It may be simple to swab a cheek or collect saliva for human DNA or RNA but that doesn’t mean there isn’t a level of complexity in selecting the right tool for forensics and genetics sample collection. For the most accurate results, it is critical that researchers select a DNA swab that reduces the risk of contamination from other sources of DNA or RNA, including the swab material itself.
Researchers and diagnostic companies rely on Puritan Medical Products for our sterile, easy-to-use, non-invasive swabs. These sterile DNA swabs come in many different shapes and sizes. We've outlined three of the most widely-used types in the field today to help you determine which DNA swab will best meet the needs of your specific application.
The types of DNA swabs
DNA testing for forensic or genetic analysis is only as effective as the sample collection method and swab type used. The use of DNA free or DNA controlled swabs limits the risk of contamination from the collection swab. Add to this an appropriate transport device, and individuals performing sampling can be confident in their results’ accuracy.
Puritan® DNA controlled swabs are manufactured in a DNA controlled and monitored clean room environment. While these manufacturing practices boost testing accuracy, there are other swab material considerations to factor in for unique applications. Below we outline the best applications for cotton, foam and flocked DNA swabs.
Cotton DNA swabs
Cotton swabs are widely used in the field of DNA sampling, for both forensics and human genetics applications. Due to their versatility and affordability, cotton swabs are a leading choice for many police department forensic labs. In addition, the medical-grade cotton used in Puritan swabs is ideal for buccal sampling, as it creates just the right friction to release the buccal cells from the inner cheek while remaining soft enough to be non-invasive.
The quality of DNA achieved from this diagnostic is ideal for many downstream applications. Diagnostic technicians may choose to cut the tip of the swab into a vial or to elute the sample into a buffer. These swabs are sterile and, to best suit your workflow, can be acquired in single or multiple swab pouches.
Here are a few of Puritan’s most popular cotton swabs for forensics and genetic applications:
- Cap-Shure 6" sterile standard cotton swab and protective cap with wooden handle is very popular for buccal sampling, evidence collection, and DNA testing. Why? Because it comes as a standalone unit, with a reclosable, ventilated cap that allows for air drying, minimizing the risk of contamination during transport.
- Fab-Swab 5" sterile DNA-controlled mini-tip cotton swab with wood handle and tube features a patented tube design with a breathable filter that covers holes to prohibit the introduction of mold spores or other airborne material.
Foam DNA swabs
A buccal swab, also known as a buccal cheek swab, is a fast, non-invasive, and relatively comfortable way to gather genetic material for forensic or genetic analysis. Due to their high particle collection capacity and soft tips, medical grade foam-tipped swabs are generally the most popular swab for buccal cell collection. A soft foam swab can be rubbed in the cheek pocket to secure a high-quality DNA sample. To release the sample, simply elute the swab into a buffer of your choice.
Foam swabs come in several varieties to accommodate larger (adult) or smaller (pediatric) surfaces. A few of the most popular Puritan foam swabs for genetic sampling include:
- 5" sterile large round foam swab with polypropylene handle features medical grade foam. The round, foam tipped head offers a large surface area for effective collection of DNA samples.
- 6" sterile small diameter foam swab with tapered acetal handle features a smaller tip to minimize patient discomfort in forensics and genetics applications.
Flocked DNA swabs
Genetic researchers and forensics investigators dealing with a small sample size and looking for a superior alternative to standard cotton or foams swab, may benefit from the use of flocked swabs. Puritan’s patented flocked swabs have been adopted in the field of forensics and genetics due to the unique design of their micro-structure. This structure results in flock fibers with superior collection and elution properties, even when cell counts are limited, compared to cotton or foam swabs.
Flocked swabs have proven gentle enough for DNA or paternity testing on newborns who may or may not have yet developed salivary glands. These polyester fibers’ uniquely designed structure can gently collect the buccal and/or saliva cells within the mouth for better cell yield.
A few of the most popular Puritan flock swabs for genetic and forensics sample collection include:
- PurFlock Ultra 6" sterile DNA-free standard flock swab with plastic handle and tube is a popular choice in DNA collection for forensic applications.
- HydraFlock 6" sterile straight flock swab with extruded polystyrene handle features a pre-molded 30mm breakpoint that allows it to easily snap off into a transport vial. These swabs are used in both forensics evidence collection and DNA testing.
- Cap-Shure 6" sterile elongated HydraFlock swab and protective cap with polystyrene handle has proven popular for use in the field and home testing due to its aerated cap that protects the specimen from potential cross-contamination.
Tips for choosing the right DNA swab
Puritan Medical Products is here to ensure we provide you with the right swab for your workflow. To help us prepare, please think about:
- How old are your donors? This will guide the selection of the appropriate swab size and material for patient comfort, as a smaller swab size may be most appropriate for pediatric patients.
- How much DNA does your application require? As test sensitivity can vary, a larger sample is generally preferred to ensure enough material is available for accurate results. This is not possible in all cases, as the swab should first address the comfort of the donor. However, some applications may demand a larger sample size. For example, a large round foam swab can be useful for collecting buccal cell samples for criminal cases, as this large swab tip can be cut to provide two separate samples, one for the prosecution and one for the defense, or one for immediate processing and one for backup.
- Is this for self-collection or assisted collection? For assisted collection, the available method of transport and/or extraction will dictate which swab is used. For self-collection, it is often easier to use a longer handled, large tip swab. This may vary depending on the donor’s age. Generally with self-collection the swab may need to be slipped back into a paper wrapper or aerated protective cap where the swab can fully dry.
- Will this swab be part of a kit? And, if the swab is for a kit, is a single or double pack desired? Most kits are single pack, even if the kit allows for multiple collections and includes a number of swabs. However, some collection applications require the use of two swabs at once. One example is pharmacogenetic applications, where a patient monitors their own state by providing a two-swab specimen, collected in one step to save them the process of swabbing twice. A double transport tube would be most appropriate for this application.
- Do you require a nucleic acid stabilization buffer? Transport medium is needed in applications where specimen integrity is essential. For example, a preservation medium is needed to ensure DNA integrity for diagnostic testing. However, if the DNA swab is used for identification only, and is allowed to dry before storage or transport, the sample will not degrade and a transport medium is not required.
- Will these samples be in transport? Not all DNA swabs will require transport. DNA swabs are often dried for home storage, such as use within a Child Safe ID kit. In other cases, a DNA sample may be collected by a practitioner, technician, or researcher with extraction capabilities who can send the sample directly to assay. However, samples being taken for diagnostic testing will need to be fine-dried and transported in an envelope or swab box designed for the safe transport of DNA specimens.
These tips can help guide you in selecting the right tools for your specific application, but the Puritan Medical team is always available to answer questions. Don’t hesitate to contact us for guidance at any time. sample collection guide today!