Amorphous titania modified with boric acid for selective capture of glycoproteins

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2017-2018

This review is the tenth update of the original article published in 1999 on the application of matrix-assisted laser desorption/ionization mass spectrometry (MALDI) mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2018. Also included are papers that describe methods appropriate to glycan and glycoprotein analysis by MALDI, such as sample preparation techniques, even though the ionization method is not MALDI. Topics covered in the first part of the review include general aspects such as theory of the MALDI process, new methods, matrices, derivatization, MALDI imaging, fragmentation and the use of arrays. The second part of the review is devoted to applications to various structural types such as oligo- and poly-saccharides, glycoproteins, glycolipids, glycosides, and biopharmaceuticals. Most of the applications are presented in tabular form. The third part of the review covers medical and industrial applications of the technique, studies of enzyme reactions, and applications to chemical synthesis. The reported work shows increasing use of combined new techniques such as ion mobility and highlights the impact that MALDI imaging is having across a range of diciplines. MALDI is still an ideal technique for carbohydrate analysis and advancements in the technique and the range of applications continue steady progress.

Preparation of a boronate affinity-functionalized metal–organic framework material for selective recognition and separation of glycoproteins at physiological pH

A boronate affinity functionalized metal–organic framework material was successfully prepared for the efficient and selective extraction of OVA glycoprotein from egg white samples and protein powder.

A Facile Strategy for Immobilizing GOD and HRP onto Pollen Grain and Its Application to Visual Detection of Glucose

Pollen grain was explored as a new carrier for enzyme immobilization. After being modified with boric acid-functionalized titania, the pollen grain was able to covalently immobilize glycosylated enzymes by boronate affinity interaction under very mild experimental conditions (e.g., pH 7.0, ambient temperature and free of organic solvent). The glucose oxidase and horse radish peroxidase-immobilized pollen grain became a bienzyme system. The pollen grain also worked as an indicator of the cascade reaction by changing its color. A rapid, simple and cost-effective approach for the visual detection of glucose was then developed. When the glucose concentration exceeded 0.5 mM, the color change was observable by the naked eye. The assay of glucose in body fluid samples exhibited its great potential for practical application.

Modification of Luffa Sponge for Enrichment of Phosphopeptides

The enrichment technique is crucial to the comprehensive analysis of protein phosphorylation. In this work, a facile, green and efficient synthetic method was set up for quaternization of luffa sponge. The resultant luffa sponge showed strong anion-exchange characteristics and a high adsorption ability for phosphate ions. Along with the unique physical properties, e.g., tenacity and porous texture, quaternized luffa sponge was demonstrated to be a well-suited solid-phase extraction (SPE) material. The quaternized luffa sponge-based SPE method was simple, cost-effective and convenient in operation, and was successfully applied to the capture of phosphopeptides from protein digests. The enrichment approach exhibited exceptionally high selectivity, sensitivity and strong anti-interference ability. Four phosphopeptides were still detected by using the digest mixture of β-casein and bovine serum albumin with a molar ratio of 1:100. 21 phosphopeptides were identified from the tryptic digest of non-fat milk.

Organic Boronate Affinity Sorbent for Capture of cis-Diol Containing Compounds Eman Alzahrani

Boronate affinity chromatography (BAC) is argued to be a critical tool in specific capture and separation of cis-diol containing compounds. In present study, organic boronate affinity monolith poly(3-acrylamido phenylboronic acid-co-ethylene dimethacrylate) (AAPBA-co-EDMA) is prepared through one-step in situ polymerization procedure within a micropipette through the application of a pre-polymerization mixture which contains functional monomer (3-acrylamido phenylboronic acid), cross-linker (ethylene dimethacrylate), porogenic solvent (methanol with poly ethylene glycol) and initiator (2,2-dimethoxy-2-phenyl-acetophenone). Following the optimization of time exposure to UV lamp with 365 nm, the macroporous organic boronate monolith was selected. Several approaches including SEM and BET analysis, FT-IR spectroscopy and measuring contact angle were applied in the characterization of the morphology of the monolith. Several cis-diol compounds that include catechol and galactose are applied in the assessment of the boronate affinity of the organic monolithic material. Additionally, the capture of glucose from urine sample is also conducted. The basic principle of the approach is that boronic acid forms covalent bond with cis-diols in basic solutions whereas the ester bonds are dissociated under acidic media. By using the study results, monolith demonstrate good selectivity towards cis-diol containing compounds. Due to the hydrophilic property of monolith, the affinity chromatography monolith can be performed for several cis-diol compounds including glycoproteins and nucleosides. Also, fabrication of the organic boronate monolithic in microfluidic equipment is essential in facilitating the extraction of boronate affinity using small-volume samples.

Magnetic boronate modified molecularly imprinted polymers on magnetite microspheres modified with porous TiO2 (Fe3O4@pTiO2@MIP) with enhanced adsorption capacity for glycoproteins and with wide operational pH range

Boronate-affinity based molecularly imprinted polymers (MIPs) are beset by the unsatisfied adsorption capacity and narrow working pH ranges. A magnetic molecularly imprinted polymer containing phenylboronic acid groups was placed on the surface of Fe₃O₄ (magnetite) microspheres coated with porous TiO₂ (Fe₃O₄@pTiO₂@MIP). In contrast to its silica analog (Fe₃O₄@SiO₂@MIP), the flowerlike Fe₃O₄@pTiO₂ offers more binding sites for templates. Thus, the adsorption capacity of the Fe₃O₄@pTiO₂@MIP is strongly enhanced. The strong electron-withdrawing effects of Ti(IV) enable the boronic acid of the MIP to have better affinity for glycoproteins at a wide pH range from 6.0 to 9.0. Consequently, the Fe₃O₄@pTiO₂@MIP exhibits higher adsorption for glycoproteins than Fe₃O₄@SiO₂@MIP in both basic and acidic medium. The Fe₃O₄@pTiO₂@MIPs were eluted with 5% acetic acid aqueous solution containing 30% acetonitrile, and the eluate was analyzed by MALDI-TOF MS. The method was applied to the selective extraction and quantitation of horseradish peroxidase (HRP) in spiked fetal bovine serum (FBS). The linear range is 0.40-10 μg·mL^-1 with the limit of detection of 0.31 μg·mL^-1. In our perception, this work has a wide scope in that is paves the way to a more widespread application of boronate affinity based MIPs for analysis of glycoproteins and related glyco compounds even at moderately acidic pH values. Graphical abstract Schematic presentation of the magnetic boronate modified molecularly imprinted polymer on magnetic spheres modified with porous TiO₂ (Fe₃O₄@pTiO₂@MIP). It was applied to extract glycoprotein in spiked both basic fetal bovine serum (FBS) and acidic urine samples prior to quantitation by MALDI-TOF mass spectrometry.