Which treatment can minimize autofluorescence in fixed cells?

• A. Increase aldehyde fixation
• B. Wash with 0.1% sodium borohydride in PBS
• C. Use stronger light source
• D. Use higher pH buffer

Answer: (B)

Autofluorescence in fixed cells mainly comes from residual aldehyde groups left by fixation, which can form fluorescent adducts and raise background signals. A reducing quench with sodium borohydride converts those aldehydes to non-fluorescent alcohols, dramatically lowering background. Using 0.1% sodium borohydride in PBS is a standard, effective way to achieve this quenching without severely compromising antigen detection when used with appropriate timing. Increasing aldehyde fixation would add more fluorescent aldehyde groups, worsening autofluorescence. A stronger light source would increase, not reduce, background fluorescence. Adjusting the buffer pH alone does not reliably eliminate autofluorescence and can affect staining. Therefore, the sodium borohydride quenching step best minimizes autofluorescence.