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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) ★ 85
Primer Design: Important Considerations and Tips for Good Primer Design
"Directly addresses primer design considerations and tips, which is the root cause of the false positive contamination issue from self-complementary primers"
Addgene ★ 78
How to Design Primers for PCR
"Focuses on primer design methodology for PCR, enabling researchers to avoid designing primers with complementary sequences that cause self-oligomerization"
Addgene ★ 72
Polymerase Chain Reaction (PCR) Protocol
"Comprehensive PCR protocol demonstration showing proper technique execution, helping identify where contamination control and primer validation fit into the experimental workflow"
Source: thermofisher.com ↗
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