Raman Research Institute, Bangalore, INDIA.
PLoS One. 2022 Apr 20;17(4):e0267207. doi: 10.1371/journal.pone.0267207. eCollection 2022.
Physical parameters of the pathogenic cells, like its volume, shape, and stiffness, are important biomarkers for diseases, chemical changes within the cell, and overall cell health. The response of pathogenic bacteria and viruses to different chemical disinfectants is studied widely. Some of the routinely employed techniques to measure these changes require elaborate and expensive equipment which limits any study to a non-mobile research lab facility. Recently, we showed a micropore-based electro-fluidic technique to have great promise in measuring subtle changes in cell volumes at high throughput and resolution. This method, however, requires commercial amplifiers, which makes this technique expensive and incompatible for in-field use. In this paper, we develop a home-built amplifier to make this technique in-field compatible and apply it to measure changes in bacterial volumes upon exposure to alcohol. First, we introduce our low-cost and portable transimpedance amplifier and characterize the maximum range, absolute error percentage, and RMS noise of the amplifier in the measured current signal, along with the amplifier's bandwidth, and compared these characteristics with the commercial amplifiers. Using our home-built amplifier, we demonstrate a high throughput detection of 1300 cells/second and resolve cell diameter changes down to 1 μm. Finally, we demonstrate measurement of cell volume changes in E. coli bacteria when exposed to ethanol (5% v/v), which is otherwise difficult to measure via imaging techniques. Our low-cost amplifier (100-fold lower than commercial alternatives) is battery-run, completely portable for point-of-care applications, and the electro-fluidic devices are currently being tested for in-field applications.
病原体细胞的物理参数，如体积、形状和硬度，是疾病、细胞内化学变化和整体细胞健康的重要生物标志物。人们广泛研究了病原体细菌和病毒对不同化学消毒剂的反应。一些常用的测量这些变化的技术需要复杂且昂贵的设备，这限制了任何研究只能在非移动研究实验室设施中进行。最近，我们展示了一种基于微孔的电动流体技术，该技术在高通量和高分辨率下测量细胞体积的细微变化方面具有很大的潜力。然而，这种方法需要商业放大器，这使得该技术昂贵且不适合现场使用。在本文中，我们开发了一种自制的放大器，使该技术能够在现场兼容，并将其应用于测量细菌在暴露于酒精时体积的变化。首先，我们介绍了我们的低成本、便携式跨阻放大器，并对放大器在测量电流信号中的最大范围、绝对误差百分比和 RMS 噪声进行了特性描述，以及放大器的带宽，并将这些特性与商业放大器进行了比较。使用我们自制的放大器，我们实现了高达 1300 个细胞/秒的高通量检测，并能够分辨出直径变化低至 1μm 的细胞。最后，我们证明了当大肠杆菌暴露于乙醇（5%v/v）时，细胞体积的变化可以通过我们的方法来测量，而通过成像技术则很难测量。我们的低成本放大器（比商业替代品低约 100 倍）由电池供电，完全便携，适用于即时护理应用，目前正在对电动流体设备进行现场应用测试。
