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Lamprogen Wins Funding to Develop 'Self-Digitizing' dPCR Platform

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NEW YORK (GenomeWeb) — Seattle-based start-up Lamprogen, a spinout of the University of Washington, is using funding from two grants to further the development of a self-digitizing microfluidic chip and instrument on which the chip will run.

Last week, the firm won National Institutes of Health funding from the National Institute of Biomedical Imaging and Engineering to support the development of the chip. That award follows a National Science Foundation Phase I Small Business Innovation Research grant awarded in January of this year that covers development of thermocycling capabilities and imaging methods for the firm's spinning disc-based self-digitization technology. Both are one-year awards, and combined they total approximately $300,000.

The five year-old company is developing a platform for digital PCR that exploits surface energies and centrifugal force to automatically aliquot droplets into wells of a microfluidic chip.

Self-digitization digital PCR, or SD dPCR, was developed in the lab of Daniel Chiu, a professor of chemistry at the University of Washington. In an interview with PCR Insider Lamprogen's Director of Microtechnology, Jason Kreutz, said that he initially joined the Chiu lab as a postdoc, "with the intention of trying to ... help them develop the self-digitization technology and then commercialize it," adding that he is currently continuing the process of transitioning "from the lab to the company."

Kreutz earned his doctorate in chemistry in the lab of Rustem Ismagilov while that group was undertaking development of their dPCR technology. "I was there when the whole SlipChip concept started, and I got to hop on to work on the statistics of digital PCR," he said.

As previously covered in PCR Insider, SlipChip uses a sliding motion of two credit card-sized plates to combine sample droplets and reagents for dPCR. However, the Lamprogen chip differs from this and other devices because of its unique droplet generating mechanism, Kreutz said.

SD dPCR relies on the differing surface energies between oil and water. The microfluidic chip is an array of thin channels and wider wells. Similar to SlipChip, it is pre-filled with oil, which is used to wet the device's interior surface. A pulse of aqueous sample is then sent into the device.

Since there is a drive for aqueous solutions to form spheres when free-floating, when provided the option to bleb off from the narrow channel into a small well, the aqueous sample will "naturally try to expand out" to lower the surface energy, Kreutz explained.

Once the aqueous solution is in the device, "you follow that with more oil; the oil displaces the aqueous that's in the channel but it leaves the aqueous that's in the wells, and that's how it digitizes," he said.

"You can essentially fill the inlet with your aqueous and your oil and start flow in some manner, and then, without having any other moving parts or valves or slipping or anything, the aqueous goes in and fills the wells, and oil comes in and digitizes it. That's why we call it self-digitization — you don't need any high-precision flow rates or valves or any other manipulation to get it to digitize. You put [the solutions] in, start flow, and it happens," Kreutz said.

The spinning disc element is used as a way of initiating flow. However, Kreutz added that the chip has "a wide tolerance in terms of what sort of flow rate or pressure you need to get the device to fill," so other methods could be used, such as syringe pump or vacuum pressure.

The NIH funding awarded last week is to develop the SD dPCR chip using centrifugal flow initiation. The NSF will fund phase I development of an instrument, which will provide the centrifugal force as well as perform the thermocycling and imaging for the platform, through the end of this year.

A similar spinning disc platform for droplet creation is also being developed by Carl Wittwer — pioneer of sub-30-second PCR and a probe-based method to characterize polymerases — at the University of Utah and his company, Espira, as reported in PCR Insider.

However, Kreutz pointed out, "There's a whole field of centrifugal-based filling microfluidics that are used for all sorts of different applications," and "while it might look like it's similar, there are some fundamental differences between how our system works and how [the Espira system] works," including that Lamprogen uses oil for the initial wetting of the device.

Using the spinning disc method has advantages. Since everything on the disc will experience the centrifugal force, "if you have many arrays on there and you spin it, they all fill at the same time, so it's a way to parallelize," Kreutz explained.

And, while the idea of centrifugal microfluidics may not be novel, "using it in the context that we are, there's not much out there," Kreutz said.

Lamprogen is also trying to extend the spinning disc concept beyond just using it for initiating flow in the microfluidic chip. Indeed, the NSF grant abstract says Lamprogen will develop "a parallelized digitization and imaging instrument prototype," with the intention of reducing cost and barriers to adoption of dPCR, although Kreutz declined to comment on these other aspects.

The Chiu lab has already published a few studies demonstrating the self-digitization method of droplet creation.

A paper in Lab on a Chip last year showed how the platform could generate tens of thousands of nanoliter-sized droplets in a high-density array in a few minutes. Previous work described self-digitization of samples using different oils and chip geometries, as well as a method to run isothermal digital loop-mediated DNA amplification, or LAMP, on the device.

Lamprogen is currently part of the University of Washington Center for Commercialization's New Ventures Facility, an on-campus building which houses the university's many spinouts.

In terms of the SBIR grant, the company has now demonstrated some "proof-of-concept aspects of how the instrument would work with the optical disc [method]," Kreutz said. Phase II will entail developing a complete prototype and finding "some sort of partner or some mechanism to start producing an actual product." With the new NIH funding, development of the SD dPCR chip will follow a parallel pattern, he said.

Kreutz was unable to comment on Lamprogen's business model or current operating conditions and relationships. In 2012 the firm inked a deal to provide Bio-Rad with fluorescent molecules and access to future technologies. But whether the deal with Bio-Rad is still in effect is unclear.

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