Plasmonic Nanomaterials Research Articles

Plasmonic nanomaterials: Characterization and applications in organic synthesis and catalysis

Plasmonic nanomaterials: Characterization and applications in organic synthesis and catalysis

Engineering the surface roughness of the gold nanoparticles for the modulation of LSPR and SERS

In this work, we reported that by using a strong thiol ligand as the morphology-directing reagent, a series of Au nanoparticles with plate-like surface sub-structures could be successfully obtained via a one-pot seedless synthesis. The size and the density of the plates on the surface of Au can be readily tuned with the amount of the thiol ligand, resembling different roughness of the surface. Arising from the different surface roughness, the localized surface plasmon resonance (LSPR) of these shape and morphological alike Au nanoparticles can be continuously tuned within the visible-NIR region. The broad LSPR absorptions and feasible tunability make the Au nanoparticles suitable candidate for plasmonic-related applications. Interestingly, huge SERS enhancement was simultaneously achieved based on the specific surface roughness. Our results demonstrate the great potentials for tuning the LSPR and SERS of Au nanostructures through the engineering of the surface morphologies, which would assist for the design, synthesis, and applications of Au-based plasmonic nanomaterials in various fields.

Anchoring of silver nanoparticles by a zinc-porphyrin covalent organic framework for synergistic photodynamic sterilization

Porphyrin-based covalent organic frameworks (Por-COFs) show great promise in photodynamic sterilization and elimination of pathogenic bacteria. In this work, a two-dimensional Por-COF was constructed using 5,10,15,20-Tetrakis-(4-aminophenyl)-porphine-Zn(II) (Zn-TAPP) and Dihydroxyterephthalaldehyde (Dha), which was post-synthetically modified with silver nanoparticles (Ag NPs). Ag@ZnPor-COF delivered extraordinary photodynamic inactivation performance against Staphylococcus aureus and Escherichia coli under visible light (99.96 % and 99.75 %, respectively, within 20 min). The localized surface plasmon resonance of the Ag NPs enhanced the absorption of visible light whilst also aiding electron-hole separation, leading to efficient generation of reactive oxygen species (ROS), especially singlet oxygen (1O2). Further, the Ag NPs imparted Ag@ZnPor-COF with photothermal properties, thereby delivering even more effective control of pathogenic bacteria. Density functional theory (DFT) calculations validated the experimental findings, identifying Ag@ZnPor-COF as a potent antibacterial platform. Results encourage the wider use of Por-COFs and plasmonic nanomaterials in the development of antibacterial systems.

Lateral Flow Assay Biotesting by Utilizing Plasmonic Nanoparticles Made of Inexpensive Metals─Replacing Colloidal Gold.

Nanoparticles (NPs) can be conjugated with diverse biomolecules and employed in biosensing to detect target analytes in biological samples. This proven concept was primarily used during the COVID-19 pandemic with gold-NP-based lateral flow assays (LFAs). Considering the gold price and its worldwide depletion, here we show that novel plasmonic NPs based on inexpensive metals, titanium nitride (TiN) and copper covered with a gold shell (Cu@Au), perform comparable to or even better than gold nanoparticles. After conjugation, these novel nanoparticles provided high figures of merit for LFA testing, such as high signals and specificity and robust naked-eye signal recognition. Since the main cost of Au NPs in commercial testing kits is the colloidal synthesis, our development with the Cu@Au and the laser-ablation-fabricated TiN NPs is exciting, offering potentially inexpensive plasmonic nanomaterials for various bioapplications. Moreover, our machine learning study showed that biodetection with TiN is more accurate than that with Au.

Ni-based plasmonic photocatalysts for solar to energy conversion: A review

Plasmonic-based semiconductors are compelling contenders of current research endeavors to drive chemical reactions via plasmonic and phononic light-matter interactions. Among various plasmonic metals, Ni as a non-precious metal has been extensively studied due to its ability to participate in interband excitation and comparable metal-hydrogen binding energy to that of noble metals including Pt and Ag. The phenomenally high charge-carrier density in photoexcited Ni-based plasmonic nanomaterials offers photochemical conversion of high-energy chemical bonds accompanied by thermal effect. Since the research on the plasmonic activity of the non-precious metal is still emerging, no comprehensive review has addressed the significance of Ni as a plasmonic photocatalyst to the best of our knowledge. This review article sums up the recent progress in the field of plasmonic photocatalysis focusing on Ni-based photocatalysts. The basic principles of the plasmonic effect have been presented, along with an explanation of why Ni may be a viable option. Ni has been investigated for use as a co-catalyst and plasmonic photocatalyst in composite photocatalysis to achieve an accelerated process. After the energy transfer mechanism has been assessed, the review covers the state-of-the-art of two significant effects—plasmon energy transfer and the localized heating effect that are responsible for increased efficiency in energy production. In conclusion, we have included a synopsis of the assessment and emphasized the problems that must be resolved before the technology can be made available for purchase. In a nutshell, the chemistry of plasmonic photocatalysis is promising; but acquiring a detailed mechanism of charge transfer and utilization of charge carriers is still a roadblock in apprehending the full potential of plasmonic photocatalysis. Therefore, this study aims to motivate the scientific community to envision impactful work in the creation of next-generation plasmonic photocatalysts.

Oxidative and Colloidal Kinetics of Size‐Controlled Copper Structures through Surface Plasmon‐Regulated Examinations for Broadband Absorbance

AbstractOut of all the candidate plasmonic metals, copper has noteworthy optical characteristics and is also economically favourable for use. However, the stability of plasmonic copper nanomaterials against the loss of the plasmonic property is a setback. The present work is on the synthesis of oxidation‐stable copper micro/nanoparticles (CuMps/NPs) at ambient conditions with chosen precursors, antioxidizing agents, polymeric capping agents and chelating ligands. The Surface Plasmon Resonance (SPR) response of the synthesized Cu structures and their morphological analyses are studied. XRD data revealed changes in crystal structure such as crystallite sizes, lattice distortions and dislocation densities as a result of variations in the synthesis conditions. We present from these analyses micro/nanostructures of oxidation‐stable plasmonic Cu. The validation of the aggregation and oxidation stabilities of the different synthesized samples make them a worthy choice for multiple plasmonic applications, along with showing the synthesis protocols as viable approaches for achieving such structures with a markedly increased shelf life.

Plasmonic Au@Ag Core-Shell Nanoisland Film for Photothermal Inactivation and Surface-Enhanced Raman Scattering Detection of Bacteria.

Plasmonic metal nanomaterials have been extensively investigated for their utilizations in biomedical sensing and treatment. In this study, plasmonic Au@Ag core-shell nanoisland films (Au@AgNIFs) were successfully grown onto a glass substrate using a seed-mediated growth procedure. The nanostructure of the Au@AgNIFs was confirmed through scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and atomic force microscopy (AFM). The UV-Vis spectra of the Au@AgNIFs exhibited a broad absorption in the visible range from 300 to 800 nm because of the surface plasmon absorption. Under simulated sunlight exposure, the temperature of optimal Au@AgNIF was increased to be 66.9 °C to meet the requirement for photothermal bacterial eradication. Furthermore, the Au@AgNIFs demonstrated a consistent photothermal effect during the cyclic on/off exposure to light. For photothermal therapy, the Au@AgNIFs revealed superior efficiency in the photothermal eradication of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). With their unique nanoisland nanostructure, the Au@AgNIFs exhibited excellent growth efficiency of bacteria in comparison with that of the bare glass substrate. The Au@AgNIFs were also validated as a surface-enhanced Raman scattering (SERS) substrate to amplify the Raman signals of E. coli and S. aureus. By integrating photothermal therapy and SERS detection, the Au@AgNIFs were revealed to be a potential platform for bacterial theranostics.

The Nanoplasmonic Purcell Effect in Ultrafast and High-Light-Yield Perovskite Scintillators.

The development of X-ray scintillators with ultrahigh light yields and ultrafast response times is a long sought-after goal. In this work, a fundamental mechanism that pushes the frontiers of ultrafast X-ray scintillator performance is theoretically predicted and experimentally demonstrated: the use of nanoscale-confined surface plasmon polariton modes to tailor the scintillator response time via the Purcell effect. By incorporating nanoplasmonic materials in scintillator devices, this work predicts over tenfold enhancement in decay rate and 38% reduction in time resolution even with only a simple planar design. The nanoplasmonic Purcell effect is experimentally demonstrated using perovskite scintillators, enhancing the light yield by over 120% to 88 ± 11 ph/keV, and the decay rate by over 60% to 2.0 ± 0.2 ns for the average decay time, and 0.7 ± 0.1 ns for the ultrafast decay component, in good agreement with the predictions of ourtheoretical framework. Proof-of-concept X-ray imaging experiments are performed using nanoplasmonic scintillators, demonstrating 182% enhancement in the modulation transfer function at four line pairs per millimeter spatial frequency. This work highlights the enormous potential of nanoplasmonics in optimizing ultrafast scintillator devices for applications including time-of-flight X-ray imaging and photon-counting computed tomography.

Flexible 3D Plasmonic Web Enables Remote Surface Enhanced Raman Spectroscopy.

Nanoplasmonic materials concentrate light in specific regions of dramatic electromagnetic enhancement: hot spots. Such regions can be employed to perform single molecule detection via surface-enhanced Raman spectroscopy. However, this phenomenon is challenging since hot spots are expected to be highly intense/abundant and positioning of molecules within such hot spots is crucial to manage with ultrasensitive SERS. Herein, it is discovered that a 3D plasmonic web embedded within a biohybrid (3D-POWER) exhibits plasmonic transmission, spontaneously absorbs the analyte, and meets these so much needed criteria in ultrasensitive SERS. 3D-POWER is built with nanopaper and self-assembled layers of graphene oxide and gold nanorods. According to in silico experiments, 3D-POWER captures light in a small region and performs plasmonic field transmission in a surrounding volume, thereby activating a plasmonic web throughout the simulated volume. The study also provides experimental evidence supporting the plasmonic field transport ability of 3D power, which operates as a SERS signal carrier (even beyond the apparatus field of view), and the ultrasensitive behavior of this ecofriendly and flexible material facilitating yoctomolar limit of detection. Besides, 3D-POWER is proven useful in food and biofluids analysis. It is foreseen that 3D-POWER can be employed as a valuable platform in (bio)analytical applications.

ZnO Nanocages Decorated with Au@AgAu Yolk-Shell Nanomaterials for SERS-Based Detection of Hyperuricemia.

Surface-enhanced Raman scattering (SERS) is widely recognized as a highly sensitive technology for chemical detection and biological sensing. In SERS-based biomedical applications, developing highly efficient sensing platforms based on SERS plays a pivotal role in monitoring disease biomarker levels and facilitating the early detection of cancer biomarkers. Hyperuricemia, characterized by abnormally high concentrations of uric acid (UA) in the blood, was associated with a range of diseases, such as gouty arthritis, heart disease, and acute kidney injury. Recent reports have demonstrated the correlation between UA concentrations in blood and tears. In this work, we report the fabrication of SERS substrates utilizing ZnO nanocages and yolk-shell-structured plasmonic nanomaterials for the noninvasive detection of UA in tears. This innovative SERS substrate enables noninvasive and sensitive detection of UA to prevent hyperuricemia-related diseases.

DNA Origami-Engineered Plasmonic Nanoprobes for Targeted Cancer Imaging.

Plasmonic nanomaterials bearing targeting ligands are of great interest for surface-enhanced Raman scattering (SERS)-based bioimaging applications. However, the practical utility of SERS-based imaging strategies has been hindered by the lack of a straightforward method to synthesize highly sensitive SERS-active nanostructures with high yield and efficiency. In this work, leveraging DNA origami principles, we report the first-in-class design of a SERS-based plasmonically coupled nanoprobe for targeted cancer imaging (SPECTRA). The nanoprobe harnesses a cancer cell targeting DNA aptamer sequence and vibrational tag with stretching frequency in the cell-silent Raman window. Through the integration of aptamer sequence specific for DU145 cells, we show the unique capabilities of SPECTRA for targeted imaging of DU145 cells. Our results demonstrate that the scalability, cost-effectiveness, and reproducibility of this method of fabrication of SERS nanoprobes can serve as a versatile platform for creating nanoprobes with broad applications in the fields of cancer biology and biomedical imaging.

Recent advances in SERS-based bioanalytical applications: live cell imaging

Abstract Raman scattering can provide information on molecular fingerprints, which have been widely applied in various fields of material science and nanobiotechnology. Notably, low interference with water molecules in obtaining the Raman spectra between 500 and 2000 cm−1 made it a powerful spectroscopic tool in biology, such as imaging and signaling for a living cell. To be a robust tool for cell biology, the performance of obtaining molecular-specific information with high sensitivity, high resolution in real time, and without inducing cell damage is strongly required. The conventional fluorescence-based method has been suffered from the rapid photobleaching of organic fluorophores and the lack of molecular information. In contrast, Raman scattering is a promising spectroscopic tool to acquire cellular information, and the extremely low signal intensity of Raman scattering could be amplified by incorporating the plasmonic nanomaterials. Along with the fundamental research focus on surface-enhanced Raman scattering (SERS), the practical approaches of SERS for cellular imaging as a new tool for drug screening and monitoring cellular signals have been extensively explored based on new optical setups and new designing strategies for the nanostructures. Diverse nanostructure and surface chemistry for targeting or sensing have been played pivotal roles in acquiring cellular information and high resolution cell imaging. In this regard, this review focused on the recent advances of SERS-based technologies for a live cell imaging investigated such as potential drug screening, signaling for chemicals or biomolecules in cell, in situ sensing, and high spatiotemporal resolution.

Plasmonic group 4 transition metal carbide interfaces for solar‐driven desalination

AbstractTo combat the dwindling supply of freshwater, solar‐driven desalination using plasmonic nanomaterials has emerged as a promising and renewable solution. Refractory plasmonic carbide nanomaterials are exciting candidates that are inexpensive and chemically robust but have not been widely explored. Herein, plasmonic carbide interfaces made of TiC, ZrC, and HfC nanoparticle aggregates loaded onto to a mixed cellulose ester (MCE) membrane were explored to gain insight into their solar‐vapor generation and desalination potential. Desalination using Atlantic Ocean water under 1 sun intensity yielded rates of 1.26 ± 0.01, 1.18 ± 0.02, and 1.40 ± 0.01 kg m−2 h−1, with efficiencies of 86%, 80%, and 96% for TiC, ZrC, and HfC, respectively. Carbide interfaces showed good stability and effectively removed heavy metal ions and salt from solutions with concentrations up to 35%. PVA hydrogel based TMC evaporators afforded rates of 3.31 ± 0.03 and 3.22 ± 0.03 kg m−2 h−1 for TiC and ZrC, respectively. The HfC‐PVA interface afforded a high solar desalination rate of 3.69 ± 0.04 kg m−2 h−1, corresponding to an efficiency of 97% under 1‐sun illumination. The hydrogel evaporators also retained their strong salt rejection action over time.

Refractory Plasmonics of Reactively Sputtered Hafnium Nitride Nanoparticles: Pushing Limits

AbstractHigh‐temperature plasmonics deals with optically active nanostructures that can withstand high temperatures. A conventional approach relying on standalone noble metal nanoparticles fails to deliver refractory plasmonic nanomaterials, and an alternative route envisions metal nitrides. The main challenge remains the development of advanced synthesis techniques and the insight into thermal stability under real‐life application conditions. Here, hafnium nitride nanoparticles (HfN NPs) can be produced by gas aggregation using reactive magnetron sputtering, a technique with a small environmental footprint are shown. As‐deposited NPs are of 10 nm mean size and consist of stoichiometric, crystalline fcc HfN. They are characterized by optical absorption below 500 nm caused by interband transitions and in the red/near‐infrared (NIR) region due to intraband transitions and localized surface plasmon resonance (LSPR). The optical response can be engineered by tuning the NP composition as predicted by finite‐difference time‐domain (FDTD) calculations. Going beyond the state‐of‐the‐art, the HfN NP thermal stability is focued under ultrahigh vacuum (UHV) and in air. During UHV annealing to 850 °C, the NPs retain their morphology, chemical and optical properties, which makes them attractive in space mission and other applications. During air annealing to 800 °C, HfN NPs remain stable until 250 °C, which sets a limit for air‐mediated use.

Plasmonic nanomaterials: Characterization and applications in organic synthesis and catalysis

Plasmonic nanomaterials: Characterization and applications in organic synthesis and catalysis

Plasmonic‐Pyroelectric Materials and Structures

AbstractWith the growing global energy crisis, research into new energy materials that can potentially transfer heat into electricity has become a worldwide imperative. Pyroelectric materials are polar materials that are able to produce electrical charge in response to temperature change. These materials are of interest for infrared sensing, energy harvesting, and emerging applications in chemistry and biology. However, unlocking their potential requires the temperature changes to be both large and rapid. To achieve this goal, pyroelectric materials can be used in synergy with plasmonic nanomaterials, which provide highly localized and rapid heating upon illumination at the plasmonic resonances. Plasmonic‐pyroelectric combinations are therefore being used for a variety of electrical, thermal, electrochemical, and biological studies and are inspiring new technological applications. In this review, the underlying mechanisms of the pyroelectric and plasmonic effects are introduced and the benefits of combining them are outlined. A range of applications is then overviewed. Critical challenges and future perspectives to further develop the underlying science of these systems and to create highly efficient plasmonic‐pyroelectric materials and structures are discussed.

Multicomponent chiral plasmonic hybrid nanomaterials: recent advances in synthesis and applications.

Chiral hybrid nanomaterials with multiple components provide a highly promising approach for the integration of desired chirality with other functionalities into one single nanoscale entity. However, precise control over multicomponent chiral plasmonic hybrid nanomaterials to enable their application in diverse and complex scenarios remains a significant challenge. In this review, our focus lies on the recent advances in the preparation and application of multicomponent chiral plasmonic hybrid nanomaterials, with an emphasis on synthetic strategies and emerging applications. We first systematically elucidate preparation methods for multicomponent chiral plasmonic hybrid nanomaterials encompassing the following approaches: physical deposition approach, galvanic replacement reaction, chiral molecule-mediated, chiral heterostructure, circularly polarized light-mediated, magnetically induced, and chiral assembly. Furthermore, we highlight emerging applications of multicomponent chiral plasmonic hybrid nanomaterials in chirality sensing, enantioselective catalysis, and biomedicine. Finally, we provide an outlook on the challenges and opportunities in the field of multicomponent chiral plasmonic hybrid nanomaterials. In-depth investigations of these multicomponent chiral hybrid nanomaterials will pave the way for the rational design of chiral hybrid nanostructures with desirable functionalities for emerging technological applications.

Thermal-effect dominated plasmonic catalysis on silver nanoislands.

Plasmonic metal nanostructures with the intrinsic property of localized surface plasmon resonance can effectively promote energy conversion in many applications such as photocatalysis, photothermal therapy, seawater desalinization, etc. It is known that not only are plasmonically excited hot electrons generated from metal nanostructures under light irradiation, which can effectively trigger chemical reactions, but also plasmonically induced heating simultaneously occurs. Although plasmonic catalysis has been widely explored in recent years, the underlying mechanisms for distinguishing the contribution of hot electrons from thermal effects are not fully understood. Here, a simple and efficient self-assembly system using silver nanoislands as plasmonic substrates is designed to investigate the photo-induced azo coupling reaction of nitro- and amino-groups at various temperatures. In the experiments, surface-enhanced Raman spectroscopy is employed to monitor the time and temperature dependence of plasmon-induced catalytic reactions. It was found that a combination of hot electrons and thermal effects contribute to the reactivity. The thermal effects play the dominant role in the plasmon-induced azo coupling reaction of nitro-groups, which suggests that the localized temperature must be considered in the development of photonic applications based on plasmonic nanomaterials.

Nanoparticles based image-guided thermal therapy and temperature feedback.

Nanoparticles have emerged as versatile tools in the realm of thermal therapy, offering precise control and feedback mechanisms for targeted treatments. This review explores the intersection of nanotechnology and thermal therapy, focusing on the utilization of nanoparticles for image-guided interventions and temperature monitoring. Starting with an exploration of local temperature dynamics compared to whole-body responses, we delve into the landscape of nanomaterials and their pivotal role in nanomedicine. Various physical stimuli employed in therapy and imaging are scrutinized, laying the foundation for nanothermal therapies and the accompanying challenges. A comprehensive analysis of nanomaterial architecture ensues, delineating the functionalities of magnetic, plasmonic, and luminescent nanomaterials within the context of thermal therapies. Nano-design intricacies, including core-shell structures and monodisperse properties, are dissected for their impact on therapeutic efficacy. Furthermore, considerations in designing in vivo nanomaterials, such as hydrodynamic radii and core sizes at sub-tissue levels, are elucidated. The review then delves into specific modalities of thermally induced therapy, including magnetically induced hyperthermia and luminescent-based thermal treatments. Magnetic hyperthermia treatment is explored alongside its imaging and relaxometric properties, emphasizing the implications of imaging formulations on biotransformation and biodistribution. This review also provides an overview of the magnetic hyperthermia treatment using magnetic nanoparticles to induce localized heat in tissues. Similarly, optical and thermal imaging techniques utilizing luminescent nanomaterials are discussed, highlighting their potential for light-induced thermal therapy and cellular-level temperature monitoring. Finally, the application landscape of diagnosis and photothermal therapy (PTT) is surveyed, encompassing diverse areas such as cancer treatment, drug delivery, antibacterial therapy, and immunotherapy. The utility of nanothermometers in elucidating thermal relaxation dynamics as a diagnostic tool is underscored, alongside discussions on PTT hyperthermia protocols. Moreover, the advancements in nanoparticle magnetic imaging and implications of imaging formulations especially in creating positive MRI contrast agents are also presented. This comprehensive review offers insights into the evolving landscape of nanoparticle-based image-guided thermal therapies, promising advancements in precision medicine and targeted interventions, underscoring the importance of continued research in optimization for the full potential of magnetic hyperthermia to improve its efficacy and clinical translation.

Constructing plasmonic electron acceptors on TiO2 for full-spectrum-driven photocatalytic hydrogen generation

W-doped TiO2 nanodots (WTO-NDs) as plasmonic electron acceptors were controllably grown on TiO2 nanosheets (TO-NSs) to construct a plasmonic isotype heterostructure of WTO-NDs/TO-NSs for full-spectrum-driven photocatalytic hydrogen evolution.