Faculty of Electrical Engineering, K. N. Toosi University of Technology, Tehran, 1631714191, Iran; Department of Physics, Umeå University, Umeå, 901 87, Sweden.
Department of Physics, Umeå University, Umeå, 901 87, Sweden.
Biosens Bioelectron. 2023 Jul 1;231:115284. doi: 10.1016/j.bios.2023.115284. Epub 2023 Mar 31.
Bacterial spores are problematic in agriculture, the food industry, and healthcare, with the fallout costs from spore-related contamination being very high. Spores are difficult to detect since they are resistant to many of the bacterial disruption techniques used to bring out the biomarkers necessary for detection. Because of this, effective and practical spore disruption methods are desirable. In this study, we demonstrate the efficiency of a compact microfluidic lab-on-chip built around a coplanar waveguide (CPW) operating at 2.45 GHz. We show that the CPW generates an electric field hotspot of ∼10 kV/m, comparable to that of a commercial microwave oven, while using only 1.2 W of input power and thus resulting in negligible sample heating. Spores passing through the microfluidic channel are disrupted by the electric field and release calcium dipicolinic acid (CaDPA), a biomarker molecule present alongside DNA in the spore core. We show that it is possible to detect this disruption in a bulk spore suspension using fluorescence spectroscopy. We then use laser tweezers Raman spectroscopy (LTRS) to show the loss of CaDPA on an individual spore level and that the loss increases with irradiation power. Only 22% of the spores contain CaDPA after exposure to 1.2 W input power, compared to 71% of the untreated control spores. Additionally, spores exposed to microwaves appear visibly disrupted when imaged using scanning electron microscopy (SEM). Overall, this study shows the advantages of using a CPW for disrupting spores for biomarker release and detection.
细菌孢子在农业、食品工业和医疗保健领域都是一个问题，其与孢子相关的污染所造成的后果代价非常高。由于孢子具有很强的抗性，能够抵御许多用于提取检测所需生物标志物的细菌破坏技术，因此很难被检测到。正因如此，人们希望能有一种有效且实用的孢子破坏方法。在本研究中，我们展示了一种围绕工作在 2.45GHz 的共面波导（CPW）构建的紧凑型微流控片上实验室的效率。我们表明，CPW 产生的电场热点约为 10kV/m，与商用微波炉相当，而仅使用 1.2W 的输入功率，从而导致样品加热可忽略不计。通过微流道的孢子会被电场破坏，并释放出钙二吡咯酸（CaDPA），这是一种存在于孢子核心中的与 DNA 并存的生物标志物分子。我们表明，使用荧光光谱法可以在散装孢子悬浮液中检测到这种破坏。然后，我们使用激光镊子拉曼光谱（LTRS）来证明单个孢子水平上 CaDPA 的损失，并且损失随辐照功率的增加而增加。与未经处理的对照孢子相比，在暴露于 1.2W 输入功率后，只有 22%的孢子含有 CaDPA。此外，用扫描电子显微镜（SEM）成像时，暴露于微波中的孢子看起来明显被破坏。总的来说，这项研究表明了使用 CPW 破坏孢子以释放和检测生物标志物的优势。
