Microfluidic Transport of Hybrid Optoplasmonic Particles for Repeatable SERS Detection
TL;DR: In this paper, a hybrid optoplasmonic microfluidic conveyer is developed, in which the movable, highly ordered optplasmonics particles are delivered to the detection spot for SERS detection.
Abstract: For its ultrahigh sensitivity, the microfluidic system combined with surface-enhanced Raman spectroscopy (SERS) becomes one of the most interesting topics in integrated online monitoring related fields. In previous reports, the commonest surface plasmon-enhanced substrates in microfluidics consist of immobilized metal nanostructures on the channel surface to overcome the disturbance of Brownian motion. In this work, a hybrid optoplasmonic microfluidic conveyer is developed, in which the movable, highly ordered optoplasmonic particles are delivered to the detection spot for SERS detection. Here, the optoplasmonic particle is the SiO2 microsphere with in situ photochemical reduced Ag nanoparticles on the surface. Because of the converged light at the SiO2 microsphere surface, the SERS spectra collected at this optoplasmonic particle in the channel exhibit excellent performance, which is confirmed by the simulated electric field distribution. In addition, the experimental data also demonstrate that the quantitative analysis is achieved at 1 nM in this optoplasmonic microfluidic conveyer. Furthermore, the used optoplasmonic particle can be ejected from the microfluidic channel by modulating the velocity of injected fluid such that the new optoplasmonic particle will be delivered to the detection spot for repeatable SERS detection in the same channel. The dynamic process of optoplasmonic particle transport is investigated in this microconveyer, and the built theoretical model to predict the particle release is highly identical with the experimental data. These data point out that our hybrid optoplasmonic microfluidic conveyer has repeatable enhanced substrates with the high SERS sensitivity to overcome the cross-contamination of different target molecules in repeatable detection.
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TL;DR: In this article , the core-satellite optoplasmonic particle comprised of the central dielectric silica sphere and the surrounding gold nanorods with varied aspect ratio (AR) were fabricated through electrostatic-assisted self-assembly.
Abstract: In this work, the core-satellite optoplasmonic particle comprised of the central dielectric silica sphere and the surrounding gold nanorods (AuNRs) with varied aspect ratio (AR) were fabricated through electrostatic-assisted self-assembly. The manipulation over the optoplasmonic resonance of the hybrid material was accomplished through tuning the AR of AuNRs at the perimeter of the silica microsphere, which enables the optimization of local plasmonic-photonic electric field enhancement in accordance with the incident wavelength. The monolayer structure assembled by the hybrid particles, termed as optoplasmonic surface, serves as a robust surface-enhanced Raman spectroscopy (SERS) sensing substrate because the building block is surprisingly agglomeration-resistive under severe conditions including the dryness and salination. The optimal SERS excitation plane of the optoplasmonic surface was found to be the equatorial one due to the geometrical factor holding the higher density of AuNRs, the plasmonic-photonic interaction between adjacent optoplasmonic particles and the light guiding effect. The fabricated optoplasmonic surface (silica sphere diameter = 4 µm, AR of AuNR = 3.2) was implemented for the SERS sensing of 3,4-methylenedioxymethamphetamine (MDMA) and the corresponding precursors including safrole and piperonal, achieving a limit of detection (LOD) down to the magnitude of 5 nM with the excitation wavelength at 785 nm. Practical SERS tests on the glassware surface and mimic drug demonstrate the compatibility of the optoplasmonic sensing platform in cooperation with the portable Raman spectrometers. This hybrid probe with engineerable resonance and elevated stability is a promising candidate for the application of SERS inspection in forensic activities.
9 citations
TL;DR: In this article , a core-satellite optoplasmonic particle containing a silica microsphere covered with gold nanoparticles (AuNPs) was developed through wet chemistry synthesis in aqueous phase.
6 citations
TL;DR: In this article , the kinetic processes of gaseous thiophenol compounds (TPC) in the plasmonic Zeolitic Imidazolate Framework (Ag@ZIF) core-shell NPs are studied by SERS spectra.
Abstract: Benefiting from the electromagnetic enhancement of noble metal nanoparticles (NPs) and the capture ability of organic frameworks, plasmonic metal-organic framework (MOF) structures have greatly promoted the development of gas detection by surface-enhanced Raman spectroscopy (SERS). In those detections, the kinetic process of gaseous molecules in plasmonic-MOF structures has a great influence on SERS spectra, which is still lacking intensive investigation in previous reports. In this work, the kinetic processes of gaseous thiophenol compounds (TPC) in the plasmonic Zeolitic Imidazolate Framework (Ag@ZIF) core-shell NPs are studied by SERS spectra. The experimental data demonstrate that the SERS intensities of gaseous TPC could be enhanced once more in an H2 mixed gas environment with different functional groups of TPC. Further results reveal that the two-step enhancement of SERS intensities is not only related to the thicknesses of the MOF shell but also affected by the ambient mixed gas. To understand this novel phenomenon, the binding energy between the gaseous molecule and ZIF is calculated based on first-principles computation. In combination with the plasmonic properties of the Ag core, a molecular collision model is introduced here to show the distribution of gaseous TPC molecules in ZIF, which could be responsible for this interesting two-step enhancement of SERS intensities. Furthermore, the H2 assisted kinetic process of gaseous p-aminothiophenol (PATP) is also analyzed by the classical pseudo-first-order kinetic model, which is consistent with our experimental SERS data. Our work not only reveals the novel phenomenon of plasmonic-MOF structures to improve the gas detection by SERS spectra but also enriches the understanding of the microcosmic process of gaseous molecules in the mixed gas environment to optimize MOF structures for gas capture and storage.
4 citations
TL;DR: In this paper , a hybrid plasmonic 2D microplates composed of Mxenes (Ti3C2Tx) microplates and in-situ synthesized Au nanoparticles (Au NPs) are fabricated in a microchannel for enhanced structures in SERS microfluidics.
References
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Donostia International Physics Center1, Rovira i Virgili University2, MacDiarmid Institute for Advanced Materials and Nanotechnology3, Victoria University of Wellington4, University of Cambridge5, University of California, Santa Barbara6, Queen's University Belfast7, Technical University of Denmark8, University of Victoria9, Chung-Ang University10, University of Jena11, Leibniz Institute of Photonic Technology12, Rutgers University13, University of Strathclyde14, University of Liverpool15, University of Iowa16, University of Minnesota17, Heidelberg University18, National Institute of Advanced Industrial Science and Technology19, Chalmers University of Technology20, Humboldt University of Berlin21, University of Michigan22, Jiangnan University23, Stanford University24, Xiamen University25, Ludwig Maximilian University of Munich26, Hokkaido University27, Seoul National University28, University of Illinois at Urbana–Champaign29, Kwansei Gakuin University30, University of Vigo31, Free University of Berlin32, Northwestern University33, University of Duisburg-Essen34, National Research Council35, Indian Institute of Science Education and Research, Thiruvananthapuram36, Duke University37, Northeastern University (China)38, Temple University39, Wuhan University40, Japan Advanced Institute of Science and Technology41, Jilin University42, Ikerbasque43
TL;DR: Prominent authors from all over the world joined efforts to summarize the current state-of-the-art in understanding and using SERS, as well as to propose what can be expected in the near future, in terms of research, applications, and technological development.
Abstract: The discovery of the enhancement of Raman scattering by molecules adsorbed on nanostructured metal surfaces is a landmark in the history of spectroscopic and analytical techniques. Significant experimental and theoretical effort has been directed toward understanding the surface-enhanced Raman scattering (SERS) effect and demonstrating its potential in various types of ultrasensitive sensing applications in a wide variety of fields. In the 45 years since its discovery, SERS has blossomed into a rich area of research and technology, but additional efforts are still needed before it can be routinely used analytically and in commercial products. In this Review, prominent authors from around the world joined together to summarize the state of the art in understanding and using SERS and to predict what can be expected in the near future in terms of research, applications, and technological development. This Review is dedicated to SERS pioneer and our coauthor, the late Prof. Richard Van Duyne, whom we lost during the preparation of this article.
1,768 citations
TL;DR: A review of the plasmon-enhanced Raman spectroscopy (PERS) field can be found in this paper, where a new generation of hotspots that are generated from hybrid structures combining PERS-active nanostructures and probe materials are discussed.
Abstract: Since 2000, there has been an explosion of activity in the field of plasmon-enhanced Raman spectroscopy (PERS), including surface-enhanced Raman spectroscopy (SERS), tip-enhanced Raman spectroscopy (TERS) and shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS). In this Review, we explore the mechanism of PERS and discuss PERS hotspots — nanoscale regions with a strongly enhanced local electromagnetic field — that allow trace-molecule detection, biomolecule analysis and surface characterization of various materials. In particular, we discuss a new generation of hotspots that are generated from hybrid structures combining PERS-active nanostructures and probe materials, which feature a strong local electromagnetic field on the surface of the probe material. Enhancement of surface Raman signals up to five orders of magnitude can be obtained from materials that are weakly SERS active or SERS inactive. We provide a detailed overview of future research directions in the field of PERS, focusing on new PERS-active nanomaterials and nanostructures and the broad application prospect for materials science and technology. Assisted by rationally designed novel plasmonic nanostructures, surface-enhanced Raman spectroscopy has presented a new generation of analytical tools (that is, tip-enhanced Raman spectroscopy and shell-isolated nanoparticle-enhanced Raman spectroscopy) with an extremely high surface sensitivity, spatial resolution and broad application for materials science and technology.
1,158 citations
TL;DR: An outlook of the key challenges in bioanalytical SERS, including reproducibility, sensitivity, and spatial and time resolution is given.
Abstract: Surface-enhanced Raman spectroscopy (SERS) inherits the rich chemical fingerprint information on Raman spectroscopy and gains sensitivity by plasmon-enhanced excitation and scattering. In particular, most Raman peaks have a narrow width suitable for multiplex analysis, and the measurements can be conveniently made under ambient and aqueous conditions. These merits make SERS a very promising technique for studying complex biological systems, and SERS has attracted increasing interest in biorelated analysis. However, there are still great challenges that need to be addressed until it can be widely accepted by the biorelated communities, answer interesting biological questions, and solve fatal clinical problems. SERS applications in bioanalysis involve the complex interactions of plasmonic nanomaterials with biological systems and their environments. The reliability becomes the key issue of bioanalytical SERS in order to extract meaningful information from SERS data. This review provides a comprehensive over...
1,073 citations
TL;DR: A universal platform that allows for the enrichment and delivery of analytes into the SERS-sensitive sites in both aqueous and nonaqueous fluids, and its subsequent quantitative detection of Rhodamine 6G down to ∼75 fM level (10−15 mol⋅L−1).
Abstract: Detecting target analytes with high specificity and sensitivity in any fluid is of fundamental importance to analytical science and technology. Surface-enhanced Raman scattering (SERS) has proven to be capable of detecting single molecules with high specificity, but achieving single-molecule sensitivity in any highly diluted solutions remains a challenge. Here we demonstrate a universal platform that allows for the enrichment and delivery of analytes into the SERS-sensitive sites in both aqueous and nonaqueous fluids, and its subsequent quantitative detection of Rhodamine 6G (R6G) down to ∼75 fM level (10(-15) mol⋅L(-1)). Our platform, termed slippery liquid-infused porous surface-enhanced Raman scattering (SLIPSERS), is based on a slippery, omniphobic substrate that enables the complete concentration of analytes and SERS substrates (e.g., Au nanoparticles) within an evaporating liquid droplet. Combining our SLIPSERS platform with a SERS mapping technique, we have systematically quantified the probability, p(c), of detecting R6G molecules at concentrations c ranging from 750 fM (p > 90%) down to 75 aM (10(-18) mol⋅L(-1)) levels (p ≤ 1.4%). The ability to detect analytes down to attomolar level is the lowest limit of detection for any SERS-based detection reported thus far. We have shown that analytes present in liquid, solid, or air phases can be extracted using a suitable liquid solvent and subsequently detected through SLIPSERS. Based on this platform, we have further demonstrated ultrasensitive detection of chemical and biological molecules as well as environmental contaminants within a broad range of common fluids for potential applications related to analytical chemistry, molecular diagnostics, environmental monitoring, and national security.
553 citations
TL;DR: In this article, a focused review on the synthesis of monodispersed silver particles with a novel, highly roughened, "flower-like" morphology by reducing silver nitrate with ascorbic acid in aqueous solutions is provided.
Abstract: Surface-enhanced Raman scattering (SERS) is a new optical spectroscopic analysis technique with potential for highly sensitive detection of molecules. Recently, many efforts have been made to find SERS substrates with high sensitivity and reproducibility. In this Research News article, we provide a focused review on the synthesis of monodispersed silver particles with a novel, highly roughened, "flower-like" morphology by reducing silver nitrate with ascorbic acid in aqueous solutions. The nanometer-scale surface roughness of the particles can provide several hot spots on a single particle, which significantly increases SERS enhancement. The incident polarization-dependent SERS of individual particles is also studied. Although the different "hot spots" on a single particle can have a strong polarization dependency, the total Raman signals from an individual particle usually have no obvious polarization dependency. Moreover, these flower-like silver particles can be measured by SERS with high enhancement several times, which indicates the high stability of the hot spots. Hence, the flower-like silver particles here can serve as highly sensitive and reproducible SERS substrates.
363 citations