Clinicians — or you and I — one day may be walking about with an iPod in the ear, and an IMPOD in the hand.
That's the — rather somewhat fantasized — hope of a team of researchers at Sandia National Laboratories (Livermore, California) which has developed a desktop, phone-sized, point-of-care device, called the IMPOD, to test saliva, which they believe can one day be a simple device to test for oral cancer and perhaps be further reduced in size to hand-carried modality.
The researchers, supported by the National Institutes of Dental and Craniofacial Research, a unit of the National Institutes of Health, say that the device, which uses lab-on-a-chip technology to measure proteins in the saliva, may also one day be used as well to detect diseases elsewhere in the body. But for now the initial disease target they are pursuing is periodontitis.
The IMPOD — for Integrated Microfluidic Platform for Oral Diagnostics — is described in the March 27 issue of the Proceedings of the National Academy of Sciences. In their report, the scientists offer the results of proof-of-principle experiments in which the system reliably measured the concentrations of MMP-8, an enzyme associated with periodontitis.
"The goal eventually is to go to something the size of a Blackberry, so, still not as small as a [cell phone]," Anup Singh, PhD, a chemical engineer at Sandia, told Medical Device Daily.
But he acknowledged the significant difficulties of further miniaturization, saying "I don't know whether we are going to get there or not." He says that these difficulties include the combination of microarray technology and liquids, and the danger of the liquids shorting out the electronics of the microarray device.
"In terms of microchip-based devices, we might be one of the smallest ones," he said. "There are some DNA microchip devices that I've seen which are smaller, but we are pretty competitive in making it as small as we could."
Singh said that the IMPOD is designed to measure up to 20 analytes, or biochemicals, at once. The researchers, he said, "haven't scaled up to that point, but we are doing multi-analyte analyses in the laboratory."
The "greatest need" they have currently is validated biomarkers, which would enable further studies, since the "basic engineering" of the device itself has been completed.
According to Singh, he and his colleagues were "intrigued" a few years ago by the many potential advantages of using saliva in diagnostic testing. Those advantages include the simplicity of collection, the avoidance of needle sticks, the portability of the test device and the potential of much lower cost compared to blood assays.
"Saliva is a mirror of blood, but with a caveat," said Singh. "It's not an exact mirror, meaning everything that is present in blood is present in saliva, but at concentrations 1,000 to 10,000 times lower. It's diluted by saliva and the other secretions in the mouth. So we needed sensitivity 1,000 to 10,000 times better than we'd need if we were screening serum samples."
For example, with the disease model of periodontitis, dentists typically diagnose with a visual examination that includes looking for bleeding in the gums, or using X-rays to determine if the gum-line or bone is receding.
"So everything is visual, based on visual measurements," which are subjective, he said. "We wanted to develop a device that could use a biochemical test."
The IMPOD has been used to screen about 40 patients, Singh told MDD, adding that another 60 patients are still to be screened.
And the current panel of biomarkers being used still must be validated, he also noted.
As published, the researchers collected saliva from 23 people – 14 with periodontitis and nine in good oral health. Loading roughly one-10th of a drop of saliva for analysis, the IMPOD processed the samples and produced a result in less than five minutes.
The results showed that on average those in good oral health had lower concentrations of the enzyme MMP, while people with periodontitis, on average, had elevated levels of the tissue-damaging enzyme. The results were confirmed with a standard ELISA blood test, currently the gold standard for this process.
Essentially, Singh said that the test, which must ultimately be approved by the FDA, is about two to three years away from commercialization, meaning use in a dental office.
Sandia, which is research-focused, licenses its technologies out for further development. "We have a very strong business office that actively seeks out companies that might be interested in licensing our technology," Singh said.
The researchers said that IMPOD might find additional uses such as testing other fluids, such as blood and urine.
"We are already talking to other companies about using the device for diagnosing symptoms of other diseases, and cancer would be one of them," Singh said. Another is cardiovascular health.
Ultimately, the hope is that this device can be miniaturized to the point that it could be a saliva test used at home, as more and more healthcare involves self-care.