Liu Yuguang, Papautsky Ian
Microbiome Program, Center for Individualized Medicine, Mayo Clinic, Rochester, MN 55905, USA.
Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA.
Micromachines (Basel). 2019 Feb 5;10(2):107. doi: 10.3390/mi10020107.
This work presents a heterogeneous immunoassay using the integrated functionalities of a channel and droplets in a digital microfluidic (DMF) platform. Droplet functionality in DMF allows for the programmable manipulation of discrete sample and reagent droplets in the range of nanoliters. Pressure-driven channels become advantageous over droplets when sample must be washed, as the supernatant can be thoroughly removed in a convenient and rapid manner while the sample is immobilized. Herein, we demonstrate a magnetic bead-based, enzyme-linked immunosorbent assay (ELISA) using ~60 nL of human interleukin-6 (IL-6) sample. The wash buffer was introduced in the form of a wall-less virtual electrowetting channel by a syringe pump at the flow rate of 10 μL/min with ~100% bead retention rate. Critical parameters such as sample wash flow rate and bead retention rate were optimized for reliable assay results. A colorimetric readout was analyzed in the International Commission on Illumination (CIE) color space without the need for costly equipment. The concepts presented in this work are potentially applicable in rapid neonatal disease screening using a finger prick blood sample in a DMF platform.
这项工作展示了一种在数字微流控（DMF）平台中利用通道和液滴的集成功能的异质免疫分析方法。DMF中的液滴功能允许对纳升范围内的离散样品和试剂液滴进行可编程操作。当必须对样品进行洗涤时，压力驱动通道相对于液滴具有优势，因为在固定样品的同时，可以方便快捷地彻底去除上清液。在此，我们展示了一种基于磁珠的酶联免疫吸附测定（ELISA），使用约60 nL的人白细胞介素-6（IL-6）样品。通过注射泵以10 μL/min的流速将洗涤缓冲液以无壁虚拟电润湿通道的形式引入，磁珠保留率约为100%。为获得可靠的测定结果，对样品洗涤流速和磁珠保留率等关键参数进行了优化。在国际照明委员会（CIE）颜色空间中分析比色读数，无需昂贵的设备。这项工作中提出的概念可能适用于在DMF平台中使用手指刺血样本进行快速新生儿疾病筛查。
