Western blot: faint bands

1. Ranked causes

   1. Primary antibody under-concentrated or partially degradedFresh aliquot or richer dilution strengthens the band; loading control unchanged.
   2. Low antigen load or over-diluted lysateLoading control also faint; increasing µg/lane restores signal proportionally.
   3. Transfer incomplete for this MW (time/voltage/buffer)Residual target stain remains in the gel after transfer.
   4. Substrate or exposure under-poweredLonger exposure or fresh ECL raises signal without new background.

2. Recovery steps

   1. Increase protein load (e.g. toward 30 µg/lane) and re-check loading controlConfirms whether the issue is amount versus detection chemistry.
   2. Use a fresher primary aliquot or increase antibody concentration one stepPartial degradation presents as uniformly faint specific bands.
   3. Extend transfer or raise voltage within membrane limits; confirm with PonceauIncomplete transfer selectively weakens some MW ranges.
   4. Lengthen exposure or replace ECL substrateUnder-detection is quick to rule in/out.

3. Controls first

   • Is the loading-control / positive-control band also faint?If yes: Load, transfer, or global detection — not target-specific biology alone.

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