Dillen Annelies, Scarpellini Claudia, Daenen Woud, Driesen Seppe, Zijlstra Peter, Lammertyn Jeroen
Department of Biosystems─Biosensors Group, KU Leuven, Willem de Croylaan 42, Box 2428, 3001Leuven, Belgium.
Department of Applied Physics─Molecular Plasmonics, Eindhoven University of Technology, De Rondom 70, 5612 APEindhoven, The Netherlands.
ACS Sens. 2023 Feb 24;8(2):811-821. doi: 10.1021/acssensors.2c02388. Epub 2023 Feb 3.
Throughout the past decades, fiber optic surface plasmon resonance (FO-SPR)-based biosensors have proven to be powerful tools for both the characterization of biomolecular interactions and target detection. However, as FO-SPR signals are generally related to the mass that binds to the sensor surface, multistep processes and external reagents are often required to obtain significant signals for low molecular weight targets. This increases the time, cost, and complexity of the respective bioassays and hinders continuous measurements. To overcome these requirements, in this work, -duplexed aptamers (DAs) were implemented on FO-SPR sensors, which underwent a conformational change upon target binding. This induced a spatial redistribution of gold nanoparticles (AuNPs) upon specific target binding and resulted in an amplified and concentration-dependent signal. Importantly, the AuNPs were covalently conjugated to the sensor, so the principle does not rely on multistep processes or external reagents. To implement this concept, first, the thickness of the gold fiber coating was adapted to match the resonance conditions of the surface plasmons present on the FO-SPR sensors with those on the AuNPs. As a result, the signal obtained due to the spatial redistribution of the AuNPs was amplified by a factor of 3 compared to the most commonly used thickness. Subsequently, the -DAs were successfully implemented on the FO-SPR sensors, and it was demonstrated that the DA-based FO-SPR sensors could specifically and quantitatively detect an ssDNA target with a detection limit of 230 nM. Furthermore, the redistribution of the AuNPs was proven to be reversible, which is an important prerequisite for continuous measurements. Altogether, the established DA-based FO-SPR bioassay holds much promise for the detection of low molecular weight targets in the future and opens up possibilities for FO-SPR-based continuous biosensing.
在过去几十年中，基于光纤表面等离子体共振（FO-SPR）的生物传感器已被证明是用于生物分子相互作用表征和目标检测的强大工具。然而，由于FO-SPR信号通常与结合到传感器表面的质量相关，对于低分子量目标，往往需要多步过程和外部试剂才能获得显著信号。这增加了相应生物测定的时间、成本和复杂性，并阻碍了连续测量。为了克服这些要求，在这项工作中，双链适配体（DAs）被应用于FO-SPR传感器，其在与目标结合时会发生构象变化。这在特异性目标结合时诱导了金纳米颗粒（AuNPs）的空间重新分布，并产生了放大的、浓度依赖性信号。重要的是，AuNPs与传感器共价结合，因此该原理不依赖于多步过程或外部试剂。为了实现这一概念，首先，调整了金纤维涂层的厚度，以使FO-SPR传感器上存在的表面等离子体的共振条件与AuNPs上的共振条件相匹配。结果，与最常用的厚度相比，由于AuNPs的空间重新分布而获得的信号放大了3倍。随后，双链适配体成功应用于FO-SPR传感器，并且证明基于双链适配体的FO-SPR传感器能够特异性地、定量地检测单链DNA目标，检测限为230 nM。此外，AuNPs的重新分布被证明是可逆的，这是连续测量一个重要前提条件。总之，已建立的基于双链适配体的FO-SPR生物测定法在未来检测低分子量目标方面具有很大前景，并为基于FO-SPR的连续生物传感开辟了可能性。
