A fully automated droplet generation and analysis device based on pressure driven push-up valves for precise pumping of fluid and volumetric metering has been developed for high resolution hormone secretion sampling and measurement. The device consists of a 3D-printer templated reservoir for single cells or single tissue culturing, a Y-shaped channel for reagents and sample mixing, a T-junction channel for droplet formation, a reference channel to overcome drifts in fluorescence signal, and a long droplet storage channel allowing incubation for homogeneous immunoassays. The droplets were made by alternating peristaltic pumping of aqueous and oil phases. Device operation was automated, giving precise control over several droplet parameters such as size, oil spacing, and ratio of sample and reference droplets. By integrating an antibody–oligonucleotide based homogeneous immunoassay on-chip, high resolution temporal sampling into droplets was combined with separation-free quantification of insulin secretion from single islets of Langerhans using direct optical readout from the droplets. Quantitative assays of glucose-stimulated insulin secretion were demonstrated at 15 second temporal resolution while detecting as low as 10 amol per droplet, revealing fast insulin oscillations that mirror well-known intracellular calcium signals. This droplet sampling and direct optical analysis approach effectively digitizes the secretory time record from cells into droplets, and the system should be generalizable to a variety of cells and tissue types.

中文翻译：

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自动化微流体液滴采样与集成的混合读取免疫测定法可解决内分泌组织分泌动态†

一种基于压力驱动上推阀的全自动液滴生成和分析装置，用于精确泵送流体和体积计量，已开发用于高分辨率激素分泌采样和测量。该装置由用于单细胞或单个组织培养的 3D 打印机模板化储存器、用于试剂和样品混合的 Y 形通道、用于液滴形成的 T 形连接通道、用于克服荧光信号漂移的参考通道以及长液滴存储通道允许孵育均质免疫测定。通过交替蠕动泵送水相和油相来制备液滴。设备操作是自动化的，可以精确控制多个液滴参数，例如尺寸、油间距以及样品和参考液滴的比率。通过在芯片上集成基于抗体-寡核苷酸的同质免疫测定，将高分辨率时间采样到液滴中，与使用液滴的直接光学读数对朗格汉斯单个胰岛的胰岛素分泌进行免分离定量相结合。葡萄糖刺激的胰岛素分泌的定量分析以 15 秒的时间分辨率进行了演示，同时检测到每滴低至 10 amol，揭示了反映众所周知的细胞内钙信号的快速胰岛素振荡。这种液滴采样和直接光学分析方法有效地将从细胞到液滴的分泌时间记录数字化，并且该系统应该可推广到各种细胞和组织类型。