Evaluating Pore Sizes of Biological Membranes with Fluorescent Microspheres
The application of a series of monodisperse fl uorescent microspheres to membrane pore-size evaluation is discussed. The microspheres are available in red, green and blue fl uorescent colors in a range of diameters from 25 nanometers to 3 micrometers. Particle retention and transmission can be monitored with an epifluorescence microscope or a fl uorescence spectrophotometer.
Once membranes are challenged with pairs of sizes and colors, the ratio of different colors upstream and downstream can be used as an indication of the membrane's particle retention properties. A case study is presented where fl uorescent spheres are used to evaluate changes in fenestral pores of rat liver.