Short segments of RNA, called microRNAs (or miRNAs), are potential biomarkers for certain diseases. But it is not cheap or easy to detect these tiny strands in blood samples. So, MIT chemical engineer Patrick Doyle and grad student Stephen Chapin, writing in the journal Analytical Chemistry, came up with a better way of detecting miRNAs, according to a report in Chemical & Engineering News.
They start with 70-micron-wide absorbent gel particles that resemble dominoes. Then, the scientists get out their tiny hammers and chisels to etch some graffiti on these dominoes into which they will embed DNA molecules that are designed to recognize the miRNA sequences they're interested in. Stick the micro-dominoes into a blood sample and the miRNA will stick to them. Next, introduce longer strands of DNA that bind and overhang from the probe. Repeat between 100 and 1,000 times and you've cooked up a batch of long DNA chains of repeating sequences at each bound miRNA site. Fluorescent tags make these overhanging strings easy for scientists to detect.
Doyle and Chapin successfully tried the technique in real serum containing miR-141, which appears in the blood of people with prostate cancer. "We're certainly in the zone where we can detect clinically relevant miRNAs in the circulatory system," Chapin tells C&E News.
The article quotes Fred Hutchinson Cancer Research Center miRNA scientist Muneesh Tewari as saying that while it is too early to tell how the technique would perform in a clinical setting, "the results so far are promising."