Long-term DNA sample preservation requires balancing stability against degradation and microbial contamination, critical for biobanking, research, and forensic archives. Microbes (bacteria, fungi) secrete nucleases that break down DNA, while environmental factors like moisture and temperature accelerate decay. Effective strategies combine physical storage conditions, chemical protectants, and contamination-control protocols to maintain DNA integrity for years to decades.
Core Preservation & Protection Methods
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Cryopreservation: Storing samples at -80°C (freezers) or -196°C (liquid nitrogen) halts microbial growth and enzymatic activity. Ideal for high-value samples but requires specialized equipment.
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Dry Preservation: Using desiccants (silica gel) or matrices like FTA cards to remove moisture, inhibiting microbial proliferation. Enables room-temperature storage for dried blood/spit samples.
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Chemical Protectants: Adding EDTA (nuclease inhibitor), ethanol, or commercial preservatives to liquid samples to suppress microbes and prevent hydrolysis.
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Sterile Handling: Aseptic techniques (gloves, sterile tools) during collection/processing reduce initial microbial load, preventing contamination before storage.
Key Features
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Microbial Inactivation: Methods target microbe growth and nuclease activity to avoid DNA breakdown.
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Environment Control: Regulates temperature/moisture to slow chemical degradation pathways.
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Cost-Efficiency: Dry preservation offers low-cost, low-maintenance storage vs. cryopreservation.
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Sample Versatility: Works for liquid (blood, saliva), solid (tissue), and environmental DNA samples.
Scope & Applications
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Biobanking: Long-term storage of human/animal DNA for clinical research and personalized medicine.
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Forensics: Archiving crime scene DNA evidence for cold case investigations and legal proceedings.
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Environmental Science: Preserving eDNA samples from soil/water for biodiversity monitoring over time.
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Agriculture: Storing crop/livestock DNA for breeding programs and pathogen resistance research.