biostudies-literatureNan JJilin UniversityChina Postdoctoral Science FoundationNational Natural Science Foundation of ChinaNCI NIH HHSState Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics9596-9605https://www.ebi.ac.uk/biostudies/studies/S-EPMC9805804biostudies-literatureUnknown22(23)Clinical serology assays for detecting the antibodies of the virus are time-consuming, are less sensitive/selective, or rely on sophisticated detection instruments. Here, we develop a sandwiched plasmonic biosensor (SPB) for supersensitive thickness-sensing via utilizing the distance-dependent electromagnetic coupling in sandwiched plasmonic nanostructures. SPBs quantitatively amplify the thickness changes on the nanoscale range (sensitivity: ∼2% nm^-1) into macroscopically visible signals, thereby enabling the rapid, label-free, and naked-eye detection of targeted biomolecular species (via the thickness change caused by immunobinding events). As a proof of concept, this assay affords a broad dynamic range (7 orders of magnitude) and a low LOD (∼0.3 pM), allowing for the extremely accurate SARS-CoV-2 antibody quantification (sensitivity/specificity: 100%/∼99%, with a portable optical fiber device). This strategy is suitable for high-throughput multiplexed detection and smartphone-based sensing at the point-of-care, which can be expanded for various sensing applications beyond the fields of viral infections and vaccination.Nano lettersThickness-Sensing Sandwiched Plasmonic Biosensors Enable Label-Free Naked-Eye Antibody Quantification.PMC9805804F32 CA2136202020M681046219750982020TQ01192017TD-0622275071Liu JShan HLiu KZhang JYang BSun WZhang SWang LLiu XZhang WChe YLiu BNan JXu WYue YHettie KSZhu SfalseThickness-Sensing Sandwiched Plasmonic Biosensors Enable Label-Free Naked-Eye Antibody Quantification.Clinical serology assays for detecting the antibodies of the virus are time-consuming, are less sensitive/selective, or rely on sophisticated detection instruments. Here, we develop a sandwiched plasmonic biosensor (SPB) for supersensitive thickness-sensing via utilizing the distance-dependent electromagnetic coupling in sandwiched plasmonic nanostructures. SPBs quantitatively amplify the thickness changes on the nanoscale range (sensitivity: ∼2% nm^-1) into macroscopically visible signals, thereby enabling the rapid, label-free, and naked-eye detection of targeted biomolecular species (via the thickness change caused by immunobinding events). As a proof of concept, this assay affords a broad dynamic range (7 orders of magnitude) and a low LOD (∼0.3 pM), allowing for the extremely accurate SARS-CoV-2 antibody quantification (sensitivity/specificity: 100%/∼99%, with a portable optical fiber device). This strategy is suitable for high-throughput multiplexed detection and smartphone-based sensing at the point-of-care, which can be expanded for various sensing applications beyond the fields of viral infections and vaccination.2022-01-01T00:00:00Z2022 Dec2025-04-04T07:47:24.2Z2025-04-04T07:47:24.2ZS-EPMC98058043639455110.1021/acs.nanolett.2c03732