Sub-micron resolution surface plasmon resonance microscopy of binding kinetics under active microfluidic mixing

近年来，对微型化生物传感的研究，无论是以微阵列还是芯片实验室的形式，都出现了爆炸性的增长。表面等离子体共振(SPR)是一种强有力的生物传感方法，在这两种情况下都得到了很好的应用。大多数SPR系统要么基于宏观(mm2或cm2)薄膜中传播的等离子体激元，要么基于纳米结构中的非传播局域表面等离子激元(LSRP)。尽管光谱两端的体系已经得到了广泛的研究，但在表面结构及其对SPR活性金属的化学反应和光学性质的影响方面，两者之间存在着知识差距。这一差距值得探讨，因为在推动“向纳米方向发展”的过程中，科学家和工程师可能并不具备就生物传感器设计的最佳规模做出明智决定的所有要素。这项研究旨在通过开发在亚微米尺度上观察SPR现象的仪器和方法来填补这一空白，该仪器和方法与表面化学动力学和微流控混合的实时测量相联系。该计划将通过一种新的成像平台来解决这些挑战，该平台能够产生与扫描电子显微镜(SEM)的图像共同配准的高分辨率断层SPR显微图像，并结合活跃的芯片上微流控混合。该系统将能够在亚微米尺度上研究与金属薄膜特性相关的表面功能化和测定动力学，并允许直接测量朗缪尔等温线。这项工作将对下一代微型生物传感器产生广泛的影响，这些传感器应用于SPR普遍存在的领域，如快速医疗诊断、环境监测以及制药和农业食品行业。这项研究的长期目标是使基于微阵列和芯片实验室的SPR系统能够达到目前无法实现的密度、小型化和测量可靠性水平。

Research into miniaturized biosensing, whether in microarray or lab-on-chip formats, has seen explosive growth in recent years. Surface plasmon resonance (SPR), a powerful method for biosensing, is well established in both cases. Most SPR systems are based either on propagating plasmons in "macroscopic" (mm2 or cm2) thin-films, or on non-propagating localized surface plasmons (LSRP) in nanostructures. Though systems at both ends of the spectrum have been extensively studied, there exists a knowledge gap between the two where surface structure and its impact on chemical reactivity and optical properties of SPR-active metals are not fully understood. This gap is important to explore because, in the push to "go nano", scientists and engineers may not have all the elements in hand to make informed decisions about optimal levels of scale in biosensor design. This research aims to fill this gap by developing instrumentation & methods for observing SPR phenomena at the sub-µm scale linked to real-time measurements of surface chemistry kinetics and microfluidic mixing. The program will address these challenges with a novel imaging platform capable of producing high-resolution tomographic SPR microscopy images co-registered with that from a scanning electron microscope (SEM), and incorporating active on-chip microfluidic mixing. This system will enable the study of surface functionalization and assay kinetics in relation to metal thin-film properties, at the sub-µm level of scale, and allow direct measurement of Langmuir isotherms. The work will have wide-ranging repercussions in next-generation miniaturized biosensors in applications where SPR is prevalent such as rapid medical diagnostics, environmental monitoring, and the pharmaceutical and agri-food industries. The long term objective of this research is to enable microarray- and lab-on-chip-based SPR systems to achieve levels of density, miniaturization, and reliability of measurement not currently possible.