Structural defects play an important role in exploitation of two-dimensional layered materials (2DLMs) for advanced biosensors with the increasingly high sensitivity and low detection limit. Grain boundaries (GBs), as an important type of structural defect in polycrystalline 2DLM films, potentially provide sufficient active defect sites for the immobilization of bioreceptor units via chemical functionalization. In this work, we report the selective functionalization of high-density GBs with complementary DNA receptors, via gold nanoparticle (AuNP) linkers, in wafer-scale polycrystalline monolayer (1L) W(Mo)S₂ films as versatile plasmonic biosensing platforms. The large surface area and GB-rich nature of the polycrystalline 1L WS₂ film enabled the immobilization of bioreceptors in high surface density with spatial uniformity, while the AuNPs perform not only as bioreceptor linkers, but also promote detection sensitivity through surface plasmon resonance enhancement effect. Therefore, the presented biosensor demonstrated highly sensitive and selective sub-femto-molar detection of representative RNA sequences from the novel coronavirus (RdRp, ORF1ad and E). This work demonstrates the immense potential of AuNP-decorated GB-rich 2DLMs in the design of ultra-sensitive biosensing platforms for the detection of biological targets beyond RNA, bringing new opportunities for novel healthcare technologies.

结构缺陷在二维层状材料 (2DLM) 的开发中起着重要作用，用于具有越来越高的灵敏度和低检测限的先进生物传感器。晶界 (GB) 作为多晶 2DLM 薄膜中一种重要的结构缺陷类型，可能为通过化学功能化固定生物受体单元提供足够的活性缺陷位点。在这项工作中，我们报告了具有互补 DNA 受体的高密度 GB 的选择性功能化，通过金纳米颗粒 (AuNP) 连接器，在晶圆级多晶单层 (1L) W(Mo)S ₂薄膜中作为多功能等离子体生物传感平台。多晶 1L WS ₂的大表面积和富含 GB 的性质薄膜能够以高表面密度和空间均匀性固定生物受体，而 AuNPs 不仅可以作为生物受体连接器，还可以通过表面等离子体共振增强效应提高检测灵敏度。因此，所提出的生物传感器展示了对来自新型冠状病毒（RdRp、ORF1ad 和 E）的代表性 RNA 序列的高灵敏度和选择性亚飞摩尔检测。这项工作证明了 AuNP 装饰的富含 GB 的 2DLM 在设计超灵敏生物传感平台以检测 RNA 以外的生物靶标方面的巨大潜力，为新型医疗保健技术带来了新机遇。