Self-Assembled Gold Nano-Bipyramids for Solution-Based Surface-Enhanced Raman Spectroscopy Detection

Abstract

In solution-based surface-enhanced Raman spectroscopy (SERS) detection, plasmonic metal nanoparticles’ controllable assembly and aggregation into highly enhanced electromagnetic coupling nanostructures remains a challenge. In this study, we demonstrate a facile and rapid strategy to control the assembly of poly­(styrene sulfonate) functionalized gold nano-bipyramids (PSS-Au BPs) as highly sensitive SERS substrates for solution-based SERS detection. The assembly process of the PSS-Au BPs was controlled by adding halide ions as aggregation agents under various concentrations in the presence of analytic molecules. In comparison, the citrate-capped spherical gold nanoparticles (Cit-Au NPs) were used to investigate the influence of the shape of NPs and their assembly state on SERS performance. Both in situ ultraviolet–visible (UV–vis) and Raman spectroscopy characterizations revealed that the shape of the NPs and aggregation state are critical to achieving a highly enhanced SERS property. The PSS-Au BPs, owing to the formation of tip-to-tip dimers, have a better electromagnetic enhancement capacity than Cit-Au NP aggregation states. Thus, the PSS-Au BPs display an improved lowest recorded concentration downs to the level of 5 × 10–11 M for crystal violet (CV) molecules, which is 2 or 3 orders of magnitude lower than those of the Cit-Au NPs.

Material design, development, and trend for surface-enhanced Raman scattering substrates

“…88 Moreover, with the help of organic linkers, NPs, especially anisotropic NPs can be assembled into different configurations, which also plays an important role in affecting the SERS enhancement. [93][94][95] Taking nanorods as an example, the end-to-end configuration tends to show higher EF than the side-by-side configuration because the gaps in the end-to-end configuration are located between high curvature regions with higher local electromagnetic fields. 93 Although liquid-phase SERS detection with metal NPs has good reproducibility for quantitative analysis, 96 its detection sensitivity is restricted seriously by the concentration of NPs.…”

Regulated synthesis of an Au NB-DT@Ag bimetallic core-molecule–shell nanostructure for reliable SERS detection

“…Penta-twinned Au seeds were synthesized through a heatinduced twinning method. 42,43 Briey, 13.75 mL of water, 6.25 mL of CTAC stock solution, 200 mL of 0.5 M CA and 200 mL of HAuCl 4 stock solution were added to a scintillation vial (25 mL) in sequence under vigorous stirring at room temperature. Then, 500 mL of fresh NaBH 4 solution (25 mM) prepared in icecold water was added to the above yellow solution and kept under vigorous stirring for 3 min, aer which the resultant brown solution was heated under gentle stirring and kept at 100 °C for 2 h. Finally, the seed solution was cooled and stored at room temperature.…”

Highly Uniform Fabrication of Gold Nanoparticles on Carbon Nanotube Sheets for Sensors Based on Surface-Enhanced Raman Spectroscopy with Improved Reproducibility

“…Although hydrothermal reduction is widely considered as one of the most commonly used methods for metallic NP coating on carbon-based substrates, − it often results in a highly nonuniform distribution of these nanostructures, which, to some extent, restricts the realistic application of SERS sensors . Considerable efforts have been devoted to solving such an issue in wet-chemistry synthesis. − One of the most effective strategies to synthesize Au nanocrystals with controllable uniformity, i.e., sizes and shapes, is the so-called seed-mediated growth, , where desirable Au nanostructures can further grow from well-designed Au seeds . Nevertheless, the seeded growth approach is a typical multiple-step method.…”