Quantitative Surface-Enhanced Raman Spectroscopy Analysis through 3D Superlattice Arrays of Au Nanoframes with Attomolar Detection

Abstract

This paper reports a methodology for synthesizing and ordering gold nanoframes into three-dimensional (3D) arrays with a controlled thickness, leading to homogeneous plasmonic superstructures, with which quantitative analysis via surface-enhanced Raman spectroscopy (SERS) has been successfully demonstrated. Because this preparation method allows for systematic control of nanoframe film thickness and the resulting 3D plasmonic superstructure, which exhibits a unique nanoporous network of hot-spots, detection limits down to 10 −18 M, corresponding to ≈6000 molecules, have been measured. Compared to analogous solid nanoparticle superstructures, the nanoframe superstructures with their unique nanoporous architecture effectively dissipate the heat inevitably generated by laser excitation during measurement, effectively suppressing the formation of carbonaceous materials and therefore their accompanying fluorescence interference, especially important for low concentration detection.

All-Hot-Spot Bulk Surface-Enhanced Raman Scattering (SERS) Substrates: Attomolar Detection of Adsorbates with Designer Plasmonic Nanoparticles

“…This strongly indicates the importance of intraparticle coupling produced from a single constituent in superlattice-based SERS platforms. To further verify the practical applicability of these materials, we increased the hot-spot density by making multilayers 37 (estimated as four layers) of Au TOh dual-rim and monorim NFs and achieved LODs of 10 −19 and 10 −18 M, respectively, both of which are extremely low (Figure S26). Importantly, when we compared the SERS sensitivity (i.e., the slope in the LOD plot) of monolayer and multilayers from both dual-rim and monorim NFs, the dual-rim NFs showed higher sensitivity (monolayer: 85.9 ± 4.4, multilayer: 79.3 ± 3.1) compared to those with monorim NFs (monolayer: 65.9 ± 9.6, multilayer: 40.8 ± 2.5), clearly indicating that the SERS substrates consisting of Au TOh dual-rim NFs are ultrasensitive toward target analytes.…”

A General Approach to Stabilize Nanocrystal Superlattices by Covalently Bonded Ligands

“…Enhanced chemical, mechanical, and other stability is an enabling factor for the applications of NC superlattices, such as in chemical and biosensing. Closely packed Au NC superlattices are promising surface enhanced Raman spectroscopy (SERS) substrates with dense and evenly distributed hot spots over the entire substrate, showing strong and consistent electromagnetic field enhancement upon interaction with analytes. ,,, These features translate to high sensitivity and equally importantly, excellent spot-to-spot and sample-to-sample reproducibility in SERS sensing. Stabilization of NC superlattices can further facilitate their uses as reusable SERS substrates, which require highly reproducible output signals during the cycles of addition/removal of analytes via solvents.…”

Synthesis of Pt Double-Walled Nanoframes with Well-Defined and Controllable Facets

“…Au cubes were prepared following our previous work with modifications. , Au seeds were prepared for the growth of Au cubes. First, 7 mL of 75 mM CTAB solution was mixed with 87.5 μL of 20 mM HAuCl 4 solution inside a 20 mL vial.…”