亲/疏水交替“微井”点阵SERS柔性基底构建及对痕量农残的超灵敏检测与原位检测应用研究

The achievement of ultrasensitive and in situ detection is vital for further applications of surface-enhanced Raman scattering (SERS). However, conventional SERS substrates do not have decent detection sensitivities due to the incapability of enriching hydrophilic molecules and their insufficient affinities to hydrophobic molecules; additionally, the rigid substrate cannot be used for in situ detection due to its non-transparency and inelasticity. In this project, a flexible and transparent SERS substrate is proposed for achieving the ultrasensitive detection of both hydrophilic and hydrophobic molecules. To achieve this promise, its surface is modified by self-assembly of Au nanoparticles and photomask-assisted patterning to form an interleaved hydrophilic/hydrophobic microwell arrays. This surface feature gives a minimum contact area between the droplets and the substrate surface, which enables targeted molecules local-enriched and make them have good affinities to the corresponding surface. How the effects between wettability, polarity, and hydrophobic interaction facilitate the ultrasensitive detection is investigated. Moreover, the flexibility and the optical penetrability under the visible-near infrared range make this SERS substrate suitable for in situ detection. Neonicotinoid insecticides and organophosphorus pesticides are selected for detection by using this novel substrate. This study provides new perspectives for ultrasensitive and in situ detection, which inspire multi-functional SERS substrate design, and promotes SERS into further application fields.

实现超灵敏检测与原位检测是推动表面增强拉曼散射(Surface-enhanced Raman Scattering, SERS)技术广泛应用的关键。然而常见SERS基底对亲水性分子不能富集，对疏水性分子不具有良好亲和力而限制灵敏度提升；同时刚性基底不能实现原位检测。为此，本项目拟在柔性材料上通过单层金粒子自组装、表面修饰及光掩膜辅助的图案化形成，构建亲/疏水微井交替分布的点阵，降低液滴与基底接触面积，使待测分子浓缩富集，并使之与相应微井表面良好地吸附，达到对亲/疏水两类分子超灵敏检测的目的，揭示润湿性、极性与疏水相互作用对实现SERS超灵敏检测的影响；利用基底的柔性和在可见-近红外光区的透明性，实现原位检测。进一步将此新型基底用于新烟碱类杀虫剂和有机磷农药的检测。本研究为痕量分子的精准快速超灵敏/原位检测提供新思路，为发展多功能化SERS基底提供新技术，推动SERS技术进一步广泛深入应用。

本项目通过不同的系列实验完成了在柔性透明基底上构建层数可控的金纳米粒子自组装薄膜，并通过制备不同粒径金纳米粒子、不同层数金薄膜，探寻了粒径、层数与基底增强能力之间的关系，运用具有最高增强能力的基底实现了对液体样品中痕量非法添加剂分子的原位SERS检测。同时通过对柔性衬底支持的单层金纳米粒子自组装薄膜进行表面修饰与光掩模辅助的图案化构建，制备了亲/疏水“微井”交替排布的新型表面阵列，这样通过降低液滴与基底的接触面积使待测分子浓缩富集，同时使待测亲/疏水分子与相应的亲/疏水表面发生良好地吸附，分别实现了对于一种亲水性分子与一种疏水性分子的超灵敏检测。为了进一步探讨提高灵敏度的方法，我们引入了动态SERS检测技术。通过将贵金属银溶胶滴至衬底上，随着溶剂的挥发会给纳米粒子一个指向圆周的力，促使咖啡环的形成。当咖啡环形成后，随着纳米颗粒由湿润变干燥的进行，SERS光谱会有一个最高被增强时刻出现，利用这一最强SERS信号时刻，我们分别对四种实际样品中的四种农药残留进行了快速、灵敏地检测与识别。接下来，我们将SERS技术作为一种监测手段，构建了一种温度敏感型的探针分子，通过SERS信号的变化可实时灵敏反映细胞内微观温度的变化，实现了在亚细胞水平上监测光热治疗，提升了光热治疗中温度监测的空间分辨率。