Three-dimensional microfluidic confinement for efficient sample delivery to biosensor surfaces. Application to immunoassays on planar optical waveguides
Three-dimensional microfluidic confinement for efficient sample delivery to biosensor surfaces. Application to immunoassays on planar optical waveguides
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DOI：
10.1021/ac025777k
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发表时间：
2002-10-15
影响因子：
7.4
通讯作者：
Manz, A
中科院分区：
文献类型：
--
作者：
Hofmann, O;Voirin, G;Manz, A
描述了一种基于微芯片的流动限制方法，用于将小体积样品快速输送到传感器表面。对于流动限制，样品流与水或样品介质的垂直补充流连接在一起。在层流条件下，补流将样品限制在感应区上方的一层薄层中，并增加其速度。这有利于限制物质传输的过程，如DNA杂交或异种免疫分析。为了验证概念，将该方法应用于具有过量捕获抗体的高亲和力免疫分析。将兔免疫球蛋白固定在氮化硅波导上。Cy5标记的抗兔免疫球蛋白通过连接有20微米深的微通道的3D-PDMS流动池在固定区被流体动力泵送。通过限制流的体积流量来调整限制程度。基于消失场的荧光检测使结合事件的监测成为可能。允许检测达到平衡，以实现批间比较的感觉图标准化。相应的分析完成时间可以从静态滴定条件下的55min减少到25：1流动限制(限制与样品流的比率)的13min。对于典型的分析应用，在不需要形成平衡的情况下，更快的响应应该转化为非常短的分析时间。与传统的全渠道样品输送相比，结合速度更快的同时，样品消耗减少了96%。分析物进入隔离层的扩散损失被认为是流动限制的主要限制，特别是对于长传感垫。
A microchip-based flow confinement method for rapid delivery of small sample volumes to sensor surfaces is described. For flow confinement, a sample flow is joined with a perpendicular makeup flow of water or sample medium. Under laminar flow conditions, the makeup flow confines the sample into a thin layer above the sensing area and increases its velocity. This can benefit mass transport limited processes such as DNA hybridization or heterogeneous immunoassays. For proof of concept, this method was applied to a high-affinity immunoassay with excess capture antibody. Rabbit IgG was immobilized onto a silicon nitride waveguide. Cy5-labeled anti-rabbit IgG was hydrodynamically pumped over the immobilized zone through an attached 3D-PDMS flow cell with 20-mum-deep microchannels. The degree of confinement was adjusted through the volume flow rate of the confining flow. Evanescent field-based fluorescence detection enabled monitoring of the binding event. Assays were allowed to reach equilibrium to enable sensorgram normalization for inter-run comparison. The corresponding assay completion times could be reduced from 55 min for static drop conditions to 13 min for 25:1 flow confinement (ratio of confining to sample flow). For typical analytical applications, where equilibrium formation is not required, the faster response should translate to very short analysis times. Concurrently with the faster binding, sample consumption was reduced by 96% compared to conventional whole-channel sample delivery. Diffusional loss of analyte into the confining layer was identified as the main limitation of flow confinement, particularly for long sensing pads.