A saliva DNA collection card is generally composed of the following parts:

The Main Body of the Collection Card

• Paper – based Substrate: Usually, a special filter paper material, such as FTA filter paper, is used. This kind of filter paper has good water absorption and water – holding capacity. It can quickly absorb saliva samples, enabling the saliva to be evenly distributed on the filter paper. Moreover, it can stably preserve DNA for a long time. It also has a certain degree of strength and toughness, which is convenient for handling and storage, and is not easy to be damaged or deformed during the collection and subsequent processing.
• Polymer Material Coating: There is usually one or more layers of polymer material coatings on the paper – based substrate. These coatings can play various roles. For example, some coatings can help fix the DNA in saliva, preventing its degradation or loss during storage. Some coatings can inhibit the growth of microorganisms, avoiding damage to DNA by microorganisms. And some coatings can react with specific reagents during the subsequent DNA extraction process to assist in the separation and purification of DNA.

Auxiliary Structures

• Sample Identification Area: Located at a specific position on the collection card, it is used to fill in relevant information of the person being sampled, such as name, gender, age, collection time, sample number, etc. This helps to accurately distinguish and manage different samples, ensuring that there is no confusion during subsequent testing and analysis.
• Desiccant or Protective Agent: Some saliva DNA collection cards are equipped with desiccants or protective agents, which are generally packaged in small packages and sealed together with the collection card. The desiccant can absorb the moisture in the environment around the collection card, keeping the collection card in a dry state, which is beneficial to the long – term preservation of DNA. The protective agent can provide a more stable preservation environment for DNA, further preventing the degradation of DNA.

Packaging Materials

• Outer Packaging: It usually takes the form of a sealed bag or a sealed box. It is used to seal the collection card to prevent external moisture, dust, microorganisms, etc. from contaminating the collection card. The sealed bag or box generally has good moisture – proof, waterproof, and dust – proof properties, and may be equipped with a self – adhesive strip or a sealed cover for easy use and storage.

The specific composition of saliva DNA collection cards may vary depending on different brands and models, but generally, they all include the main components mentioned above to achieve functions such as saliva sample collection, DNA preservation, and subsequent testing and analysis.