UCLA engineers invent small, inexpensive RNA detector to quickly test for infections
By Sarah C.P. Williams
The new technology could lead to point-of-care medical tests for infections with results in just 15 minutes or less. It could also be used to detect harmful pathogens in food and the environment.
Today, most medical tests to detect bacteria or viruses in body fluids take hours or days to process.
Now, researchers at the UCLA Samueli School of Engineering have invented a new technology to detect genetic material—such as that in microorganisms that cause disease—in a way that’s faster, cheaper, and does not require sophisticated equipment. A team led by Harold Monbouquette, professor of chemical and biomolecular engineering, and Jacob Schmidt, professor of bioengineering, patented their device, published the first description of the technology, and established a start-up company to begin developing prototypes of a commercial version of the detector.
“We’re working on developing a device that’s useful right at the point of care,” said Monbouquette, who is also the school’s associate dean for research and physical resources. “That means it can be easily run in a doctor’s office, clinic, or emergency room without samples being sent away to a lab.”
Nearly a decade ago, Monbouquette and Schmidt crossed paths—at a UCLA poster session—and discovered that they were both working on approaches to simplify the detection of nucleic acids, the DNA or RNA that defines cells’ and organisms’ identities. Rather than compete with each other, they teamed up and combined their ideas.
The new device relies on a 1-centimeter square glass slide that has an electric current flowing through it and is contacted by tiny plastic beads, each around 800 nanometers wide— less than one one-thousandth of a millimeter. Every plastic bead has molecules called peptide nucleic acid (PNA) coating its surface.
The PNAs are designed to bind specifically to whatever nucleic acid the test is detecting. If a doctor is interested in whether a patient has chlamydia, for instance, the PNA will only bind to a stretch of RNA that’s unique to chlamydia. If there’s even a tiny amount of that exact bit of RNA present, it will bind to the corresponding PNA and immediately interrupt the flow of the electric current, telling the doctor that the disease is present.
“It’s like a yes-or-no pregnancy test,” explained Monbouquette. “And that’s adequate for a lot of pathogens — you just want to know whether a patient is infected or not.”
In a recent paper, published in the journal Lab on a Chip in July, Monbouquette and Schmidt described the detection method’s high sensitivity— able to detect the equivalent of one bacterium in half a glass of wine. Even when a mixture of bacteria was tested, the chip could detect the presence of Escherichia coli when there were 1 million-times more RNA molecules from another bacterium, Pseudomonas putida. Moreover, the technique had no false positive results during the initial experiments.
The researchers think the technology—once it’s adapted to a form that can be mass-produced—will give doctors the ability to run faster tests to diagnose a variety of infections.
“There are a lot of diseases where the doctor takes a sample, sends it off to the lab, and doesn’t get results for days,” said Schmidt. “We can do it in 15 minutes or less, which means you can sit in the waiting room, wait for an answer, and potentially start getting treated before you ever leave the doctor’s office.”
He envisions a small toaster-sized device in which different cartridges— each containing the glass slides for a specific pathogen— can be inserted depending on what test needs to be run. It’s hard to predict the cost since a manufacturable prototype hasn’t been developed yet, but Schmidt said each test will be “easily under $50.”
With that kind of application and price point in mind, Monbouquette, Schmidt, and former UCLA Samueli doctoral student Youngsam Bae have founded Electronucleics, a company that will oversee further development of the nucleic acid detection technology. Their first goal is to streamline the processing needed for samples to be run on the machine—in the lab, they’ve been using filters, pipets, test tubes and a handful of reagents to process samples before injecting them into the detector. Next, they will work with an outside firm to develop a planned prototype featuring push-button simplicity.
They plan to first optimize the technology for use in detecting gonorrhea and chlamydia infections—there’s an unmet need for rapid diagnosis of these sexually transmitted diseases, the researchers said. But they envision other applications in the future, including the diagnosis of respiratory illnesses and flu, or the detection of pathogens in food and water.