All Bands Including Ladder Faint or Absent (Western Blot (Detection Problems))

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All bands on the blot, including the molecular weight ladder, are difficult to see or completely absent, indicating a systemic technical problem rather than target-specific detection failure. Common causes: 1) Ineffective protein transfer due to incorrect transfer direction or improper PVDF membrane preparation (not pre-soaked in methanol then transfer buffer) 2) Excessive washing between steps removing detection reagents 3) Bacterial contamination in wash or incubation buffers from airborne spores or fibers 4) Reagent loss of activity from improper storage, excessive freeze-thaw cycles, or fluorophore light damage 5) Wrong filter settings for detection wavelengths or insufficient exposure time during imaging Solutions: 1) Verify successful transfer using reversible stain (Ponceau S) before immunostaining; ensure SDS-negative charged proteins transfer toward positive electrode 2) Reduce washing duration or number of steps to retain detection reagents 3) Use fresh sterile buffer (e.g., sterile PBS) for all steps 4) Store fluorophores and conjugated antibodies in dark (wrap in foil); avoid excessive freeze-thaw cycles 5) Set correct wavelength filters on instrument; optimize exposure time with longer durations