When excited over a periodic metamaterial lattice of gold nanoparticles (~ 100 nm), localized plasmon resonances (LPR) can be coupled by a diffraction wave propagating along the array plane, which leads to a drastic narrowing of plasmon resonance lineshapes (down to a few nm full-width-at-half-maximum) and the generation of singularities of phase of reflected light. These phenomena look very promising for the improvement of performance of plasmonic biosensors, but conditions of implementation of such diffractively coupled plasmonic resonances, also referred to as plasmonic surface lattice resonances (PSLR), are not always compatible with biosensing arrangement implying the placement of the nanoparticles between a glass substrate and a sample medium (air, water). Here, we consider conditions of excitation and properties of PSLR over arrays of glass substrate-supported single and double Au nanoparticles (~ 100–200 nm), arranged in a periodic metamaterial lattice, in direct and Attenuated Total Reflection (ATR) geometries, and assess their sensitivities to variations of refractive index (RI) of the adjacent sample dielectric medium. First, we identify medium (PSLR_air, PSLR_wat for air and water, respectively) and substrate (PSLR_sub) modes corresponding to the coupling of individual plasmon oscillations at medium- and substrate-related diffraction cut-off edges. We show that spectral sensitivity of medium modes to RI variations is determined by the lattice periodicity in both direct and ATR geometries (~ 320 nm per RIU change in our case), while substrate mode demonstrates much lower sensitivity. We also show that phase sensitivity of PSLR can exceed 10⁵ degrees of phase shift per RIU change and thus outperform the relevant parameter for all other plasmonic sensor counterparts. We finally demonstrate the applicability of surface lattice resonances in plasmonic metamaterial arrays to biosensing using standard streptavidin-biotin affinity model. Combining advantages of nanoscale architectures, including drastic concentration of electric field, possibility of manipulation at the nanoscale etc, and high phase and spectral sensitivities, PSLRs promise the advancement of current state-of-the-art plasmonic biosensing technology toward single molecule label-free detection.

当在金纳米颗粒的周期性超材料晶格（〜100 nm）上激发时，局部等离振子共振（LPR）可以通过沿阵列平面传播的衍射波耦合，从而导致等离振子共振线形急剧缩小（减小到几个最大半纳米宽度）和反射光相位奇异点的产生。这些现象对于改善等离子生物传感器的性能看起来非常有希望，但是这种衍射耦合等离子共振（也称为等离子表面晶格共振（PSLR））的实施条件并不总是与暗示着纳米颗粒放置的生物传感装置兼容。在玻璃基板和样品介质（空气，水）之间。这里，我们考虑了在玻璃衬底支撑的单和双Au纳米颗粒（〜100–200 nm）的阵列上的激发条件和PSLR的性质，这些纳米颗粒排列在周期性超材料晶格中，具有直接和衰减的全反射（ATR）几何形状，并评估了它们的对相邻样品电介质的折射率（RI）变化的敏感性。首先，我们确定媒介（PSLR_空气，PSLR_笏分别用于空气和水）和底物（PSLR_子在中期对应于各等离振子振荡的耦合）模与基板相关的衍射截止边。我们表明，中型模式对RI变化的光谱敏感性由直接和ATR几何中的晶格周期性决定（在我们的情况下，每个RIU改变约为320 nm），而基质模式显示出低得多的敏感性。我们还证明了PSLR的相位灵敏度可以超过10 ⁵每个RIU改变的相移度，因此优于所有其他等离子传感器对应物的相关参数。我们最终证明了使用标准链霉亲和素-生物素亲和力模型在等离激元超材料阵列中对生物传感的表面晶格共振的适用性。PSLR结合了纳米级架构的优势，包括电场的剧烈集中，在纳米级上进行操作的可能性等，以及高的相位和光谱灵敏度，从而有望将当前最先进的等离激元生物传感技术朝着无单分子标记的方向发展检测。