High-throughput light-induced immunoassay with milliwatt-level laser under one-minute optical antibody-coating on nanoparticle-imprinted substrate

The efficient detection of protein biomarkers is critical for public health. However, the sensitivity of conventional antigen test kits is relatively low for early diagnosis, and laboratory immunoassays require complex pretreatment processes overnight. If target nanomaterials could be remotely guided to the detection site, simpler and faster methods would be developed. Here, we reveal the mechanism of light-induced immunoassay that anti-spike-protein antibodies for SARS-CoV-2 were coated on our developed nanoparticle-imprinted plasmonic substrate (NPI-PS) over the submillimeter area within one minute and nanoparticles modified with spike proteins can be selectively detected within a few minutes at one or two orders of higher sensitivity via a two-step optical condensation using NPI-PS. NPI-PS exhibits high-performance optical condensation with high photothermal properties even under milliwatt-class nonresonant laser irradiation, enabling a wide range of quantitative measurements. These findings support an innovative strategy to mitigate pandemic threats and various diseases through the high-throughput detection of protein biomarkers.