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 Brown assay is called A Simple Method for Amplifying RNA Targets (SMART). The biochip is essentially a series of tubes, with bulbs on the ends of each, etched like channels into the biochip.
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 latches 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 probes are attached to magnetic beads that carry the genetic sequence for the influenza RNA sequence. A magnet is then used to bring 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. The process serves to separate the RNA-probe pairs from the surrounding biological debris, allowing for the isolation of influenza strains or other target for analysis. This separation step is crucial to the detection process. If the target is not present in the sample, there will be no probes at the end bulb.
Once separated, or amplified, the RNA can be analyzed using conventional techniques, such as nucleic acid sequence-based amplification (NASBA).
“We wanted to make something simple,” said Anubhav Tripathi, Associate Professor of Engineering at Brown University and lead author on the SMART study recently 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.”
The chips 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 research was supported by the National Institutes of Health and the National Science Foundation.
Image courtesy of Michael Cohea, Brown University