Enhancement of Gold Nanoparticle Coupling with a 2D Plasmonic Crystal at High Incidence Angles

Abstract

2D nanoplasmonic substrates excited in transmission spectroscopy are ideal for several biosensing, metamaterial, and optical applications. We show that their excellent properties can be further improved with plasmonic coupling of Au nanoparticles (AuNPs) on gold-coated nanodisk arrays excited at large incidence angles of up to 50°. The Bragg modes (BM) thereby strongly couple to AuNP immobilized on the plasmonic substrate due to shorter decay length of the plasmon at higher incidence angles, leading to a further enhanced field between the AuNP and the plasmonic substrate. The field was highest and two hotspots were created at orthogonal positions for AuNP located close to the corner of the Au film and Au nanodisk, which was also observed for AuNP dimers. Hybridization between single-stranded DNA (ssDNA) immobilized on the surface of the AuNPs and the capture ssDNA on the gold-coated nanodisk arrays led to at least a 5-fold signal improvement and a 7-fold lower limit of detection at 7 pM for ssDNA-functionalized AuNPs at large incident angles. Thus, we demonstrate that higher field strength can be accessed and the significant advantages of working with high incidence angles with AuNP on a 2D plasmonic crystal in plasmonic sensing.

Advanced in developmental organic and inorganic nanomaterial: a review

“…The binding of molecules to the particle surface can change the plasmon resonance frequency directly, which is visible by scattered light. In addition, the influence of the inter-AuNP distance on the plasmon resonance, when this distance is reduced to less than the particle diameter, is the crucial factor in the sensor application, and linking the NPs with a biological analyte results in a color change that makes the basis of sensing [65]. The first colorimetric sensing of nucleic acids was reported and is now the most recognized example of a gold-based biosensor [66].…”

4-Mercaptopyridine Modified Fiber Optic Plasmonic Sensor for Sub-nM Mercury (II) Detection

“…At the same time, the coating ability of sodium citrate itself is used as a protective group, so that the atomic Au is not easily aggregated with other ions, thereby forming gold nanoparticles. In order to provide sufficient coupling power between the deposit nanoparticles and the gold film on the sensor surface and reduce AuNPs' physical adsorption on the sensor surface due to the large particle size, 20 nm AuNPs are selected for modification [31]. For the sensor in this article, 20 nm is much smaller than the depth of the evanescent field on the surface of the TFBG sensor covered with a 50 nm gold film [32].…”

Label‐Free Near‐Infrared Plasmonic Sensing Technique for DNA Detection at Ultralow Concentrations

“…The nanomolar detection range can be reached without any chemical or biological amplification due to the effect of the NT array on the sensing surface, which can increase the local field intensity and improve the surface-sensitivity. Surface-sensitivity is related to near-field distribution, [31,34,49,50] so the characteristic of the near-field distribution corresponding to flat gold film and gold-coated NT array were simulated as shown in Figure S9 in the Supporting Information. Compared with flat gold film, ssDNA is located the stronger near-field around edge and vertex, which can result in high surface-sensitivity of ssDNA specific binding.…”

“…A wide variety of complex nanostructures and their assemblies were designed, such as nanoslit, [26,27] nanohole [28,29] and nanodisk. [30,31] Metallic nanostructures can obtain strong enhancement of the local field and large confinement, which can achieve the high sensitivity and the low LOD. However, strong local field enhancement comes at the expense of a reduced bulk-sensitivity and a decreased decay depth.…”