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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Free-surface microfluidic control of surface-enhanced Raman spectroscopy for the optimized detection of airborne molecules
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Free-surface microfluidic control of surface-enhanced Raman spectroscopy for the optimized detection of airborne molecules

机译：表面增强拉曼光谱的自由表面微流控，可优化检测机载分子

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摘要

We present a microfluidic technique for sensitive, real-time, optimized detection of airborne water-soluble molecules by surface-enhanced Raman spectroscopy (SERS). The method is based on a free-surface fluidic device in which a pressure-driven liquid micro-channel flow is constrained by surface tension. A colloidal suspension of silver nanoparticles flowing through the microchannel that is open to the atmosphere absorbs gas-phase 4-aminobenzenethiol (4-ABT) from the surrounding environment. As surface ions adsorbed on the colloid nanoparticles are substituted by 4-ABT, the colloid aggregates, forming SERS "hot spots" whose concentrations vary predictably along the microchannel flow. 4-ABT confined in these hot spots produces SERS spectra of very great intensity. An aggregation model is used to account quantitatively for the extent of colloid aggregation as determined from the variation of the SERS intensity measured as a function of the streamwise position along the microchannel, which also corresponds to nanoparticle exposure time. This allows us to monitor simultaneously the nanoparticle aggregation process and to determine the location at which the SERS signal is optimized.
机译：我们提出了一种微流体技术，用于通过表面增强拉曼光谱（SERS）灵敏，实时，优化地检测空气中的水溶性分子。该方法基于自由表面流体装置，其中压力驱动的液体微通道流动受到表面张力的约束。流经向大气开放的微通道的银纳米粒子的胶态悬浮液从周围环境中吸收气相4-氨基苯硫醇（4-ABT）。当吸附在胶体纳米颗粒上的表面离子被4-ABT取代时，胶体聚集，形成SERS“热点”，其浓度沿微通道流动可预测地变化。限制在这些热点中的4-ABT产生非常高强度的SERS光谱。聚集模型用于定量说明胶体聚集的程度，这是根据沿微通道的流向位置而测得的SERS强度的变化确定的，SERS强度也对应于纳米粒子的暴露时间。这使我们可以同时监视纳米粒子的聚集过程，并确定SERS信号最优化的位置。

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