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PCR (Invitrogen Guide) critical

False Positive Amplification from Contamination

Symptom
PCR products appear in negative control reactions without template. Products may appear in samples expected to be negative.
Common Causes
  1. 1 Primers containing complementary sequences causing self-oligomerization and amplification
  2. 2 Crossover contamination of DNA in work environment
  3. 3 Carryover contamination from previous PCR products
  4. 4 Non-dedicated pipettes or work areas spreading amplicons
Solutions
  1. 1 Redesign primers avoiding complementary and self-complementary sequences that favor primer-dimer formation
  2. 2 Follow general PCR setup recommendations; dedicate separate work area and decontaminate after each use
  3. 3 Use pipette tips with aerosol barriers for all pipetting steps
  4. 4 Implement dUTP incorporation with UDG treatment for carryover control
  5. 5 Maintain separate pre-PCR and post-PCR areas with dedicated equipment
Related Video (3)
YouTube (Curated Tutorials) ★ 88
Primer Design: Important Considerations and Tips for Good Primer Design
"Directly addresses primer design considerations and tips, which is the root cause of false positive amplification from self-complementary primer sequences"
Addgene ★ 82
How to Design Primers for PCR
"Covers primer design fundamentals for PCR, essential for understanding how to avoid complementary sequences that cause self-oligomerization and false amplification"
Addgene ★ 71
Polymerase Chain Reaction (PCR) Protocol
"Provides complete PCR protocol walkthrough that demonstrates proper technique execution and control setup to prevent contamination-related false positives"
Source: thermofisher.com ↗
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