Understanding the interaction between macrophage cells and Bacillus anthracis spores is of significant importance with respect to both anthrax disease progression, spore detection for biodefense, as well as understanding cell clearance in general. While most detection systems rely on specific molecules, such as nucleic acids or proteins and fluorescent labels to identify the target(s) of interest, label-free methods probe changes in intrinsic properties, such as size, refractive index, and morphology, for correlation with a particular biological event. Optical chromatography is a label free technique that uses the balance between optical and fluidic drag forces within a microfluidic channel to determine the optical force on cells or particles. Here we show an increase in the optical force experienced by RAW264.7 macrophage cells upon the uptake of both microparticles and B. anthracis Sterne 34F2 spores. In the case of spores, the exposure was detected in as little as 1 h without the use of antibodies or fluorescent labels of any kind. An increase in the optical force was also seen in macrophage cells treated with cytochalasin D, both with and without a subsequent exposure to spores, indicating that a portion of the increase in the optical force arises independent of phagocytosis. These results demonstrate the capability of optical chromatography to detect subtle biological differences in a rapid and sensitive manner and suggest future potential in a range of applications, including the detection of biological threat agents for biodefense and pathogens for the prevention of sepsis and other diseases.

中文翻译：

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使用分析光学力测量无标记检测巨噬细胞中炭疽芽孢杆菌的孢子摄取。

了解巨噬细胞与炭疽芽孢杆菌之间的相互作用孢子对于炭疽病的进展，用于生物防御的孢子检测以及一般地了解细胞清除都具有重要的意义。尽管大多数检测系统依靠特定分子（例如核酸或蛋白质和荧光标记物）来识别目标靶标，但无标记法可探测内在性质（例如大小，折射率和形态）的变化以实现相关性与特定的生物学事件有关。光学色谱法是一种无标记技术，它利用微流体通道内的光学和流体阻力之间的平衡来确定作用在细胞或颗粒上的光学力。在这里，我们显示了当摄取微粒和炭疽芽孢杆菌时，RAW264.7巨噬细胞经历的光学力增加。斯特恩34F2孢子。对于孢子，在不使用任何类型的抗体或荧光标记的情况下，仅需1小时即可检测到暴露。在用细胞松弛素D处理的巨噬细胞中，无论是否暴露于孢子下，光力也都增加了，这表明光力增加的一部分是独立于吞噬作用而产生的。这些结果证明了光学色谱法能够以快速和灵敏的方式检测细微的生物学差异，并暗示了其在一系列应用中的潜在潜力，包括检测生物防御的生物威胁剂和预防败血症和其他疾病的病原体。