Industry 4.0 Convergence Bionics Engineering, Pukyong National University, Busan, 48513, Republic of Korea.
School of Electrical Engineering, Pukyong National University, Busan, 48513, Republic of Korea.
Mikrochim Acta. 2022 Aug 6;189(9):321. doi: 10.1007/s00604-022-05413-3.
The label-free detection of SARS-CoV-2 spike protein is demonstrated by using slightly tapered no-core fiber (ST-NCF) functionalized with ACE2. In the fabricated sensor head, abrupt changes in the mode-field diameter at the interfaces between single-mode fiber and no-core fiber excite multi-guided modes and facilitate multi-mode interference (MMI). Its slightly tapered region causes the MMI to be more sensitive to the refractive index (RI) modulation of the surrounding medium. The transmission minimum of the MMI spectrum was selected as a sensor indicator. The sensor surface was functionalized with ACE2 bioreceptors through the pretreatment process. The ACE2-immobilized ST-NCF sensor head was exposed to the samples of SARS-CoV-2 spike protein with concentrations ranging from 1 to 10 ng/mL. With increasing sample concentration, we observed that the indicator dip moved towards a longer wavelength region. The observed spectral shifts are attributed to localized RI modulations at the sensor surface, which are induced by selective bioaffinity binding between ACE2 and SARS-CoV-2 spike protein. Also, we confirmed the capability of the sensor head as an effective and simple optical probe for detecting antigen protein samples by applying saliva solution used as a measurement buffer. Moreover, we compared its detection sensitivity to SARS-CoV-2 and MERS-CoV spike protein to examine its cross-reactivity. In particular, we proved the reproducibility of the bioassay protocol adopted here by employing the ST-NCF sensor head reconstructed with ACE2. Our ST-NCF transducer is expected to be beneficially utilized as a low-cost and portable biosensing platform for the rapid detection of SARS-CoV-2 spike protein.
利用 ACE2 功能化的无芯光纤（ST-NCF）实现了对 SARS-CoV-2 刺突蛋白的无标记检测。在制造的传感器头部中，单模光纤和无芯光纤之间的界面处模场直径的突然变化激发了多导模，并促进了多模干涉（MMI）。其逐渐变细的区域使 MMI 对周围介质的折射率（RI）调制更加敏感。选择 MMI 光谱的传输最小值作为传感器指标。传感器表面通过预处理过程用 ACE2 生物受体功能化。将 ACE2 固定在 ST-NCF 传感器头部上，然后将其暴露于浓度范围为 1 至 10 ng/mL 的 SARS-CoV-2 刺突蛋白样品中。随着样品浓度的增加，我们观察到指示陷波向更长的波长区域移动。观察到的光谱位移归因于传感器表面的局部 RI 调制，这是由 ACE2 和 SARS-CoV-2 刺突蛋白之间的选择性生物亲和结合引起的。此外，我们通过将唾液溶液用作测量缓冲液来确认传感器头部作为检测抗原蛋白样品的有效简便光学探针的能力。此外，我们还比较了传感器头部对 SARS-CoV-2 和 MERS-CoV 刺突蛋白的检测灵敏度，以检查其交叉反应性。特别是，我们通过使用带有 ACE2 的 ST-NCF 传感器头证明了所采用的生物测定协议的重现性。我们的 ST-NCF 换能器有望作为一种低成本，便携式的生物传感平台，用于快速检测 SARS-CoV-2 刺突蛋白。
