Multiwavelength Microflow Cytometer

摘要

Fluorescence-based flow cytometry dates back to the 1960s. Essentially, cells or particles are aligned in a flow stream and optically interrogated. Size, density, and fluorescence at multiple wavelengths can be quantified. In many cases, tags, such as fluorescently labeled antibodies, are mixed with the samples prior to analysis so that specific targets or cell functions can be identified. Currently, large, complex, laboratory- based flow cytometers are required to perform medical diagnostics, such as white blood cell counts and immunoassays to detect infection, or for environmental monitoring applications, such as classification of marine algae. In the traditional design, the sample containing the particles or cells is pumped out of a small tube into a much larger, concentric pipe that is carrying filtered water. This hydrodynamic focusing puts all the particles into the center of the wider 'sheath' stream, which then is tapered to a smaller diameter. The particles are thus 'focused' and pass single-file through the laser beams for analysis. Over the last decade, flow cytometers have become smaller in size and less expensive, but this sheath flow design is not amenable to miniaturization to the point that the systems are portable. NRL's Center for Bio/Molecular Science and Engineering has developed a microfluidic sheath flow system that is robust, simple to fabricate, and very compact. This sheath flow device forms the basis of a microflow cytometer that has demonstrated the capability for 4- color analysis that is competitive with the larger, commercial systems.