Mesoporous One-Component Gold Microshells as 3D SERS Substrates

Abstract

Surface-enhanced Raman scattering (SERS) is a powerful analytical tool for label-free analysis that has found a broad spectrum of applications in material, chemical, and biomedical sciences. In recent years, a great interest has been witnessed in the rational design of SERS substrates to amplify Raman signals and optionally allow for the selective detection of analytes, which is especially essential and challenging for biomedical applications. In this study, hard templating of noble metals is proposed as a novel approach for the design of one-component tailor-made SERS platforms. Porous Au microparticles were fabricated via dual ex situ adsorption of Au nanoparticles and in situ reduction of HAuCl4 on mesoporous sacrificial microcrystals of vaterite CaCO3. Elimination of the microcrystals at mild conditions resulted in the formation of stable mesoporous one-component Au microshells. SERS performance of the microshells at very low 0.4 µW laser power was probed using rhodamine B and bovine serum albumin showing enhancement factors of 2 × 108 and 8 × 108, respectively. The proposed strategy opens broad avenues for the design and scalable fabrication of one-component porous metal particles that can serve as superior SERS platforms possessing both excellent plasmonic properties and the possibility of selective inclusion of analyte molecules and/or SERS nanotags for highly specific SERS analysis.

Advances in Nanoarchitectonics: A Review of “Static” and “Dynamic” Particle Assembly Methods

“…Nanoparticle arrays hold promising applications across diverse fields. They can serve as sophisticated photonic structures, finding utility in structural coloration and advanced optical biosensing [ 70 , 74 , 75 ]. Furthermore, they offer the potential to develop electronic nano-devices and chemical/biological sensors.…”

“…Table 1 provides the advantages and disadvantages of each assembly technique studied in this review. Static methods like layer-by-layer assembly [ 51 , 52 , 53 , 58 , 59 , 60 , 61 , 62 ] and template-assisted assembly [ 2 , 10 , 16 , 29 , 70 , 72 , 73 , 74 , 75 ] may need specific substrates. Polymer brushes [ 83 , 84 , 85 , 86 ] offer adjustability but risk aggregation.…”

Formulation and Biodegradation of Surface-Supported Biopolymer-Based Microgels Formed via Hard Templating onto Vaterite CaCO3 Crystals

“…In general, vaterite-based hard templating has attracted significant scientific attention in the past due to the biocompatible conditions used to decompose the templates, offering an option to work with fragile (bio)molecules to form micro-sized particles loaded with sensitive proteins and enzymes as well as other biologically active small and large molecules of different natures [ 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 ]. Moreover, the internal structure of the vaterite crystals allows for the forming of an inverted replica of the solid crystals made of soft polymers [ 26 ] or hard nanoparticles [ 27 , 28 , 29 , 30 , 31 , 32 ].…”

Dextran and Its Derivatives: Biopolymer Additives for the Modulation of Vaterite CaCO3 Crystal Morphology and Adhesion to Cells

“…[21,[26][27][28][29] One of the main drawbacks of vaterite crystals are their inherent metastability and rather quick degradation/recrystallization in aqueous environments. [30] Degradation/decomposition of vaterite is required for hard templating of polymer, protein, inorganic or hybrid structures [22,[31][32][33][34] by means of loading the vaterite pores, followed by vaterite solubilisation. Although such properties may be beneficial for some medical applications, for example, pH-triggered release in tumor sites, [35][36][37] many other applications require the stabilization of vaterite and the suppression of its recrystallization.…”