The dependence of medium refractive index on optical properties of gold nanorods and their SERS application

Abstract

In this article, the influence of the medium refractive index on optical properties of gold nanorods (GNRs) and their surface enhanced Raman spectroscopy application were studied. In particular, GNRs have been applied in biomedical sensors to detect diseases by monitoring the changes in the environment. In this study, the changes in optical properties of GNRs were investigated according to the medium refractive index changes in the cationic surfactant cetyltrimethylammonium bromide (CTAB) during synthesis processes as well as GNR dispersion in different medium refractive indices. For instance, in the solutions with different concentrations of CTAB, GNRs were coated by biomolecules [such as PEG, bovine serum albumin (BSA), and glutathione (GSH)], which have different refractive indices. The fundamental reason for the change in optical properties of GNRs is also elucidated. GNRs have been used to enhance surface Raman scattering to detect indigo molecules. The results showed that due to the surface plasmon resonance effect, the GNRs could strongly enhance the scattering signal of indigo dyes, with the lowest detectable concentration of up to 10−8 M and with an enhancement coefficient of over 2000 times.

Unveiling the Synergy of Coupled Gold Nanoparticles and J-Aggregates in Plexcitonic Systems for Enhanced Photochemical Applications

“…Figure 1 c demonstrates the UV-Vis-NIR spectra of AuBPs before and after the ligand exchange process. The slight blue shift of the LSPR peak after TMA functionalization [ 38 ] is due to the change in the refractive index of the medium from 1.46 (in CTAB) to 1.33 (in water) [ 39 ]. Crucially, -potential measurements confirm the positive charge on AuBPs following TMA functionalization ( -potential: +47.9 ± 19 mV).…”

NGHIÊN CỨU QUÁ TRÌNH HÌNH THÀNH CỦA CÁC CẤU TRÚC LÕI VỎ AuR@Ag DƯỚI SỰ PHÁT TRIỂN BẤT ĐẲNG HƯỚNG CỦA LỚP VỎ Ag

“…Các hạt nano vàng là vật liệu phân tán tốt nhất trong nước và chúng thường được sử dụng làm đầu dò cho các ứng dụng phân tích hoặc các ứng dụng sinh hóa vì tính ổn định cấu trúc và có tần số cộng hưởng plasmon nằm trong vùng ánh sáng khả kiến và hồng ngoại gần [5]- [7]. Đã có rất nhiều các công trình nghiên cứu tổng hợp các hạt nano vàng với các hình dạng và kích thước khác nhau như dạng cầu [3], [8], [9], dạng thanh [10], [11], dạng tam giác [12], [13] hay dạng dây nano [14], [15]. Các hạt nano vàng đồng dạng và phân tán tốt đã được chuẩn bị bằng các phương pháp khác nhau để làm vật liệu lõi cho các cấu trúc lõi @ vỏ [16]- [18].…”

Highly uniform core/shell structures AuR/Ag and AuR/Ag@BSA with various shell thicknesses for surface-enhanced Raman scattering

“…However, it is a fact that the synthesis of silver nanorods with uniaxial anisotropic structures faces many challenges [21][22][23]. Meanwhile, the synthesis of AuRs with a controllable aspect ratio is relatively simple [22][23][24][25][26]. The synthesis of core/shell nanostructures (AuR/Ag) both overcomes the difficulty in synthesising silver nanorods and taking advantage of the superior plasmonic properties of silver nanocrystals.…”

“…On that basis, the enhanced surface Raman scattering properties of AuR/Ag were investigated and compared with the SERs effect of AuRs. AuRs were synthesised by the seed-mediated method as reported in our previous work [24,25]. To prepare the Ag coating on the AuR, the AuRs were dispersed in 0.08M CTAC solution with the same original CTAB volume.…”