Magnetophoretic-based microfluidic device for DNA Concentration

Abstract

Nucleic acids serve as biomarkers of disease and it is highly desirable to develop approaches to extract small number of such genomic extracts from human bodily fluids. Magnetic particles-based nucleic acid extraction is widely used for concentration of small amount of samples and is followed by DNA amplification in specific assays. However, approaches to integrate such magnetic particles based capture with micro and nanofluidic based assays are still lacking. In this report, we demonstrate a magnetophoretic-based approach for target-specific DNA extraction and concentration within a microfluidic device. This device features a large chamber for reducing flow velocity and an array of μ-magnets for enhancing magnetic flux density. With this strategy, the device is able to collect up to 95 % of the magnetic particles from the fluidic flow and to concentrate these magnetic particles in a collection region. Then an enzymatic reaction is used to detach the DNA from the magnetic particles within the microfluidic device, making the DNA available for subsequent analysis. Concentrations of over 1000-fold for 90 bp dsDNA molecules is demonstrated. This strategy can bridge the gap between detection of low concentration analytes from clinical samples and a range of micro and nanofluidic sensors and devices including nanopores, nano-cantilevers, and nanowires.

Flow-through Capture and in Situ Amplification Can Enable Rapid Detection of a Few Single Molecules of Nucleic Acids from Several Milliliters of Solution

“…Many passive capture processessuch as wicking through a porous matrix or mixing with beadsrely on slow transport rates to achieve high Da . These processes capture efficiently at small length scales in microliter volumes; − , however, for milliliter volumes and large length scales, passive capture processes would require impractical amounts of capture agent or time for Da to be greater than 1. A fast binding reaction with diffusion-limited kinetics would enable higher transport rates (and thus faster flow rates) without adversely affecting capture efficiency.…”

“… ,− Concentration factors up to 15X , and limits-of-detection as sensitive as 10 4 copies/mL or 500 cells/mL have been reported. While these methods have clear advantages over traditional solid-phase extraction methods, processing time and lowest detectable concentration are still limited by their inability to handle large sample volumes (>1 mL) − , and/or their slow processing rates, which range from μL/min to μL/h. ,,,,, Thus, current methodswhether commercialized or from literaturelack the required combination of sensitivity, speed, and ease of implementation, leaving a gap in the current NA detection workflow.…”

Sorting and manipulation of biological cells and the prospects for using optical forces

“…In a recent study, magnetophoresis in a microfluidic device was also used for manipulation and concentration of DNA, showing its promise for manipulation of large molecules [52].…”

Biological Particle Control and Separation using Active Forces in Microfluidic Environments

“…The H5N1 magnetic nanoparticle complexes are formed using aptamerbiotin-streptavidin binding and injected to three-dimensionally printed magnetophoretic platform which experiences magnetic field from external neodymium magnets, to migrate the complexes from the original sample flow to phosphate-buffered saline carrier flow. Shim et al [34] demonstrate the magnetophoretic capture of DNA-conjugated magnetic particles in microfluidic device by short-range magnetic field gradient exerted by micro-patterned nickel array on the bottom surface of the separation channel, as well as enhancement with oppositely oriented array of external permanent magnet for a long-range magnetic field gradient at the interfaces between magnets. The DNA is then collected by performing detachment from the captured DNA magnetic particle conjugates by enzymatic reaction with uracil-specific excision reagent enzyme.…”