Alkaline Hydrolysis Behavior of Metal–Organic Frameworks NH₂-MIL-53(Al) Employed for Sensitive Immunoassay via Releasing Fluorescent Molecules

Abstract

Nanosized metal–organic frameworks (MOFs) NH2-MIL-53­(Al) were synthesized from 2-aminoterephthalic acid (NH2·H2BDC) and AlCl3 by a facile hydrothermal method. The synthesized MOFs displayed good stability and a uniform particle size in a netural medium and were hydrolyzed in alkaline medium to release a large amount of fluorescent ligand NH2·H2BDC. Therefore, they can act as large-capability nanovehicles to load signal molecules for investigating various biorecognition events. In this work, based on the alkaline hydrolysis behavior of MOFs NH2-MIL-53­(Al), a sensitive immunoassay method was developed for the detection of aflatoxin B1 (AFB1) by employing them as fluorescent signal probes. With a competitive immunoassay mode on microplate, AFB1 can be detected within a linear range of 0.05–25 ng mL–1. The method was successfully employed to detect AFB1 spiked in Job tears, Polygala tenuifolia and with acceptable recovery values of 83.00–114.00%. The detection results for moldy Fructus xanthii displayed an acceptable agreement with those from the high-performance liquid chromatography method, with relative errors of −14.21 to 3.49%. With the merits of high sensitivity, facile manipulation, and ideal reliability, the approach can also be extended to other areas such as aptasensor and receptor-binding assay.

Designing bimetallic zeolitic imidazolate frameworks (ZIFs) for aqueous catalysis: Co/Zn-ZIF-8 as a cyclic-durable catalyst for hydrogen peroxide oxidative decomposition of organic dyes in water

“…It is important to mention that the selection of pH 6.5, near neutral, was decided to avoid probable metal ion leaching from Co/Zn-ZIF-8 structure by acidity and to avoid possible hydrolysis by alkalinity. 16 In addition, such selection is appropriate to circumvent Co/Zn-ZIF-8 surface interaction with acidity or alkalinity, because of the probable buffering MIM moieties, which might affect H 2 O 2 -produced oxidative species. 17,18 In addition, the decomposition rate of H 2 O 2 by Co/Zn-ZIF-8 was monitored and recorded by the traditional triiodide-Ghormley method.…”

Hydroxide ion-conducting metal–organic frameworks for anion-exchange membrane applications

“…52 Even MOFs considered as highly stable chemically, such as UiO-66(Zr), ZIF-8 or MIL-53(Al) show signs of degradation in alkaline media. 53,54 In order to construct a reliable working fuel cell device therefore it is indispensable that the MOF, which the exchange-membrane is made up of withstand the harsh conditions, which can amount to 6 M KOH 55 , as pure material, or alternative processing technique must be developed improving the frameworks' chemical resistance. Although ion-exchange membranes when integrated in a fuel cell are immersed in a liquid electrolyte, in order to achieve the very high ion conductivity approaching that afforded by the current proton-exchange membrane technology, high intrinsic hydroxide-ion conductivities must be achieved in the frameworks, as it will be seen, current materials offer significantly lower ion conductivities for hydroxide ions than for protons.…”

Nanoassemblies Based on a Cationic Perylene Diimide Derivative and Sodium Dodecyl Sulfate: A Simple Fluorescent Platform for Efficient Analysis of Aflatoxin B1

“…Aflatoxins (AFs) are a group of secondary metabolites of low molecular weight produced by Aspergillus flavus and Aspergillus parasiticus, which could contaminate grains and other agricultural commodities. , Due to the capacity of binding to cellular DNA, aflatoxin B 1 (AFB 1 ) is one of the most carcinogenic compounds found in nature and possesses the highest toxicity among aflatoxins, resulting in significant health risk and damage to humans and animals. − So far, many countries have established the maximum residue levels (MRLs) of AFB 1 in the range of 2–20 μg kg –1 . , The high stability of AFB 1 to physical and chemical treatments enables their survival through these treatments including various food manufacturing processes at elevated temperatures, making it exceedingly challenging to prevent their entry into the food chain. , Therefore, accurate and sensitive determination of AFB 1 residues in agricultural commodities is highly needed.…”