SFI Insight Centre for Data Analytics; National Centre for Sensor Research; School of Chemical Sciences, Dublin City University, Dublin 9, Ireland.
Departamento de Química Analítica, Nutrición y Bromatología, Instituto Universitario de Materiales, Universidad de Alicante, PO Box 99, 03080 Alicante, Spain.
Langmuir. 2023 Jun 13;39(23):8100-8108. doi: 10.1021/acs.langmuir.3c00462. Epub 2023 May 26.
Phenylboronic acids (BAs) are important synthetic receptors that bind reversibly to cis-diols enabling their use in molecular sensing. When conjugated to magnetic iron oxide nanoparticles, BAs have potential for application in separations and enrichment. Realizing this will require a new understanding of their inherent binding modes and measurement of their binding capacity and their stability in/extractability from complex environments. In this work, 3-aminophenylboronic acid was functionalized to superparamagnetic iron oxide nanoparticles (MNPs, core diameter 8.9 nm) to provide stable aqueous suspensions of functionalized particles (BA-MNPs). The progress of sugar binding and its impact on BA-MNP colloidal stability were monitored through the pH-dependence of hydrodynamic size and zeta potential during incubation with a range of saccharides. This provided the first direct observation of boronate ionization p in grafted BA, which in the absence of sugar shifted to a slightly more basic pH than free BA. On exposure to sugar solutions under MNP-limiting conditions, p moved progressively to lower pH as maximum capacity was gradually attained. The p shift is shown to be greater for sugars with greater BA binding affinity, and on-particle sugar exchange effects were inferred. Colloidal dispersion of BA-MNPs after binding was shown for all sugars at all pHs studied, which enabled facile magnetic extraction of glucose from agarose and cultured extracellular matrix expanded in serum-free media. Bound glucose, quantified following magnetophoretic capture, was found to be proportional to the solution glucose content under glucose-limiting conditions expected for the application. The implications for the development of MNP-immobilized ligands for selective magnetic biomarker capture and quantitation from the extracellular environment are discussed.
苯硼酸（BAs）是重要的合成受体，可与顺式二醇可逆结合，从而使其可用于分子传感。当与磁性氧化铁纳米粒子偶联时，BAs 有可能应用于分离和富集。要实现这一目标，需要对其固有结合模式有新的认识，并测量其结合能力及其在复杂环境中的稳定性和可提取性。在这项工作中，3-氨基苯硼酸被功能化到超顺磁性氧化铁纳米粒子（MNP，核心直径 8.9nm）上，以提供功能化颗粒（BA-MNP）的稳定水悬浮液。通过在与一系列糖孵育过程中监测水动力粒径和 ζ 电位的 pH 依赖性，监测了糖结合的进展及其对 BA-MNP 胶体稳定性的影响。这首次直接观察到接枝 BA 中硼酸的离解 p，在没有糖的情况下，p 比游离 BA 稍微向更碱性的 pH 移动。在 MNP 限制条件下暴露于糖溶液中时，随着最大容量逐渐达到，p 逐渐向更低的 pH 移动。p 位移显示对于与 BA 结合亲和力更大的糖更大，并且推断出了粒子上的糖交换效应。在研究的所有 pH 值下，所有糖都显示出 BA-MNP 结合后的胶体分散性，这使得从琼脂糖和无血清培养基中培养的细胞外基质中轻松提取葡萄糖成为可能。在磁捕获后定量结合的葡萄糖发现，在预期用于应用的葡萄糖限制条件下，与溶液葡萄糖含量成正比。讨论了用于从细胞外环境中选择性捕获和定量磁生物标志物的固定化 MNPs 配体的发展的影响。
