Sandia National Laboratories researchers have developed a new immunoassay platform called SpinDx that they say could offer substantial improvements over standard ELISAs in terms of cost, speed, and sensitivity.
Given these potential advantages, the lab envisions the device as particularly well suited to point-of-care medical diagnostic applications, Anup Singh, manager of Sandia's biotechnology and bioengineering department, told ProteoMonitor. He added that the lab is currently in talks with several diagnostic firms about licensing the device and expects to sign the first licenses for it within a month.
The SpinDx platform consists of a small disc similar to a CD containing 64 "spokes" that can be preloaded with antibodies and other reagents used in a standard immunoassay. A user loads a drop of sample into a well in the center of a plate and the disc is placed inside a benchtop instrument and spun to distribute the sample and manipulate it within the wells.
The device can multiplex up to 64 assays per run and, according to Singh, requires no sample preparation and takes fifteen minutes to complete, giving it great potential as a point-of care tool, he said.
"My vision is that this device would sit in a doctor's office," Singh said. "And the nurse can take a little bit of blood, put it in this device, and by the time you get to see the doctor, he will actually have the results of some of the things you and he want to talk about – cardiac panel markers, for instance."
"That's the goal, and by taking away the requirement for sample prep and making it very fast we think this offers an advantage over anything that is out there," he said.
The device also offer advantages over conventional immunoassay platforms in terms of the amounts of sample and reagents required, Singh said, noting that it typically uses between 2 and 5 microliters of sample and roughly 20 times less antibody than a traditional immunoassay.
Given that antibodies comprise a significant portion of the cost of the typical immunoassay, the reduced reagent requirements mean SpinDx could enable significantly cheaper assays, he said, adding that "if you look at current ELISAs that are clinically useful, we are about five to ten times cheaper."
That, he suggested, could prove an incentive for companies considering licensing the technology. "A company that commercializes this will make money not necessarily on the [device], but on the consumables," he said. "And the fact that you use much less reagent per [assay] can really improve your profit margins."
The researchers have also found that the device offers improved sensitivity compared to conventional immunoassays, Singh said, noting that they have seen up to ten-fold improvements compared to traditional ELISAs.
This, he said, is due to the device's centrifugal approach to mixing the assay components. Each well contains a density gradient media that can only be penetrated by the antibody-bound beads used in the assay. When the disc spins, these beads, along with the antibodies and target proteins they've bound, collect at the bottom of the well, separate from the other sample components that might otherwise contribute to background and non-specific binding.
"So the analytes and the antibodies on the beads pass very readily through the density media, but everything else in the blood or saliva or urine stays behind, so you have very little background," Singh said. "That isn't true for most immunoassay platforms where the entire blood is being integrated with the antibodies."
Reproducibility for assays on the device is roughly equivalent to that "of the best ELISAs you can find on the market," he said. He added that because the device's 64 wells are discrete channels, cross-reactivity – a problem that has limited multiplexing in conventional immunoassays – is significantly reduced.
The SpinDx platform is applicable to a number of areas, including food safety testing and homeland security, but thus far, Singh said, most interest has come from companies interested in licensing it for medical diagnostic purposes.
Sandia plans to offer multiple licenses to the technology, each exclusive within a particular disease area, he said. "For example, one company could come in and have, say, market share in [protein markers for] cardiac monitoring, and we would say 'Yes, this company knows what they are doing; they already have [share in] this market segment, let's give them an exclusive license for cardiac medical diagnostics.' The next company could come in for sepsis, or neonatal screening, or something else."
Singh said he expects to sign licenses primarily with smaller, early-stage firms, "because the risk is still fairly high in terms of developing [the platform] further. In my experience, for bigger [in vitro diagnostic] companies like Roche, the risk might still be too high for them," he said.
Sandia is in discussions with several companies currently and plans to sign the first license in the next month, with additional deals following in the next three to six months.
In addition to point-of-care medical diagnostics, the device could prove useful for clinical research and validation of protein biomarkers, given its multiplexing ability and low sample requirements. However, Singh said, for such an application, researchers would likely need to develop a robotic interface for the device to allow automated, high-throughput processing of samples.
The SpinDx device is not alone in trying to streamline conventional ELISAs. In May, for instance, biotech firm Courtagen Life Sciences submitted a pre-investigational device exemption information package to the US Food and Drug Administration for its Avantra Q400 Biomarker Workstation, which is similarly designed to take on the point-of-care market by offering faster, simpler immunoassays (PM 5/11/2012).
According to Courtagen officials, that platform generates results in 15 minutes to 30 minutes with coefficiencies of variation of under 10 percent and requires no sample prep.