Label-free smartphone quantitation of bacteria by darkfield imaging of light scattering in fluoropolymer micro capillary film allows portable detection of bacteriophage lysis
Label-free smartphone quantitation of bacteria by darkfield imaging of light scattering in fluoropolymer micro capillary film allows portable detection of bacteriophage lysis
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DOI：
10.1016/j.snb.2020.128645
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发表时间：
2020-11-15
影响因子：
8.4
通讯作者：
Edwards, Alexander D.
中科院分区：
文献类型：
--
作者：
Donmez, Sultan Ilayda;Needs, Sarah H.;Edwards, Alexander D.
传统的细菌检测和定量方法是缓慢的，费力的，需要实验室。微流体系统提供更快和便携式的测试，智能手机摄像头可以记录比色或荧光生物测定，但这需要添加染料。在这里，我们首次展示了通过暗场微流体成像来测量细菌和噬菌体裂解的细菌光散射的无标记智能手机检测。单个LED和便携式3D打印成像盒允许通过细菌光散射的直接成像来测量细菌浓度和生长。在由熔融挤出的含氟聚合物微毛细管膜制成的10通道微流体装置内检测噬菌体裂解，从而允许快速检测宿主特异性。消除不必要的反射和优化照明角度对于成功的暗场细菌成像至关重要，15度可提供最大强度。在微流体装置内直接观察到细菌沉降，通过允许细菌沉降30分钟，检测灵敏度显著提高。使用这种简单，低成本的3D打印系统，可以测量光密度低至0.1的细菌浓度，对应于每个微装置8 × 10（4）菌落形成单位（CFU），接近传统细菌计数器的灵敏度。可以在一系列起始细胞浓度下检测到噬菌体裂解。在低起始细胞浓度的情况下，在噬菌体存在下防止了光散射信号随孵育的增加。相反，在高起始细胞浓度的情况下，当加入噬菌体时，在开始时检测到的光散射信号被清楚地消除，表明这种简单的系统允许直接可视化噬菌体，从而通过裂解消除光散射。
Conventional methods for the detection and quantitation of bacteria are slow, laborious and require a laboratory. Microfluidic systems offer faster and portable testing, and smartphone cameras can record colorimetric or fluommetric bioassays, but this requires dye addition. Here, we demonstrate for the first time label-free smartphone detection of bacterial light scattering by darkfield micmfluidic imaging to measure bacteria and bacteriophage lysis. A single LED and portable 3D printed imaging box allowed bacterial concentration and growth to be measured by direct imaging of bacterial light scattering. Bacteriophage lysis was detected within a 10-channel microfluidic device made from melt-extruded fluoropolymer micro capillary film, allowing rapid detection of host specificity. Elimination of unwanted reflections and optimising illumination angle are critical for successful darkfield bacterial imaging, with 15 degrees giving maximal intensity. Bacterial sedimentation was directly observed within microfluidic devices, and detection sensitivity significantly increased by allowing bacteria to sediment for 30 min. With this simple, low-cost, 3D printed system bacterial concentrations down to an optical density of 0.1 could be measured corresponding to 8 x 10(4) colony forming units (CFU) per microdevice, approaching the sensitivity of conventional spectrophotometers. Bacteriophage lysis could be detected at a range of starting cell concentrations. With a low starting cell concentration, the increase in light scatter signal with incubation was prevented in the presence of bacteriophage. Conversely, with high starting cell concentration, the light scatter signal detected at the start was clearly eliminated when phage were added, indicating this simple system allows direct visualisation of bacteriophage eliminating light scattering by lysis.