Automated DNA extraction systems are vital in the fight to identify and isolate bacteriological pathogens. Practical Patient Care talks to Sanna Laakso and Juha Kirveskari, members of the research and development team at biotech firm Mobidiag, about how its sample turnaround rate is being revolutionised by PerkinElmer’s chemagic Prepito-D instrument.
Along with the associated efficient detection methods, automated DNA extraction systems are now considered essential in the accurate identification of pathogens and harmful bacteria within biological samples.
There are a number of reasons for this: process times for extraction methods such as cherry picking and serial dilution can be streamlined when automated, and such a system typically also includes features such as PCR protocols and temperature control. The devices are used in a wide range of applications, from forensics to pathology, drug discovery and biological research.
Molecular diagnostic kits
The primary aim of Mobidiag – a biotech company founded in 2000 in Finland – is to counter increasing levels of gastrointestinal infections with a range a molecular diagnostics tools. With a particular focus on the diagnosis of infectious diseases, the company works towards the widespread use of automated extraction methods, along with efficient detection methods, to quickly identify and isolate a range of pathogens, in hospitals, laboratories and clinics across Europe.
Its first port of call in this regard is the chemagic Prepito-D instrument, an automated DNA extraction system able to analyse up to 12 samples per run in sizes of up to 1,000µl. The Prepito Kits and protocols available on the chemagic Prepito-D are able to extract DNA from anything from body fluid and tissue, to blood and plasma samples.
Quick and easy testing
"The main sample matrix we use analyses patient stool samples," says Sanna Laakso, one of Mobidiag’s senior research scientists. "The main thing is to get the sample into a liquid format, so we can place it into the automated extraction system."
Once placed inside the chemagic Prepito-D, biological samples undergo magnetic separation, through the use of binding M-PVA magnetic beads that capture the sample’s constituent DNA/RNA. The beads are then attracted to metal rods, which are externally magnetised. Resuspension of the sample can be easily achieved by simply switching the magnet off and rotating the rods. Typically a difficult process to conduct during manual sample analysis, the chemagic Prepito-D transforms nucleic acid isolation into a quick and easy part of the testing regime, resulting in isolated products with high purities and yields.
According to Juha Kirveskari, Mobidiag’s research and development director, that means that there’s little need for pre-treatment. "The chemagic Prepito-D is so effective that, during this process, it removes the DNA and RNA inhibitors in the sample," he says. "In that regard, it’s a user-friendly system for small and medium-sized laboratories."
Cost-reduction
"The device also doesn’t require as many pre-treatment steps," Laakso adds. "That’s quite an important feature, as the user doesn’t need to spend as much effort preparing the sample before pushing it into the device. The chemagic Prepito-D is also quite a small instrument, with a high throughput, which reduces costs for those customers who do not require results on as high a number of samples as others might."
Fundamentally, the chemagic Prepito-D instrument is specifically designed to reduce costs on the part of the operator, via the automated dispensing of its buffers into standard plastic devices, instead of the more expensive prefilled cartridges commonly found on the market.
Above all, the greatest reduction the device offers is in the time it takes to analyse an individual sample: processing time can be under an hour, including pre-treatment, for one 12-sample batch.
"The device itself is quite easy to use," concludes Laakso. After extraction, the DNA/RNA eluates are ready to use in various downstream applications with no need for additional extraction from the same sample, reducing overall analytical cost and processing time.
