Altamore Ilaria, Lanzano Luca, Gratton Enrico
Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, California.
Meas Sci Technol. 2013 Jun 1;24(6):65702. doi: 10.1088/0957-0233/24/6/065702.
We describe a novel method to detect very low concentrations of bacteria in water. Our device consists of a portable horizontal geometry small confocal microscope with large pinhole and a holder for cylindrical cuvettes containing the sample. Two motors provide a fast rotational and slow vertical motion of the cuvette so the device looks like a simplified flow cytometer without flow. To achieve high sensitivity the design has two detection channels. Bacteria are stained by two different nucleic acid dyes and excited with two different lasers. Data are analyzed with a correlation filter based on particle passage pattern recognition. The passage of a particle through the illumination volume is compared with a Gaussian pattern in both channels. The width of the Gaussian correlates with the time of passage of the particle so one particle is counted when the algorithm finds a match with a Gaussian in both channels. The concentration of particles in the sample is deduced from the total number of coincident hits and the total volume scanned. This portable setup provides higher sensitivity, low cost and it could have a wide use ranging from clinical applications to pollution monitors and water and air quality control.
我们描述了一种检测水中极低浓度细菌的新方法。我们的设备由一台带有大针孔的便携式水平几何小型共聚焦显微镜和一个用于放置装有样品的圆柱形比色皿的支架组成。两个电机为比色皿提供快速旋转和缓慢垂直运动，因此该设备看起来像一台简化的无流动流式细胞仪。为了实现高灵敏度，该设计有两个检测通道。细菌用两种不同的核酸染料染色，并用两种不同的激光激发。数据通过基于粒子通过模式识别的相关滤波器进行分析。在两个通道中，将粒子通过照明体积的情况与高斯模式进行比较。高斯曲线的宽度与粒子通过的时间相关，因此当算法在两个通道中都找到与高斯曲线匹配时，就会计数一个粒子。样品中粒子的浓度由同时命中的总数和扫描的总体积推导得出。这种便携式装置具有更高的灵敏度、低成本，并且可以广泛应用于从临床应用到污染监测以及水和空气质量控制等领域。
