Patent Issued for Sample Collection Device Suitable for Low-Volume Extraction

By a News Reporter-Staff News Editor at Health & Medicine Week -- According to news reporting originating from Alexandria, Virginia, by NewsRx journalists, a patent by the inventor Saul, David James (Auckland, NZ), filed on September 4, 2009, was cleared and issued on July 24, 2012 (see also Zygem Corporation Limited).

The assignee for this patent, patent number 8226906, is Zygem Corporation Limited (Hamilton, NZ).

Reporters obtained the following quote from the background information supplied by the inventors: "The present application relates generally to sample collection devices, and more specifically, to collection devices suitable for low-volume extraction.

"Frequently, substances must be detected that are present in only trace quantities. This is true for chemical agents, such as explosives and pharmaceuticals, and biological agents, such as microorganisms or trace amounts of nucleic acids. Commonly, these agents are obtained by swabbing a surface and then the swab is used to transfer the material to a vessel containing diagnostic reagents or a solution to extract the agents of interest.

"An underlying problem with this strategy is that the swab requires the agent to be removed by using a washing solution and this step dilutes the concentration of the agent making it more difficult to detect. Two strategies are generally used to alleviate this limitation:

"An example where these methods can be used is in the detection of trace (i.e., low copy number (LCN)) nucleic acids in forensic samples.

"There are a number of situations where strategy 1 is used. For example, in U.S. Pat. No. 6,475,165 the cells from cervical swabs are washed from the sampling device and sedimented by centrifugation. While this method is acceptable for many samples, there are instances where such a method is unacceptable. For example, if a forensic sample is degraded then it is likely that the cells are not intact and so DNA would be solublized and therefore not sedimented by centrifugation. This can be overcome by washing the collection device in ethanol or isopropanol but such an action results in the nucleic acid being presented to subsequent steps in the presence of alcohols.

"The most widely used methods for trace nucleic acid sampling follow strategy 2 and commercial kits are available (DNA IQ.TM. (Promega, Madison, Wis., USA) and QiaAmp.RTM. (Qiagen, Valencia, Calif., USA).

"One system takes the extract and then binds the nucleic acids to paramagnetic beads that are concentrated by using a magnet. Although this system is an effective method for concentrating the nucleic acid from the solvent, the procedure has many steps that can only be automated using specialist equipment. More importantly for forensic samples, it requires the tube to be opened several times and so enhances the risk of contamination from extraneous nucleic acid. Ref. 1.

"The filtration/column methods use silica or charged resin columns that bind the nucleic acid. These systems also require a number of additional steps for loading, washing and elution of the nucleic acid. For automation, vacuum manifolds are often used and these present a risk of contaminating, extraneous nucleic acid material being drawn through the column. Ref. 2.

"DNA extraction using these methods can be automated but in general they require customized robotic systems. For the QiaAmp.RTM. system, the Qiagen Corporation provides a robot known as the QIACube.RTM.. In the example shown in the paper by Montpetit et al., the Biorobot EZ1 performs bead-based DNA extraction/concentration. Such equipment generally can only be used for the purpose of their design and therefore can, in some cases, represent a significant outlay for a single-use device. Ref. 6.

"Other methods include a concentration step using ultra-filtration through a membrane filter, for example Microcon.RTM. columns (Millipore, Bedford, Mass., USA). Ref. 3.

"Yet other methods concentrate the nucleic acids by the addition of ethanol or isopropanol to precipitate the DNA or RNA. This is then separated by centrifugation.

"Yet other methods concentrate the eluate by using n-butanol which in effect draws the water from the extractive.

"Neither of the latter two methods can be readily automated and both risk exposing the sample to extraneous contamination.

"LCN Forensic DNA Extraction

"The use of LCN DNA in forensic analysis is presents several potential difficulties. Because the samples often contain little DNA (just a few genomes in some cases) the environment surrounding the tube, the people handling the samples, and the laboratory equipment are all often better sources of DNA than the sample itself. Therefore all effort must be made to protect the integrity of the sample. For example, Van Oorschot and Jones reported that DNA on laboratory equipment and on a casework samples persisted for long periods of time. Ref. 4.

"A notable example of the outcome of forensic samples being compromised is the case of The Queen v. Sean Hoey, in which the defendant had been previously charged with twenty-nine counts of murder in a terrorist attack in a shopping centre in Omagh, Northern Ireland on the 15 Aug. 1988. Ref. 5. The prosecution relied on LCN DNA tests that, on re-examination, were shown to have 'very many unsatisfactory matters'. These included the likelihood of cross-contamination in the laboratory with other samples and also in the recovery and storage of the items by the Army, Police and Scene of Crime Officers.

"The case demonstrated the potential deficiencies in sampling, storage and laboratory handling of LCN samples, which require very exacting standards."

In addition to obtaining background information on this patent, NewsRx editors also obtained the inventor's summary information for this patent: "In one exemplary embodiment, a sample collection device suitable for low-volume extraction includes a substantially tubular collection vessel having a closed end, an open end, and one or more sidewalls defining a vessel chamber having a vessel volume. The device further includes a swab for sample collection; the swab formed using a substantially closed-celled polymer foam and the swab having an uncompressed volume greater than 25% of the vessel volume, preferably approximating the vessel volume. During use of the exemplary sample collection device, the surface of the swab can be extracted in the small volume of solvent held between the swab and the vessel wall.

"In one exemplary embodiment, a sample collection device suitable for low-volume extraction includes a substantially tubular collection vessel having a closed end, an open end, and one or more sidewalls defining a vessel chamber having a vessel volume. The device further includes a swab for sample collection; the swab formed using a substantially closed-celled polymer foam and the swab having an uncompressed volume greater than 25% of the vessel volume, preferably approximating the vessel volume. During use of the exemplary sample collection device, the surface of the swab can be extracted in the small volume of solvent held between the swab and the vessel wall."

For more information, see this patent: Saul, David James. Sample Collection Device Suitable for Low-Volume Extraction. U.S. Patent Number 8226906, filed September 4, 2009, and issued July 24, 2012. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=82&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=4052&f=G&l=50&co1=AND&d=PTXT&s1=20120724.PD.&OS=ISD/20120724&RS=ISD/20120724

Keywords for this news article include: Robotics, DNA Research, Legal Issues, Machine Learning, Emerging Technologies, Zygem Corporation Limited.

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