Opt Express. 2022 Jun 6;30(12):22233-22246. doi: 10.1364/OE.461428.
We propose a measurement method for sensitive and label-free detections of virus-like particles (VLPs) using color images of nanoplasmonic sensing chips. The nanoplasmonic chip consists of 5×5 gold nanoslit arrays and the gold surface is modified with specific antibodies for spike protein. The resonant wavelength of the 430-nm-period gold nanoslit arrays underwater environment is about 570 nm which falls between the green and red bands of the color CCD. The captured VLPs by the specific antibodies shift the plasmonic resonance of the gold nanoslits. It results in an increased brightness of green pixels and decreased brightness of red pixels. The image contrast signals of (green - red) / (red + green) show good linearity with the surface particle density. The experimental tests show the image contrast method can detect 100-nm polystyrene particles with a surface density smaller than 2 particles/µm. We demonstrate the application for direct detection of SARS-CoV-2 VLPs using a simple scanner platform. A detection limit smaller than 1 pg/mL with a detection time less than 30 minutes can be achieved.
我们提出了一种使用纳米等离子体感测芯片的彩色图像对病毒样颗粒（VLPs）进行灵敏、无标记检测的测量方法。纳米等离子体芯片由 5×5 个金纳米狭缝阵列组成，金表面用针对刺突蛋白的特异性抗体修饰。在水下环境中，430nm 周期的金纳米狭缝阵列的共振波长约为 570nm，位于颜色 CCD 的绿色和红色波段之间。被特异性抗体捕获的 VLPs 会改变金纳米狭缝的等离子体共振。这导致绿色像素的亮度增加，红色像素的亮度降低。(green - red)/(red + green)的图像对比度信号与表面粒子密度呈良好的线性关系。实验测试表明，该图像对比方法可以检测到表面密度小于 2 个/μm2 的 100nm 聚苯乙烯颗粒。我们使用简单的扫描仪平台展示了直接检测 SARS-CoV-2 VLPs 的应用。可以达到小于 1pg/mL 的检测限和小于 30 分钟的检测时间。
