Abstract

Biomolecule detection has become important in many applications such as medical diagnosis, forensic analysis, basic biological studies, and food quality assessment. In particular, the Mid-infrared range offers an important opportunity for biomolecular sensing as it covers the molecular vibrational spectra of vital biochemicals such as Deoxyribonucleic acid, Ribonucleic Acid, and proteins. In this study, a double band absorbing plasmonic nanoantenna array with two gold disk resonators is proposed. The biosensing ability of this structure was investigated using the protein-goat anti-mouse immunoglobulin G model and Polymethyl methacrylate film. The basic structural bonds of protein monolayer, namely Amide-I, Amide-II, and Amide-III showed vibrational signatures at 6010 nm (∼1664 cm⁻¹), 6496 nm (∼1539 cm⁻¹), and 6989 nm (∼1431 cm⁻¹) wavelengths, respectively. In addition, the spectral response of the proposed antenna structure was investigated using a Polymethyl methacrylate film by detecting the C=O and the C-H bonds. The strong dipole moment at C=O showed a strong absorption deep at 5782 nm (∼1730 cm⁻¹) while the C-H bond has shown a relatively low absorption deep at 3350 nm (∼2985 cm⁻¹) and 3395 nm (∼2946 cm⁻¹). Our findings indicate that the double spacer disk configuration detects the spectral signature of the protein monolayer and Polymethyl methacrylate film in each band, simultaneously. The dual-band can be tuned independently by carefully engineering the radii of the double disks without making an effect on the other band. The proposed structure can be used as a characterization tool for identifying unknown complex molecules by simply detecting their spectral fingerprints in each mode of the dual-band, independently. Also, this design strategy can be insight to multi-mode SEIRA platforms, where more complex chemical molecules are needed to be detected or identified in biology, chemistry, and defense areas.

摘要

生物分子检测在许多应用中变得很重要，例如医学诊断、法医分析、基础生物学研究和食品质量评估。特别是，中红外范围为生物分子传感提供了重要机会，因为它涵盖了重要生物化学物质（如脱氧核糖核酸、核糖核酸和蛋白质）的分子振动光谱。在这项研究中，提出了一种具有两个金盘谐振器的双波段吸收等离子体纳米天线阵列。使用蛋白质-山羊抗小鼠免疫球蛋白G模型和聚甲基丙烯酸甲酯薄膜研究了该结构的生物传感能力。蛋白质单层的基本结构键，即 Amide-I、Amide-II 和 Amide-III 在 6010 nm (~1664 cm ^-1 )、6496 nm (~1539 cm^-1 ), 和 6989 nm (∼1431 cm ^-1 ) 波长。此外，通过检测 C=O 和 CH 键，使用聚甲基丙烯酸甲酯薄膜研究了所提出的天线结构的光谱响应。C=O 处的强偶极矩在 5782 nm（~1730 cm ^-1）处显示出强烈的吸收深度，而 CH 键在 3350 nm（~2985 cm ^-1）和 3395 nm（~2946厘米^-1). 我们的研究结果表明，双间隔盘配置可同时检测每个波段中蛋白质单层和聚甲基丙烯酸甲酯薄膜的光谱特征。双波段可以通过仔细设计双圆盘的半径来独立调谐，而不会对其他波段产生影响。所提出的结构可以用作识别未知复杂分子的表征工具，只需在双波段的每种模式下独立地检测它们的光谱指纹即可。此外，这种设计策略可以洞察多模式 SEIRA 平台，在这些平台上，需要在生物学、化学和国防领域检测或识别更复杂的化学分子。