Dual-enhancement and dual-tag design for SERS-based sandwich immunoassays: evaluation of a metal–metal effect in 3D architecture

Abstract The design of a sandwich-type SERS immunoassay (surface-enhanced Raman spectroscopy) is demonstrated operating in dual surface enhancement and dual-tag paradigm. The capture and detection antibodies are linked to two SERS-active substrates and form together the three-dimensional (3D) structure after specific binding to interleukin 6. A variety of metal combinations is tested (Au–Ag, Au–Au, and Ag–Ag), but an enhanced electromagnetic field is generated only due to coupling of Ag and Au nanoparticles with an Au hexagonal nanoarray. The amplified in that way Raman signals improve the limit of detection over 3 times in comparison to the assay with only one SERS-active substrate. It is also shown that the proper readout of the true-positive signal can be achieved in assays with two Raman tags, and this approach also improves LOD. For the optimal combination of the metal–metal junction and Raman tags, a linear relationship between the Raman signal and the concentration of IL-6 is obtained in the range 0–1000 pg⋅mL−1with LOD of 25.2 pg mL−1and RSD < 10%. The presented proof-of-concept of the SERS immunoassay with the dual-enhancement and dual-tag opens additional opportunities for engineering reliable SERS biosensing. Graphical abstract

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Liquid Surface-Enhanced Raman Spectroscopy (SERS) Sensor-Based Au-Ag Colloidal Nanoparticles for Easy and Rapid Detection of Deltamethrin Pesticide in Brewed Tea

Crystals ◽

10.3390/cryst12010024 ◽

2021 ◽

Vol 12 (1) ◽

pp. 24

Author(s):

Affi Nur Hidayah ◽

Djoko Triyono ◽

Yuliati Herbani ◽

Rosari Saleh

Keyword(s):

Raman Spectroscopy ◽

Liquid Surface ◽

Limit Of Detection ◽

Surface Enhanced Raman Spectroscopy ◽

Ease Of Use ◽

Raman Signal ◽

Colloidal Nanoparticles ◽

Sers Substrate ◽

Surface Enhanced ◽

Surface Enhanced Raman

Deltamethrin pesticides can cause inflammation, nephrotoxicity and hepatotoxicity as well as affect the activity of antioxidant enzymes in tissues. As a result of this concern, there is a rising focus on the development of fast and reliable pesticide residue testing to minimise potential risks to humans. The goal of this study is to use Au-Ag colloid nanoparticles as liquid surface-enhanced Raman spectroscopy (SERS) to improve the Raman signal in the detection of deltamethrin pesticide in a brewed tea. The liquid SERS system is fascinating to study due to its ease of use and its unlikeliness to cause several phenomena, such as photo-bleaching, combustion, sublimation and even photo-catalysis, which can interfere with the Raman signal, as shown in the SERS substrate. Our liquid SERS system is simpler than previous liquid SERS systems that have been reported. We performed the detection of pesticide analyte directly on brewed tea, without diluting it with ethanol or centrifuging it. Femtosecond laser-induced photo-reduction was employed to synthesise the liquid SERS of Au, Au-Ag, and Ag colloidal nanoparticles. The SERS was utilised to detect deltamethrin pesticide in brewed tea. The result showed that liquid SERS-based Ag NPs significantly enhance the Raman signal of pesticides compared with liquid SERS-based Au NPs and Au-Ag Nanoalloys. The maximum residue limits (MRLs) in tea in Indonesia are set at 10 ppm. Therefore, this method was also utilised to detect and improve, to 0.01 ppm, the deltamethrin pesticide Limit of Detection (LOD).

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Enabling three-dimensional porous architectures via carbonyl functionalization and molecular-specific organic-SERS platforms

Nature Communications ◽

10.1038/s41467-021-26385-7 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Ibrahim Deneme ◽

Gorkem Liman ◽

Ayse Can ◽

Gokhan Demirel ◽

Hakan Usta

Keyword(s):

Film Growth ◽

Low Cost ◽

Three Dimensional ◽

Surface Enhanced Raman Spectroscopy ◽

Molecular Engineering ◽

Raman Signal ◽

Chemical Enhancement ◽

Out Of Plane ◽

Surface Enhanced Raman ◽

Anti Stokes

AbstractMolecular engineering via functionalization has been a great tool to tune noncovalent intermolecular interactions. Herein, we demonstrate three-dimensional highly crystalline nanostructured D(C7CO)-BTBT films via carbonyl-functionalization of a fused thienoacene π-system, and strong Raman signal enhancements in Surface-Enhanced Raman Spectroscopy (SERS) are realized. The small molecule could be prepared on the gram scale with a facile synthesis-purification. In the engineered films, polar functionalization induces favorable out-of-plane crystal growth via zigzag motif of dipolar C = O···C = O interactions and hydrogen bonds, and strengthens π-interactions. A unique two-stage film growth behavior is identified with an edge-on-to-face-on molecular orientation transition driven by hydrophobicity. The analysis of the electronic structures and the ratio of the anti-Stokes/Stokes SERS signals suggests that the π-extended/stabilized LUMOs with varied crystalline face-on orientations provide the key properties in the chemical enhancement mechanism. A molecule-specific Raman signal enhancement is also demonstrated on a high-LUMO organic platform. Our results demonstrate a promising guidance towards realizing low-cost SERS-active semiconducting materials, increasing structural versatility of organic-SERS platforms, and advancing molecule-specific sensing via molecular engineering.

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Surface Enhanced Raman Spectroscopy for DNA Biosensors—How Far Are We?

Molecules ◽

10.3390/molecules24244423 ◽

2019 ◽

Vol 24 (24) ◽

pp. 4423 ◽

Cited By ~ 3

Author(s):

Edyta Pyrak ◽

Jan Krajczewski ◽

Artur Kowalik ◽

Andrzej Kudelski ◽

Aleksandra Jaworska

Keyword(s):

Raman Spectroscopy ◽

Limit Of Detection ◽

Surface Enhanced Raman Spectroscopy ◽

Diagnostic Tools ◽

Strong Increase ◽

Raman Signal ◽

Silver Nanostructures ◽

Dna Sensors ◽

Surface Enhanced ◽

Surface Enhanced Raman

A sensitive and accurate identification of specific DNA fragments (usually containing a mutation) can influence clinical decisions. Standard methods routinely used for this type of detection are PCR (Polymerase Chain Reaction, and its modifications), and, less commonly, NGS (Next Generation Sequencing). However, these methods are quite complicated, requiring time-consuming, multi-stage sample preparation, and specially trained staff. Usually, it takes weeks for patients to obtain their results. Therefore, different DNA sensors are being intensively developed by many groups. One technique often used to obtain an analytical signal from DNA sensors is Raman spectroscopy. Its modification, surface-enhanced Raman spectroscopy (SERS), is especially useful for practical analytical applications due to its extra low limit of detection. SERS takes advantage of the strong increase in the efficiency of Raman signal generation caused by a local electric field enhancement near plasmonic (typically gold and silver) nanostructures. In this condensed review, we describe the most important types of SERS-based nanosensors for genetic studies and comment on their potential for becoming diagnostic tools.

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Human Spermatozoa on Nanostrucutured Ag Deposited on GaAs Surface

MRS Proceedings ◽

10.1557/proc-735-c10.8 ◽

2002 ◽

Vol 735 ◽

Cited By ~ 2

Author(s):

Lucia G. Quagliano

Keyword(s):

Structural Information ◽

Surface Enhanced Raman Spectroscopy ◽

Human Spermatozoa ◽

Raman Signal ◽

Ag Particles ◽

Surface Enhanced ◽

Surface Enhanced Raman ◽

Active Substrate ◽

Promising Application ◽

Nanoscale Science

ABSTRACTMotivated by the SERS (Surface Enhanced Raman Spectroscopy) sensitivity to very small amounts of material we are interested in the application of the SERS technique for studying complex biological systems, such as cells.Using nanometer-sized Ag particles deposited on GaAs surfaces as SERS-active substrate we have observed an enhancement of Raman signal from human spermatozoa. We have obtained structural information on extremely small amounts of biomaterials and at the same time evidence that the bio-systems are preserved on the surface.In our opinion, this kind of SERS-active substrates with nanometer-sized Ag particles on semiconductors might have promising application in nanoscale science and technology. In fact bio-molecules, cells and processes of their interfacing with Si, GaAs, silver and gold and other inorganic substrates, form the basis of bio-electronics a new emerging field at the crossing of molecular biology and nano-electronics with numerous electronic and biotechnological applications.

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Preparation of Fe3O4@PDA@Au@GO Composite as SERS Substrate and Its Application in the Enrichment and Detection for Phenanthrene

Micromachines ◽

10.3390/mi13010128 ◽

2022 ◽

Vol 13 (1) ◽

pp. 128

Author(s):

Junyu Liu ◽

Yiwei Liu ◽

Yida Cao ◽

Shihua Sang ◽

Liang Guan ◽

...

Keyword(s):

Surface Enhanced Raman Spectroscopy ◽

Raman Signal ◽

Sers Substrate ◽

Visible Absorption ◽

Highly Active ◽

Electromagnetic Enhancement ◽

Surface Enhanced Raman ◽

Active Substrate ◽

Polycyclic Aromatic ◽

Sers Active Substrate

In this study, highly active Fe3O4@PDA@Au@GO surface-enhanced Raman spectroscopy (SERS) active substrate was synthesized for application in the enrichment and detection of trace polycyclic aromatic hydrocarbons (PAHs) in the environment. The morphology and structure were characterized by transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD) and UV–visible absorption spectrum (UV–vis spectra). The effect of each component of Fe3O4@PDA@Au@GO nanocomposites on SERS was explored, and it was found that gold nanoparticles (Au NPs) are crucial to enhance the Raman signal based on the electromagnetic enhancement mechanism, and apart from enriching the PAHs through π–π interaction, graphene oxide (GO) also generates strong chemical enhancement of Raman signals, and polydopamine (PDA) can prevent Au from shedding and agglomeration. The existence of Fe3O4 aided the quick separation of substrate from the solutions, which greatly simplified the detection procedure and facilitated the reuse of the substrate. The SERS active substrate was used to detect phenanthrene in aqueous solution with a detection limit of 10−7 g/L (5.6 × 10−10 mol/L), which is much lower than that of ordinary Raman, it is promising for application in the enrichment and detection of trace PAHs.

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3D Hotspot Matrix of Au Nanoparticles on Au Nanostructures with a Spacer Layer of Dithiol Molecules for Highly Sensitive Surface-Enhanced Raman Spectroscopy

10.21203/rs.3.rs-757278/v1 ◽

2021 ◽

Author(s):

Dong-Jin Lee ◽

Dae Yu Kim

Keyword(s):

Au Nanoparticles ◽

Three Dimensional ◽

Surface Enhanced Raman Spectroscopy ◽

Raman Signal ◽

Large Area ◽

Spacer Layer ◽

Highly Sensitive ◽

Surface Enhanced ◽

Surface Enhanced Raman ◽

Enhanced Raman Scattering

Abstract Engineering of efficient plasmonic hotspots has been receiving great attention to enhance the sensitivity of surface-enhanced Raman scattering (SERS). In the present study, we propose a highly sensitive SERS platform based on Au nanoparticles (AuNPs) on Au nanostructures (AuNSs) with a spacer layer of 1,4-benzenedimethanethiol (BDMT). The three-dimensional (3D) hotspot matrix has been rationally designed based on the idea of employing 3D hotspots with a vertical nanogap between AuNSs and AuNPs after generating large area two-dimensional hotspots of AuNSs. AuNP@BDMT@AuNSs are fabricated by functionalizing BDMT on AuNSs and then immobilizing AuNPs. The Raman signal of the AuNP@BDMT@AuNSs is approximately twelve times higher than that of AuNSs at 100 nM of rhodamine 6G. The AuNP@BDMT@AuNSs are then employed to detect thiram, which is used as a fungicide, with a detection limit of 13 nM. Our proposed platform thus shows significant potential for use in highly sensitive SERS sensors.

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Rapid uropathogen identification using surface enhanced Raman spectroscopy active filters

Scientific Reports ◽

10.1038/s41598-021-88026-9 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Simon D. Dryden ◽

Salzitsa Anastasova ◽

Giovanni Satta ◽

Alex J. Thompson ◽

Daniel R. Leff ◽

...

Keyword(s):

Raman Spectroscopy ◽

Bacterial Infections ◽

Surface Enhanced Raman Spectroscopy ◽

Active Filters ◽

Raman Signal ◽

Rapid Diagnostics ◽

Bacterial Classification ◽

Surface Enhanced ◽

Surface Enhanced Raman

AbstractUrinary tract infection is one of the most common bacterial infections leading to increased morbidity, mortality and societal costs. Current diagnostics exacerbate this problem due to an inability to provide timely pathogen identification. Surface enhanced Raman spectroscopy (SERS) has the potential to overcome these issues by providing immediate bacterial classification. To date, achieving accurate classification has required technically complicated processes to capture pathogens, which has precluded the integration of SERS into rapid diagnostics. This work demonstrates that gold-coated membrane filters capture and aggregate bacteria, separating them from urine, while also providing Raman signal enhancement. An optimal gold coating thickness of 50 nm was demonstrated, and the diagnostic performance of the SERS-active filters was assessed using phantom urine infection samples at clinically relevant concentrations (105 CFU/ml). Infected and uninfected (control) samples were identified with an accuracy of 91.1%. Amongst infected samples only, classification of three bacteria (Escherichia coli, Enterococcus faecalis, Klebsiella pneumoniae) was achieved at a rate of 91.6%.

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Sunflower-Like Nanostructure with Built-In Hotspots for Alpha-Fetoprotein Detection

Molecules ◽

10.3390/molecules26041197 ◽

2021 ◽

Vol 26 (4) ◽

pp. 1197

Author(s):

Xiaoyu Zhao ◽

Aonan Zhu ◽

Yaxin Wang ◽

Yongjun Zhang ◽

Xiaolong Zhang

Keyword(s):

Rapid Detection ◽

Clinical Medicine ◽

Electromagnetic Coupling ◽

Low Cost ◽

Surface Enhanced Raman Spectroscopy ◽

Alpha Fetoprotein ◽

Low Concentrations ◽

Surface Enhanced Raman ◽

Active Substrate ◽

Array Structures

In the present study, a sunflower-like nanostructure array composed of a series of synaptic nanoparticles and nanospheres was manufactured through an efficient and low-cost colloidal lithography technique. The primary electromagnetic field contribution generated by the synaptic nanoparticles of the surface array structures was also determined by a finite-difference time-domain software to simulate the hotspots. This structure exhibited high repeatability and excellent sensitivity; hence, it was used as a surface-enhanced Raman spectroscopy (SERS) active substrate to achieve a rapid detection of ultra-low concentrations of Alpha-fetoprotein (AFP). This study demonstrates the design of a plasmonic structure with strong electromagnetic coupling, which can be used for the rapid detection of AFP concentration in clinical medicine.

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Fabrication-friendly polarization-sensitive plasmonic grating for optimal surface-enhanced Raman spectroscopy

Journal of the European Optical Society Rapid Publications ◽

10.1186/s41476-020-00144-5 ◽

2020 ◽

Vol 16 (1) ◽

Author(s):

Arpan Dutta ◽

Tarmo Nuutinen ◽

Khairul Alam ◽

Antti Matikainen ◽

Peng Li ◽

...

Keyword(s):

Raman Spectroscopy ◽

Fill Factor ◽

Surface Enhanced Raman Spectroscopy ◽

Transverse Magnetic ◽

Raman Signal ◽

Optical Resonance ◽

Excitation Light ◽

Surface Enhanced ◽

Surface Enhanced Raman ◽

Plasmonic Gratings

Abstract Plasmonic nanostructures are widely utilized in surface-enhanced Raman spectroscopy (SERS) from ultraviolet to near-infrared applications. Periodic nanoplasmonic systems such as plasmonic gratings are of great interest as SERS-active substrates due to their strong polarization dependence and ease of fabrication. In this work, we modelled a silver grating that manifests a subradiant plasmonic resonance as a dip in its reflectivity with significant near-field enhancement only for transverse-magnetic (TM) polarization of light. We investigated the role of its fill factor, commonly defined as a ratio between the width of the grating groove and the grating period, on the SERS enhancement. We designed multiple gratings having different fill factors using finite-difference time-domain (FDTD) simulations to incorporate different degrees of spectral detunings in their reflection dips from our Raman excitation (488 nm). Our numerical studies suggested that by tuning the spectral position of the optical resonance of the grating, via modifying their fill factor, we could optimize the achievable SERS enhancement. Moreover, by changing the polarization of the excitation light from transverse-magnetic to transverse-electric, we can disable the optical resonance of the gratings resulting in negligible SERS performance. To verify this, we fabricated and optically characterized the modelled gratings and ensured the presence of the desired detunings in their optical responses. Our Raman analysis on riboflavin confirmed that the higher overlap between the grating resonance and the intended Raman excitation yields stronger Raman enhancement only for TM polarized light. Our findings provide insight on the development of fabrication-friendly plasmonic gratings for optimal intensification of the Raman signal with an extra degree of control through the polarization of the excitation light. This feature enables studying Raman signal of exactly the same molecules with and without electromagnetic SERS enhancements, just by changing the polarization of the excitation, and thereby permits detailed studies on the selection rules and the chemical enhancements possibly involved in SERS.

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Detection of Triphenylmethane Drugs in Fish Muscle by Surface-Enhanced Raman Spectroscopy Coupled with Au-Ag Core-Shell Nanoparticles

Journal of Nanomaterials ◽

10.1155/2014/730915 ◽

2014 ◽

Vol 2014 ◽

pp. 1-8 ◽

Cited By ~ 18

Author(s):

Lu Pei ◽

Yiqun Huang ◽

Chunying Li ◽

Yuanyuan Zhang ◽

Barbara A. Rasco ◽

...

Keyword(s):

Raman Spectroscopy ◽

Malachite Green ◽

Crystal Violet ◽

Bimetallic Nanoparticles ◽

Limit Of Detection ◽

Fish Muscle ◽

Surface Enhanced Raman Spectroscopy ◽

Vis Spectroscopy ◽

Surface Enhanced ◽

Surface Enhanced Raman

Silver-coated gold bimetallic nanoparticles were synthesized and used as substrates for surface-enhanced Raman spectroscopy (SERS) in detecting prohibited triphenylmethane drugs (including crystal violet and malachite green) in fish muscle. The optical properties and physical properties of bimetallic nanospheres were characterized by UV-Vis spectroscopy and transmission electron microscopy. The optimal nanospheres selected had relatively uniform size (diameter: 33 ± 3 nm) with a silver layer coated on the surface of gold seed (diameter: 18 ± 2 nm). For both crystal violet and malachite green, characteristic SERS spectral features could be identified at concentration as low as 0.1 μg/L with these bimetallic nanospheres. Crystal violet and malachite green residues in fish muscle could also be detected at levels as low as 0.1 ng/g, which could meet the most restricted regulatory requirements for the limit of detection in terms of analytical methods for crystal violet or malachite green in fish muscle. This study provides a basis for applying SERS technology with bimetallic nanoparticles to the identification of trace amounts of prohibited substances in aquatic food products, and the methodology could be extended to analyses of other hazardous chemicals in complex food matrices like vegetables and meats.

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