Method and apparatus for imaging target components in a biological sample using permanent magnets

Abstract

A system for enumeration of cells in fluids by image cytometry is described for assessment of target populations such as leukocyte subsets in different bodily fluids or bacterial contamination in environmental samples, food products and bodily fluids. Briefly, fluorescently labeled target cells are linked to magnetic particles or beads. In one embodiment, a small, permanent magnet is inserted directly into the chamber containing the labeled cells. The magnets are coated with PDMS silicone rubber to provide a smooth and even surface which allows imaging on a single focal plane. The magnet is removed from the sample and illuminated with fluorescent light emitted by the target cells captured by a CCD camera. In another embodiment, a floater having a permanent magnet allows the target cells to line up along a single imaging plane within the sample solution. Image analysis can be performed with a novel algorithm to provide a count of the cells on the surface, reflecting the target cell concentration of the original sample.