Improving sensitivity of gold nanoparticle-based lateral flow assays by using wax-printed pillars as delay barriers of microfluidics.

Although lateral flow assays (LFAs) are currently being used in some point-of-care applications (POC), they cannot still be extended to a broader range of analytes for which higher sensitivities and lower detection limits are required. To overcome such drawbacks, we propose here a simple and facile alternative based on the use of delay hydrophobic barriers fabricated by wax printing so as to improve LFA sensitivity. Several wax pillar patterns were printed onto the nitrocellulose membrane in order to produce delays as well as pseudoturbulence in the microcapillary flow. The effect of the proposed wax pillar-modified devices was also mathematically simulated, corroborating the experimental results obtained for the different patterns tested afterwards for detection of HIgG as model protein in a gold nanoparticle-based LFA. The effect of the introduction of such wax-printed pillars was a sensitivity improvement of almost 3-fold compared to the sensitivity of a conventional free-barrier LFA.