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Sonodynamic therapy (SDT) has garnered significant attention in cancer treatment, however, the low-yield reactive oxygen species (ROS) generation from sonosensitizers remains a major challenge. In this study, titanium boride nanosheets (TiB 2 NSs) with photo-enhanced sonodynamic efficiency was fabricated for SDT of glioblastoma (GBM). Compared with commonly-used TiO 2 nanoparticles, the obtained TiB 2 NSs exhibited much higher ROS generation efficiency under ultrasound (US) irradiation due to their narrower band gap (2.50 eV). Importantly, TiB 2 NSs displayed strong localized surface plasmon resonance (LSPR) effect in the second near-infrared (NIR II) window, which facilitated charge transfer rate and improved the separation efficiency of US-triggered electron–hole pairs, leading to photo-enhanced ROS generation efficiency. Furthermore, TiB 2 NSs were encapsulated with macrophage cell membranes (CM) and then modified with RGD peptide to construct biomimetic nanoagents (TiB 2 @CM-RGD) for efficient blood-brain barrier (BBB) penetrating and GBM targeting. After intravenous injection into the tumor-bearing mouse, TiB 2 @CM-RGD can efficiently cross BBB and accumulate in the tumor sites. The tumor growth was significantly inhibited under simultaneous NIR II laser and US irradiation without causing appreciable long-term toxicity. Our work highlighted a new type of multifunctional titanium-based sonosensitizer with photo-enhanced sonodynamic efficiency for GBM treatment. Titanium boride nanosheets (TiB 2 NSs) with photo-enhanced sonodynamic efficiency was fabricated for SDT of glioblastoma (GBM). The obtained TiB 2 NSs displayed strong localized surface plasmon resonance (LSPR) effect in the second near-infrared (NIR II) window, which facilitated charge transfer rate and improved the separation efficiency of US-triggered electron-hole pairs, leading to photo-enhanced ROS generation efficiency. Furthermore, TiB 2 NSs were encapsulated with macrophage cell membranes (CM) and then modified with RGD peptide to construct biomimetic nanoagents (TiB 2 @CM-RGD) for efficient blood-brain barrier (BBB) penetrating and GBM targeting. After intravenous injection into the tumor-bearing mouse, TiB 2 @CM-RGD can efficiently cross BBB and accumulate in the tumor sites. The tumor growth was significantly inhibited under simultaneous NIR II laser and US irradiation without causing appreciable long-term toxicity. [Display omitted] [ABSTRACT FROM AUTHOR]

Cervical cancer is a disease that affects a lot of people all over the world. The success of treatment is significantly increased by early detection. The new surface plasmon resonance sensor (SPRS) described in this article is constructed from layers of silver, BaTiO3, and graphene, as well as a coupling prism. The transfer matrix (TM) approach is used to evaluate the SPRS structure. To obtain the highest sensitivity of the suggested SPRS, the thicknesses of the Ag and BaTiO3 and the number of Gr sheets are evaluated. Investigations are done on all factors of performance of the proposed device. Exemplary efficiency is achieved using 4 nm (BaTiO3) and 60 nm (Ag) materials. Three layers are chosen as the optimal amount of graphene after investigation. When the optimal thicknesses are employed, the suggested SPRS's greatest sensitivity of 300° RIU−1 has been attained. The suggested SPRS displays better sensitivity when compared to SPRS structures that have already been published in the literature. This SPRS is promising to be used in different biosensing applications due to its high performance. [ABSTRACT FROM AUTHOR]

In this paper, synthetically scaled-up degenerately n-type doped indium tin oxide (Sn:In2O3) nanocrystals are described as highly transparent conductive materials possessing both optoelectronic and crystalline properties. With tin dopants serving as n-type semiconductor materials, they can generate free-electron carriers. These free electrons, vibrating in resonance with infrared radiation, induce strong localized surface plasmon resonance (LSPR), resulting in efficient infrared absorption. To commercialize products featuring Sn:In2O3 with localized surface plasmon resonance, a scaled-up synthetic process is essential. To reduce the cost of raw materials during synthesis, we aim to proceed with synthesis in a large reactor using industrial raw materials. Sn:In2O3 can be formulated into ink dispersed in solvents. Infrared-absorbing ink formulations can capitalize on their infrared absorption properties to render opaque in the infrared spectrum while remaining transparent in the visible light spectrum. The ink can serve as a security ink material visible only through infrared cameras and as a paint absorbing infrared light. We verified the transparency and infrared absorption properties of the ink produced in this study, demonstrating consistent characteristics in scaled-up synthesis. Due to potential applications requiring infrared absorption properties, it holds significant promise as a robust platform material in various fields. [ABSTRACT FROM AUTHOR]

Simultaneous conversion of CO2 and biomass into value-added chemicals through solar-driven catalysis holds tremendous importance for fostering a sustainable circular economy. Herein, plasmonic Bi quantum dots were immobilized on phosphoric acid modified attapulgite (P-ATP) nanorod using an in-situ reduction–deposition method, and were employed for photocatalytic reduction of CO2 coupled with oxidation of biomass-derived benzyl alcohol. Results revealed that Bi atoms successfully integrated into the basal structure of P-ATP, forming chemically coordinated Bi–O–Si bonds that served as efficient transportation channels for electrons. The incorporation of high-density monodispersed Bi quantum dots induced a surface plasmon resonance (SPR) effect, expanding the light absorption range into the near-infrared region. As a consequence, the photo-thermal transformation was significantly accelerated, leading to enhanced reaction kinetics. Notably, 50% Bi/P-ATP nanocomposite exhibited the highest plasmon-mediated photocatalytic CH4 generation (115.7 µmol·g−1·h−1) and CO generation (44.9 µmol·g−1·h−1), along with remarkable benzaldehyde generation rate of 79.5 µmol·g−1·h−1 in the photo-redox coupling system under solar light irradiation. The hydrogen protons released from the oxidation of benzyl alcohol facilitated the incorporation of more hydrogen protons into CO2 to form key CH3O− intermediates. This work demonstrates the synergistic solar-driven valorization of CO2 and biomass using natural mineral based catalyst. [ABSTRACT FROM AUTHOR]

[Display omitted] The development of a full-spectrum responsive photocatalytic germicide with excellent charge separation efficiency to harvest high antimicrobial efficacy is a key goal yet a challenging conundrum. Herein, graphitic carbon nitride nanosheet (PCNS)/Ti 3 C 2 T x MXene/TiO 2 (PMT) Z-scheme heterojunctions with robust interface contact were crafted by in situ interfacial engineering. The strong internal electrical field (IEF) from PCNS to TiO 2 , evinced by the Kelvin Probe Force Microscopy (KPFM) characterization, can obtain high charge separation efficiency with 73.99%, compared to Schottky junction PCNS/Ti 3 C 2 T x (PM, 32.88%) and PCNS (17.70%). The Ti 3 C 2 T x component can not only serve as a transfer pathway to accelerate the recombination of photoexcited electrons of TiO 2 and holes of PCNS under the Ultraviolet–visible (UV–vis) light irradiation, but also replenish the photogenic electron concentrations to semiconductors in the near-infrared (NIR) light illumination. Meanwhile, the increased temperature due to the localized surface plasmon resonance (LSPR) can further boost the electronic activity to the generation of reactive oxygen species (ROS). Taken together, the PMT performs a high disinfection efficiency up to 99.40% under full solar spectrum illumination, 3.88 and 9.75 times higher than PCNS and TiO 2 , respectively, surpassing many reported Z-scheme heterojunctions. This work offers guidance for the design of Z-scheme heterojunction with the implanting of plasmons to secure excellent full-spectrum responsive photocatalytic sterilization performance. [ABSTRACT FROM AUTHOR]

Cu is extremely cheaper and more easily recyclable than Au, Ag. Additionally, Cu nanomaterials induced localized surface plasmon resonance (LSPR) has been found to be tuned from visible to the near infrared spectrum by changing their shape and size and it provides Schottky junction when it is combined with other semiconductor material. It has many other remarkable features. For that reason, Cu based photocatalysis has become a research hotspot in view of its enormous practical applications in dye degradation, catalysis, photocatalytic H2 production, photocatalytic CO2 reduction reaction (CO2 RR) and other topics. Herein, we review the latest advances in copper-based photocatalysts in many fields and their improved activity due to LSPR, Schottky barier etc. The outstanding characteristics of Cu, principle of LSPR of copper combined with different nanomaterials during photocatalysis are also discussed in detail. [ABSTRACT FROM AUTHOR]

The streamlines of the energy flux (Poynting vectors) and chirality flux as well as the intensity of the electric field around various plasmonic nanostructures (nanocube, nanocuboid, nanotriangle, hexagonal nanoplate and bowtie nanoantenna) induced by a circularly polarized (CP) or linearly polarized (LP) light were studied theoretically. The boundary element method combined with the method of moment was used to solve a set of surface integral equations, based on the Stratton–Chu formulation, for analyzing the highly distorted electromagnetic (EM) field in the proximity of these nanostructures. We discovered that the winding behavior of these streamlines exhibits versatility for various modes of the surface plasmon resonance of different nanostructures. Recently, using plasmonic nanostructures to facilitate a photochemical reaction has gained significant attention, where the hot carriers (electrons) play important roles. Our findings reveal a connection between the flow pattern of energy flux and the morphology of the photochemical deposition around various plasmonic nanostructures irradiated by a CP light. For example, numerical results exhibit vertically helical streamlines of the Poynting vector around an Au nanocube and transversely twisted-roll streamlines around a nanocuboid. Additionally, the behaviors of the winding energy and chirality fluxes at the gap and corners of a plasmonic bowtie nanoantenna, implying a highly twisted EM field, depend on the polarization of the incident LP light. Our analysis of the streamlines of the Poynting vector and chirality flux offers an insight into the formation of plasmon-enhanced photocatalysis. [ABSTRACT FROM AUTHOR]

The interaction of nanostructured metal particles with the molecular components of biosystems differs significantly from the processes that take place in the presence of ions of the same metals. This unequivocally indicates the need to take into account not only the course of chemical processes but also implies to discuss certain physical effects that are usually neglected when considering such interactions. In this work, we studied the interaction of silver nanoparticle dispersion (Ag-NP) in ethylene glycol with a particle size less than 100 nm (Sigma-Aldrich 658804) with glutathione in a water and carbonate buffer (pH 10). The choice of glutathione (GSH) is due to the fact that it plays a significant role in intracellular processes, participating in the protection of intracellular components from the toxic effects of heavy metal ions; at the same time, differences in its interaction with silver ions and nanoparticles were experimentally demonstrated. A series of optical studies of the absorption and emission spectra of solutions of silver nanoparticles with GSH was carried out in order to establish the dominant processes in the system. It was shown that the above-mentioned silver nanoparticles in aqueous solutions spontaneously decompose over time, while glutathione differently affects these processes in water and carbonate buffer. It was shown that not only the local surface plasmon resonance bands but also the emission spectra of Ag-NP~GSH solutions in the region of 350–550 nm change with time. The sources of such radiation can be carbon quantum dots (CQD), which, according to published data, can be formed during the synthesis of silver nanoparticles and effectively luminesce in this region of the spectrum. Raman spectroscopy data confirm the presence of CQD in the Ag-NPs solution. The presence of quantum dots in the system makes it possible to indirectly track the presence of silver nanoparticles, which are booster centers, enhancing the emission of CQDs. The studies allow us to state that the interaction of glutathione with silver nanoparticles is a complex topochemical process in which, in addition to chemical reactions, the processes of transformation of silver nanoparticles and changes in the distribution of their sizes and chemical/physical functionality take place. [ABSTRACT FROM AUTHOR]

Photocatalytic degradation has been extensively investigated toward the removal emerging contaminants (ECs) from water. In this study, a series of Ag-Bi3O4Cl plasmon photocatalysts were synthesized through the photo-deposition of metallic Ag on the Bi3O4Cl surface. The effects of plasmon modification on the catalytic performance of bismuth oxychlorides were analyzed. Ag addition did not alter the morphology of Bi3O4Cl. With the increasing Ag content, the number of oxygen defects on the catalyst surface first increased and then decreased. Moreover, the surface plasmon resonance effect of Ag suppressed the recombination of electron-hole pairs, promoting the migration and separation of photocarriers and improving the light absorption efficiency. However, the addition of excessive Ag reduced the number of active sites on the Bi3O4Cl surface, hindering the catalytic degradation of pollutants. The optimal Ag-Bi3O4Cl photocatalyst (Ag ratio: 0.025; solution pH: 9; dosage: 0.8 g/L) achieved 93.8 and 94.9% removal of ciprofloxacin and tetrabromobisphenol A, respectively. The physicochemical and photoelectric properties of Ag-Bi3O4Cl were determined through various characterization techniques. This study demonstrates that introducing metallic Ag alters the electron transfer path of the catalyst, reduces the recombination rate of electron-hole pairs, and effectively improves the catalytic efficiency of Bi3O4Cl. Furthermore, the pathways of ciprofloxacin degradation products and their biotoxicity were revealed. [ABSTRACT FROM AUTHOR]

The Mie scattering theory investigates the optical, electric, and magnetic properties of the gold nanospheres. It explains the nanospheres plasmonic phenomenon in a vacuum and metallic medium by using the finite-size model. It also investigated the effect of particle radius on these properties by varying the radius from 10 to 50 nm. We reported that the optical efficiency shows the existence of plasmon surrounding the nanoparticle, and the polarizability explains the quantity of the plasmon. In addition, the polarizability increases at the specific incident energy of electromagnetic waves which indicated the existence of the plasmon surrounding the nanosphere particle. [ABSTRACT FROM AUTHOR]

• The finite difference time domain (FDTD) method is utilized to design and analyze the optical properties of silver@gold nanorods (Ag@Au-NR) that interact with waterborne pathogens. • Optimization of the Ag@Au-NR structure was conducted using response surface methodology to obtain nanoparticles that have superior detection performance. • The aspect ratio, width, and Au-thickness significantly influence the absorption spectrum and detection performance of the biosensor. • We propose a novel method to recognize waterborne pathogens such as Vibrio cholerae , Escherichia coli , and Salmonella typhimurium based on the absorption spectrum of Ag@Au-NR. The global issue of waterborne pathogen transmission in developing nations necessitates innovative solutions for pathogenic bacterial detection in drinking water sources. In this investigation, we present an innovative method for pathogen detection utilizing silver@gold nanorods (Ag@Au-NR) as optical-based biosensors, designed using the finite difference time domain approach. Additionally, we utilize response surface methodology to investigate and enhance the structure of Ag@Au-NR, thereby improving its performance in detecting specific pathogenic bacteria. Our research focuses on addressing the presence of three critical waterborne pathogens: Vibrio cholerae, Escherichia coli, and Salmonella typhimurium. We systematically optimize the Ag@Au-NR structure by varying parameters such as aspect ratio, nanorod width, and Au-thickness. Key response variables evaluated encompass localized surface plasmon resonance (LSPR) peak shift and detection accuracy. By employing rigorous calculations and optimization procedures, we obtained an Ag@Au-NR structure capable of undergoing a substantial shift in LSPR peak, reaching up to 13.099 nm. This achieved outcome is accompanied by a high detection accuracy of 0.016 during interactions with pathogens. This study also explores an optimal Ag@Au-NR structure to generate distinct LSPR peaks for individual pathogens, aiming to enhance the biosensor's selectivity properties. We present a two-step pathogen recognition approach reliant on the absorption peaks generated throughout the detection process. This method involves (i) discerning pathogens based on the LSPR peak shifting and (ii) evaluating the area under the absorption curve. The remarkable detection performance achieved in this study with Ag@Au-NR signifies a pivotal advancement in LSPR-based biosensors. This breakthrough offers promising avenues for developing highly efficient biosensors for safeguarding public health and addressing waterborne pathogen contamination in resource-constrained regions. [ABSTRACT FROM AUTHOR]

In this work, we report the fabrication and spectroscopic characterization of subwavelength aluminum nanocavitiesâ€"consisting of hexamer or tetramer clusters of sub 10 nm width Al nanorodsâ€"with tunable localized surface plasmon resonance (LSPR) energies on suspended SiN x membranes. Here the volume plasmon (VP) and LSPR modes of lithographically-fabricated Al nanocavities are revealed by low-loss electron energy-loss spectroscopy (EELS) in an aberration corrected scanning transmission electron microscope (STEM). We show that the existence of grain boundaries (GBs) in these nanocavities results in shifts in the VP energy and a reduction in the VP lifetime. We map the VP energy and lifetime across GBs and we observe a decrease in VP energy and lifetime at GBs that is consistent with a reduction in free carrier density and increased plasmon scattering at these locations. Dipolar LSPR modes resonant in the UV and blue regions of the electromagnetic spectrum as well as higher-energy optically dark quadrupolar and hexapolar LSPR modes are also observed and mapped by STEM and EELS. All LSPR modes are confirmed via electromagnetic simulations based on the boundary element method. Both tetramer and hexamer structures support the excitation of dipolar bright and dipolar dark modes. Finally, we find that asymmetries in fabricated nanorod hexamer and tetramer nanocavities result in a mode mixing leading to a shift in dipolar dark LSPR modes. [ABSTRACT FROM AUTHOR]

The twinned nanotip of the Au nanoflower and the large lattice mismatch between Au and Cu can induce formation of twin defects during the growth process, resulting in asymmetric deposition of Cu atoms. [Display omitted] The metallic Janus nanoparticle is an emerging plasmonic nanostructure that has attracted attention in the fields of materials science and nanophotonics. The instability of the Cu nanostructure leads to very complex nucleation and growth kinetics, and synthesis of Cu Janus nanoparticle has challenges. Here, we report a new method for synthesis of Au–Cu Janus nanojellyfish (JNF) by using twinned tips of Au nanoflower (NF) as seeds. The twinned nanotip of the Au NF and the large lattice mismatch between Au and Cu can induce formation of twin defects during the growth process, resulting in asymmetric deposition of Cu atoms. The symmetry-breaking using different sizes of Au NF and Cu nanodomains within the Au–Cu JNF can controllably change the localized surface plasmon resonance (LSPR) modes. The asymmetric Au–Cu JNF can induce plasmon coupling between dipolar and multipolar modes, which leads to clear electric-field enhancement in the near-infrared region. An Au–Cu JNF with multiple LSPR modes was chosen to simultaneously match the excitation and emission bands of the lanthanide-doped upconversion nanoparticles (UCNPs). A 5000-fold enhancement of the upconversion luminescence was achieved by using single plasmonic Au–Cu JNF. The Au–Cu JNF can also provide a guide for new metallic Janus nanoparticles in the fields of plasmonic, photothermal conversion, and nanomotors. [ABSTRACT FROM AUTHOR]

In this article, a highly sensitive surface plasmon resonance biomedical sensor based on barium titanate, MXene and nickel hybrid nanostructure has been reported. The present paper is based on a modified Kretschmann configuration. In this configuration, multilayers are vertically stacked together to improve the optical and electronic properties of the proposed surface plasmon resonance sensor. Barium titanate and MXene have unique properties like large surface area, chemical stability, tunable bandgap, small work function, layered structure and good matter-light interaction to improve the performance parameters of the proposed surface plasmon resonance sensor. Nickel also plays a vital role to enhance the performance parameters because it has high metallic conductivity, a large number of absorption sites and hydrophilicity. The optimized performance parameters are angular sensitivity (3160RIU−1), detection accuracy (0.3072 deg−1), figure of merit (97.075 RIU−1) and limit of detection (3.164 × 10−6) for CaF2 prism/Ag/BaTiO3/Ni/MXene/Sensing medium at 633 nm wavelength. The strong transverse magnetic field intensity is also plotted for the biomedical sensor to analyze the penetration depth. The designed surface plasmon resonance sensor's optimal penetration depth into the sensing medium is 137 nm. The above results will open a new way to design and develop such type of surface plasmon resonance biomedical sensor. [ABSTRACT FROM AUTHOR]

This report brings out the role of Au plasmons as the subjacent layer below TiO2 in PEC water splitting for hydrogen generation. Au was deposited on an ITO sheet using DC sputtering with 5 nm and 20 nm thickness and annealed at 300 °C for 20 min in the N2 atmosphere. TiO2 in the form of the thin film was coated on the already deposited Au layer using a sol–gel spin coating method. Thin films were characterized using tools such as X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, and optical absorption spectroscopy. The presence of Au as the subjacent layer in TiO2 shows enhanced absorption (visible region) due to the plasmonic properties displayed by Au nanoparticles. TiO2 with subjacent Au layer (5 nm thickness) was found to exhibit eight times higher photoresponse than the pristine sample at 1.0 V/SCE which can be ascribed to the plasmonic effect of gold nanoparticles extending absorption in the visible region of sunlight. [ABSTRACT FROM AUTHOR]

Revealing the charge transfer path is very important for studying the photocatalytic mechanism and improving photocatalytic performance. In this work, the charge transfer path turned by the piezoelectricity in Ag-BaTiO3 nanofibers is discussed through degrading methyl orange. The piezo-photocatalytic degradation rate of Ag-BaTiO3 is much higher than the photocatalysis of Ag-BaTiO3 and piezo-photocatalysis of BaTiO3, implying the coupling effect between Ag nanoparticle-induced localized surface plasmon resonance (LSPR), photoexcited electron-hole pairs, and deformation-induced piezoelectric field. With the distribution density of Ag nanoparticles doubling, the LSPR field increases by one order of magnitude. Combined with charge separation driven by the piezoelectric field, more electrons in BaTiO3 nanofibers are excited by plasmon-induced resonance energy transfer to improve the photocatalytic property. [ABSTRACT FROM AUTHOR]

Citrate-capped silver nanoparticles (Ag@Cit NPs) were synthesized by a simple plasma-assisted reduction method. Homogenous colloidal Ag@Cit NPs solutions were produced by treating a A g N O 3 -trisodium citrate-deionized water with an atmospheric-pressure argon plasma jet. The plasma-synthesized Ag@Cit NPs exhibited quasi-spherical shape with an average particle diameter of about 5.9−7.5 nm, and their absorption spectra showed surface plasmon resonance peaks at approximately 406 nm. The amount of Ag@Cit NPs increased in a plasma exposure duration-dependent manner. Plasma synthesis of Ag@Cit NPs was more effective in the 8.5 cm plume jet than in the shorter and longer plume jets. A larger amount of Ag@Cit NPs were produced from the 8.5 cm plume jet with a higher pH and a larger number of aqua electrons, indicating that the synergetic effect between plasma electrons and citrate plays an important role in the plasma synthesis of Ag@Cit NPs. Plasma-assisted citrate reduction facilitates the synthesis of Ag@Cit NPs, and citrate-capped nanoparticles are stabilized in an aqueous solution due to their repulsive force. Next, we demonstrated that plasma-synthesized Ag@Cit NPs exhibited a significant degradation of methylene blue dye. [ABSTRACT FROM AUTHOR]

A highly sensitive hybrid structure for biosensing application based on surface plasmon resonance for the detection of blood cancer has been proposed in this article. The biosensor comprises of a CaF2 Prism, Ag metal, an oxide layer Al2O3 and a 2D nanomaterial graphene, which is grounded on Kretschmann configuration. The transfer matrix method is used to interrogate the performance parameters of proposed biosensor. To analyze the change in refractive index, the analyte has been considered over the graphene layer. To achieve maximum sensitivity and minimum reflectance the thickness of Ag, Al2O3 layers and number of graphene layers have been optimized. The suggested structure’s sensitivity can be enhanced up to 427.43 deg/RIU with the optimized value for the detection accuracy and FOM of 0.7027 deg−1 and 217 RIU−1 respectively. The work focuses on the development of plasmonic sensors with high performance and stability. Role of different material layers is also analyzed in terms of enhancement in sensitivity and evanescent field. The paper offers better optimization technique and selection of material than previously reported works, which eventually leads to enhancement in both sensitivity and FOM. This research could lead to the development of a useful biological sample sensing tool for the quick and precise detection of the blood cancer in its early stages. [ABSTRACT FROM AUTHOR]

• Integration of Explainable Artificial Intelligence (XAI) models on fiber optic SPR sensors. • Insights into the intricate patterns and features learned by the model are attained. • A comparative analysis of XAI models, namely SHAP and LIME is carried out. • LIME and SHAP methods jointly find that metal layer thickness has considerably greater influence than wavelength on sensing performance. • This finding is consistent with the concept of radiation damping related to fiber optic SPR sensor. In recent years, there has been a significant surge in interest surrounding the utilization of machine learning techniques to optimize the performance of fiber optic sensors. This paper delves into the integration of machine learning methodologies, with a specific focus on Explainable Artificial Intelligence (XAI) models, within the domain of fiber optic surface plasmon resonance (SPR) sensors. We implement XAI techniques into a previously-trained Gaussian Process Regression (GPR) model to gain insights into the intricate patterns and features learned by the model, thereby providing valuable insights into its decision-making process. Furthermore, we present a comparative analysis of XAI models, namely SHAP and LIME , to elucidate the individual impact of light wavelength (λ) and metal layer thickness (d m) on the enhancement of sensor's figure of merit (FOM). The results obtained from both LIME and SHAP methods lead to a common finding that compared to λ, it is the value of d m that possesses a significantly greater influence on achieving maximum FOM. Furthermore, this finding is in complete agreement with the concept of radiation damping related to fiber optic SPR sensor structures. This study has the potential to contribute to the refinement of design and fabrication processes related to fiber optic SPR sensor for a wide variety of applications. [ABSTRACT FROM AUTHOR]

Herein, dispersed Ni species over the surface of plasmonic TiN nanocrystals (TiN@Ni) are manufactured by using wetness impregnation method. This developmental material holds abundant surface sites and local surface plasmon resonance property. To further satisfy the requirement as the electrocatalyst for dye-sensitized solar cell (DSSC), bifunctional TiN@Ni nanocrystals are incorporated with monolayer MXene to construct the continuous conductive matrix. The yielded TiN@Ni-MXene film serves as counter electrode, power conversion efficiency(PCE) of corresponding DSSC under conventional irradiation condition is 8.08%, which surpasses as-reference Pt-based DSSC(7.59%). When further adding the NIR irradiation from counter electrode side of device, DSSC achieves an impressive PCE of 8.45%. The superior performance of TiN@Ni-MXene electrode should be attributed to the created active sites on the surface of TiN support, and the plasmonic effect from TiN@Ni nanoparticles via utilizing NIR light. Ni species provide more adsorption sites for triiodide ions, meanwhile the elevated temperature from plasmon-induced photothermal effect can effectively boost the triiodide reducing reaction rates at the interface of electrode and electrolyte. Thus electrocatalytic performance of TiN@Ni-MXene counter electrode is remarkablely enhanced. The strategy here will be beneficial for the design of highly active and stable electrocatalyst for DSSC, as well as realizing the efficient utilization for wide-spectrum solar energy. • The intrinsic electrocatalysis activity of TiN is enhanced by anchoring abundant • Ni species over the surface of TiN nanocrystallines. • The plasmonic and electrocatalytic TiN@Ni nanocrystallines are incorporated with monolayer MXene to form the conductive network. • The kind of dual-function counter electrode can utilize the NIR light which is not absorbed by traditional DSSC. • The kind of dual-function counter electrode presents the superior electrocatalytic performances [ABSTRACT FROM AUTHOR]

This paper presents a theory that allows one to calculate the energy absorbed by spheroidal metal nanoparticles when irradiated by ultrashort laser pulses of different duration in the region of surface plasmon resonance. Simple analytical expressions are obtained to calculate the absorption energy dependent on the frequency of carrier laser wave, on the pulse duration, and on the ratio between the axes of the ellipsoids. It is shown that at the frequency of the carrier (laser) wave, which coincides with that of the surface plasmon, the maximum absorption is observed for spherical nanoparticles. As the carrier frequency deviates from the surface plasmon one, two maxima appear in the absorption spectrum, dependent on the ratio of spheroidal axes: one corresponds to the elongated particles and the other to the flattened ones. [ABSTRACT FROM AUTHOR]

On-demand manipulation of the plasmon dephasing time plays critical roles in many important applications of localized surface plasmon resonance. Here, we systemically investigate the influence of the far-field coupling on plasmon dephasing time in different nanostructure arrays supporting single or multiple modes by for the first time applying the harmonic oscillator analysis model combined with the finite-difference time-domain numerical simulation. The results show that the dephasing time of a bright mode in the nanodisk array can be well on-demand manipulated based on the far-field coupling through varying the individual nanodisk size and array period. In particular, the dephasing time of nanodisk array with adjusting periods exhibits the behavior of first increasing and then decreasing, and it is also modified to different extents under different nanodisk sizes. Furthermore, for the heptamer array supporting multiple modes, we demonstrate that the influence of array period on dephasing time also exists for a bright mode, but a negligible effect appears for dark mode due to the negligible far-field coupling. These findings provide a potential solution to manipulate the dephasing time of plasmonic nanostructure and thereby offer flexible controllability of the ultrafast on-off process of plasmonic switching and photocatalytic efficiency. [ABSTRACT FROM AUTHOR]

As one kind of noble metal nanostructures, the plasmonic gold nanostructures possess unique optical properties as well as good biocompatibility, satisfactory stability, and multiplex functionality. These distinctive advantages make the plasmonic gold nanostructures an ideal medium in developing methods for biosensing and bioimaging. In this review, the optical properties of the plasmonic gold nanostructures were firstly introduced, and then biosensing in vitro based on localized surface plasmon resonance, Rayleigh scattering, surface-enhanced fluorescence, and Raman scattering were summarized. Subsequently, application of the plasmonic gold nanostructures for in vivo bioimaging based on scattering, photothermal, and photoacoustic techniques has been also briefly covered. At last, conclusions of the selected examples are presented and an outlook of this research topic is given. [ABSTRACT FROM AUTHOR]

As a naturally abundant resource, biomass holds significant potential as an alternative to non-renewable fossil feedstock for producing value-added chemicals and fuels. However, its applications are limited by low conversion efficiency and product selectivity. In this study, we synthesized plasmonic CuS/phosphoric acid-modified attapulgite (P-ATP) nanocomposites using a microwave hydrothermal approach. The formation of an S-type heterostructure between CuS and P-ATP markedly improved the separation of electrons and holes. Additionally, the CuS/P-ATP nanocomposites featured numerous acidic sites, significantly enhancing the conversion of 5-hydroxymethylfurfural (HMF) into furan-2,5-dicarbaldehyde (DFF). CuS-induced localized surface plasmon resonance (LSPR) extended the absorption spectrum into the near-infrared region, raising the surface temperature and substantially improving photocatalytic activity. The 30 % CuS/P-ATP exhibited the highest hydrogen evolution rate of 286 μmol g−1 h−1 and the highest DFF generation rate of 31 μmol g−1 h−1, while maintaining a 95 % selectivity for DFF. This study demonstrates the commercial potential of clay minerals for biomass valorization coupled with hydrogen production. • CuS/phosphoric acid-modified attapulgite nanocomposite was obtained. • CuS and P-ATP formed S-type heterojunction favored the separation of e-/h+. • P-ATP owned abundant acidic sites accelerating the selective oxidation of HMF. • CuS-induced LSPR extended the light absorption and increased the temperature. • Superior hydrogen evolution rate and high selectivity for DFF both realized. [ABSTRACT FROM AUTHOR]

Metallic nanoparticles supporting a localized surface plasmon resonance have emerged as promising platforms for nanoscopic labels, sensors, and (photo-) catalysts. To use nanoparticles in these capacities, and to gain mechanistic insight into the reactivity of inherently heterogeneous nanoparticles, single-particle characterization approaches are needed. Single-particle scattering spectroscopy has become an important, highly sensitive tool for localizing single plasmonic nanoparticles and studying their optical properties, local environment, and reactivity. In this review, we discuss approaches taken for collecting the scattered light from single particles, their advantages and disadvantages, and present some recent applications. We introduce techniques for the excitation and detection of single-particle scattering such as high-angle dark-field excitation, total internal reflection dark-field excitation, scanning near-field microscopy, and interferometric scattering. We also describe methods to achieve polarization-resolved excitation and detection. We then discuss different approaches for scanning, ratiometric, snapshot, and interferometric hyperspectral imaging techniques used to extract spectral information. Finally, we provide a brief overview of specialized setups for in situ measurements of nanoparticles in liquid systems and setups coupled to scanning tip microscopes. [ABSTRACT FROM AUTHOR]

This article describes the scientific career of our dear friend Richard P. Van Duyne. Rick was the discoverer of surface‐enhanced Raman spectroscopy (SERS), and over the period from the mid‐1970s until his death in 2019, he served as both the intellectual leader of the field, and the technical genius who pushed the field forward through his numerous inventions and discoveries. Rick's work went through many phases, and even involved a significant period of inactivity that Rick was able to break out of, but especially after 2000, there was a period of incredible creativity that ultimately led to a detailed understanding of what the SERS enhancement factor is all about and also led to fabrication techniques for making optimum SERS substrates such that applications of SERS to a wide variety of real‐world problems in sensing became possible. In addition, Rick's SERS work spawned numerous related technologies, including index of refraction sensing based on localized surface plasmon resonance (LSPR) measurements, and the extension of SERS to its tip‐enhanced cousin TERS, to electrochemical versions of SERS and TERS, and to ultrafast nonlinear techniques. The practical applications he pursued included diagnostics for diseases such as cancer, hand‐held glucose sensing, and SERS studies related to art conservation. However, Rick's legacy will probably be best known through the numerous students, postdocs, and collaborators that passed through his lab and who are now active researchers in areas related to SERS at universities and industrial labs around the world. [ABSTRACT FROM AUTHOR]

• A novel DSSC based on TiO 2 /Al@ZnO nanocomposite photoanode features 11.4% PCE. • Plasmon-induced PL in TiO 2 /Al@ZnO is ascribed to resonant excitation of Al plasmons. • Remarkable enhancement of conductivity in TiO 2 /Al@ZnO under illumination. • Establishment of a facile silver counter electrode via thermal curing process. We report the synthesis, characterization and effect of infusion of aluminium plasmons (Al3+) into titania/zinc oxide (TiO 2 /Al@ZnO or TAZ) nanocomposite photoanode on the efficiency of novel plasmonic Dye-Sensitized Solar Cells (DSSCs). On comparison with bare titania/zinc oxide (TiO 2 /ZnO or TZ) nanocomposite, plasmonic TAZ exhibits a negligible change in crystallographic and morphological properties, whereas the photoconduction and light harvesting capability are significantly enhanced. Prompted by surface plasmon modes, TAZ exhibits strong emissions in the blue-yellow region of visible spectrum, as observed with photoluminescence (PL) study. Owing to plasmon-induced PL, light enhancement takes place within the photoanode. Therefore, photoconductivity of TAZ is observed to be 4 folds higher than that of TZ. The narrowing of bandgap upon Al3+ infusion is confirmed by Kubelka-Munk plot and cyclic voltammetry. Specifically, we also focused on the architecture of novel DSSCs with silver counter electrode via a facile preparation method for the first time. Blending the advantages of nanocomposite, surface plasmon resonance and bandgap narrowing, the multifaceted TAZ features with short-circuit current density J SC ~ 33 mA cm−2, open-circuit voltage V OC ~ 0.41 V, Fill-factor FF ~ 0.81 and a remarkable efficiency of 11.4%, which opens up the opportunity to optimize and design a new class of next generation plasmonic DSSCs. [ABSTRACT FROM AUTHOR]

This study reported comprehensive and systematic investigations on size and shape control of silver nanoplates (SNPs) through a simple synthesis route where individual effects of each reactant on surface plasmon resonance of silver nanoplates were thoroughly investigated. SNPs were successfully fabricated via chemical reduction of AgNO3 with the aid of TSC, PVP, NaBH4, and H2O2 as a primary capping agent, secondary capping agent, reducing agent, and oxidative etchant, respectively. The role and effects of each reagent on the size and uniformity of SNPs during the synthesis were deeply investigated. The results showed that both TSC and H2O2 played critical roles in the growth of SNPs. Sufficient amount of TSC in the solution ([TSC]:[Ag+] molar ratio ≤ 22.5) would favor the formation of small-sized SNPs, while large-sized SNPs could be obtained at an excessive concentration of TSC. In addition to TSC, H2O2 was also essential for the formation of SNPs whose size increased with the addition of H2O2. In contrast, PVP did not play a major role in the formation of SNPs. It functioned as a secondary capping agent to prevent the formation of larger SNPs and facilitated the production of small-sized SNPs with equal uniformity. This role of PVP was particularly significant at the low level of TSC. The results were crucial for deeply understanding the individual effects of each reagent on the size and uniformity of SNPs so as to control the size and shape of SNPs for better surface-enhanced Raman scattering (SERS) signals of 4-mercapto benzoic acid (4-MBA). [ABSTRACT FROM AUTHOR]

Surface plasmon resonance (SPR) can be generated in metal nanostructures such as gold, silver, copper and aluminium, which are promising materials in the fields of optoelectronics and plasmonics. The SPR in periodic arrays has aroused great interest because of its uniform optical properties which can be applied in integrated optoelectronics device, including solar cells (SC). The optical spectra of structures with Ag nanoparticles on the surface of Si wafer were calculated. The simulation was carried out using finite-difference time-domain method (FDTD). The FDTD method is a powerful numerical algorithm for the direct solution of Maxwell's equations. As a source of radiation, a plane wave with a range of wavelengths 300–1240 nm is used. The enhancement of solar light absorption of structures with Ag nanoparticles has been demonstrated. The Localized Surface Plasmon Resonance peaks have been obtained in the wavelength range of 830–865 nm that is in good agreement with experimentally revealed one. It was shown that the period of Ag nanoparticles replacement significantly influences on the spectra and LSPR peak position. The measurement of current–voltage characteristics of solar cells with and without Ag nanoparticles demonstrated significant enhancement of short current density in case of AgNPs on SCs surface. [ABSTRACT FROM AUTHOR]

Dividing a metal nanoparticle into smaller components and the occurrence of the plasmonic phenomenon in the gap between these components can improve the sensitivity of the detector to variation of the refraction coefficient of liquid. In this paper, in a constant volume of metal, a golden disk is divided into two rings and one smaller disk. With a proper arrangement of these components, the surface plasmon resonance phenomenon takes place at the wavelength of 945.7 nm. The occurrence of this phenomenon increases the field in the distance between nanoparticles surrounded by liquid. The sensitivity of the detector that designed using nanodisks is 300 nm/RIU while it increases to 500 nm/RIU for the new structure. The increase of LSPR displacement, for a variation of 0.01 in the liquid refraction coefficient, from 3 nm for a disk to 5 nm for a proposed structure verifies a 67% improvement in the sensitivity of the sensor. [ABSTRACT FROM AUTHOR]

This review article discusses progress in surface plasmon resonance (SPR) of two-dimensional (2D) and three-dimensional (3D) chip-based nanostructure array patterns. Recent advancements in fabrication techniques for nano-arrays have endowed researchers with tools to explore a material's plasmonic optical properties. In this review, fabrication techniques including electron-beam lithography, focused-ion lithography, dip-pen lithography, laser interference lithography, nanosphere lithography, nanoimprint lithography, and anodic aluminum oxide (AAO) template-based lithography are introduced and discussed. Nano-arrays have gained increased attention because of their optical property dependency (light-matter interactions) on size, shape, and periodicity. In particular, nano-array architectures can be tailored to produce and tune plasmonic modes such as localized surface plasmon resonance (LSPR), surface plasmon polariton (SPP), extraordinary transmission, surface lattice resonance (SLR), Fano resonance, plasmonic whispering-gallery modes (WGMs), and plasmonic gap mode. Thus, light management (absorption, scattering, transmission, and guided wave propagation), as well as electromagnetic (EM) field enhancement, can be controlled by rational design and fabrication of plasmonic nano-arrays. Because of their optical properties, these plasmonic modes can be utilized for designing plasmonic sensors and surface-enhanced Raman scattering (SERS) sensors. [ABSTRACT FROM AUTHOR]

We demonstrate potential molecular monolayer detection using measurements of surface plasmon resonance (SPR) and angular Goos-Hänchen (GH) shift. Here, the molecular monolayer of interest is a benzenethiol self-assembled monolayer (BT-SAM) adsorbed on a gold (Au) substrate. Excitation of surface plasmons enhanced the GH shift which was dominated by angular GH shift because we focused the incident beam to a small beam waist making spatial GH shift negligible. For measurements in ambient, the presence of BT-SAM on a Au substrate induces hydrophobicity which decreases the likelihood of contamination on the surface allowing for molecular monolayer sensing. This is in contrast to the hydrophilic nature of a clean Au surface that is highly susceptible to contamination. Since our measurements were made in ambient, larger SPR angle than the expected value was measured due to the contamination in the Au substrate. In contrast, the SPR angle was smaller when BT-SAM coated the Au substrate due to the minimization of contaminants brought about by Au surface modification. Detection of the molecular monolayer acounts for the small change in the SPR angle from the expected value.

• A new colorimetric sensor based on CDs-Au NPs was developed. • Aggregation of the S-CD functionalized Au NPs in the presence of DA and Fe3+. • The decrease in LSPR band of S-CD@Au NPs at 520 nm and appearance of a band at 670 nm. • The ratio of the LSPR band at 670 nm to 520 nm was proportional to DA concentration. • The proposed sensor was applied for determination of DA in biological samples. A highly selective, sensitive, and rapid colorimetric sensor for the determination of dopamine (DA) was developed using the color change of S-doped carbon dots functionalized gold nanoparticles (S-CDs@Au NPs). The base of the method is the formation of a complex between the amine groups of dopamine with carboxylic groups of S-CDs@Au NPs followed by their aggregation with Fe3+ ions which acts as the linkers causing a red shift from 520 to 670 nm in the localized surface plasmon peak of S-CDs@Au NPs. The ratio of absorbance intensity at 670 nm to 520 nm was monitored as the analytical signal for determination of dopamine. The parameters affecting the analytical signal including reaction time, solution pH, the concentration of Au NPs and concentration of Fe3+ were optimized. At optimized conditions, the calibration curve was linear in the concentration range of 0.81–16.80 μM of dopamine. The detection and quantification limits were 0.23 μM and 0.77 μM, respectively. The intra-day and inter-day relative standard deviation (RSDs) at 5.0 μM of DA were 3.9% and 5.6%, respectively (n = 5). The applicability of the method for determination of DA in dopamine ampoule, urine and serum human samples was investigated. [ABSTRACT FROM AUTHOR]

Cuprous selenide nanocrystals have hallmark attributes, especially tunable localized surface plasmon resonances (LSPRs) and super‐ionic behavior. These attributes of cuprous selenide are now integrated with a one‐dimensional morphology. Essentially, Cu2Se nanowires (NWs) of micrometer‐scale lengths and about 10 nm diameter are prepared. The NWs exhibit a super‐ionic phase that is stable at temperatures lower than in the bulk, owing to compressive lattice strain along the radial dimension of the NWs. The NWs can be switched between oxidized and reduced forms, which have contrasting phase transition and LSPR characteristics. This work thus makes available switchable, one‐dimensional waveguides and ion‐conducting channels. [ABSTRACT FROM AUTHOR]

The photoluminescence spectra of the InP/ZnS quantum dots (QDs) and the composite structure of the InP/ZnS QDs coupled with Au nanorods are investigated in this paper. In the luminescence spectra of the two samples, the recombination of the bright–dark doublet exciton states and an upper bright exciton state are observed at the temperature 11–130 K. The temperature dependence of the main emission peaks of the InP/ZnS QDs and the composite structure can be expressed by the Varshni expression in the temperature range of 11–300 K. The coupling between the QDs and the surface plasmon resonance (SPR) states has a great effect on the exciton recombination and the defect recombination. Because of the coupling, the variation range of the main emission peak of the composite structure is about 28 meV more than the pure QDs with the temperature from 11 K to 300 K. The red shift of the defect emission with increasing temperature is coincident with the red shift of the SPR energy with increasing temperature. The experimental results confirm that the energy transfer from the SPR states is the main source of the defect emission. [ABSTRACT FROM AUTHOR]

Low energy N2+ ion beam with 600 keV energy has been used to irradiate BiVO 4 and Au nanoparticles loaded BiVO 4 (BiVO 4 /Au) thin films deposited over fluorine doped tin oxide substrates via spray pyrolysis technique. Ion irradiation results in tailoring the optical, electrical, and morphological properties of the thin films and thence also responsible for changes in electrochemical properties. The scanning electron microscope images reveal the evolution of Au nanoparticles after irradiation at 2 × 1015 fluence to a nanourchins type of morphology. In consequence of morphological changes, the signature of surface plasmon resonance peak exhibited by Au nanoparticles in BiVO 4 /Au shows improvement. An increase of approximately 92% in photocurrent density in comparison to pristine BiVO 4 has been found after irradiation in BiVO 4 /Au photoanode at 2 × 1015 ions/cm2 fluence. Moreover, irradiation also aids in improving photoelectrochemical response of BiVO 4 photoanodes without Au nanoparticles. The enhancement can be attributed to the notable changes in onset potential, charge separation, charge transfer resistance and optical properties. Image 1 • Ion beam irradiation study with 600 keV N2+ ion on BiVO 4 and BiVO 4 /Au thin films. • Photocurrent density increased ten times in irradiated sample compared to pristine. • Formation of nano-urchins type of morphology of Au nanoparticles after irradiation. [ABSTRACT FROM AUTHOR]

In this paper, we analyze the SPR fiber optic sensor based on array of 10-gold nanorods which are circular in shape. The proposed structure of the sensor is simulated using COMSOL multyphysics FEM method simulation software. Circular shape of the gold nanorod has been chosen for the optimal performance of the sensor in sensing of the particular refractive index. We simulate the sensor with optimized size of the gold nanorods and fiber parameters for best performance. We have shown that how the size of circular gold nanorod effects the sensitivity of the sensor. The maximum sensitivity exhibited by the sensor is 2200 n m. R I U - 1. From the simulated data, we have found that co-efficient of determination (COD) is very high. Improved sensitivity and high co-efficient of determination are achieved after sensor structural optimization. The proposed sensor structure can be useful in label-free optical platform for bio-sensing applications. [ABSTRACT FROM AUTHOR]

Long-range surface plasmon resonance (LRSPR)-based sensors exhibit high sensitivity as compared to the conventional SPR sensors due to low losses. A high refractive index prism and low refractive index dielectrics are required to excite long-range surface plasmon (LRSP) mode. In this work, a symmetrical structure consisting of metal (Au) layer sandwiched between the two similar refractive index dielectrics has been utilized to excite LRSPR modes. Two dielectrics, i.e., LiF and MgF2 thin films have been chosen for glucose sensing. Theoretical simulations for optimizing the thickness of two dielectrics have been carried out. Highly sensitive refractive index sensors based on LRSPR have been developed using the two dielectric thin films and their sensitivities have been compared. [ABSTRACT FROM AUTHOR]

This paper demonstrates a low-cost and portable multichannel surface plasmon resonance (SPR) based optical transducer. The system's portability is achieved through the development of compact web-cam based spectrometer, and edge coupling to the SPR chip. Here, two configurations are presented: single-channel integrated system and two-channel system where the SPR chip and the spectrometer are coupled by a pair of plastic optical fibers. For the two-channel configuration, two different approaches are utilized to extract the optical spectrum: manual region cropping and automatic regions detection. For both approaches, image distortion and the size of the fiber tip affect the measured spectrum. For all configurations, mechanical alignment and mounting are made by 3D printing. The developed systems are tested with water and glycerol solution of different concentrations. The measured sensitivity is in the order of 10-4 RIU (refractive index unit) for all systems under the ambient condition. [ABSTRACT FROM AUTHOR]

The relationship between plasma frequency and crystal structure was revealed in terms of the heat-shielding ability of materials wherein they transmit visible-light and absorb near-infrared light by localized surface plasmon resonance. It has been shown that the plasma frequency can be predicted from compositional information of a material, but its relationship with crystal structure remains unclear. It is important to clarify the relationship between them, because a change in crystal structure can lead to a change in electronic state. We calculated the plasma frequency of 1390 oxides and nitrides with high-throughput calculations under the first-principles framework. Subsequently, all the materials were classified into seven crystal systems. We found that the cubic system was the crystal system with the highest plasma frequency, whereas the monoclinic system had the lowest plasma frequency. We investigated crystal structures that exhibit high plasma frequencies. We evaluated structural similarity and found that the composition of cubic and monoclinic systems can be represented by the general chemical formula A B C 3 , that is, both have a perovskite crystal structure. The cubic and monoclinic perovskite structures can be distinguished based on the presence of the rotation of the B C 6 octahedron. Therefore, changes in plasma frequency due to the rotation of the B C 6 octahedron was calculated. We found that B C 6 rotation reduced plasma frequency. Furthermore, we investigated the visible-light absorption characteristics of cubic structure to evaluate their suitability for heat-shielding materials. We found the cubic perovskite structure appropriate for heat-shielding materials. [Display omitted] [ABSTRACT FROM AUTHOR]