No or Very Low Signal Due to Poor Plate Binding (ELISA (Signal Problems))

Question

Accepted Answer

No detectable signal or extremely weak signal in ELISA even when target protein is expected to be present. Signal may be inconsistent across wells. Common causes: 1) Target protein or antibody adsorbs poorly to the polystyrene plate surface 2) Epitope recognition is blocked when antigen is directly adsorbed to plate (direct or indirect ELISA) 3) Standard binding plates have insufficient surface chemistry for the specific protein 4) Small peptides lack sufficient contact points for stable plate adsorption Solutions: 1) Pre-treat wells with coating enhancers or blocking agents before adding target 2) Use plates with enhanced binding surfaces (e.g., high-binding or MaxiSorp plates) 3) Conjugate small peptides to large carrier proteins (e.g., BSA, KLH) before coating onto plate 4) Optimize coating buffer pH (typically pH 7.2-9.5) to maximize electrostatic interactions