Department of Chemical Engineering, College of Engineering, Kyung Hee University, 1 Seochon-dong, Giheung-gu, Yongin-si, Gyeonggi-do, 17140, Republic of Korea.
Sci Rep. 2020 Sep 15;10(1):15123. doi: 10.1038/s41598-020-72095-3.
The increasing risk of infectious pathogens, especially in the under-developed countries, is demanding the development of point-of-care (POC) nucleic acid testing in the low-resource setting conditions. Here, we describe a methodology for colorimetric quantitative analysis of nucleic acid using an easy-to-build smartphone-based platform, offering low-cost, portability, simplicity in operation, and user-friendliness. The whole system consists of a hand-held box equipped with a smartphone, a film heater, a white LED, a loop-mediated isothermal amplification (LAMP) chip, and a DC converter, and all the processes were powered by a portable battery of 5 V. Upon the amplification of the target gene by an Eriochrome Black T-mediated LAMP reaction, the color of the LAMP reaction was changed from violet to blue that was real-time recorded by a smartphone camera. To keep track of the progress of the color change, we developed a novel mobile app in which a hue value was accepted as an indicator for color transition and for determining the threshold time of the amplification reaction. A calibration curve could be generated by plotting the logarithm of the known concentration of the DNA templates versus the threshold time, and it can be used to predict the copy number of nucleic acids in the test samples. Thus, the proposed mobile platform can inform us of not only qualitative but also quantitative results of the pathogens. We believe that this advanced colorimetric approach and the mobile app can expand the potentials of the smartphone for the future POCT system in the bio-diagnostic fields.
在欠发达地区，传染性病原体的风险不断增加，这就要求在资源有限的环境下开发即时检测（POC）核酸检测技术。在这里，我们描述了一种使用易于构建的基于智能手机的平台进行核酸比色定量分析的方法，该方法具有低成本、便携性、操作简单和用户友好等特点。整个系统由一个配备有智能手机、薄膜加热器、白色 LED、环介导等温扩增（LAMP）芯片和 DC 转换器的手持盒组成，所有过程均由 5V 便携式电池供电。在靶基因通过 Eriochrome Black T 介导的 LAMP 反应扩增后，LAMP 反应的颜色从紫色变为蓝色，智能手机摄像头实时记录颜色变化。为了跟踪颜色变化的进展，我们开发了一种新型移动应用程序，其中色调值被接受为颜色转换的指示符，并用于确定扩增反应的阈值时间。通过绘制已知 DNA 模板浓度的对数与阈值时间的关系，可以生成校准曲线，并用于预测测试样品中核酸的拷贝数。因此，该移动平台不仅可以提供定性结果，还可以提供病原体的定量结果。我们相信，这种先进的比色方法和移动应用程序可以扩展智能手机在生物诊断领域未来 POCT 系统中的潜力。
