Use of fluorescent europium chelates as labels in microscopy allows glutaraldehyde fixation and permanent mounting and leads to reduced autofluorescence and good long‐term stability

Abstract

In the present study europium chelates were introduced as alternative fluorescent labels for microscopy and their effect on enhanced autofluorescence caused by the glutaraldehyde fixative was investigated. Glutaraldehyde fixation was used to stabilize the cells for a permanent mount after the immunocytochemical reaction. The europium signal in time‐resolved fluorescence microscopy was shown to be free of autofluorescence when strong cross‐linking fixation with glutaraldehyde was used and the signal‐to‐background ratio obtained was 2,400 or better. It was also shown that the europium signal was stable in daylight and at room temperature. Fluorescent europium chelate used in this experiment provides excellent contrast and long‐term stability for the samples with glutaraldehyde fixation and permanent mounting.