Contrast agents for confocal microscopy: how simple chemicals affect confocal images of normal and cancer cells in suspension.

Normal and malignant human cervical cancer cells were imaged in vivo with confocal, phase contrast, and brightfield microscopies. Results were compared between cells in growth medium before and after addition of acetic acid, hypertonic saline solution, toluidine blue, and Lugol's iodine. The exogenous agents changed the backscattering characteristics of the cells when measured with confocal microscopy at 808 nm. A tendency toward higher scattering was observed in treated cells. Acetic acid and toluidine blue increased the brightness of the nucleus with respect to the cytoplasm in normal and cancer cells. Hypertonic saline solution made the cytoplasm brighter than the nucleus in both types of cells. The results indicate that simple chemicals can be used to enhance confocal microscopy's ability to differentiate intracellular components, such as nuclear size and shape. This can further confocal microscopy's ability to assess disease in cells and tissues.