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U of Illinois Group Developing Smartphone-Based Biosensor to Detect Proteins, Other Analytes

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Researchers at the University of Illinois are developing a smartphone-based biosensor to measure molecules including proteins.

Working under a three-year, $600,000 grant from the National Science Foundation, the scientists plan to adapt smartphone cameras for use as high-resolution optical spectrometers, University of Illinois researcher and project leader Brian Cunningham told ProteoMonitor. This, he said, would allow them to use the phones for assays such as ELISAs and photonic crystal-based detection of protein-protein interactions.

The system consists of a small cradle that turns a smartphone camera into an optical spectrometer. Currently, the researchers are working with an Apple iPhone 4, but have yet to make a final decision on what make of phone they will ultimately use, Cunningham said. He added that they have filed a patent application for the device and hope to develop it into a commercial product.

The device isn't intended to compete with high-end laboratory-based biosensors, but could prove useful in point-of-care and field settings, Cunningham said, noting that smartphones' broad adoption and networking abilities make them particularly attractive for such applications.

"So much work has gone into smartphone infrastructure in terms of making them low cost and getting them into the hands of so many people, that we thought it could be a platform that would be pretty inexpensive and pretty widely adopted," he said.

Such devices, Cunningham said, could allow doctors to more easily monitor patients, with, for instance, the phone sending regular measurements of biomarkers to a physician, and perhaps alerting them when a value is out of range.

Researchers might also use the phones' mapping and cloud computing capabilities to obtain real-time pictures of events like disease outbreaks or environmental contamination, he said.

"Our thoughts are motivated by how powerful smartphones have become both in terms of their computational abilities and their ability to connect and network and perform certain work in the cloud," Cunningham said. "You can take a photo of the subject. You can get GPS location information. You can imagine using this technology to map [contamination] in a water resource, like wells or groundwater, and using a distributed bunch of sensors to pretty quickly get a picture of what is going on."

In the abstract for their NSF grant, the University of Illinois team notes four applications it plans to pursue using this funding: detection of protein biomarkers indicative of nutritional status in children; detection of an HIV viral antibody; detection of a toxin that can contaminate harvested corn; and detection of a bacterial pathogen by identification of certain mRNA sequences.

Thus far, Cunningham said, the researchers have managed with a prototype device to detect protein-protein interactions and specific DNA sequences, using data from these efforts in their grant application. The prototype detected DNA in the nanomolar range, and Cunningham said he expects the device will be able to detect proteins with similar sensitivity.

"It turns out that phone cameras are pretty good," he said. "With all those megapixels we can make a pretty decent spectrometer. It's not something that is going to replace every laboratory-based clinical diagnostic instrument – things that incorporate high-powered lasers and very sensitive detectors – but there are a lot of applications where the phone's capabilities are quite good."

The effort began as the senior thesis project of several of Cunningham's undergraduate students. "Really with no funding we set about doing some of the initial demonstrations, building a rudimentary app for the iPhone 4 and making a first-generation optical cradle in our machine shop," he said.

The researchers started with an iPhone because "I like Apple products and have an iPhone 4, so I just bought a second one and gave it to the student to use for building the initial system," Cunningham said. However, he added, the team has not yet decided what platform would be best to use going forward. Currently they are looking primarily at Apple and Android devices, he said.

One major consideration will be what phone best allows them to get access to and control the various hardware and software functions – the camera's autofocus, for instance. Apple products aren't the easiest to work with on this front, Cunningham said.

Another key is the stability of the platform. "We want to pick a platform that will be around for awhile," he said. "Because when we develop our system, we need the camera and the LED not to be changing all the time. We need to pick one platform that we will program in and then stay with that for the duration of the NSF grant."

Cunningham and his team aren't alone in eyeing smartphones as potential biosensors. In 2011, researchers at the Korea Advanced Institute of Science and Technology published a paper in Angewandte Chemie on using a smartphone's touchscreen to measure DNA concentrations.

And, ProteoMonitor sister publication PCR Insider has reported on several groups conducting similar work. One group, led by Changchun Liu at the University of Pennsylvania, is developing a non-instrumented, isothermal, microfluidic sample-to-answer assay for detecting HIV that can use a smartphone camera as a readout device (PCR Insider 6/7/2012). Another, led by Jeong-Yeol Yoon at the University of Arizona, is using a microscope designed to work with an iPhone camera as an optical detection system for a real-time PCR device under development (PCR Insider 12/6/2012).

In addition, a Michigan State University team is using iPhone and Android products to operate a handheld nucleic acid testing device using isothermal amplification methods (PCR Insider, 3/22/2012).

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