Automated Microfluidic Droplet-Based Sample Chopper for Detection of Small Fluorescence Differences Using Lock-In Analysis.
Automated Microfluidic Droplet-Based Sample Chopper for Detection of Small Fluorescence Differences Using Lock-In Analysis.
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DOI：
10.1021/acs.analchem.7b00991
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发表时间：
2017-06-06
影响因子：
7.4
通讯作者：
Easley CJ
中科院分区：
文献类型：
--
作者：
Negou JT;Avila LA;Li X;Hagos TM;Easley CJ
荧光被广泛用于小体积分析，是微流体设备中芯片检测的主要工具，但超灵敏测量需要额外的专业知识，更精细的光学和锁相检测器。最近，我们设计了一个微流体模拟光束斩波器（μ斩波器），交替形成皮升体积的样品和参考液滴。无需复杂的光学器件，该器件消除了大信号漂移（1/f噪声），允许在仅27 μm的光路中进行吸光度检测。在这里，我们将μChopper概念扩展到使用标准宽视场显微镜光学器件的荧光检测。μChopper中液滴控制的精度通过气动阀的自动化来提高，允许荧光测量在0.04 Hz带宽下严格锁相到在3.50 Hz下产生的液滴。当取样20个液滴时，达到12 pM荧光素的检测限，并且在单个液滴（8.8 nL）中可检测到少至310 zeptomole（3.1 × 10−19 mol）。当应用于3 T3-L1脂肪细胞的游离脂肪酸（FFA）摄取时，该μChopper首次允许将单细胞FFA摄取速率定量为3.5 ± 0.2 × 10−15 mol cell−1。此外，液滴中的均相免疫测定显示胰岛素检测限为9.3 nM或190阿莫尔（1.9 × 10−16 mol）。这种新型的自动μChopper与锁定检测相结合，提供了一个高性能平台，用于检测标准荧光光学器件的微小差异，特别是在样品体积有限的情况下。该技术应易于实施到各种其他液滴射流装置中。
Fluorescence is widely used for small-volume analysis and is a primary tool for on-chip detection in microfluidic devices, yet additional expertise, more elaborate optics, and phase-locked detectors are needed for ultrasensitive measurements. Recently, we designed a microfluidic analog to an optical beam chopper (μChopper) that alternated formation of picoliter volume sample and reference droplets. Without complex optics, the device negated large signal drifts (1/f noise), allowing absorbance detection in a mere 27 μm optical path. Here, we extend the μChopper concept to fluorescence detection with standard wide-field microscope optics. Precision of droplet control in the μChopper was improved by automation with pneumatic valves, allowing fluorescence measurements to be strictly phase locked at 0.04 Hz bandwidth to droplets generated at 3.50 Hz. A detection limit of 12 pM fluorescein was achieved when sampling 20 droplets, and as few as 310 zeptomoles (3.1 × 10−19 mol) were detectable in single droplets (8.8 nL). When applied to free fatty acid (FFA) uptake in 3T3-L1 adipocytes, this μChopper permitted single-cell FFA uptake rates to be quantified at 3.5 ± 0.2 × 10−15 mol cell−1 for the first time. Additionally, homogeneous immunoassays in droplets exhibited insulin detection limits of 9.3 nM or 190 amol (1.9 × 10−16 mol). The combination of this novel, automated μChopper with lock-in detection provides a high-performance platform for detecting small differences with standard fluorescence optics, particularly in situations where sample volume is limited. The technique should be simple to implement into a variety of other droplet fluidics devices.
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影响因子：
15.9
作者：
Kahn, BB;Flier, JS
通讯作者：
Flier, JS
DOI：
10.1039/c4an01725k
发表时间：
2015-02-21
期刊：
The Analyst
影响因子：
--
作者：
Godwin LA;Brooks JC;Hoepfner LD;Wanders D;Judd RL;Easley CJ
通讯作者：
Easley CJ
DOI：
10.1039/c6an01055e
发表时间：
2016-10-21
期刊：
The Analyst
影响因子：
--
作者：
Brooks JC;Ford KI;Holder DH;Holtan MD;Easley CJ
通讯作者：
Easley CJ
影响因子：
14.8
作者：
Mazutis, Linas;Gilbert, John;Ung, W. Lloyd;Weitz, David A.;Griffiths, Andrew D.;Heyman, John A.
通讯作者：
Heyman, John A.
影响因子：
7.4
作者：
Deal, Kennon S.;Easley, Christopher J.
通讯作者：
Easley, Christopher J.