Surface modified microprojection arrays for the selective extraction of the dengue virus NS1 protein as a marker for disease.

While advances in assay chemistry and detection continue to improve molecular diagnostics technology, blood samples are still collected using the 150-year-old needle/syringe method. Surface modified microprojection arrays have been developed as a novel platform for in vivo, needle-free biomarker capture. These devices are gold coated silicon arrays with >20,000 projections per cm(2), which can be applied to the skin for tunable penetration into the epidermis or dermis. The microprojection array conceptually offers several advantages over the current methods including: minimally invasive sample collection, no need for sample processing and concentration of specific markers at the device surface for sensitive detection. In this study, Microprojection arrays were coated with antibodies to capture an early marker of dengue virus infection, NS1, from the skin of live mice. We also developed a complementary "total IgG" assay which could be used as a positive control for adequate penetration of the projections. Surface modifications designed for selective extraction were tested against standard microtiter plate ELISA. We also investigated the use of Protein G-mediated antibody immobilization in order to orient capture antibodies. While we found that capture efficiency could be improved, the direct EDC-based antibody immobilization resulted in a significantly higher surface density leading to a higher degree of NS1 capture. Using mice intravenously injected with recombinant dengue virus type 2 NS1 as a pseudomodel for dengue infection, NS1 was successfully extracted using microprojection arrays sampling from skin fluid, with a detection limit of 8 μg/mL.