Bimetallic Core-Shell Nanoparticles of Gold and Silver via Bioinspired Polydopamine Layer as Surface-Enhanced Raman Spectroscopy (SERS) Platform.

Asli Yilmaz,Mehmet Yilmaz

doi:10.3390/nano10040688

Abstract

Despite numerous attempts to fabricate the core–shell nanoparticles, novel, simple, and low-cost approaches are still required to produce these efficient nanosystems. In this study, we propose the synthesis of bimetallic core–shell nanoparticles of gold (AuNP) and silver (AgNP) nanostructures via a bioinspired polydopamine (PDOP) layer and their employment as a surface-enhanced Raman spectroscopy (SERS) platform. Herein, the PDOP layer was used as an interface between nanostructures as well as stabilizing and reducing agents for the deposition of silver ions onto the AuNPs. UV-vis absorption spectra and electron microscope images confirmed the deposition of the silver ions and the formation of core–shell nanoparticles. SERS activity tests indicated that both the PDOP thickness and silver deposition time are the dominant parameters that determine the SERS performances of the proposed core–shell system. In comparison to bare AuNPs, more than three times higher SERS signal intensity was obtained with an enhancement factor of 3.5 × 105.

Highlights

Core–shell nanoparticles are defined as composite nanomaterials constructed with inner material and outer layer material, both at a nanoscale [1]
For the first time, we report the novel synthesis of bimetallic core–shell nanoparticles of gold and silver via bioinspired polydopamine (PDOP) layer
TEM images of bare AuNPs indicated an efficient synthesis of spherical metallic nanoparticles with an average size of 18 nm (Figure 1a)

Summary

Introduction

Core–shell nanoparticles are defined as composite nanomaterials constructed with inner material (cores) and outer layer material (shells), both at a nanoscale [1]. The report by Lim et al indicated well-defined gold nanobridged nanogap particles through DNA molecules [3] They could load Raman dyes to the gap (1 nm) between the gold core and gold shell. Bian et al showed that a thin layer of graphene deposited onto the gold nanostructures improved the biocompatibility of the core–shell system [7] With their unique properties, core–shell nanostructures have a wide range of applications including enhanced optical devices, energy storage materials, bionanotechnology, fuel cell, tailored magnetic devices, optical devices, bioimaging systems, and catalytic processes [1,2,8,9,10,11,12]

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