Li Jinfeng, Nemati Zahra, Haddadi Kamel, Wallace Douglas C, Burke Peter J
Department of Physics and Astronomy, University of California, Irvine, Irvine, CA 92697, USA.
Integrated Nanosystems Research Facility, University of California, Irvine, Irvine, CA 92697, USA.
IEEE MTTS Int Microw Symp. 2018 Jun;2018:115-118. doi: 10.1109/MWSYM.2018.8439645. Epub 2018 Aug 20.
We demonstrate imaging using scanning microwave microscopy (SMM) of vital mitochondria in respiration buffer. The mitochondria are isolated from cultured HeLa cells and tethered to a solid graphene support. The mitochondria are kept vital (alive) using a respiration buffer, which provides nutrients to sustain the Krebs cycle. We verify that the mitochondria are "alive" by measuring the membrane potential using a voltage sensitive fluorescent dye (TMRE). The organelles are measured capacitively at 7 GHz. Several technical advances are demonstrated which enable this work: 1) The SMM operates in an electrophysiologically relevant liquid (hence conducting) environment; 2) The SMM operates in tapping mode, averaging the microwave reflection measurement over many tapping periods; 3) A tuned reflectometer enables increased sensitivity; 4) Variable frequencies up to 18 GHz are used; 5) In contrast with traditional matching/resonant methods that exhibit high quality factor that fail in the presence of liquids, interferometric/tuned reflectometer gives the possibility to adjust the quality factor or sensitivity even in the presence of the liquid.
我们展示了在呼吸缓冲液中对活线粒体进行扫描微波显微镜（SMM）成像的方法。线粒体从培养的HeLa细胞中分离出来，并固定在固体石墨烯载体上。使用呼吸缓冲液使线粒体保持活性（存活），该缓冲液提供营养物质以维持克雷布斯循环。我们通过使用电压敏感荧光染料（TMRE）测量膜电位来验证线粒体是“存活的”。在7吉赫兹频率下对细胞器进行电容测量。展示了实现这项工作的多项技术进展：1）SMM在电生理相关的液体（因此具有导电性）环境中运行；2）SMM以轻敲模式运行，在多个轻敲周期内对微波反射测量进行平均；3）调谐反射计提高了灵敏度；4）使用高达18吉赫兹的可变频率；5）与传统的匹配/谐振方法不同，传统方法在存在液体时会出现高品质因数失效的情况，干涉测量/调谐反射计即使在有液体的情况下也能调整品质因数或灵敏度。
