DNA cards are specially treated pieces of paper designed for the straightforward collection, long-term storage, and transport of biological samples containing genetic material. These cards offer a practical solution for preserving DNA at room temperature, eliminating the need for refrigeration. They serve as a stable medium for genetic information, allowing for future analysis without immediate processing. The technology behind DNA cards provides a simple and cost-effective way to manage biological specimens.
How DNA Cards Preserve Genetic Material
DNA cards are made from an absorbent cellulose paper impregnated with a chemical mixture. This proprietary blend contains reagents that work to lyse, or break open, cells immediately upon contact, releasing the DNA within. The chemicals also denature proteins, including enzymes called nucleases that would otherwise degrade the DNA molecules.
The treated paper also incorporates antimicrobial agents, such as nano-silver solution, to prevent the growth of bacteria and fungi that could compromise the sample’s integrity. This chemical action immobilizes the DNA within the paper’s fibers, protecting it from environmental damage like oxidation and UV light. DNA stored on these cards can remain stable for years at ambient temperatures, making them suitable for situations where cold storage is impractical.
Common Uses for DNA Cards
DNA cards have found widespread application due to their convenience and stability. One foundational use is in newborn screening programs, where they are often referred to as “Guthrie cards”. A few drops of blood collected from a newborn’s heel are spotted onto these cards to screen for metabolic and genetic disorders, enabling early diagnosis.
Forensic science utilizes DNA cards for collecting and preserving biological evidence at crime scenes. Samples like blood or saliva can be applied directly to the card, which then stabilizes the DNA for transport to a laboratory, simplifying the handling of potentially infectious or sensitive materials. This method ensures that valuable genetic evidence remains intact for later analysis, even from minute samples.
DNA cards are also widely used in scientific research and biobanking, particularly for large-scale genetic studies and field collections. Their ability to preserve DNA at room temperature makes them ideal for gathering samples in remote locations where access to freezers is limited. Biobanks use these cards to store vast collections of genetic material from diverse populations, facilitating research into genetic diseases and human identification.
The DNA Collection and Analysis Process
Collecting a sample on a DNA card is a straightforward procedure designed for ease of use. A biological sample, such as a drop of blood from a heel prick or a buccal (cheek) swab, is applied directly onto a designated circle on the card. For blood, typically a volume of 50 to 125 microliters is sufficient to fill a spot. Once the sample is applied, it is allowed to air dry completely at room temperature, usually for several hours. After drying, the card is ready for transport to a laboratory.
In the lab, a small circular disk, often called a “punch,” is taken from the dried sample spot using a specialized tool. This punch, which contains the immobilized DNA, can then be processed directly for analysis. The punch is washed to remove inhibitors and then added to a Polymerase Chain Reaction (PCR) mixture. PCR amplifies specific regions of the DNA, creating millions of copies, which are then ready for genetic testing or sequencing.