A collaborative study led by researchers at Nagoya University has developed a pioneering nanobiodevice that can separate microRNA (miRNA) from DNA/RNA mixtures obtained from cells in less than 100 ms. Previous research has shown that miRNA levels in bodily fluids strongly correlate with the presence and advance of various cancers—meaning that as long as miRNA can be isolated by a rapid, efficient process, it can act as an easily accessible biomarker to diagnose disease.
In the current study, which was published recently in Scientific Reports in an article entitled “A millisecond micro-RNA separation technique by a hybrid structure of nanopillars and nanoslits,” the Japanese researchers constructed a nanobiodevice consisting of a quartz substrate containing a 25×100 μm array of "nanopillars" (small columns with a diameter of 250 nm and height of 100 nm) in shallow "nanoslits" with a height of 100 nm and fabricated in a microchannel by electron beam lithography. The ability of the nanobiodevice to separate microRNA from DNA was first investigated using mixtures containing components with known concentrations. The team optimized the separation conditions, achieving almost complete separation of microRNA from DNA in just 20 ms.
"We believe that the nanobiodevice separates microRNA from mixtures through a combination of two different physical behaviors of confined polymers in the nanopoillar array, non-equilibrium transport, and entropic trapping," explained corresponding author Noritada Kaji, Ph.D., associate professor in the graduate school of engineering at Nagoya University. "The applied electric field combines with the unique nanostructure of the nanobiodevice to generate a strong electric force that induces rapid concentration and separation."
After their initial experiments using defined mixtures of miRNA and DNA. The investigators looked at separating mixtures of miRNA, RNA, and DNA from isolated cells using the nanobiodevice. The research team was able to isolate the nucleic acids with high resolution in 100 ms. The nanobiodevice separated microRNA from RNA and DNA because of the different mobilities of these materials through the nanopillar region of the microchannel.
The speed at which this nanobiodevice can separate microRNA from complex mixtures means that it is promising for integration with nanopore DNA sequencing, which aims to realize direct sequencing of DNA or RNA at a rate of 1 base/ms. The developed nanobiodevice separation approach may lead to faster, more reliable isolation of microRNA, facilitating its use as a biomarker to allow quicker and easier detection of cancer.