Highly sensitive and reliable SERS probes based on nanogap control of a Au–Ag alloy on silica nanoparticles

Pham, Xuan‐Hung; Lee, Minwoo; Shim, Seongbo; Jeong, Seong‐Min; Kim, Hyung‐Mo; Hahm, Eunil; Lee, Sang Hun; Lee, Jun Young; Jun, Bong‐Hyun

doi:10.1039/c6ra26213a

Cited by 49 publications

(59 citation statements)

References 48 publications

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“…A broad plasmonic adsorption peak was observed between 320 nm and 700 nm, with its maximum at ca. 430 nm, after deposition of Ag metal on SiO 2 @AuNPs, which can be attributed to the formation of Ag shells on the surface of SiO 2 @Au NPs 56 – 58 . In addition, the intensities of peaks at 430 nm (Ag) and 510 nm (Au) were proportional to the concentration of ascorbic acid across a broad range (2, 4, 6, 8, 10, 20, 40, 60, 80, and 100 µM), indicating proportional growth of the Ag shells on SiO 2 @Au@Ag (Figs 2B and S3 ) 58 , 59 .…”

Section: Resultsmentioning

confidence: 98%

Enzyme-catalyzed Ag Growth on Au Nanoparticle-assembled Structure for Highly Sensitive Colorimetric Immunoassay

Pham

Hahm

Kim

et al. 2018

Sci Rep

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We have developed a sensitive colorimetric immunoassay with broad dynamic range using enzyme-catalyzed Ag growth on gold nanoparticle (NP)-assembled silica (SiO2@Au@Ag). To reduce Ag+ ion content and promote Ag growth on the assembled Au NPs, alkaline phosphatase (AP)-based enzymatic amplification was incorporated, which considerably increased the colorimetric read-out. As a model study, sandwich enzyme-linked immunosorbent assay (ELISA) was used to quantify target IgG. The immune complexes capture the Ab-IgG-AP-labeled detection Ab and trigger the enzyme-catalyzed reaction to convert 2-phospho-L-ascorbic acid to ascorbic acid in the presence of the target IgG. Ascorbic acid reduced Ag+ to Ag, which formed Ag shells on the surface of SiO2@Au and enhanced the absorbance of the SiO2@Au@Ag solution. Plasmonic immunoassay showed a significant linear relationship between absorbance and the logarithm of IgG concentration in the range of ca. 7 × 10−13 M to 7 × 10−11 M. The detection limit was at 1.4 × 10−13 M, which is several hundred folds higher than that of any conventional colorimetric immunoassay. Thus, our novel approach of signal-amplification can be used for highly sensitive in vitro diagnostics and detection of target proteins with the naked eye without using any sophisticated instrument.

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Section: Resultsmentioning

confidence: 98%

Enzyme-catalyzed Ag Growth on Au Nanoparticle-assembled Structure for Highly Sensitive Colorimetric Immunoassay

Pham

Hahm

Kim

et al. 2018

Sci Rep

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“…Briefly, colloidal Au NPs (2–3 nm) were prepared by reducing HAuCl 4 with tetrakis(hydroxymethyl)phosphonium chloride (THPC), as reported by Duff et al [ 56 ], with some modifications. Silica NPs were prepared by the Stober method, and the surface of the NPs was functionalized with amino groups using 3-aminopropyltriethoxysilane (APTS) [ 27 , 28 ]. The Au NPs were immobilized on the aminated silica NPs by gentle shaking.…”

Section: Resultsmentioning

confidence: 99%

“…The optical properties of SiO 2 @Au@Ag in the absence and presence of ATP was investigated in Figure S2 . SiO 2 @Au@Ag showed the broad absorbance band in the range of 320 to 800 nm with a maximum peak at 457 nm [ 27 ], while ATP exhibited the characteristic peak of adenosine ring at 260 nm [ 57 ]. When ATP was added into the SiO 2 @Au@Ag solution, the maximum peak position showed a little shift and their intensities were also increased slightly.…”

Section: Resultsmentioning

confidence: 99%

“…SiO 2 @Au@Ag NPs were prepared as previously reported [ 27 , 28 ]. Au-Ag core-shell NPs were prepared in aqueous medium by reducing and depositing the Ag source with ascorbic acid on gold NPs in the presence of PVP.…”

Section: Methodsmentioning

confidence: 99%

“…Because the structures and components of metallic nanoparticles (NPs) are critical factors affecting the sensitivity and reproducibility of the SERS signal, various shapes of Au and Ag NPs have been studied as sensitive SERS substrates. Recently, we developed a novel SERS substrate, SiO 2 @Au@Ag NPs, which exhibited a sensitive and reproducible SERS signals, wherein the “hot spot” could be controlled carefully by varying the concentration of Ag + [ 27 , 28 ].…”

Section: Introductionmentioning

confidence: 99%

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Adenosine Triphosphate-Encapsulated Liposomes with Plasmonic Nanoparticles for Surface Enhanced Raman Scattering-Based Immunoassays

Pham

Hahm

Kim

et al. 2017

Sensors

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In this study, we prepared adenosine triphosphate (ATP) encapsulated liposomes, and assessed their applicability for the surface enhanced Raman scattering (SERS)-based assays with gold-silver alloy (Au@Ag)-assembled silica nanoparticles (NPs; SiO2@Au@Ag). The liposomes were prepared by the thin film hydration method from a mixture of l-α-phosphatidylcholine, cholesterol, and PE-PEG2000 in chloroform; evaporating the solvent, followed by hydration of the resulting thin film with ATP in phosphate-buffered saline (PBS). Upon lysis of the liposome, the SERS intensity of the SiO2@Au@Ag NPs increased with the logarithm of number of ATP-encapsulated liposomes after lysis in the range of 8 × 106 to 8 × 1010. The detection limit of liposome was calculated to be 1.3 × 10−17 mol. The successful application of ATP-encapsulated liposomes to SiO2@Au@Ag NPs based SERS analysis has opened a new avenue for Raman label chemical (RCL)-encapsulated liposome-enhanced SERS-based immunoassays.

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Advancing Mycotoxin Detection in Food and Feed: Novel Insights from Surface‐Enhanced Raman Spectroscopy (SERS)

Logan,

Cao,

Freitag

et al. 2024

Advanced Materials

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The implementation of low‐cost and rapid technologies for the on‐site detection of mycotoxin‐contaminated crops is a promising solution to address the growing concerns of the agri‐food industry. Recently, there have been significant developments in Surface‐enhanced Raman spectroscopy (SERS) for the direct detection of mycotoxins in food and feed. This review provides an overview of the most recent advancements in the utilization of SERS through the successful fabrication of novel nanostructured materials. Various bottom‐up and top‐down approaches have demonstrated their potential in improving sensitivity, while many applications exploit the immobilization of recognition elements and molecular imprinted polymers (MIPs) to enhance specificity and reproducibility in complex matrices. Therefore, the design and fabrication of nanomaterials is of utmost importance and are presented herein. We uncover that limited studies establish limits of detection (LODs) or conduct validation using naturally contaminated samples. One decade on, SERS is still lacking significant progress and there is a disconnect between the technology, the European regulatory limits, and the intended end‐user. Ongoing challenges and potential solutions are discussed including nanofabrication, molecular binders, and data analytics. Recommendations to assay design, portability, and substrate stability are made to help improve the potential and feasibility of SERS for future on‐site agri‐food applications.This article is protected by copyright. All rights reserved

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Highly sensitive and reliable SERS probes based on nanogap control of a Au–Ag alloy on silica nanoparticles

Abstract: We developed highly sensitive surface-enhanced Raman scattering (SERS) probes based on SiO2@Au@Ag nanoparticles (NPs) using the Ag growth onto Au NP seeds method.

Cited by 49 publications

References 48 publications

Enzyme-catalyzed Ag Growth on Au Nanoparticle-assembled Structure for Highly Sensitive Colorimetric Immunoassay

Enzyme-catalyzed Ag Growth on Au Nanoparticle-assembled Structure for Highly Sensitive Colorimetric Immunoassay

Adenosine Triphosphate-Encapsulated Liposomes with Plasmonic Nanoparticles for Surface Enhanced Raman Scattering-Based Immunoassays

Advancing Mycotoxin Detection in Food and Feed: Novel Insights from Surface‐Enhanced Raman Spectroscopy (SERS)

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