Double Detection of Mycotoxins Based on SERS Labels Embedded Ag@Au Core–Shell Nanoparticles

Abstract

A sensitive surface-enhanced Raman scattering (SERS) signal dependent double detection of mycotoxins is achieved for the first time, without the aid of nucleic acid amplification strategies. SERS labels embedded Ag@Au core-shell (CS) nanoparticles (NPs) as novel SERS tags are successfully prepared through a galvanic replacement-free deposition. SERS tags produce stable and quantitative SERS signal, emerging from the plasmonic coupling at the junction of Ag core and Au shell. SERS tags engineered Raman aptasensors are developed for the double detection of ochratoxin A (OTA) and aflatoxin B1 (AFB1) in maize meal. The limits of detection (LODs) are as low as 0.006 ng/mL for OTA and 0.03 ng/mL for AFB1. The developed protocol can be extended to a large set of different SERS tags for the sensitive detection of multiple targets that possess different lengths of aptamers.

Dynamic Chiral Nanoparticle Assemblies and Specific Chiroplasmonic Analysis of Cancer Cells

“…[ 5 ] Noticeably, Ag intrinsically possesses the best plasmonic enhancement at visible frequencies in comparison to other noble metal NPs, and Au featured with excellent biocompatible and stability could serve as an outer shell on the surface of Ag NPs. [ 6 ] All these characteristics allow Ag@Au core-shell (CS) NPs to be a natural candidate to generate a gigantic and customized plasmonic CD response, yet little is known about the plasmonic chiro-optical activity of Ag@Au CS NPs. Rationally understanding the dynamic plasmonic CD responses of Ag@Au CS NP assemblies holds promise for fundamental investigation of the real-time coupling of the optical rotation spectral signature in comparison to Ag NP assemblies.…”

Direct Synthesis of Gold Nanoparticle‐Over‐Nanosheet for Sensitive SERS Detection

“…[5,6] Highperformance SERS substrates require both high sensitivity and good reproducibility. [7] Along with this demand, some novel structures constituted by two or more noble metals, such as core-shell, [8][9][10] multilayer, [11,12] and periodic array, [13] have been designed with the aim to promote the activity of those ordinary In order to solve this contradiction, we designed a composite structure, which is composed of AuNP and AuNS. AuNS was prepared first as a homogeneous, flexible, and 2D substrate.…”

Three-Dimensional SERS Substrates Formed with Plasmonic Core-Satellite Nanostructures

“…Given that DNA molecules of different lengths and sequences can be synthesized easily, nanoparticles can be assembled into a designed nanostructure through DNA hybridization or attachment of end-labelled functional groups 18–23 . For example, it has been demonstrated that Au-Ag core-shell nanodumbbells 12,13 and plasmonic core-satellite nanostructures can be assembled through DNA hybridization 14,24–28 or binding of other linker molecules 29–34 . The SERS effects of the nanoparticle-based nanostructures can be optimized by controlling the gaps between adjacent nanoparticles through coating Ag shells around the nanoparticles 12–14 .…”

“…The SERS effects of the nanoparticle-based nanostructures can be optimized by controlling the gaps between adjacent nanoparticles through coating Ag shells around the nanoparticles 12–14 . In addition, when a DNA aptamer is used as a linker to attach two nanoparticles, an analyte-controllable SERS hot spot at the nanogap between the nanoparticles can be created 28,35–37 .…”

“…Some other studies used core-satellite nanostructures for enhancing Raman reporter molecules that were placed at the hot spots but not for determining the concentrations of molecules 30,31,33,34,48–50 . Many of the core-satellite nanostructures used for SERS detection of molecules were based on detection schemes that utilized either DNA aptamers and Raman reporter molecules 28,29,36,37,51–53 or certain kinds of chemical interactions 54–56 , but the availability of suitable aptamers and chemical reactions could limit the use of the nanostructures for the detection of other molecules. Some of the SERS substrates formed with core-satellite nanostructures did not have many SERS hot spots in the z-direction, and the density of the nanostructures in the xy-plane was not maximized 14,27,57 .…”