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

Lourdes Rivas, Mariana Medina, Alfredo de la Escosura-Muñiz and Arben Merkoçi. Lab Chip, 2014, 14, 4406-4414

Although lateral flow assays (LFA) 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 the LFA sensitivity. Several wax pillars patterns were printed onto nitrocellulose membrane in order to produce delays as well as pseudo turbulences into the microcapillary flow. The effect of the proposed wax pillar modified devices were 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 the sensitivity improvement of almost 3-folds in comparison to a conventional free-barrier LFA.