Boronate affinity materials, as efficient sorbents for extraction, separation and enrichment of glycoproteins, have attracted more and more attention in recent years. However, conventional boronate affinity materials suffer from low binding affinity due to the use of single boronic acids, which makes the extraction of glycoproteins in trace concentration rather difficult or impossible. Here we present a type of high boronate avidity material, polyethyleneimine (PEI)-assisted boronic acid-functionalized magnetic nanoparticles (MNPs). Branched PEI was used as a scaffold to amplify the number of boronic acid moieties, while 2,4-difluoro-3-formyl-phenylboronic acid (DFFPBA), exhibiting high affinity and excellent water solubility toward cis-diol-containing compounds, was employed as an affinity ligand. Due to the PEI-assisted synergistic multivalent binding, the boronate avidity MNPs exhibited a high binding affinity toward glycoproteins with dissociation constants of 10⁻⁶–10⁻⁷ M, which was the highest among the reported boronic acid-functionalized materials that can be applied for a glycoproteomic analysis. Such an avidity enabled the selective extraction of trace glycoproteins as low as 2 × 10⁻¹⁵ M. This feature greatly favored the selective enrichment of trace glycoproteins from real samples. Meanwhile, the boronate avidity MNPs were tolerant to the interference of abundant sugars. In addition, the PEI-based boronate avidity MNPs exhibited high binding capacity and low binding pH. The feasibility for practical applications was demonstrated with the selective enrichment of trace glycoproteins in human saliva.

中文翻译：

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支链聚乙烯亚胺辅助的硼酸官能化磁性纳米粒子，用于选择性富集痕量糖蛋白

硼酸盐亲和材料作为糖蛋白的提取，分离和富集的有效吸附剂，近年来受到越来越多的关注。然而，由于使用单一的硼酸，常规的硼酸酯亲和力材料具有低的结合亲和力，这使得痕量浓度的糖蛋白的提取相当困难或不可能。在这里，我们介绍一种高硼酸盐亲和力的材料，聚乙烯亚胺（PEI）辅助的硼酸官能化的磁性纳米粒子（MNPs）。支链PEI用作支架来扩增硼酸部分的数量，而2,4-二氟-3-甲酰基-苯基硼酸（DFFPBA）具有高亲和力和对顺式的优异水溶性含α-二醇的化合物被用作亲和配体。由于PEI辅助的协同多价结合，硼酸亲和性MNP对糖蛋白表现出高结合亲和力，其解离常数为10 ^-6 –10 ^-7 M，在可应用的硼酸官能化材料中最高用于糖蛋白组学分析。这样的亲合力使得选择性提取微量糖蛋白的能力低至2×10 ^-15M.这一特征极大地促进了从真实样品中选择性富集痕量糖蛋白。同时，硼酸亲和力的MNP可以耐受大量糖分的干扰。另外，基于PEI的硼酸酯亲和性MNP表现出高结合能力和低结合pH。在人唾液中选择性富集微量糖蛋白证明了实际应用的可行性。