A SMART(er) way to track influenza

Brown University researchers have created a reliable and fast flu-detection test that can be carried in a first-aid kit. The novel prototype device isolates influenza RNA using a combination of magnetics and microfluidics, then amplifies and detects probes bound to the RNA. The technology could lead to real-time tracking of influenza. Results are published in the Journal of Molecular Diagnostics.

PROVIDENCE, R.I. [Brown University] — In April 2009, the world took notice as reports surfaced of a virus in Mexico that had mutated from pigs and was being passed from human to human. The H1N1 “swine flu,” as the virus was named, circulated worldwide, killing more than 18,000 people, according to the World Health Organization. The Centers for Disease Control and Prevention in the United States said it was the first global pandemic in more than four decades.

Swine flu will not be the last viral mutation to cause a worldwide stir. One way to contain the next outbreak is by administering tests at the infection’s source, pinpointing and tracking the pathogen’s spread in real time. But such efforts have been stymied by devices that are costly, unwieldy and unreliable. Now, biomedical engineers at Brown University and Memorial Hospital in Rhode Island have developed a biochip that can detect the presence of influenza by zeroing in on the specific RNA sequence and then using tiny magnets in a tube to separate the flu-ridden sequence from the rest of the RNA strand. The result: A reliable, fast prototype of a flu-detection test that potentially can be carried in a first-aid kit and used as easily as an iPhone.

“We wanted to make something simple,” said Anubhav Tripathi, associate professor of engineering at Brown and the corresponding author on the paper, published in the Journal of Molecular Diagnostics. “It’s a low-cost device for active, on-site detection, whether it’s influenza, HIV, or TB (tuberculosis).”

The Brown assay is called SMART, which stands for “A Simple Method for Amplifying RNA Targets.” Physically, it is essentially a series of tubes, with bulbs on the ends of each, etched like channels into the biochip.

There are other pathogen-diagnostic detectors, notably the Polymerase Chain Reaction device (which targets DNA) and the Nucleic Acid Sequence Based Amplification (which also targets RNA). The SMART detector is unique in that the engineers use a DNA probe with base letters that match the code in the targeted sequence. This ensures the probe will latch on only to the specific RNA strand being assayed. The team inundates the sample with probes, to ensure that all RNA molecules bind to a probe.

“The device allows us to design probes that are both sensitive and specific," Tripathi said.

Anubhav Tripathi
“We wanted to make something simple. (This is) a low-cost device
for active, on-site detection, whether it’s influenza, HIV, or TB.”
Credit: Mike Cohea/Brown University

This approach creates excess — that is, probes with no RNA partners. That’s OK, because the Brown-led team then attached the probes to 2.8 micron magnetic beads that carry the genetic sequence for the influenza RNA sequence. The engineers then use a magnet to slowly drag the RNA-probe pairs collected in the bulb through a tube that narrows to 50 microns and then deposit the probes at a bulb at the other end. This convergence of magnetism (the magnetized probes and the dragging magnets) and microfluidics (the probes’ movement through the narrowing channel and the bulbs) serves to separate the RNA-probe pairs from the surrounding biological debris, allowing clinicians to isolate the influenza strains readily and rapidly for analysis. The team reports that it tracks the RNA-probe beads flawlessly at speeds up to 0.75 millimeters per second.

“When we amplify the probes, we have disease detection,” Tripathi said. “If there is no influenza, there will be no probes (at the end bulb). This separation part is crucial.”

Once separated, or amplified, the RNA can be analyzed using conventional techniques, such as nucleic acid sequence-based amplification (NASBA).

The chips created in Tripathi’s lab are less than two inches across and can fit four tube-and-bulb channels. Tripathi said the chips could be commercially manufactured and made so more channels could be etched on each.

The team is working on separate technologies for biohazard detection.

Stephanie McCalla, who earned her doctorate at Brown last year and is now at the California Institute of Technology, is the first author on the paper. Brown professors of medicine Steven Opal and Andrew Artenstein, with Carmichael Ong and Aartik Sarma, who earned their undergraduate degrees at Brown, are contributing authors.

The U.S. National Institutes of Health and the National Science Foundation funded the research.

- by David Orenstein

Magnetically controlled pills could boost body’s absorption of drugs

Many drugs can only be absorbed in very specific parts of the intestine. In a new paper, Brown University scientists describe a new system that can safely hold a magnetic gelatin capsule in place anywhere in the gastrointestinal tract of a rat. In humans, the system could improve drug delivery and pharmacological research.

A place for everything
A tiny magnet inside a gelatin capsule allow researchers
to hold medicine at an exact place in the intestine
where it is best absorbed.Credit: Mathiowitz Lab/Brown University 

PROVIDENCE, R.I.  — Do you want that in a pill or a shot?

Most patients never have that choice. The problem with administering many medications orally is that a pill often will not dissolve at exactly the right site in the gastrointestinal tract where the medicine can be absorbed into the bloodstream. A new magnetic pill system developed by Brown University researchers could solve the problem by safely holding a pill in place in the intestine wherever it needs to be.

The scientists describe the harmless operation of their magnetic pill system in rats online the week of Jan. 17 in theProceedings of the National Academy of Sciences. Applied to people in the future, said senior author Edith Mathiowitz, the technology could provide a new way to deliver many drugs to patients, including those with cancer or diabetes. It could also act as a powerful research tool to help scientists understand exactly where in the intestine different drugs are best absorbed.

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Hold it right there!
As a magnet moves closer and farther from a small magnetic pill in a rat’s intestine, it keeps track of the force between it and the pill. The technology can be used to safely hold a pill in the right place to maximize absorption of the medicine it carries.
 Credit: Mathiowitz Lab/Brown University

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“With this technology you can now tell where the pill is placed, take some blood samples and know exactly if the pill being in this region really enhances the bioavailability of the medicine in the body,” said Mathiowitz, professor of medical science in Brown’s Department of Molecular Pharmacology, Physiology, and Biotechnology. “It’s a completely new way to design a drug delivery system.”

The two main components of the system are conventional-looking gelatin capsules that contain a tiny magnet, and an external magnet that can precisely sense the force between it and the pill and vary that force, as needed, to hold the pill in place. The external magnet can sense the pill’s position, but because the pill is opaque to x-rays, the researchers were also able to see the pill in the rat’s bodies during their studies.

Safety first

The system is not the first attempt to guide pills magnetically, but it is the first one in which scientists can control the forces on a pill so that it’s safe to use in the body. They designed their system to sense the position of pills and hold them there with a minimum of force.

“The most important thing is to be able to monitor the forces that you exert on the pill in order to avoid damage to the surrounding tissue,” said Mathiowitz. “If you apply a little more than necessary force, your pill will be pulled to the external magnet, and this is a problem.”

To accomplish this, the team including lead author and former graduate student Bryan Laulicht took careful measurements and built an external magnet system with sophisticated computer control and feedback mechanisms.

“The greatest challenges were quantifying the required force range for maintaining a magnetic pill in the small intestines and constructing a device that could maintain intermagnetic forces within that range,” said Laulicht, who is now a postdoctoral scholar at MIT.

Even after holding a pill in place for 12 hours in the rats, the system applied a pressure on the intestinal wall that was less than 1/60th of what would be damaging.

The next step in the research is to begin delivering drugs using the system and testing their absorption, Mathiowitz and Laulicht said.

“Then it will move to larger animal models and ultimately into the clinic,” Laulicht said. “It is my hope that magnetic pill retention will be used to enable oral drug delivery solutions to previously unmet medical needs.”

In addition to Mathiowitz and Laulicht, authors on the paper include Brown researchers Nicholas Gidmark and Anubhav Tripathi. Brown University funded the research.