Showing papers on "Surface plasmon resonance published in 2017"
TL;DR: The general overview of the field and the background for appropriate modelling of the physical phenomena are provided and the current state of the art and most recent applications of plasmon resonance in Au NPs are reported.
Abstract: In the last two decades, plasmon resonance in gold nanoparticles (Au NPs) has been the subject of intense research efforts. Plasmon physics is intriguing and its precise modelling proved to be challenging. In fact, plasmons are highly responsive to a multitude of factors, either intrinsic to the Au NPs or from the environment, and recently the need emerged for the correction of standard electromagnetic approaches with quantum effects. Applications related to plasmon absorption and scattering in Au NPs are impressively numerous, ranging from sensing to photothermal effects to cell imaging. Also, plasmon-enhanced phenomena are highly interesting for multiple purposes, including, for instance, Raman spectroscopy of nearby analytes, catalysis, or sunlight energy conversion. In addition, plasmon excitation is involved in a series of advanced physical processes such as non-linear optics, optical trapping, magneto-plasmonics, and optical activity. Here, we provide the general overview of the field and the background for appropriate modelling of the physical phenomena. Then, we report on the current state of the art and most recent applications of plasmon resonance in Au NPs.
1,205 citations
TL;DR: This Perspective reviews the current status of the field, showcasing a series of early successes in the application of SPR for clinical analysis and detailing aseries of considerations regarding sensing schemes, exposing issues with analysis in biofluids, and comparing SPR with ELISA, while providing an outlook of the challenges currently associated with plasmonic materials, instrumentation, microfluidics, bioreceptor selection, selection of aclinical market, and validation of a clinical assay.
Abstract: The design and application of sensors for monitoring biomolecules in clinical samples is a common goal of the sensing research community. Surface plasmon resonance (SPR) and other plasmonic techniques such as localized surface plasmon resonance (LSPR) and imaging SPR are reaching a maturity level sufficient for their application in monitoring biomolecules in clinical samples. In recent years, the first examples for monitoring antibodies, proteins, enzymes, drugs, small molecules, peptides, and nucleic acids in biofluids collected from patients afflicted with a series of medical conditions (Alzheimer’s, hepatitis, diabetes, leukemia, and cancers such as prostate and breast cancers, among others) demonstrate the progress of SPR sensing in clinical chemistry. This Perspective reviews the current status of the field, showcasing a series of early successes in the application of SPR for clinical analysis and detailing a series of considerations regarding sensing schemes, exposing issues with analysis in bioflui...
448 citations
TL;DR: Due to the simplicity of its geometry structure and its easiness to be fabricated, the proposed high figure of merit and sensitivity sensor indicates a competitive candidate for applications in sensing or detecting fields.
Abstract: A perfect ultra-narrow band infrared metamaterial absorber based on the all-metal-grating structure is proposed. The absorber presents a perfect absorption efficiency of over 98% with an ultra-narrow bandwidth of 0.66 nm at normal incidence. This high efficient absorption is contributed to the surface plasmon resonance. Moreover, the surface plasmon resonance-induced strong surface electric field enhancement is favorable for application in biosensing system. When operated as a plasmonic refractive index sensor, the ultra-narrow band absorber has a wavelength sensitivity 2400 nm/RIU and an ultra-high figure of merit 3640, which are much better than those of most reported similar plasmonic sensors. Besides, we also comprehensively investigate the influences of structural parameters on the sensing properties. Due to the simplicity of its geometry structure and its easiness to be fabricated, the proposed high figure of merit and sensitivity sensor indicates a competitive candidate for applications in sensing or detecting fields.
446 citations
TL;DR: Both in vitro and in vivo studies indicate that the light-triggered cross-linking can dramatically shift the surface plasmon resonance of Au nanoparticles to near-infrared regions, which remarkably enhances their efficacy for photothermal therapy and photoacoustic imaging of tumors in vivo.
Abstract: Photocross-linkable Au nanoparticles are prepared through surface decoration of photolabile diazirine moieties. Both in vitro and in vivo studies indicate that the light-triggered cross-linking can dramatically shift the surface plasmon resonance of Au nanoparticles to near-infrared regions, which in consequence remarkably enhances their efficacy for photothermal therapy and photoacoustic imaging of tumors in vivo.
419 citations
TL;DR: In this paper, a surface plasmon resonance (SPR) biochemical sensor based on the different heterostructures of few-layer black phosphorus (BP) and graphene/transition metal dichalcogenides (TMDCs) was proposed.
Abstract: The heterostructure of two-dimensional (2D) materials are promising and useful in the field of surface plasmon resonance (SPR) biochemical sensors. To enhance the sensitivity, we design a novel SPR biochemical sensor by using heterostructures of few-layer black phosphorus (BP) and graphene/transition metal dichalcogenides (TMDCs). The SPR biochemical sensor based on the different heterostructures of BP and graphene/TMDCs are analyzed, and the highest sensitivity with 279°/RIU for the heterostructure of BP and bilayer WSe2 is obtained. Moreover, the proposed biochemical sensor can be used to detect the analyte with different refractive index. The most prominent advantage of the proposed structure is its high sensitivity. The maximum sensitivity of our proposed SPR biochemical sensor is about 2.4 times of the conventional biochemical sensor. We believe that this biochemical sensor could find potential applications in chemical examination, medical diagnosis and biological detection.
294 citations
TL;DR: In this article, earth abundant aluminum is embedded in cuprous oxide antenna-reactor heterostructures that operate more effectively and selectively for the reverse water-gas shift reaction under milder illumination than in conventional thermal conditions.
Abstract: The rational combination of plasmonic nanoantennas with active transition metal-based catalysts, known as 'antenna-reactor' nanostructures, holds promise to expand the scope of chemical reactions possible with plasmonic photocatalysis. Here, we report earth-abundant embedded aluminum in cuprous oxide antenna-reactor heterostructures that operate more effectively and selectively for the reverse water-gas shift reaction under milder illumination than in conventional thermal conditions. Through rigorous comparison of the spatial temperature profile, optical absorption, and integrated electric field enhancement of the catalyst, we have been able to distinguish between competing photothermal and hot-carrier driven mechanistic pathways. The antenna-reactor geometry efficiently harnesses the plasmon resonance of aluminum to supply energetic hot-carriers and increases optical absorption in cuprous oxide for selective carbon dioxide conversion to carbon monoxide with visible light. The transition from noble metals to aluminum based antenna-reactor heterostructures in plasmonic photocatalysis provides a sustainable route to high-value chemicals and reaffirms the practical potential of plasmon-mediated chemical transformations.Plasmon-enhanced photocatalysis holds promise for the control of chemical reactions. Here the authors report an Al@Cu2O heterostructure based on earth abundant materials to transform CO2 into CO at significantly milder conditions.
284 citations
TL;DR: In this paper, plasmonic Bi metal was inserted as an electron-conduction bridge between g-C3N4 and the surface of Bi2WO6 microspheres to enhance visible light absorption due to the surface Plasmon resonance effect and facilitate efficient electron-carrier separation.
Abstract: A low-cost semiconductor-based photocatalyst using visible light energy has attracted increasing interest for energy generation and environmental remediation. Herein, plasmonic Bi metal was deposited in situ in g-C3N4@Bi2WO6 microspheres via a hydrothermal method. As an electron-conduction bridge, metallic Bi was inserted as the interlayer between g-C3N4 and the surface of Bi2WO6 microspheres to enhance visible light absorption due to the surface plasmon resonance (SPR) effect and facilitate efficient electron-carrier separation. Different characterization techniques, including XRD, SEM, TEM, UV–vis, XPS, photoluminescence, and photocurrent generation, were employed to investigate the morphology and optical properties of the as-prepared samples. The results indicated that the g-C3N4(20%)@Bi@Bi2WO6 microsphere sample exhibited an extraordinary enhanced photocatalytic activity, higher than those of the g-C3N4, Bi2WO6, and g-C3N4(20%)@Bi2WO6 samples. It implies that the heterostructured combination of g-C3N4...
281 citations
TL;DR: This review focuses on recent advances in single molecule detection using plasmonic metal nanostructures as a sensing platform, particularly using a single particle–single molecule approach.
Abstract: Single-molecule detection has long relied on fluorescent labeling with high quantum-yield fluorophores. Plasmon-enhanced detection circumvents the need for labeling by allowing direct optical detection of weakly emitting and completely nonfluorescent species. This review focuses on recent advances in single molecule detection using plasmonic metal nanostructures as a sensing platform, particularly using a single particle–single molecule approach. In the past decade two mechanisms for plasmon-enhanced single-molecule detection have been demonstrated: (1) by plasmonically enhancing the emission of weakly fluorescent biomolecules, or (2) by monitoring shifts of the plasmon resonance induced by single-molecule interactions. We begin with a motivation regarding the importance of single molecule detection, and advantages plasmonic detection offers. We describe both detection mechanisms and discuss challenges and potential solutions. We finalize by highlighting the exciting possibilities in analytical chemistry ...
260 citations
TL;DR: In this paper, the authors demonstrate the importance of the direct plasmonic coupling across the chemical interface for hot electron generation at a prototypical Ag nanocluster/TiO2 heterojunction by direct probing of the coherence and hot electron dynamics with two-photon photoemission spectroscopy.
Abstract: Integrating plasmonic nanoparticles with semiconductor substrates introduces strong optical resonances that extend and enhance the spectrum of photocatalytic and photovoltaic activity. The effect of plasmonic resonances has been variously attributed to the field nanoconfinement, plasmon–exciton coupling, hot electron transfer, and so on, based on action spectra of enhanced photoactivity. It remains unclear, however, whether energized carriers in the substrate are generated by the transfer of plasmonically generated hot electrons from the metal, as broadly believed, or directly by dephasing of the plasmonic field at the interface. Here, we demonstrate the importance of the direct plasmonic coupling across the chemical interface for hot electron generation at a prototypical Ag nanocluster/TiO2 heterojunction by direct probing of the coherence and hot electron dynamics with two-photon photoemission spectroscopy. Energy, time and material distributions of excitations in the Ag nanocluster/TiO2 heterojunction indicate that dielectric coupling with the substrate renormalizes the plasmon resonance of the Ag nanoparticle, and its dephasing directly generates hot electrons in TiO2 on a <10 fs timescale.
225 citations
TL;DR: The analysis shows that the PCF-SPR sensor is suitable for mid-infrared detection and the coupling characteristics and sensing properties are numerically analyzed by the finite element method.
Abstract: A surface plasmon resonance (SPR) sensor with two open-ring channels based on a photonic crystal fiber (PCF) is described. The sensor is designed to detect low refractive indexes between 1.23 and 1.29 with the operation wavelength in mid-infrared region between 2550 nm and 2900 nm. The coupling characteristics and sensing properties are numerically analyzed by the finite element method. The average spectral sensitivity is 5500 nm/RIU and a maximum resolution of 7.69 × 10-6 RIU can be obtained. Our analysis shows that the PCF-SPR sensor is suitable for mid-infrared detection.
219 citations
TL;DR: This study investigates the size dependence of CID by following the plasmon line width of gold nanorods during the adsorption process of thiols on the gold surface with single particle spectroscopy and shows that CID scales inversely with the effective path length of electrons, i.e., the average distance of electrons to the surface.
Abstract: Metallic nanoparticles show extraordinary strong light absorption near their plasmon resonance, orders of magnitude larger compared to nonmetallic nanoparticles. This “antenna” effect has recently been exploited to transfer electrons into empty states of an attached material, for example to create electric currents in photovoltaic devices or to induce chemical reactions. It is generally assumed that plasmons decay into hot electrons, which then transfer to the attached material. Ultrafast electron–electron scattering reduces the lifetime of hot electrons drastically in metals and therefore strongly limits the efficiency of plasmon induced hot electron transfer. However, recent work has revived the concept of plasmons decaying directly into an interfacial charge transfer state, thus avoiding the intermediate creation of hot electrons. This direct decay mechanism has mostly been neglected, and has been termed chemical interface damping (CID). CID manifests itself as an additional damping contribution to the...
TL;DR: The irradiation of gold nanorod colloids with a femtosecond laser can be tuned to induce controlled nan orod reshaping, yielding colloid clusters with exceptionally narrow localized surface plasmon resonance bands.
Abstract: The irradiation of gold nanorod colloids with a femtosecond laser can be tuned to induce controlled nanorod reshaping, yielding colloids with exceptionally narrow localized surface plasmon resonance bands. The process relies on a regime characterized by a gentle multishot reduction of the aspect ratio, whereas the rod shape and volume are barely affected. Successful reshaping can only occur within a narrow window of the heat dissipation rate: Low cooling rates lead to drastic morphological changes, and fast cooling has nearly no effect. Hence, a delicate balance must be achieved between irradiation fluence and surface density of the surfactant on the nanorods. This perfection process is appealing because it provides a simple, fast, reproducible, and scalable route toward gold nanorods with an optical response of exceptional quality, near the theoretical limit.
TL;DR: In this article, a facile photochemical reduction process followed by post-annealing was used to synthesize Ag-TiO2−−x nanocomposites for NO removal under visible light.
Abstract: Integration of semiconductors with plasmonic noble metal nanoparticles for visible- light driven photocatalysis has become an interesting research field recently. In this work, Ag-TiO2 − x nanocomposites were successfully synthesized via a facile photochemical reduction process followed by post-annealing. The deposition of Ag nanoparticles greatly increases the light absorption and charge separation. Compared with commercial P25, the Ag-TiO2 − x nanocomposites are not only superior in visible-light photocatalytic NO removal, but also in inhibiting the production of NO2, whose toxicity is 4–5 times higher than NO. As confirmed by gas chromatography, the photo-oxidation of NO and selective photo-reduction of NO to N2 occur simultaneously during the process of NO removal by Ag-TiO2 − x. The oxidation of NO was due to the synergic effect between h+ and O2−; while the selective photo-reduction was resulted from introduced oxygen vacancies in TiO2. In addition, the light wavelength dependence measurement reveals that the surface plasmon resonance effect of Ag is responsible for the improvement of the visible-light photoactivity. The present study will provide an alternative approach to design highly selective photocatalysts for NO removal under visible-light.
TL;DR: It is demonstrated that electrochemical reactions can also be accelerated by plasmonic nanoparticles upon LSPR excitation, and promises potential applications in (bio)electrochemical energy conversion, electroanalysis, and electrochemical devices.
Abstract: Direct photocatalysis making use of plasmonic metals has attracted significant attention due to the light-harnessing capabilities of these materials associated with localized surface plasmon resonance (LSPR) features. Thus far, most reported work has been limited to plasmon-induced chemical transformations. Herein, we demonstrate that electrochemical reactions can also be accelerated by plasmonic nanoparticles upon LSPR excitation. Using glucose electrocatalysis as a model reaction system, the direct plasmon-accelerated electrochemical reaction (PAER) on gold nanoparticles is observed. The wavelength- and solution-pH-dependent electrochemical oxidation rate and the dark-field scattering spectroscopy results confirm that the hot charge carriers generated during plasmon decay are responsible for the enhanced electrocatalysis performance. Based on the proposed PAER mechanism, a plasmon-improved glucose electrochemical sensor is constructed, demonstrating the enhanced performance of the non-enzyme sensor upon...
TL;DR: Furube et al. as discussed by the authors highlight the recent progress in two rising areas: solar energy conversion through plasmon-assisted interfacial electron transfer and PLASMIC nanofabrication.
Abstract: Localized surface plasmon resonance (LSPR) of plasmonic nanoparticles and nanostructures has attracted wide attention because the nanoparticles exhibit a strong near-field enhancement through interaction with visible light, enabling subwavelength optics and sensing at the single-molecule level. The extremely fast LSPR decays have raised doubts that such nanoparticles have use in photochemistry and energy storage. Recent studies have demonstrated the capability of such plasmonic systems in producing LSPR-induced hot electrons that are useful in energy conversion and storage when combined with electron-accepting semiconductors. Due to the femtosecond timescale, hot-electron transfer is under intense investigation to promote ongoing applications in photovoltaics and photocatalysis. Concurrently, hot-electron decay results in photothermal responses or plasmonic heating. Importantly, this heating has received renewed interest in photothermal manipulation, despite the developments in optical manipulation using optical forces to move and position nanoparticles and molecules guided by plasmonic nanostructures. To realize plasmonic heating-based manipulation, photothermally generated flows, such as thermophoresis, the Marangoni effect and thermal convection, are exploited. Plasmon-enhanced optical tweezers together with plasmon-induced heating show potential as an ultimate bottom-up method for fabricating nanomaterials. We review recent progress in two fascinating areas: solar energy conversion through interfacial electron transfer in gold-semiconductor composite materials and plasmon-induced nanofabrication. Quantum-level interactions between light and metal nanoparticles could boost the efficiency of solar cells and be used for nanoengineering. A photon and numerous electrons on the surface of a metal can couple together to form a hybrid particle known as a plasmon. Akihiro Furube and Shuichi Hashimoto from Tokushima University review how plasmons can both improve solar energy conversion and provide a means of nanoscale engineering. When plasmons decay, they can create high-energy electrons. Furube and Hashimoto summarize how these ‘hot’ electrons broaden the range of wavelengths over which solar cells operate so that they absorb more light. They also review how researchers can harness the heat created by hot electrons to physically move DNA, proteins and other tiny objects, which will enable complex nanostructures to be constructed with a high level of precision. In this review, we highlight the recent progress in two rising areas: solar energy conversion through plasmon-assisted interfacial electron transfer and plasmonic nanofabrication. Localized surface plasmon resonance (LSPR) of plasmonic nanoparticles and nanostructures has attracted increasing attention because of their strong near-field enhancement by interacting with visible light. Recent studies have demonstrated the capability of such plasmonic systems in producing ‘LSPR-induced hot-electrons’ that are useful in photoenergy conversion and storage when combined with electron-accepting semiconductors. Concurrently, ‘hot-electron decay’ results in strong photothermal responses or plasmonic local heating. This heating has received renewed interest in photothermal manipulation of nanoparticles and molecules.
TL;DR: In this paper, a surface plasmon resonance imaging platform integrated with a smartphone is used in the field with high-throughput biodetection, which allows taking SPR measurements from more than 20.000 individual pixels.
Abstract: We demonstrate a surface plasmon resonance imaging platform integrated with a smartphone to be used in the field with high-throughput biodetection. Inexpensive and disposable SPR substrates are produced by metal coating of commercial Blu-ray discs. A compact imaging apparatus is fabricated using a 3D printer which allows taking SPR measurements from more than 20.000 individual pixels. Real-time bulk refractive index change measurements yield noise equivalent refractive index changes as low as 4.12 × 10−5 RIU which is comparable with the detection performance of commercial instruments. As a demonstration of a biological assay, we have shown capture of mouse IgG antibodies by immobilized layer of rabbit anti-mouse (RAM) IgG antibody with nanomolar level limit of detection. Our approach in miniaturization of SPR biosensing in a cost-effective manner could enable realization of portable SPR measurement systems and kits for point-of-care applications.
TL;DR: In this article, the optical properties of monolayer molybdenum disulfide (MoS2)/Ag nanoparticle (NP) hybrids and their application to surface catalytic reactions were studied by transmission, photoluminescence (PL) and Raman spectroscopies.
TL;DR: In this article, a D-shaped photonic crystal fiber based surface plasmon resonance sensor is proposed for refractive index sensing, and a very high average sensitivity of 7700nm/RIU with the resolution of 1.30 × 10−5 RIU is obtained for the analyte of different refractive indices.
Abstract: In this article, a D-shaped photonic crystal fiber based surface plasmon resonance sensor is proposed for refractive index sensing. Surface plasmon resonance effect between surface plasmon polariton modes and fiber core modes of the designed D-shaped photonic crystal fiber is used to measure the refractive index of the analyte. By using finite element method, the sensing properties of the proposed sensor are investigated, and a very high average sensitivity of 7700 nm/RIU with the resolution of 1.30 × 10−5 RIU is obtained for the analyte of different refractive indices varies from 1.43 to 1.46. In the proposed sensor, the analyte and coating of gold are placed on the plane surface of the photonic crystal fiber, hence there is no necessity of the filling of voids, thus it is gentle to apply and easy to use.
TL;DR: In this article, the authors demonstrate a highly sensitive Au-MoS2-Graphene based hybrid surface plasmon resonance (SPR) biosensor for the detection of DNA hybridization.
TL;DR: In this article, carbon quantum dots (CQDs) were used as an electron reservoir to trap electrons generated from Cu nanoparticles and hinder the recombination of electron-hole pair.
Abstract: Exploration of broad spectrum photocatalyst for photocatalytic reaction is of great importance. Cu nanoparticles (NPs) were used for photocatalytic hydrogen evolution due to its surface plasmon resonance (SPR) effect and broad spectrum response. Here, Cu NPs were modified with carbon quantum dots (CQDs) for further improvement of photocatalytic ability. Cu/CQDs composites were prepared by facile in-situ photoreduction and a much higher H2 evolution rate was achieved than that of pure Cu NPs. The highest H2 evolution rate was 64 mmol g−1 h−1 for sample C which contains 15.6 wt% of CQDs. CQDs act as an electron reservoir to trap electrons generated from Cu NPs and hinder the recombination of electron-hole pair. Due to surface plasmon resonance (SPR) effect of Cu nanoparticles, broad spectrum photocatalytic activities of these samples were achieved under monochromatic light irradiation at 700, 800 and 900 nm, respectively. A possible mechanism is illustrated for the photocatalytic activity improvement of Cu nanoparticles modified with CQDs.
TL;DR: In this article, the authors proposed a highly sensitive surface plasmon resonance (SPR) biosensor based on the Otto configuration using a heterostructured MoS2/aluminum (Al) film.
Abstract: MoS2-graphene-based hybrid structures are biocompatible and useful in the field of biosensors. Herein, we propose a heterostructured MoS2/aluminum (Al) film/MoS2/graphene as a highly sensitive surface plasmon resonance (SPR) biosensor based on the Otto configuration. The sensitivity of the proposed biosensor is enhanced by using three methods. First, prisms of different refractive index have been discussed and it is found that sensitivity can be enhanced by using a low refractive index prism. Second, the influence of the thickness of the air layer on the sensitivity is analyzed and the optimal thickness of air is obtained. Finally, the sensitivity improvement and mechanism by using molybdenum disulfide (MoS2)–graphene hybrid structure is revealed. The maximum sensitivity ∼ 190.83°/RIU is obtained with six layers of MoS2 coating on both surfaces of Al thin film.
TL;DR: The experimental results of the plasmon resonance wavelength sensitivity agree well with the theoretical results, and the presented gold-coated D-shaped PCF SPR sensor could be used as a simple, cost-effective, high sensitivity device in bio-chemical detection.
Abstract: The refractive index sensing characteristics of the side-polished photonic crystal fiber (PCF) surface plasmon resonance (SPR) sensor are detailed investigated in this paper. We used the finite element method (FEM) to study the influences of the side-polished depth, air hole size, lattice constant, and the refractive index (RI) of the PCF material on sensing performance. The simulation results show that the side-polished depth, air hole size, lattice pitch have significant influence on the coupling strength between core mode and surface plasmon polaritons (SPPs), but have little influence on sensitivity; the coupling strength and sensitivity will significant increase with the decrease of RI of the PCF material. The sensitivity of the D-shaped PCF sensor is obtained to be as high as 21700 nm/RIU in the refractive index environment of 1.33-1.34, when the RI of the PCF material is controlled at 1.36. It revealed a new method of making ultra-high sensitivity SPR fiber sensor. Then we experimental demonstrated a SPR refractive sensor based on the side-polished single mode PCF and investigated the sensing performance. The experimental results of the plasmon resonance wavelength sensitivity agree well with the theoretical results. The presented gold-coated D-shaped PCF SPR sensor could be used as a simple, cost-effective, high sensitivity device in bio-chemical detection.
TL;DR: The results proved that the proposed aptamer-targeted Zr-MOF nanocomposite can be utilized in multiple-functionally biosensing, further promoting the potential application of Z-MoF-related nanomaterials in clinical diagnosis.
Abstract: This study reported a novel biosensor based on the nanocomposite of zirconium metal–organic framework (Zr-MOF, UiO-66) embedded with silver nanoclusters (Ag NCs) using the carcinoembryonic antigen (CEA)-targeted aptamer as template (AgNCs@Apt@UiO-66). The synthesized AgNCs@Apt@UiO-66 nanocomposite not only possesses good biocompatibility, active electrochemical performance, and strong bioaffinity, but also can be dispersed to form two-dimensional nanocomposite with nanoscale thickness. As such, the use of the AgNCs@CEA-aptamer enables AgNC@Apt@UiO-66 with sensitive and selective detection capacity of trace CEA, further concurrently being exploited as scaffold for surface plasmon resonance spectroscopy (SPR) and electrochemical biosensors. The results showed that the proposed electrochemical AgNC@Apt@UiO-66-based aptasensor exhibits high sensitivity with a low detection limit (LOD) of 8.88 and 4.93 pg·mL–1 deduced from electrochemical impedance spectroscopy and differential pulse voltammetry, respectively,...
TL;DR: In this paper, an oxygen-deficient molybdenum oxide quantum dots (MoO3-x QDs), which possess matching absorption-spectrum to solar light in both visible and near infrared regions, for proof-of-concept of interfacial water evaporation.
TL;DR: A novel method to obtain amorphous molybdenum oxide (MoO3 ) nanosheets is designed, in which it combines the oxidation of MoS2 and subsequent supercritical CO2 -treatment, which is a crucial step for the achievement of amorphously structure of MoO3.
Abstract: As a remarkable class of plasmonic materials, two dimensional (2D) semiconductor compounds have attracted attention owing to their controlled manipulation of plasmon resonances in the visible light spectrum, which outperforms conventional noble metals. However, tuning of plasmonic resonances for 2D semiconductors remains challenging. Herein, we design a novel method to obtain amorphous molybdenum oxide (MoO3 ) nanosheets, in which it combines the oxidation of MoS2 and subsequent supercritical CO2 -treatment, which is a crucial step for the achievement of amorphous structure of MoO3 . Upon illumination, hydrogen-doped MoO3 exhibits tuned surface plasmon resonances in the visible and near-IR regions. Moreover, a unique behavior of the amorphous MoO3 nanosheets has been found in an optical biosensing system; there is an optimum plasmon resonance after incubation with different BSA concentrations, suggesting a tunable plasmonic device in the near future.
TL;DR: In this paper, a photonic crystal fiber (PCF)-based surface plasmon resonance (SPR) sensor is presented and numerically characterized, and the authors theoretically analyze the influence of the air hole sizes of the PCF and the thicknesses of graphene layer and Ag layer on the performance of the designed sensor using wavelength and amplitude interrogations.
Abstract: We present and numerically characterize a photonic crystal fiber (PCF)-based surface plasmon resonance (SPR) sensor. By adjusting the air hole sizes of the PCF, the effective refractive index (RI) of core-guided mode can be tuned effectively and the sensor exhibits strong birefringence. Alternate holes coated with graphene-Ag bimetallic layers in the second layer are used as analyte channels, which can avoid adjacent interference and improve the signal to noise ratio (SNR). The graphene’s good features can not only solve the problem of silver oxidation but also increase the absorption of molecules. We theoretically analyze the influence of the air hole sizes of the PCF and the thicknesses of graphene layer and Ag layer on the performance of the designed sensor using wavelength and amplitude interrogations. The wavelength sensitivity we obtained is as high as 2520 nm/RIU with the resolution of 3.97 × 10−5 RIU, which can provide a reference for developing a high-sensitivity, real-time, fast-response, and distributed SPR sensor.
TL;DR: This sensitive and versatile surface plasmon resonance (SPR) biosensor was used for cancer cell detection coupled with the cell-specific aptamer modified magnetic nanoparticles and showed high selectivity toward single-base mismatch.
TL;DR: The recent advances in label-free optical biosensing technology are reviewed by focusing on the potential competitive advantage provided in selected emerging applications, grouped on the basis of the target type.
Abstract: Abstract Innovative technical solutions to realize optical biosensors with improved performance are continuously proposed. Progress in material fabrication enables developing novel substrates with enhanced optical responses. At the same time, the increased spectrum of available biomolecular tools, ranging from highly specific receptors to engineered bioconjugated polymers, facilitates the preparation of sensing surfaces with controlled functionality. What remains often unclear is to which extent this continuous innovation provides effective breakthroughs for specific applications. In this review, we address this challenging question for the class of label-free optical biosensors, which can provide a direct signal upon molecular binding without using secondary probes. Label-free biosensors have become a consolidated approach for the characterization and screening of molecular interactions in research laboratories. However, in the last decade, several examples of other applications with high potential impact have been proposed. We review the recent advances in label-free optical biosensing technology by focusing on the potential competitive advantage provided in selected emerging applications, grouped on the basis of the target type. In particular, direct and real-time detection allows the development of simpler, compact, and rapid analytical methods for different kinds of targets, from proteins to DNA and viruses. The lack of secondary interactions facilitates the binding of small-molecule targets and minimizes the perturbation in single-molecule detection. Moreover, the intrinsic versatility of label-free sensing makes it an ideal platform to be integrated with biomolecular machinery with innovative functionality, as in case of the molecular tools provided by DNA nanotechnology.
TL;DR: Hexagonally patterned vanadium dioxide (VO2) nanoparticle array with average diameter down to sub-100 nm as well as 160 nm of periodicity is fabricated, exhibiting distinct size, media, and temperature-dependent localized surface plasmon resonance switching behaviors, which fits well with the predication of simulations.
Abstract: A universal approach to develop various two-dimensional ordered nanostructures, namely nanoparticle, nanonet and nanodome arrays with controllable periodicity, ranging from 100 nm to 1 μm, has been developed in centimeter-scale by nanosphere lithography technique. Hexagonally patterned vanadium dioxide (VO2) nanoparticle array with average diameter down to sub-100 nm as well as 160 nm of periodicity is fabricated, exhibiting distinct size-, media-, and temperature-dependent localized surface plasmon resonance switching behaviors, which fits well with the predication of simulations. We specifically explore their decent thermochromic performance in an energy saving smart window and develop a proof-of-concept demo which proves the effectiveness of patterned VO2 film to serve as a smart thermal radiation control. This versatile and facile approach to fabricate various ordered nanostructures integrated with attractive phase change characteristics of VO2 may inspire the study of temperature-dependent physical responses and the development of smart devices in extensive areas.
TL;DR: The recent advances in Surface plasmon resonance technologies focusing on detection speed, sensitivity, and portability are described and significant advances of the vast developments in nanotechnology-associated SPR sensing for sensitivity enhancements are reviewed.
Abstract: Abstract Surface plasmon resonance (SPR) biosensor is a powerful tool for studying the kinetics of biomolecular interactions because they offer unique real-time and label-free measurement capabilities with high detection sensitivity. In the past two decades, SPR technology has been successfully commercialized and its performance has continuously been improved with lots of engineering efforts. In this review, we describe the recent advances in SPR technologies. The developments of SPR technologies focusing on detection speed, sensitivity, and portability are discussed in details. The incorporation of imaging techniques into SPR sensing is emphasized. In addition, our SPR imaging biosensors based on the scanning of wavelength by a solid-state tunable wavelength filter are highlighted. Finally, significant advances of the vast developments in nanotechnology-associated SPR sensing for sensitivity enhancements are also reviewed. It is hoped that this review will provide some insights for researchers who are interested in SPR sensing, and help them develop SPR sensors with better sensitivity and higher throughput.