Zhou Bokun, Govyadinov Alexander, Kornilovitch Pavel, Remcho Vincent T
Department of Chemistry, College of Science, Oregon State University, Corvallis, Oregon 97331, United States.
Materials Science Program, College of Engineering, Oregon State University, Corvallis, Oregon 97331, United States.
ACS Omega. 2024 Jun 24;9(27):29401-29409. doi: 10.1021/acsomega.4c01607. eCollection 2024 Jul 9.
Spiropyran is a dynamic organic compound that is distinguished by its reversible conversion between two forms: the colorless closed spiropyran (SP) form and the purple open merocyanine (MC) form. Typically triggered by UV light and reversed by visible light, spiropyran-functionalized surfaces offer reversible conversion in properties including color, polarity, reactivity, and fluorescence, making them applicable to diverse applications in chemical sensors, biosensors, drug delivery, and heavy metal extraction. While spiropyran has been successfully incorporated into various material platforms with SiO surfaces, its application on flat surfaces has been limited due to surface area constraints and a lack of standardized evaluation methods, which largely depend on the integration approach and substrate type used. In this study, we systematically review the existing literature and categorize integration methods and substrate types first and then report on our experimental work, in which we developed a streamlined three-step immobilization protocol, which includes surface activation, amination with (3-aminopropyl) triethoxysilane (APTES), and subsequent functionalization with carboxylic spiropyran (SP-COOH). Using SiO surfaces as a demonstration, we have also established a robust characterization protocol, consisting of contact angle measurements, X-ray photoelectron spectroscopy (XPS), ellipsometry, and fluorometric analysis. Our results evaluate the newly developed immobilization protocol, demonstrating effective activation and optimal amination using a 2% APTES solution, achieved in 5 min at room temperature. Fluorescence imaging provided clear contrast between the SP and the MC forms. Furthermore, we discuss limitations in the surface density of functional groups and steric hindrance and propose future improvements. Our work not only underscores the versatility of spiropyran in surface patterning but also provides optimized protocols for its immobilization and characterization on SiO surfaces, which may be adapted for use on other substrates. These advancements lay the groundwork for on-chip sensing technologies and other applications.
螺吡喃是一种动态有机化合物，其特点是能在两种形式之间进行可逆转换：无色的闭环螺吡喃（SP）形式和紫色的开环部花青（MC）形式。螺吡喃功能化表面通常由紫外光触发，并由可见光逆转，在颜色、极性、反应性和荧光等性质方面提供可逆转换，使其适用于化学传感器、生物传感器、药物递送和重金属提取等多种应用。虽然螺吡喃已成功地整合到各种具有SiO表面的材料平台中，但由于表面积限制和缺乏标准化评估方法，其在平面表面上的应用受到限制，这些评估方法在很大程度上取决于所使用的整合方法和底物类型。在本研究中，我们系统地回顾了现有文献，首先对整合方法和底物类型进行分类，然后报告我们的实验工作，其中我们开发了一种简化的三步固定化方案，包括表面活化、用（3-氨丙基）三乙氧基硅烷（APTES）进行胺化，以及随后用羧基螺吡喃（SP-COOH）进行功能化。以SiO表面为例，我们还建立了一个强大的表征方案，包括接触角测量、X射线光电子能谱（XPS）、椭偏仪和荧光分析。我们的结果评估了新开发的固定化方案，证明使用2%的APTES溶液在室温下5分钟内可实现有效的活化和最佳的胺化。荧光成像提供了SP和MC形式之间的清晰对比。此外，我们讨论了官能团表面密度和空间位阻的局限性，并提出了未来的改进方向。我们的工作不仅强调了螺吡喃在表面图案化方面的多功能性，还提供了在SiO表面上进行固定化和表征的优化方案，这些方案可能适用于其他底物。这些进展为片上传感技术和其他应用奠定了基础。
