Makela Megan, Tu Dandan, Lin Zhihai, Coté Gerard, Lin Pao Tai
Department of Materials Science and Engineering, Texas A&M University, College Station, TX 77843, USA.
Center for Remote Health Systems and Technologies, Texas A&M University, College Station, TX 77843, USA.
Nanomaterials (Basel). 2024 Nov 29;14(23):1927. doi: 10.3390/nano14231927.
Chip-scale optical waveguide-assisted surface-enhanced Raman spectroscopy (SERS) that used nanoparticles (NPs) was demonstrated. The Raman signals from Raman reporter (RR) molecules on NPs can be efficiently excited by the waveguide evanescent field when the molecules are in proximity to the waveguide surface. The Raman signal was enhanced by plasmon resonance due to the NPs close to the waveguide surface. The optical waveguide mode and the NP-induced field enhancement were calculated using a finite difference method (FDM). The sensing performance of the waveguide-assisted SERS device was experimentally characterized by measuring the Raman scattering from various RRs, including 4-mercaptobenzoic acid (4-MBA), 5,5'-dithio-bis-(2-nitrobenzoic acid) (DTNB), and malachite green isothiocyanate (MGITC). The observed Raman spectral features were identified and assigned to the complex vibrational modes associated with different reporters. A low detection limit of 1 nM was achieved. In addition, the device sensing method was applied to the detection of the biomarker cardiac troponin I (cTnI) using an aptamer sandwich assay immobilized on the device surface. Overall, the optical waveguides integrated with SERS show a miniaturized sensing platform for the detection of small molecules and large proteins, potentially enabling multiplexed detection for clinically relevant applications.
展示了使用纳米颗粒（NPs）的芯片级光波导辅助表面增强拉曼光谱（SERS）。当拉曼报告分子（RR）靠近光波导表面时，光波导的倏逝场能够有效激发NPs上RR分子的拉曼信号。由于靠近光波导表面的NPs，拉曼信号通过等离子体共振得到增强。使用有限差分法（FDM）计算了光波导模式和NP诱导的场增强。通过测量来自各种RR（包括4-巯基苯甲酸（4-MBA）、5,5'-二硫代双（2-硝基苯甲酸）（DTNB）和异硫氰酸孔雀石绿（MGITC））的拉曼散射，对光波导辅助SERS装置的传感性能进行了实验表征。识别并确定了观察到的拉曼光谱特征与不同报告分子相关的复杂振动模式。实现了1 nM的低检测限。此外，使用固定在装置表面的适体夹心分析法，将该装置传感方法应用于生物标志物心肌肌钙蛋白I（cTnI）的检测。总体而言，与SERS集成的光波导展示了一个用于检测小分子和大蛋白质的小型化传感平台，有可能实现临床相关应用的多重检测。
