Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, United States.
Department of Physics, Duke University, Durham, North Carolina 27708, United States.
Nano Lett. 2020 Jun 10;20(6):4330-4336. doi: 10.1021/acs.nanolett.0c01051. Epub 2020 May 14.
Fluorescence-based microarrays are promising diagnostic tools due to their high throughput, small sample volume requirements, and multiplexing capabilities. However, their low fluorescence output has limited their implementation for diagnostics applications in point-of-care (POC) settings. Here, by integration of a sandwich immunoassay microarray within a plasmonic nanogap cavity, we demonstrate strongly enhanced fluorescence which is critical for readout by inexpensive POC detectors. The immunoassay consists of inkjet-printed antibodies on a polymer brush which is grown on a gold film. Colloidally synthesized silver nanocubes are placed on top and interact with the underlying gold film creating high local electromagnetic field enhancements. By varying the thickness of the brush from 5 to 20 nm, up to a 151-fold increase in fluorescence and 14-fold improvement in the limit-of-detection is observed for the cardiac biomarker B-type natriuretic peptide (BNP) compared to the unenhanced assay, paving the way for a new generation of POC clinical diagnostics.
基于荧光的微阵列由于其高通量、小样本量需求和多重检测能力，是很有前途的诊断工具。然而，它们的低荧光输出限制了它们在即时检测（POC）环境中的诊断应用。在这里，通过在等离子体纳米间隙腔体内集成夹心免疫分析微阵列，我们证明了强烈的荧光增强，这对于通过廉价的 POC 探测器进行读出至关重要。免疫分析由聚合物刷上喷墨打印的抗体组成，聚合物刷生长在金膜上。胶体合成的银纳米立方体放置在顶部并与下面的金膜相互作用，从而产生高的局域电磁场增强。通过将刷的厚度从 5nm 变化到 20nm，与未增强的检测相比，心脏标志物 B 型利钠肽（BNP）的荧光强度增加了 151 倍，检测限提高了 14 倍，为新一代 POC 临床诊断铺平了道路。
