Development and characterization of a capillary-flow microfluidic device for nucleic acid detection

We have developed a capillary flow-driven microfluidic biosensor to meet the needs of diagnostics for resource-limited areas. The device combined elements of lateral flow assays and microfluidic technology resulting in a hybrid with benefits of both formats. The biosensor was achieved by bonding two pieces of polymethyl methacrylate with channels ablated by a CO 2 laser, and enclosing an absorbent pad. The channels were UV/ozone treated to increase hydrophilicity which enabled capillary flow. The absorbent pad allowed for continuous flow in the channels once filled. The application of biosensor was demonstrated by detection of DNA with a sandwich assay. The target DNA was hybridized with nucleic acid modified magnetic beads as well as Ru(bpy) 3 2+ doped silica nanoparticles. Fluorescent signals were quantified in a holder fabricated to fit in a fluorescent microtiter plate reader. The capillary flow microfluidic was capable to detect 1 pmol target. The assay format which features rapid analysis and does not require the use of pumps could allow for inexpensive point of care diagnostics in the future.