Mesoporous One-Component Gold Microshells as 3D SERS Substrates.

Anna S Vikulina,Inna Y Stetsyura,M Serdar Onses,Andre G Skirtach,Dmitry Volodkin,Erkan Yilmaz

doi:10.3390/bios11100380

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.

Highlights

In the last decade, surface-enhanced Raman spectroscopy (SERS) has attracted increasing attention as a strong bioanalytical tool that possesses cost-effective, highly selective, and non-destructive multimodal testing [1]
The prominent multiplexing capabilities of Raman spectroscopy provide this technique with advanced capabilities for serving as an all-in-one single platform that combines in vivo diagnostics and therapy [4]
It should be noted that the control of the obtained pore sizes and internal structure in such SERS platforms can be achieved via the design of the vaterite microcrystals used as decomposable templates [28]

Summary

Introduction

Surface-enhanced Raman spectroscopy (SERS) has attracted increasing attention as a strong bioanalytical tool that possesses cost-effective, highly selective, and non-destructive multimodal testing [1]. The prominent multiplexing capabilities of Raman spectroscopy provide this technique with advanced capabilities for serving as an all-in-one single platform that combines in vivo diagnostics and therapy [4] This theranostic strategy is a game changer for modern medicine allowing wide opportunities for personalized medicine. The size of single NPs seriously limits their applicability for cell imaging because these NPs are invisible by conventional optical microscopy; they are too small to be manipulated, and it is difficult to place them on the point of interest and to ensure their presence [11] This drawback can be overcome by the self-assembly of colloidal NPs into homogeneous and ordered 2D micro-patterned layers and arrays, [1] or by fabrication of 3D SERS platforms which are easier to manipulate, generally have higher colloidal stability, and facilitate hot spot formation in all three dimensions. Biosensors 2021, 11, 380 crystal size [26], shape [27], and porosity [28], without any additives, opens broad avenues for the utilization of these crystals as decomposable templates

Materials

Findings

Conclusions and Perspectives