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Western Blot (Sigma Protocol) minor

Black Spots on Membrane

Symptom
Random black spots or speckles appear on the western blot membrane
Common Causes
  1. 1 Blocking reagent has clumped and antibodies are binding to aggregates
  2. 2 Contaminating enzymes present in sample or blocking buffer
Solutions
  1. 1 Filter the blocking reagent before use
  2. 2 Filter the blocking buffer to remove particulates
Related Video (3)
Cell Signaling Technology ★ 92
Western Blot Troubleshooting Guide
"Directly addresses Western blot troubleshooting, the most relevant resource for diagnosing and understanding the black spots failure symptom."
Bilibili (China-Accessible Mirrors) ★ 78
Western blot hands-on: Protein extraction through detection
"Hands-on protocol with explicit emphasis on troubleshooting common pitfalls, directly applicable to blocking reagent aggregation issues."
Bilibili (China-Accessible Mirrors) ★ 76
Western Blot — Full Protocol Walkthrough (Bio-Techne)
"Complete protocol walkthrough covering blocking step and antibody incubation, key stages where reagent clumping manifests as artifacts."
Source: sigmaaldrich.com ↗
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