Boric-Acid-Functionalized Covalent Organic Framework for Specific Enrichment and Direct Detection of cis-Diol-Containing Compounds by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry

Abstract

Design and synthesis of a novel matrix that serves as highly selective adsorption material are significant for the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis of small molecules in complicated biosamples. In this work, we presented a facile one-pot strategy for the synthesis of boric-acid-functionalized covalent organic frameworks (B-COFs) by using 2,4,6-trihydroxy-1,3,5-benzenetrialdehyde, benzidine, and 4-aminophenyl-boronic acid as ligands. Compared with bare COFs, the B-COFs have similar crystallinity, specific surface, and well-developed pore structure. The surface area and average pore size of B-COFs were 238.0 m2/g and 1.2 nm, respectively. The resulting material was used as an adsorbent for selective enrichment of cis-diol-containing compounds based on an affinity reaction between phenylboronic acid and cis-diol. Using luteolin, riboflavin, and pyrocatechol as model analytes, the enrichment ability of B-COFs as a matrix was examined by MALDI-TOF MS assay, and its high selectivity against target analytes was obtained in the presence of 100 times more anti-nonspecific compounds than that even in the complicated biosample. The limits of detection for luteolin, riboflavin, and pyrocatechol were as low as fg/mL with B-COF enrichment. The B-COFs were further employed and validated for specific enrichment and direct detection of target analytes with complex samples such as human serum, milk, and Capsicum samples. Large surface area, numerous boric-acid active sites, and super stability make B-COFs with high enrichment capacity, high selectivity and sensitivity, satisfying reproducibility, and excellent applicability in MALDI-TOF MS assays.

Inorganic Matrices Assisted Laser Desorption/Ionization Mass Spectrometry for Metabolic Analysis in Biofluids

“…As a promising matrix candidate, those organic components comprise plentiful π‐π stacking structures [45] to offer high UV‐visible absorption, and the covalent bonds enhance thermostability and chemical stability for lower interference background [46] . Hu et al [47] . synthesized boric‐acid‐functionalized covalent organic frameworks (B‐COFs) with outstanding optical absorption property, large specific surface(238.0 m 2 /g of surface area), and well‐developed pore structure (1.2 nm of average pore size) as a novel matrix for LDI MS. Due to the affinity reaction between cis‐diol and phenylboronic acid, this nanomaterial can offer high selectivity and sensitivity, excellent reproducibility, and satisfying applicability in the detection of cis‐diol‐containing compounds in LDI MS. Ouyang et al [48] .…”

Covalent Organic Frameworks for Water Treatment

“…Beyond toxic heavy metal and radionuclide ion capture, there are several reports on COFs as adsorbents for lanthanide ions (Nd 3+ ), [ 98 ] perrhenate (ReO 4 − ), [ 99 ] phosphorus (PO 4 3− ), [ 100 ] arsenic (AsO 4 3− ), [ 100 ] organic compounds, [ 66,67,101–104 ] and even proteins. [ 105 ] Valtchev's group reported a carboxy‐functionalized COF (3D‐COOH‐COF) through the postsynthetic modification method and applied the 3D‐COOH‐COF in selective adsorption for lanthanide ion Nd 3+ over Sr 2+ and Fe 3+ .…”

Preparation of P(EGDMA‐co‐VPBA) Adsorbent and Its Application in the Separation of Steviol Glycosides

“…[6] In recent years, with the development of adsorption materials, the adsorption method has been regarded as a high efficiency separation method. [7] The adsorption materials commonly used in current research involve MOFs, [8] silica-based materials, [9,10] carbon-based materials, [11,12] magnetic composite [13][14][15] and macroporous adsorption resin (MAR), COFs, [16,17] molecularly imprinted polymers (MIPs), [18][19][20][21][22][23][24] and other organic polymers. [25][26][27][28][29] Organic polymer adsorbents have become universal adsorbent materials with varieties of attractive merits, for example adjustable monomer components, relatively low-cost, structure diversity, and facile functionalization.…”