ClO-. The specificity was realized by the size-selective effect of MOF-801 with an ultra-small aperture, which can inhibit the entry of large-sized interferents into the cages of MOFs. A universal "ship in a bottle" approach has been proposed to construct this novel sensory platform, in which a large class of luminescent molecules containing carboxylic groups serve as modulators and combine with Zr6 clusters, eventually becoming the luminescent genes of these novel designed MOF-801. Luminescent molecules were readily locked in the framework since they were larger than the small pore entrance of MOF-801, skillfully solving the possible issue of dye leakage. By introducing active sites of 5-aminofluorescein (AF) into MOF-801 (AF@MOF-801) as an example, an excellent ClO- sensing probe was fabricated, which showed strong reliability and excellent sensing performance toward intracellular ClO- with an ultrahigh linear correlation of the Stern-Volmer equation, a rapid response time as short as 30 s and a limit of detection (LOD) as low as 0.05172 µM. Compared with the free AF molecular probe, the specificity of AF@MOF-801 NPs toward ClO- was scarcely affected by other possibly coexistent large-sized interferents in biosystems. The in vitro monitoring of ClO- was also tested with these newly developed AF@MOF-801 NPs, prefiguring their great promise as a robust imaging tool to disclose the complexities of ClO- homeostasis and its pathophysiological contributions.

Selective Separation of Isomeric Dicarboxylic Acid by the Preferable Crystallization of Metal-Organic Frameworks.

Simple and effective separation of isomeric organic molecules is an important but challenging task. Herein, we successfully developed a selective crystallization strategy to separate the mixtures of isomeric dicarboxylic acids (DCAs) for the first time. The target DCAs could be preferably combined with crystallization inducer of Zr4+ ions to form a pre-designed metal-organic frameworks (MOFs) crystal structure whereas the entry of non-target isomeric DACs into the MOFs lattice could be exclusively inhibited. Several isomeric pairs were exemplified to verify the extensibility and validity of the developed strategy.