Weak bands (faint signal) (Western Blot)

Question

Accepted Answer

Bands are visible but barely detectable; long exposure times are needed, and the internal control also appears weak. Common causes: 1) Insufficient protein loading 2) Primary or secondary antibody concentration too low 3) Target protein is naturally low-abundance 4) Incomplete transfer of high-MW proteins 5) Exposure time too short or low-sensitivity ECL Solutions: 1) Increase loading or concentrate samples by TCA / acetone precipitation 2) Increase antibody concentration or extend incubation (overnight at 4 C) 3) Optimize transfer time/current; for >100 kDa proteins, extend transfer or use semi-dry with lower voltage 4) Extend exposure or switch to high-sensitivity ECL (e.g., SuperSignal West Femto) 5) Verify target expression in your sample by qPCR or use a positive control lysate