School of Engineering, RMIT University, Melbourne, VIC, 3000, Australia.
School of Science, RMIT University, Melbourne, VIC, 3000, Australia.
Small. 2019 Jan;15(1):e1804683. doi: 10.1002/smll.201804683. Epub 2018 Nov 28.
A universal femtoliter surface droplet-based platform for direct quantification of trace of hydrophobic compounds in aqueous solutions is presented. Formation and functionalization of femtoliter droplets, concentrating the analyte in the solution, are integrated into a simple fluidic chamber, taking advantage of the long-term stability, large surface-to-volume ratio, and tunable chemical composition of these droplets. In situ quantification of the extracted analytes is achieved by surface-enhanced Raman scattering (SERS) spectroscopy by nanoparticles on the functionalized droplets. Optimized extraction efficiency and SERS enhancement by tuning droplet composition enable quantitative determination of hydrophobic model compounds of rhodamine 6G, methylene blue, and malachite green with the detection limit of 10 to 10 m and a large linear range of SERS signal from 10 to 10 m of the analytes. The approach addresses the current challenges of reproducibility and the lifetime of the substrate in SERS measurements. This novel surface droplet platform combines liquid-liquid extraction and highly sensitive and reproducible SERS detection, providing a promising technique in current chemical analysis related to environment monitoring, biomedical diagnosis, and national security monitoring.
提出了一种通用的皮升表面液滴基平台，用于直接定量分析水溶液中痕量疏水性化合物。皮升液滴的形成和功能化，以及将分析物浓缩在溶液中，都集成到一个简单的流体腔室中，利用这些液滴的长期稳定性、大的表面积与体积比和可调的化学组成。通过功能化液滴上的纳米粒子，通过表面增强拉曼散射（SERS）光谱实现了对提取的分析物的原位定量。通过调整液滴组成优化了萃取效率和 SERS 增强，实现了对疏水性模型化合物罗丹明 6G、亚甲蓝和孔雀石绿的定量测定，检测限为 10 到 10 米，分析物的 SERS 信号线性范围从 10 到 10 米。该方法解决了 SERS 测量中重现性和基底寿命的当前挑战。这种新型的表面液滴平台结合了液-液萃取和高灵敏度、重现性好的 SERS 检测，为当前与环境监测、生物医学诊断和国家安全监测相关的化学分析提供了一种很有前途的技术。
