Characterization and minimization of cellular autofluorescence in the study of oligonucleotide uptake using confocal microscopy.

Intrinsic autofluorescent signals can interfere with extrinsic fluorophore signals when living cells are viewed under a confocal laser scanning microscope. The general pattern of this endogenous fluorescence is initially diffuse and cytoplasmic, but it can redistribute and intensify to become punctate and perinuclear as cells age. To reduce the contribution of autofluorescence when tracking the location of an extrinsic fluorophore, such as a fluorescently-labeled oligonucleotide, laser power settings, aperture settings, laser scanning rates, pH buffering environments, and excitatory wavelengths can be modulated. Decreasing laser power settings and aperture sizes, increasing laser scanning rates and excitatory wavelengths, and surrounding cells in a pH buffer all act to delay the signal transformation. In addition, the presence of an exogenous fluorophore can hasten the autofluorescent redistribution and intensification when compared to similar untreated cells.