Surface‐Plasmon‐Polaritons for Reversible Assembly of Gold Nanoparticles, In Situ Nanogap Tuning, and SERS

Abstract

A transportable reversible assembly of gold nanoparticles (AuNPs) in an aqueous environment addresses the need for in situ surafce‐enhanced Raman spectroscopy (SERS) hotspot creation for biological applications. Usually, light‐directed AuNP assembly methods use higher laser powers and surfactants and are, hence, unsuitable for biological applications. Here, surface plasmon polaritons‐assisted dynamic assembly of AuNPs are demonstrated at laser power density as low as 100 nW µm−2. The AuNP assembly with multiple controllable hotspots is generated in an Au–water interface for solution‐based SERS measurements. The major advantage of the method is that the interparticle nanogap is tunable to achieve analyte and AuNP‐specific optimum SERS enhancement. The SERS intensity is reproducible on multiple reassembly cycles and assembly attempts, proving repeatability in the produced nanogap pattern. The assembly experiments reveal the influence of AuNP surface charge and the resulting polarizability on the SPP forces. The developed system and method can detect sulforhodamine 101 (SR101) dye molecules at concentrations as low as 10−10 m. Further, the SERS measurements on double‐stranded DNA suggest that the molecules are oriented in a fashion to expose adenosine to the enhanced field, leading to its dominance in the recorded spectra.

Studying the Effects and Competitive Mechanisms of YOYO-1 on the Binding Characteristics of DOX and DNA Molecules Based on Surface-Enhanced Raman Spectroscopy and Molecular Docking Techniques

“…Peaks at 783, 800, and 1097 cm −1 correspond to the O-P-O bond in the phosphate group, the main chain, and the O=P=O double bond in PO 2 , respectively. [12,17,35,36]. The specific peak assignments are as follows: Peaks at 672, 728, 1178, 1249, 1312, 1337, 1374, 1420, 1488, and 1573 cm −1 are attributed to vibrations related to the base regions of the ctDNA molecule.…”

“…Figure 3(a1) depicts the molecular structure of ctDNA. In Figure 3(a2), the Raman spectrum of the ctDNA solution (8.7 × 10 −2 M) shows prominent Raman peaks at 672, 728, 783, 800, 967, 1010, 1097, 1178, 1249, 1312, 1337, 1374, 1420, 1488, and 1573 cm −1[12,17,35,36]. The specific peak assignments are as follows: Peaks at 672, 728, 1178, 1249, 1312, 1337, 1374, 1420, 1488, and 1573 cm −1 are attributed to vibrations related to the base regions of the ctDNA molecule.…”