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Since Fe(III) ions are of importance in biological systems, the development of new sensors for detecting Fe(III) with excellent selectivity and low detection limit is desirable. Herein, a new stable hydrazone-linked covalent organic framework (COF), namely, Tfpa–Mth COF, was synthesized by the Schiff-base condensation reaction between tris(4-formylphenyl) amine (Tfpa) and a chiral hydrazide precursor (Mth). The ethanol-dispersed Tfpa–Mth COF can be used as a fluorescence sensor for the detection of Fe(III) ions, showing high selectivity and low detection limit (64 nM). Moreover, a novel COF-based quartz crystal microbalance (QCM) sensor has been fabricated by the in situ growth of the Tfpa–Mth COF on an amino-modified QCM chip. Such a COF-based QCM sensor, with a uniform surface and thickness of the Tfpa–Mth COF film on the surface, is able to monitor Fe(III) ions in real-time with high selectivity. The recognition process, as a result of Fe(III) immobilization on the Tfpa–Mth COF framework, is further verified by zeta potential measurements and X-ray photoelectron spectroscopy. To the best of our knowledge, this represents the first report on the development of COF-based QCM sensors for metal ion detection. Exploration of the COF-based QCM sensor in our work demonstrates the new pathway for the selective detection of metal ions. [ABSTRACT FROM AUTHOR]

The development of a robust and efficient stationary phase for chromatographic biopharmaceutical purification is of prime importance but remains challenging. Herein, we have developed a series of protein A-mesoporous silica composites for the first time by covalently coupling protein A with the tagged carbonyl imidazole moieties in the column, which constitutes a facile and efficient route for the preparation of protein A immunoaffinity materials. The resultant composites are employed as the stationary phase for chromatographic purification of immunoglobulin G (IgG). The effect of silica's pore size and coupled protein A on the antibody purification is systematically investigated. When the pore size of silica increased from 100 to 1000 Å, the amount of coupled protein A decreased, and the surface coverage on the silica significantly improved, accompanied by an increase in the amount of purified rabbit IgG. With an increasing coupled protein A, the surface coverage increased at first and decreased subsequently, which shows a similar trend to the amount of purified IgG and specific activity. When practically implemented for purifying several immunoglobulins that are central for commercial ELISA Kits, the protein A-mesoporous silica composite exhibited superior performance compared to the GE-Mabselcetxtra rProtein A column, particularly in the purification of immunoglobulin M (IgM), which cannot be realized by the GE-Mabselcetxtra rProtein A column. This study sheds new light on the rational development of protein-affinity chromatography for biopharmaceutical purification. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks are a new class of crystalline porous materials that have various potential applications. However, utilization of covalent organic frameworks as new stationary phases for gas chromatography separation has been less explored. In this work, a hydrazone‐linked chiral covalent organic framework has been covalently bonded onto the inner surface of fused silica capillary. The fabricated hydrazone‐linked covalent organic framework‐bound capillary column displays a moderate polarity nature and exhibits relatively high resolution performances for separation of linear alkanes and alcohols, as well as aromatic positional isomers including xylene, nitrotoluene, chloronitrobenzene, benzenediol, and naphthol isomers. The present study reveals that the hydrazone‐linked covalent organic framework‐bound capillary column is quite promising for the gas chromatography separation of aromatic positional isomers. [ABSTRACT FROM AUTHOR]