Do-it-yourself protein arrays as high-throughput immunoassays enabled by confined droplets on patterned plasmonic chips

Protein chips and arrays in parallel enable high-throughput protein detection in small-volume biological fluids, however, the limitations in sensitivity, dependence on expensive/bulky external equipment, and the need for specialized technical personnel have restricted their application in clinical and laboratory settings. Here, we present a droplet-based do-it-yourself (DBDIY) array on patterned plasmonic chips for high-throughput immunoassays, via confined droplets and plasmonic enhanced near-infrared (NIR) fluorescence. The assay allows equipment-free microarray fabrication and highly sensitive detection using only a pipette. It dynamically profiles 10 cytokines over 40 days in individual mice with just 6 µL of serum/blood per time point and achieves 100% sensitivity and specificity for C-reactive protein (CRP) in 1 nL of peripheral whole blood samples from 112 children. Scalable to high-throughput analysis of cell culture and serum, this accessible system simplifies workflows, extends utility in resource-limited settings, and offers a next-generation tool for longitudinal animal studies and clinical diagnostics. Protein detection typically requires bulky equipment and large sample volumes. Here, the authors develop a do-it-yourself plasmonic array that enables high-throughput immunoassays from minute volumes using only a pipette, showcasing their approach through longitudinal animal studies and pediatric diagnostics.