Xiong Yang, Fu Tong, Zhang Daxiao, Zhang Shunping, Xu Hongxing
The Institute for Advanced Studies, Wuhan University, Wuhan 430072, China.
School of Physics and Technology, Center for Nanoscience and Nanotechnology, and Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, Wuhan University, Wuhan 430072, China.
Nanoscale. 2021 Feb 4;13(4):2429-2435. doi: 10.1039/d0nr06148d.
Easy-to-use and sensitive quantification of biomarkers has a great significance in disease prediction, diagnosis, and monitoring. Here, we report a biosensor for simple and sensitive biomarker detection based on the strong light scattering (brightness) of superradiative plasmonic nanoantennas. This nanoantenna is constructed using antibody-decorated gold nanoparticles (Au NPs) immobilized onto a gold mirror by the target antigen, forming a nanoparticle-on-mirror (NPOM) configuration. The NPOM produces an order of magnitude stronger light scattering in the red region compared with isolated Au NPs on the dielectric substrate, due to the strong near-field coupling of surface plasmons across the gap between the Au NPs and the gold film. The increased brightness allows one to observe the captured Au NPs with the naked eye using a dark-field optical microscope. The particle density of the Au NPs varies linearly with the concentration of the target antigen over a broad dynamic range from 10-3 to 103 ng mL-1. This dynamic range is three orders of magnitude broader than that obtained from the previous work based on a dark-field optical microscope. The limit of detection is 1 pg mL-1 (6.67 fM), which is three orders of magnitude more sensitive than that obtained in the previous work using similar conditions. The uniform spatial distribution of the Au NPs on the gold film was allowed to quantify biomarkers with a relative standard deviation as small as 1-7%. Biosensing using superradiative NPs can lower the detection limit, simplify, and speed up the detection procedure for biomarker detection.
易于使用且灵敏的生物标志物定量分析在疾病预测、诊断和监测中具有重要意义。在此，我们报道了一种基于超辐射等离子体纳米天线的强光散射（亮度）用于简单灵敏生物标志物检测的生物传感器。这种纳米天线是通过目标抗原将抗体修饰的金纳米颗粒（Au NPs）固定在金镜上构建而成，形成了镜上纳米颗粒（NPOM）结构。与介电基底上的孤立Au NPs相比，NPOM在红色区域产生的光散射要强一个数量级，这是由于Au NPs与金膜之间间隙处表面等离子体的强近场耦合所致。亮度的增加使得使用暗场光学显微镜就能用肉眼观察到捕获的Au NPs。在10⁻³至10³ ng mL⁻¹的宽动态范围内，Au NPs的颗粒密度与目标抗原浓度呈线性变化。这个动态范围比之前基于暗场光学显微镜的工作所获得的范围宽三个数量级。检测限为1 pg mL⁻¹（6.67 fM），比之前在类似条件下工作所获得的检测限灵敏三个数量级。金膜上Au NPs的均匀空间分布使得能够以低至1 - 7%的相对标准偏差对生物标志物进行定量。使用超辐射纳米颗粒进行生物传感可以降低检测限，简化并加速生物标志物检测的程序。
