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.

中文翻译：

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厚度感应夹心等离子体生物传感器可实现无标记裸眼抗体定量

用于检测病毒抗体的临床血清学检测非常耗时，灵敏度/选择性较低，或者依赖于复杂的检测仪器。在这里，我们通过利用夹层等离子体纳米结构中的距离依赖性电磁耦合，开发了一种用于超灵敏厚度传感的夹层等离子体生物传感器 (SPB)。SPBs 定量放大纳米级范围内的厚度变化（灵敏度：~2% nm ^–1) 转化为宏观可见信号，从而能够快速、无标记和肉眼检测目标生物分子种类（通过免疫结合事件引起的厚度变化）。作为概念证明，该测定提供了广泛的动态范围（7 个数量级）和低 LOD（~0.3 pM），允许极其准确的 SARS-CoV-2 抗体定量（灵敏度/特异性：100%/~ 99%，带有便携式光纤设备）。该策略适用于护理点的高通量多重检测和基于智能手机的传感，可以扩展到病毒感染和疫苗接种领域以外的各种传感应用。