The Ångström Laboratory, Department of Engineering Sciences , Uppsala University , Box 534, SE-751 21 Uppsala , Sweden.
MedTech West and the Institute of Neuroscience and Physiology , University of Gothenburg , SE-405 30 Göteborg , Sweden.
ACS Sens. 2019 Sep 27;4(9):2381-2388. doi: 10.1021/acssensors.9b00969. Epub 2019 Aug 22.
Assays are widely used for detection of various targets, including pathogens, drugs, and toxins. Homogeneous assays are promising for the realization of point-of-care diagnostics as they do not require separation, immobilization, or washing steps. For low concentrations of target molecules, the speed and sensitivity of homogeneous assays have hitherto been limited by slow binding kinetics, time-consuming amplification steps, and the presence of a high background signal. Here, we present a homogeneous differential magnetic assay that utilizes a differential magnetic readout that eliminates previous limitations of homogeneous assays. The assay uses a gradiometer sensor configuration combined with precise microfluidic sample handling. This enables simultaneous differential measurement of a positive test sample containing a synthesized target and a negative control sample, which reduces the background signal and increases the readout speed. Very low concentrations of targets down to femtomolar levels are thus detectable without any additional amplification of the number of targets. Our homogeneous differential magnetic assay method opens new possibilities for rapid and highly sensitive diagnostics at the point of care.
分析方法被广泛用于检测各种目标物，包括病原体、药物和毒素。均相分析方法有望实现即时诊断，因为它们不需要分离、固定或洗涤步骤。对于目标分子的低浓度，均相分析方法的速度和灵敏度迄今为止受到缓慢的结合动力学、耗时的扩增步骤和高背景信号的限制。在这里，我们提出了一种均相差分式磁分析方法，该方法利用差分式磁读出消除了均相分析方法的先前限制。该分析方法使用梯度计传感器配置结合精确的微流控样品处理。这使得同时对包含合成目标物的阳性测试样品和阴性对照样品进行差分测量成为可能，从而降低了背景信号并提高了读数速度。因此，即使没有对目标物数量进行任何额外的扩增，也可以检测到低至飞摩尔浓度的目标物。我们的均相差分式磁分析方法为即时诊断提供了快速、高灵敏度诊断的新可能性。
