Fixation-Induced Aldehyde Fluorescence

Symptom

Strong blue-green autofluorescence haze in formalin or glutaraldehyde-fixed tissues. Background increases with fixation duration and disproportionately contaminates lower-wavelength channels. Amplified by paraffin embedding and overfixation.

1. 1 Aldehyde crosslinks generate fluorescent adducts
2. 2 Prolonged fixation time
3. 3 Use of glutaraldehyde or high-concentration formaldehyde
4. 4 Drop-fixation after perfusion (overshooting)
5. 5 Paraffin embedding process

1. 1 Minimize fixation time to preserve morphology and epitopes only
2. 2 Use non-aldehyde fixatives when possible
3. 3 Avoid drop-fixation after perfusion
4. 4 Apply 0.1 M glycine in PBS or 0.1 M Tris for ~30 min at RT to bind free aldehydes
5. 5 Use sodium borohydride (NaBH₄) conservatively only if glycine/Tris insufficient
6. 6 For snap-frozen tissue, limit drop-fix duration to minimum needed

Related Video (2)

Current Protocols ★ 85

Deciding on an Approach for Mitigating Autofluorescence

"Directly addresses autofluorescence mitigation strategies and panel optimization, core to understanding and preventing fixation-induced aldehyde fluorescence"

JoVE (Open Access) ★ 78

Measuring Interactions between Fluorescent Probes and Lignin in Plant Sections by sFLIM Based on Native Autofluorescence

"Demonstrates measurement of native autofluorescence in plant tissue sections, providing practical context for detecting and characterizing tissue autofluorescence background"