Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Japan.
Lab Chip. 2019 Aug 21;19(16):2678-2687. doi: 10.1039/c9lc00370c. Epub 2019 Jul 17.
Droplet-based digital bioassays enable highly sensitive and quantitative analysis of biomolecules, and are thought to be suitable for point-of-care diagnosis. However, digital bioassays generally require fluorescence microscopy for detection, which is too large for point-of-care testing. Here, we developed a simple smartphone-based mobile imaging platform for digital bioassays. The size of the mobile imaging platform was 23 × 10 × 7 cm (length × width × height). With this platform, a digital enzyme assay of bovine alkaline phosphatase was successfully completed. Digital influenza virus counting-based on a fluorogenic assay for neuraminidase activity of the virus-was also demonstrated. Distinct fluorescence spots derived from single virus particles were observed with the mobile imaging platform. The number of detected fluorescence spots showed good linearity against the virus titer, suggesting that high sensitivity and quantification were achieved, although the imaging with the mobile platform detected 60% of influenza virus particles that were identified with conventional fluorescence microscopy. The lower detection efficiency is due to its relatively lower signal-to-noise ratio than that found with conventional microscopes, and unavoidable intrinsic heterogeneity of neuraminidase activity among virus particles. Digital influenza virus counting with the mobile imaging platform still showed 100 times greater sensitivity than that with a commercial rapid influenza test kit. Virus detection of clinical samples was also successfully demonstrated, suggesting the potential to realize a highly sensitive point-of-care system for influenza virus detection with smartphones.
基于液滴的数字生物分析可实现对生物分子的高灵敏度和定量分析，被认为适用于即时诊断。然而，数字生物分析通常需要荧光显微镜进行检测，这对于即时诊断来说过于庞大。在这里，我们开发了一种简单的基于智能手机的移动成像平台，用于数字生物分析。该移动成像平台的尺寸为 23×10×7cm（长×宽×高）。利用该平台，成功完成了基于牛碱性磷酸酶的数字酶分析。还展示了基于病毒神经氨酸酶活性的荧光法数字流感病毒计数。利用移动成像平台观察到源自单个病毒粒子的明显荧光斑点。检测到的荧光斑点数量与病毒滴度呈良好的线性关系，表明实现了高灵敏度和定量分析，尽管移动平台的成像检测到了与传统荧光显微镜识别的流感病毒粒子的 60%。较低的检测效率是由于其信号与噪声比相对低于传统显微镜，以及病毒粒子之间神经氨酸酶活性不可避免的固有异质性。移动成像平台的数字流感病毒计数的灵敏度仍比商业快速流感测试试剂盒高 100 倍。还成功地对临床样本进行了病毒检测，表明有可能利用智能手机实现高灵敏度的即时流感病毒检测系统。
