Catalan Karina N, Ratschow Aaron D, Butt Hans-Jürgen, Koynov Kaloian
Max Planck Institute for Polymer Research, 55128 Mainz, Germany.
J Phys Chem Lett. 2025 Aug 28;16(34):8869-8876. doi: 10.1021/acs.jpclett.5c02002. Epub 2025 Aug 21.
Functionalized silica-based surfaces are widely used across industries, from semiconductors to pharmaceuticals. Aminosilanes are commonly employed as coupling agents during surface functionalization to anchor diverse functional molecules. However, the surface modifications perturb interfacial physicochemical properties, resulting in a significant shift in interfacial pH compared to the bulk solution. This shift complicates direct measurement and accurate monitoring of interfacial conditions. To overcome this challenge, we functionalized glass surfaces with aminosilane-coupled pH-sensitive fluorescent dyes and utilized confocal microscopy to measure their fluorescence response to changes in bulk pH. Complementing these experiments, we developed a theoretical model describing equilibrium surface chemistry taking into account electrostatic interactions at aminosilane-functionalized glass interfaces. It revealed a linear relationship between interfacial and bulk pH, with the interfacial pH varying over a narrowed range compared to the bulk pH. Building upon these insights, we calibrate the fluorescence response of the grafted pH-sensitive dyes. This integrated approach enables precise and reliable in situ monitoring of interfacial pH under various conditions, demonstrating significant potential for environmental sensing and advanced material characterization.
功能化的硅基表面在从半导体到制药等众多行业中广泛应用。在表面功能化过程中，氨基硅烷通常用作偶联剂以锚定各种功能分子。然而，表面改性会扰乱界面物理化学性质，导致与本体溶液相比界面pH发生显著变化。这种变化使界面条件的直接测量和精确监测变得复杂。为了克服这一挑战，我们用氨基硅烷偶联的pH敏感荧光染料对玻璃表面进行功能化，并利用共聚焦显微镜测量它们对本体pH变化的荧光响应。作为这些实验的补充，我们开发了一个理论模型，该模型考虑了氨基硅烷功能化玻璃界面处的静电相互作用，描述了平衡表面化学。它揭示了界面pH与本体pH之间的线性关系，与本体pH相比，界面pH在较窄的范围内变化。基于这些见解，我们校准了接枝的pH敏感染料的荧光响应。这种综合方法能够在各种条件下对界面pH进行精确可靠的原位监测，显示出在环境传感和先进材料表征方面的巨大潜力。
