Fu Jing-Lin, Fang Qun, Zhang Ting, Jin Xin-Hua, Fang Zhao-Lun
Institute of Microanalytical Systems, Zhejiang University, Hangzhou, 310028 China.
Anal Chem. 2006 Jun 1;78(11):3827-34. doi: 10.1021/ac060153q.
In this work, a simple LIF detection system based on an orthogonal optical arrangement for microfluidic chips was developed. Highly sensitive detection was achieved by detecting the fluorescence light emitted in the microchannel through the sidewall of the chip to reduce scattered light interference from the laser source. A special crossed-channel configuration, with a 1.5-mm distance from the separation channel to the sidewall of the glass chip, was designed in order to facilitate collection of emitted fluorescence light through the sidewall. The significant difference in intensity distribution of scattered laser light on the chip plane observed in this study was fully exploited to optimize S/N ratio of detected signals by rejection of scattered light, both through systematic measurements and employing ray-tracing simulation. A fluorescence collection angle of 45 degrees in the chip plane gave the best result, with a scattered light intensity 1/38 of that obtained at an angle of 90 degrees. Sodium fluorescein and fluorescein isothiocyanate-labeled amino acids were used as model samples to demonstrate the performance of the LIF system. A detection limit (S/N = 3) of 1.1 pM fluorescein was obtained, which is comparable to that of optimized confocal LIF systems for chip-based capillary electrophoresis. Apart from the high detection power, the system also has the advantages of simple optical structure, compactness, and ease in building.
在这项工作中，开发了一种基于用于微流控芯片的正交光学布置的简单激光诱导荧光（LIF）检测系统。通过检测从芯片侧壁发射到微通道中的荧光来实现高灵敏度检测，以减少来自激光源的散射光干扰。设计了一种特殊的交叉通道配置，从分离通道到玻璃芯片侧壁的距离为1.5毫米，以便于通过侧壁收集发射的荧光。通过系统测量和采用光线追踪模拟，充分利用了本研究中观察到的芯片平面上散射激光光强度分布的显著差异，通过排除散射光来优化检测信号的信噪比。在芯片平面上45度的荧光收集角度给出了最佳结果，散射光强度是90度角度时的1/38。使用荧光素钠和异硫氰酸荧光素标记的氨基酸作为模型样品来证明LIF系统的性能。获得了1.1 pM荧光素的检测限（信噪比 = 3），这与用于基于芯片的毛细管电泳的优化共聚焦LIF系统相当。除了高检测能力外，该系统还具有光学结构简单、紧凑且易于构建的优点。
