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This paper reports the synthesis and characterization of some spherical crystalline copper (Cu), nickel (Ni), and their bimetallic (Cu–Ni) nanoparticles (NPs) produced in deionized (DI) water via pulse laser ablation in liquid (PLAL) technique. XRD and SAED patterns showed the high crystallinity of the synthesized nanostructures with face-centered cubic structure. The TEM and HRTEM images revealed the nucleation of spherical nanocrystals with a size range of 2.5–25 nm, and no remarkable aggregation was seen. Some core–shell oxidized Cu and Ni nanostructures related to the dissolved oxygen in DI water were detected. The UV–Vis absorption spectra at different aging times showed that pure metal nanoparticles are more stable than bimetallic nanoparticles. Localized surface plasmon resonance (LSPR) absorption peaks were recorded at 645 nm and 596 nm wavelengths for Cu and Cu–Ni colloidal solutions, respectively. The PL emission peaks at shorter wavelengths indicated that synthesized nanoparticles are blue luminescent. The achievement of pure and spherical copper, nickel, and their bimetallic nanoparticles with enhanced optical properties could be beneficial for advancing photocatalysis and antibacterial activity. [ABSTRACT FROM AUTHOR]

This tutorial min review discusses the important features of nanotechnology of colour generation by the quantum dots (QDs), nanostructured photonic crystals (PCs) and plasmonic metal nanoparticles. Quantum dots (QDs) are characterized by the tunable and size dependent strong fluorescence emission properties. Photonic crystals (PCs) generate the material independent structural colour ( iridescent colour dependent on the angle of observation ) due to the constructive interference arising from Bragg diffraction by the nanostructured photonic crystals (PCs) producing the diffraction gratings. It causes the vibrant colour in the opals and pearls, wings of peacocks and butterflies, in the necks of pigeons, variable colours in chameleons, etc. Plasmonic nanoparticles like Au-, Ag- and Cu-nanoparticles show the both light absorption and scattering properties that can be tuned by varying the size, morphology and composition of the nanoparticles. Structural colour ( iridescent colour ) by PCs is used by nature while colouring by QDs and plasmonic nanoparticles are due to the man made activities. The nanotechnology based colour is superior to the organic pigment based colour in terms of brightness and photostability and this field is an emerging area of research with a great promise in terms of applications in various fields. [ABSTRACT FROM AUTHOR]

Template-assisted colloidal self-assembly has gained significant attention due to its flexibility and versatility. By precisely controlling the shape of the template, it is possible to achieve custom-designed nanoparticle assemblies. However, a major challenge remains in fabricating these templates over large areas at a low cost. Recently, one-dimensional (1D) nano-wrinkle structures have been effectively used for the linear assembly of single-chain or multi-chain nanoparticles, which feature abundant interparticle nanogaps that facilitate efficient plasmonic coupling. To further enhance these assemblies by incorporating diffraction modes, we develop two-dimensional (2D) zigzag wrinkle structures that successfully assemble nanoparticles into plasmonic zigzag chains. Micro spectral measurements and FDTD simulations reveal that zigzag assemblies of plasmonic nanoparticle chains offer isotropic behavior and exhibit stronger plasmonic coupling compared to 1D assemblies, which could be highly beneficial for sensing applications. Due to the responsive PANI shell encapsulating the gold nanoparticles, this 2D zigzag assembly enables flexible tuning of plasmonic resonance under pH regulation. [ABSTRACT FROM AUTHOR]

Significant progress has been made through the optimization of modelling and device architecture solar cells has proven to be a valuable and highly effective approach for gaining a deeper understanding of the underlying physical processes in solar cells. Consequently, this research has conducted a two-dimensional (2D) perovskite solar cells (PSCs) simulation to develop an accurate model. The approach utilized in this study is based on the finite element method (FEM). Initially, a new configuration was introduced by incorporating a CH3NH3SnI3 layer as the absorber within the PSC structure, forming a parallel architecture. As a result, the power conversion efficiency (PCE) of PSC increased up to 26.89%. The light trapping process plays an essential role in enhancing the performance of PSCs. For this purpose, we utilized arrays of metal nanostructures on the active layer (AL) which resulted in significantly enhancing light absorption within these layers. In this research, the influence of nanoparticles position within the AL, the radius of nanoparticles and their composition (gold (Au) and silver (Ag)) on enhancing absorption in PSCs are examined by determining the cross-sectional area of light scattering and absorption on Au and Ag nanoparticles. The optimal position for the plasmonic nanoparticles was determined to be inside the MASnI3 as the complementary AL, 60 nm for the radius and Ag as champion composition. As a result of these modifications, the PCE reached 29.52%, representing an approximate 64% improvement compared to the planar structure. Subsequently, dielectric-metal-dielectric nanoparticles were introduced into the MASnI3 layer, replacing the previously embedded metallic nanoparticles, in order to enhance their chemical and thermal stability. According to optical-electrical simulation results, the short-circuit current density (Jsc) of the proposed parallel PSC, featuring triple core-shell nanoparticles composed of TiO2@Ag@TiO2 and SiO2@Ag@SiO2, has been improved by approximately 40% and 41.5%, respectively, compared to a PSC lacking nanoparticles. Moreover, under optimal conditions for the PSC, the open-circuit voltage (Voc), Jsc, fill factor (FF), and PCE were simulated at 1.01 V, 35.17 mA/cm², 84.16, and 30.18%, respectively. This approach paves the way for advancements in the development of perovskite solar cells, offering significant potential for practical applications and enhanced efficiency. [ABSTRACT FROM AUTHOR]

Designing pressure-sensitive paint (PSP) to achieve high luminescence and high pressure sensitivity at near-atmospheric pressures increases the signal-to-noise ratio of the luminescence images, facilitating aerodynamic studies of low-speed flows. Here, we investigate a PSP formulation that incorporates silica-coated silver nanoparticles (Ag@SiO2), along with Pt-(II) meso-tetra-(pentafluorophenyl)-porphine (PtTFPP) embedded in a sol–gel matrix. The Ag@SiO2 nanoparticles enhance the luminescence of PtTFPP by localized surface plasmon resonance (LSPR)-induced electric field enhancement rather than through altering the radiative decay rate of PtTFPP. The thickness of the silica layer and the mass ratio of Ag/PtTFPP are essential for optimizing the luminescence enhancement. In comparison to Ag-free PSP, the Ag@SiO2-doped PSP exhibits a 2-fold luminescence enhancement while maintaining a high pressure sensitivity of 0.94%/kPa normalized to atmospheric pressure data. The high luminescence and pressure sensitivity not only offer increased signal strength for imaging low-speed airflows but also hold promising potential for future designs of PSP formulations using MEL. [ABSTRACT FROM AUTHOR]

Surfactants and polymers are widely used as shape-directing agents in the synthesis of colloidal plasmonic nanostars, consequently acting as non-negligible players in all those high-performance applications in which processes occur at their interfaces, such as surface enhanced Raman spectroscopy (SERS) and plasmon-induced catalysis. Therefore, elucidating surfactant- and polymer-metal interactions is critical to rationally improving the performance of nanostars in the same range of applications. In this mini-review, we present traditional and state-of-the-art characterization methods that can be used to investigate the ligand-surface interactions that occur on mature nanostars. Due to historically based limitations in the availability of nanostar-specific literature, we utilize nanorod literature as a starting point to critically infer which analytical approaches can be seamlessly translated to nanostar systems, and which instead need to be adapted to intercept the peculiar needs imposed by the branched nanoparticle morphology. [ABSTRACT FROM AUTHOR]

In this study, we investigated the optical properties of the rhodamine B, methylene blue, and saffron dyes in the presented silver nanoparticles (Ag NPs). We detected that the absorption of the rhodamine B and methylene blue increased by interacting with NPs due to plasmon-induced quenching this effected can be utilized to manipulate and enhance optical properties and as a laser active medium. The highest value of the absorption coefficient for pure rhodium tincture was 222.86 cm-1, and for saffron dye tinged with silver nanoparticles was 486.98 cm-1. We studied the nonlinear optical responses of silver nanoparticles and these dyes. We detected that the silver nanoparticles have a high linear response at all selected laser excitations. In additionally, rhodamine B has a higher nonlinear response at a wavelength of 450 nm, which was further enhanced by the silver nanoparticles. Methylene blue has nonlinear responses, especially at the maximum absorption wavelength of 650 nm, and saffron dye showed nonlinear responses at all wavelengths, but the best response was at the 405 nm laser. The nanoparticles enhanced the nonlinear refraction of the saffron dye to fit the absorption spectra. The highest value of the nonlinear refractive index for saffron dye a doped with silver nanoparticles at a 405 nm laser was 3.48 × 10-11. These results indicate that the addition of nanoparticles can enhance the nonlinear properties of these dyes with the use of dye-appropriate lasers in Z-Scan technology. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) have emerged as versatile materials with remarkably high surface areas and tunable properties, attracting significant attention for various applications. In this work, the modification of a UiO-66 MOF with metal nanoparticles (NPs) is investigated for the purpose of enhancing its photocatalytic activity for CO2 reduction to liquid fuels. Several NPs (Au, Cu, Ag, Pd, Pt, and Ni) were loaded into the UiO-66 framework and employed as photocatalysts. The synergistic effects of plasmonic resonance and MOF characteristics were investigated to improve photocatalytic performance. The synthesized materials were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS), confirming the successful integration of metal NPs onto the UiO-66 framework. Morphological analysis revealed distinct distributions and sizes of NPs on the UiO-66 surface for different metals. Photocatalytic CO2 reduction experiments demonstrated enhanced activity of plasmonic MOFs, yielding methanol and ethanol. The findings revealed by this study provide valuable insights into tailoring MOFs for improved photocatalytic applications through the incorporation of plasmonic metal nanoparticles. [ABSTRACT FROM AUTHOR]

Obtaining high‐performance films of organo‐metallic halide perovskites is still a challenging task, with tremendous potential outcomes for devices involving light absorption such as next‐generation photovoltaics or photodetectors. In many experimental reports, particularly on perovskite solar cells, the addition of metallic nanoparticles (gold, silver…) has demonstrated promising performance improvements. However, while light management strategies based on plasmonic resonances are the initial motivation for these experiments, various other explanations have been proposed and the plasmonic nature of the performance boost is not always clear. In this article, optical simulation analysis is combined with a general review of the experimental reports to elucidate the role of nanoparticles in perovskite devices from a multifaceted perspective. Performance improvements were recently reported for various devices (solar cells, photodetectors) of different perovskite materials where gold nanoparticles were introduced either by spin coating or evaporation. Alongside a comprehensive examination of conventional optical effects, a novel function is identified of nanoparticles in regulating the crystallization rate of perovskite films, leading to enhanced film quality and ultimately boosting light absorption and device optical performance. This analysis enriches the mechanistic understanding for future studies on the use of nanoparticles in perovskite‐based devices, offering a novel approach for optimizing perovskite films. [ABSTRACT FROM AUTHOR]

Supercrystals, extended lattices of closely packed nanoparticles (NPs), present exciting possibilities for various applications. Under high pressures, typically in the gigapascal (GPa) range, supercrystals undergo significant structural changes, including adjustable interparticle distances, phase transformations, and the formation of new nanostructures through coalescence. While prior research has focused on ligand engineering's impact on supercrystal mechanical response, the influence of NP shape remains unexplored, especially for NPs larger than 10 nm coated with hydrosoluble ligands. This study examines the effects of NP shape on the mechanical properties of supercrystals using high‐pressure small‐angle X‐ray scattering and focused ion beam–scanning electron microscopy tomography. Notably, supercrystals exhibit higher hardness levels compared to previously reported values for gold supercrystals, attributed to the use of larger NPs. Spherical and tetrahedral NPs rearrange before collapsing under pressure, whereas rods and octahedra coalesce without prior structural rearrangement, likely due to their higher packing fraction. Additionally, anisotropic deformation of NP lattices and sintering does not always correlate with deviatoric stresses. These findings refine the understanding of complex processes governing supercrystal structure under high pressure, opening new avenues for NP engineering and advancing plasmonic applications under extreme conditions. [ABSTRACT FROM AUTHOR]

This paper deals with the detection of molecules in a solution using luminescent nanoparticles. Plasmonic nanoparticles change their photoluminescence due to the Purcell and Förster effects, the latter leading to luminescence quenching. Modeling these effects in colloidal solution allows us to determine the conditions of amplification and quenching, which opens the way to improving the sensitivity of sensors based on photoluminescence. [ABSTRACT FROM AUTHOR]

The optical cross sections of plasmonic nanoparticles are intricately linked to their morphologies. Accurately capturing this link could allow determination of particles' shapes from their optical cross sections alone. Electromagnetic simulations bridge morphology and optical properties, provided they are sufficiently accurate. This study examines key factors affecting simulation precision, comparing common methods and detailing the impacts of meshing accuracy, dielectric function selection, and substrate inclusion within the boundary element method. To support the method's complex parameterization, we develop a workflow incorporating reconstruction, meshing, and mesh simplification, to enable the use of electron tomography data. We analyze how choices of reconstruction algorithm and image segmentation affect simulated optical cross sections, relating these to shape errors minimized during data processing. Optimal results are obtained using the total variation minimization (TVM) reconstruction method with Otsu thresholding and light smoothing, ensuring reliable, watertight surface meshes through the marching cubes algorithm, even for complex shapes. [ABSTRACT FROM AUTHOR]

Abstract This paper reports the synthesis and characterization of some spherical crystalline copper (Cu), nickel (Ni), and their bimetallic (Cu–Ni) nanoparticles (NPs) produced in deionized (DI) water via pulse laser ablation in liquid (PLAL) technique. XRD and SAED patterns showed the high crystallinity of the synthesized nanostructures with face-centered cubic structure. The TEM and HRTEM images revealed the nucleation of spherical nanocrystals with a size range of 2.5–25 nm, and no remarkable aggregation was seen. Some core–shell oxidized Cu and Ni nanostructures related to the dissolved oxygen in DI water were detected. The UV–Vis absorption spectra at different aging times showed that pure metal nanoparticles are more stable than bimetallic nanoparticles. Localized surface plasmon resonance (LSPR) absorption peaks were recorded at 645 nm and 596 nm wavelengths for Cu and Cu–Ni colloidal solutions, respectively. The PL emission peaks at shorter wavelengths indicated that synthesized nanoparticles are blue luminescent. The achievement of pure and spherical copper, nickel, and their bimetallic nanoparticles with enhanced optical properties could be beneficial for advancing photocatalysis and antibacterial activity.

Abstract Treating lung and prostate cancer cells is a major health problem that may be solved through the interactions of laser beams with nanoparticles. In the paper, Au-H2Ti3O7 nanotubes (NTs) are proposed as a treatment agent and the interactions of different laser beams with the nanostructure are considered to solve the mentioned health problem. Also, the NTs are employed to treat the cancers in dark conditions. The results are motivating because Au-H2Ti3O7 NPs do not affect healthy cells, while they strongly affect cancer cells, and the viability percentage of LNCap cells reaches 16% for incubation times of 48 h. Furthermore, treating LNCap cells using the irradiated Au-H2Ti3O7 NTs by NIR beam at 808 nm has no cytotoxicity, while cytotoxicity of 92% is obtained using an irradiation laser beam at 532 nm. Also, applying the laser beam at 635 nm to the NTs leads to a cytotoxicity of ∼53% in lung cancer (A549 cells). In total, the Au-H2Ti3O7 NTs have a selective effect on cancer cells and greatly reduce the viability in the given dark and irradiation conditions, leading to the introduction of them as a promising agent for the non-invasive treatment of prostate cancer and a moderate candidate for lung cancer therapy.

Perovskite solar cells (PSCs) have garnered immense attention in recent years due to their outstanding optoelectronic properties and cost-effective fabrication methods, establishing them as promising candidates for next-generation photovoltaic technologies. Among the diverse strategies aimed at enhancing the power conversion efficiency (PCE) of PSCs, the incorporation of plasmonic nanoparticles has emerged as a pioneering approach. This review summarizes the latest research advancements in the utilization of plasmonic nanoparticles to enhance the performance of PSCs. We delve into the fundamental principles of plasmonic resonance and its interaction with perovskite materials, highlighting how localized surface plasmons can effectively broaden light absorption, facilitate hot-electron transfer (HET), and optimize charge separation dynamics. Recent strategies, including the design of tailored metal nanoparticles (MNPs), gratings, and hybrid plasmonic–photonic architectures, are critically evaluated for their efficacy in enhancing light trapping, increasing photocurrent, and mitigating charge recombination. Additionally, this review addresses the challenges associated with the integration of plasmonic elements into PSCs, including issues of scalability, compatibility, and cost-effectiveness. Finally, the review provides insights into future research directions aimed at advancing the field, thereby paving the way for next-generation, high-performance perovskite-based photovoltaic technologies. [ABSTRACT FROM AUTHOR]

The development of a stable, non‐toxic material that emits electrons following absorption of visible light may have a major impact on the solar photocatalysis of difficult reactions such as CO2 and N2 reduction, as well as for targeted chemical transformations in general. Diamond is a good candidate, however it is a wide bandgap material requiring deep UV photons ( λ ${{\rm{{\rm \lambda} }}}$ <227 nm) to promote electrons from the valence band into the conduction band. Embedding silver nanoparticles under the diamond surface allows the photoconductivity of the diamond in the spectral region of the surface plasmon resonance to be increased, while also leading to an enhancement of visible light photoemission. Considering the low intensity of the light sources used in this work and the spectral properties of the enhanced photoconductivity and photoemission a mechanism based on plasmonically enhanced photoconductivity which in turn allows surface states emptied by photoemission to be recharged thus leading to enhanced photoemission in the visible range is proposed. [ABSTRACT FROM AUTHOR]

Surface plasmon resonance (SPR) conventionally occurs at the interface of a thin metallic film and an external dielectric medium in fiber optics through core‐guided light. However, this work introduces theoretical and experimental evidence suggesting that the SPR in optical fibers can also be induced through light scattering from Au nanoparticles (NPs) on the thin metallic film, defined as nanoparticle‐induced SPR (NPI‐SPR). This method adheres to phase‐matching conditions between SPR dispersion curves and the wave vectors of scattered light from Au NPs. Experimentally, these conditions are met on an etched optical fiber, enabling direct interaction between light and immobilized Au NPs. Compared to SPR, NPI‐SPR exhibits stronger field intensity in the external region and wavelength tuning capabilities (750 to 1250 nm) by varying Au NP diameters (20 to 90 nm). NPI‐SPR demonstrates refractive index sensitivities of 4000 to 4416 nm per refractive index unit, nearly double those of typical SPR using the same optical fiber configuration sans Au NPs. Additionally, NPI‐SPR fiber configuration has demonstrated its applicability for developing biosensors, achieving a remarkable limit of detection of 0.004 nm for thrombin protein evaluation, a twenty‐fold enhancement compared to typical SPR. These findings underscore the intrinsic advantages of NPI‐SPR for sensing. [ABSTRACT FROM AUTHOR]

Hyperthermia plays a significant role in cancer treatment by inducing cell damage through temperature elevation, often used alongside other treatment modalities. During hyperthermia therapy, temperature control is crucial. Here, we report on a simple synthesis route of hybrid plasmonic nanodiamonds either completely wrapped with an Au shell (NV@Au) or densely covered with Au NPs (NV@SiO2@Au). Such integration of nanodiamonds with Au NPs is advantageous both for heating and precise thermometry at nanoscale. After structural and optical investigations, heating abilities of the obtained plasmonic nanodiamonds were thoroughly inspected on glass, in association with living cells, and in tissue slices ex vivo, revealing their effective heat generation under excitation with light using a single excitation source. The developed hybrid plasmonic nanodiamonds were finally applied for local photothermal therapy of melanoma in vivo, demonstrating their efficacy in eradicating cancer cells and monitoring temperature during the process. [ABSTRACT FROM AUTHOR]

Abstract Nanoparticle (NP) arrays, particularly those with plasmonic properties, have diverse applications in electronics, photonics, catalysis, and biosensing, but their precise and scalable fabrication remains challenging. In this work, a facile chemical‐based strategy is presented for the fabrication of precise NP patterns using a combination of soft thermal nanoimprinting and template‐directed assembly. The approach enables the creation of well‐defined NP arrays with single‐particle resolution and yields over 99%, covering a diverse range of NP sizes from 30 to 150 nm. These patterns can be transferred onto various substrates including semiconductors, insulators, 2D materials, and flexible polymers, maintaining high uniformity and repeatability for over 60 cycles with minimal degradation. Moreover, the method enables the fabrication of extensive NP arrays up to 1 cm2 with a positional accuracy of ±11 nm for 30 nm NPs. As a result, the obtained silver NP arrays exhibit ultranarrow surface lattice resonances with a linewidth of 4 nm and a quality factor (Q) of 216. The method offers new avenues for the creation of plasmonic NP arrays for flexible and wearable devices.

Surfactants and polymers are widely used as shape-directing agents in the synthesis of colloidal plasmonic nanostars, consequently acting as non-negligible players in all those high-performance applications in which processes occur at their interfaces, such as surface enhanced Raman spectroscopy (SERS) and plasmon-induced catalysis. Therefore, elucidating surfactant- and polymer-metal interactions is critical to rationally improving the performance of nanostars in the same range of applications. In this mini-review, we present traditional and state-of-the-art characterization methods that can be used to investigate the ligand-surface interactions that occur on mature nanostars. Due to historically based limitations in the availability of nanostar-specific literature, we utilize nanorod literature as a starting point to critically infer which analytical approaches can be seamlessly translated to nanostar systems, and which instead need to be adapted to intercept the peculiar needs imposed by the branched nanoparticle morphology.

The supramolecular interactions between graphene and biopolymers, such as chitosan, determine both whether nanostructured-hybrid materials are formed and their technologically relevant physical/chemical properties. However, there is still a fundamental lack of knowledge about how nanocomposites based on chitosan and graphene are formed, as well as their intrinsic structure and interaction with plasmonic nanoparticles. In this work, we provide an in-depth understanding of the supramolecular interactions between chitosan and graphene in the formation of graphene–chitosan nanocomposites with gold or silver nanoparticles. To do so, we employ a combination of Raman spectroscopy, Fourier-transformed infrared (FTIR) spectroscopy, atomic force microscopy (AFM), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) measurements with density functional theory (DFT) calculations to reveal the mechanism and driving forces behind these supramolecular interactions between graphene and chitosan. Specifically, we show they are based on a charge transfer process derived from the protonation of the amine groups of chitosan in acidic media. The understanding of the supramolecular interaction between graphene and chitosan that we provide herein should prove of great importance and interest to the material sciences and biomedical engineering fields.

We developed an unconventional seed-mediated in situ synthetic method, whereby gold nanostars are formed directly on the internal walls of microfluidic reactors. The dense plasmonic substrate coatings were grown in microfluidic channels with different geometries to elucidate the impacts of flow rate and profile on reagent consumption, product morphology, and density. Nanostar growth was found to occur in the flow-limited regime and our results highlight the possibility of creating shape gradients or incorporating multiple morphologies in the same microreactor, which is challenging to achieve with traditional self-assembly. The plasmonic-microfluidic platforms developed herein have implications for a broad range of applications, including cell culture/sorting, catalysis, sensing, and drug/gene delivery.

Plasmonic nanoparticles have been intensely used in research because they possess powerful optical properties. Gold nanorods (Au NRs), in particular, feature the interesting ability to absorb and scatter light in the near-infrared region through their longitudinal localized surface plasmon resonance. This property is particularly interesting in biology because these wavelengths are associated with maximum tissue penetration. The interplay between plasmonic nanoparticles and fluorophores has also triggered exciting research. Specifically, illuminating the Au NRs produces an enhanced electromagnetic field in the vicinity of the particles. This allows nearby fluorophores to feature enhanced optical properties through a phenomenon known as surface-enhanced fluorescence. This effect, however, must be counterbalanced by potential quenching that can happen from the Au NRs to the fluorophore. Systems have been developed whereby a spacer layer insulates the Au NR from the fluorophore. Multiple studies have explored different materials to use as the spacer layer such as silica or polyelectrolyte multilayers. Many of these studies have also investigated the optimal spacer thickness for achieving maximum enhancement. This review summarizes and provides an outlook on important developments in this field that have been reported in the last 10 years. [ABSTRACT FROM AUTHOR]

Nanoscale metal–organic frameworks (NMOFs) exhibit unique properties for drug delivery, including ultrahigh storage capabilities, biocompatibility, biodegradability, and sustained release of encapsulated cargo. However, due to their localized electronic states, MOFs are nonresponsive to external stimuli such as light or magnetic fields. This study investigates the integration of light‐responsive nanoantennas into NMOFs to enhance their application as smart drug delivery nanosystems. By integrating gold bipyramid nanoantennas within ZIF‐8 and NU‐1000 NMOFs, core@shell nanosystems are created with photothermal capabilities. Utilizing cresyl violet as a model drug, the loading and release dynamics of these nanosystems are analyzed, demonstrating controlled drug release under near‐infrared (NIR) light stimulation. Photothermal release studies conducted in living cells reveal the potential of these nanocomposites for spatiotemporal targeted, light‐activated drug delivery. Further evaluation of the NU‐1000 nanocomposite loaded with chemotherapeutics—doxorubicin, carboplatin, and oxaliplatin—in both 2D and 3D cell cultures shows the nanosystem effectiveness in cell internalization and therapeutic NIR activation. The findings demonstrate that the incorporation of stimuli‐responsive elements into NMOFs offers a promising approach for developing advanced drug delivery platforms. [ABSTRACT FROM AUTHOR]

By introducing a novel photothermal radiator that effectively harnesses diffused light through plasmonic Fe3O4@Cu2−xS nanoparticles, it is sought to offer a sustainable solution for maintaining comfortable indoor temperatures without heavy reliance on traditional solar sources. The approach involves the use of ultraviolet (UV) and infrared (IR) lights to photothermally activate transparent Fe3O4@Cu2−xS thin films, showcasing a proactive strategy to optimize energy capture even in low‐light scenarios such as cloudy days or nighttime hours. This innovative technology carries immense potential for energy‐neutral buildings, paving the way to reduce dependence on external energy grids and promoting a more sustainable future for indoor heating and comfort control. The developed photothermal radiator incorporates multiple transparent thin films infused with plasmonic Fe3O4@Cu2−xS nanoparticles, known for their robust UV and IR absorptions driven by localized surface plasmon resonance. Through the application of UV and IR lights, these thin films efficiently convert incident photons into thermal energy. The experiments within a specially constructed diffused light photothermal box, designed to simulate indoor environments, demonstrate the system's capability to raise temperatures above 50 °C effectively. This pioneering photothermal radiator offers a promising pathway for sustainable heat generation in indoor spaces, harnessing ubiquitous diffused light sources to enhance energy efficiency. [ABSTRACT FROM AUTHOR]

The luminescent nature of plasmonic nanoparticles (NPs) has been intensively investigated in recent years. Plasmon-enhanced electronic Raman scattering and the radiation channels of metallic photoluminescence (PL) involving conventional carrier recombinations and emergent particle plasmons are proposed in the past few decades but largely limited to weak excitation regimes. Here, we systematically examine the PL evolution of plasmonic NPs under different excitation power levels. The spectral resonances and chromaticity of PL are investigated within and beyond the scope of geometry conservation. Results indicate the nature of PL in plasmonic NPs could be a process of graybody radiation, including one factor of plasmonic emissivity in the weak excitation regime and the other factor of blackbody radiation in the strong excitation regime. This comprehensive analysis provides a fundamental understanding of the luminescent nature of plasmonic NPs and highlights their potential applications in transient temperature detection at the nanometer scale. [ABSTRACT FROM AUTHOR]

Cetyltrimethylammonium bromide (CTAB), a surfactant commonly used in the synthesis of gold nanorods (AuNR), presents challenges owing to cytotoxicity in biological applications, limiting their biomedical applicability, particularly in cancer therapy. This study introduces a straightforward methodology for the effective removal of CTAB by utilizing a combination of ligand replacement and surface bioconjugation processes that efficiently eliminates CTAB and simultaneously functionalizes nanorods with hyaluronic acid (HA) to enhance biocompatibility and introduce targeting capabilities toward cancer cells. The surface chemistry modification of CTAB-capped and CTAB-free AuNR, before and after the functionalization with HA, was scrutinized by UV–visible, surfaceenhanced Raman scattering (SERS), attenuated total reflectance (ATR) Fouriertransform infrared (FTIR), and X-ray photoelectron (XPS) spectroscopies. The surface charge, size, and morphology of the different plasmonic nanoparticles were characterized by zeta potential, dynamic light scattering (DLS), and transmission electron microscopy (TEM). The photothermal response was assessed by laser irradiation and thermal camera measurements. Proof-ofwork in vitro cellular experiments of cytotoxicity and oxidative stress were carried out on prostate cancer cells, PC-3, overexpressing the CD44 cell surface receptor specifically recognized by HA, in comparison with the CD44- negative murine fibroblasts (3T3 cell line) by MTT and MitoSOX assays, respectively. Cellular uptake and organelle alteration were scrutinized by confocal laser scanning microscopy (LSM), while the perturbative effects on cell migration were studied by optical microscopy (wound scratch assay). The study’s findings offer a promising pathway to tune the gold nanorod properties in cancer treatment by reducing cytotoxicity and enhancing targeted therapeutic efficacy, as well as in the control of scar tissue formation. [ABSTRACT FROM AUTHOR]

The limitations of conventional template‐based methods for the deposition of nanoparticle assemblies into defined patterns on solid substrates call for the development of techniques that do not require templates or lithographic masks. The use of optically‐induced thermal gradients to drive the migration of colloids toward or away from a laser spot, known as opto‐thermophoresis, has shown promise for the low‐power trapping and optical manipulation of a variety of colloidal species. However, the printing of colloids using this technique has so far not been established. Herein, a method for the optically directed printing of noble metal nanoparticles, specifically gold nanospheres is reported. The thermophoresis of the polymer polyvinylpyrrolidone and gold nanospheres toward a laser spot led to the deposition of nanoparticle aggregates, capable of serving as surface‐enhanced Raman scattering substrates. The influence of heating laser power and the concentrations of polymer, salt, and surfactant on the nanoparticle deposition rate and structure of the printed pattern are studied, showing that a variety of conditions can permit printing, suggesting facile generalization to different nanoparticle compositions, sizes, and shapes. These findings will greatly benefit future efforts for directed nanoparticle assembly, and drive applications in sensing, photothermal heating, and relevant applications in biomedicine and devices. [ABSTRACT FROM AUTHOR]

Recently, direct absorption solar collector (DASC) system has emerged a new class of solar collectors with much improved solar thermal conversion potential over conventional surface-based absorption solar collectors. Further, introducing noble metallic particles like Ag, Au, Al, TiN, or Cu (at nano ranges) in the working fluids enhanced the optical properties of the working fluid and hence the overall thermal performance of such DASC systems. However, these novel thermal systems are prone to high emissive and radiative losses at high-temperature ranges. Additionally, the nanoparticles used in the working fluid are expensive, toxic after use, complex to synthesize, and mostly non-biodegradable. In the present study, a medium-flux asymmetric compound parabolic concentrator (ACPC) based concentrating DASC system has been tested over clear sky days in the months of September and October, 2022 at the composite climate of Jalandhar (latitude 31.25 deg N, longitude 75.44 deg E), India. A hybrid heat transfer fluid is prepared using Azadirachta Indica leaves' extract and blended with gold plasmonic nanoparticles (Au nanoparticles of mean sizes ~ 40 nm, mass fraction ~ 4 ppm) to improve the overall thermal performance of the concentrating DASC system. Stored energy fraction of hybrid heat transfer fluid at a depth of 2 cm reached about 74.9%, which is about 67% higher than base fluid water. The outdoor experiments showed that hybrid heat transfer fluid had about 10.4 °C higher temperature gains in concentrating DASC system, and the photo-thermal efficiency was enhanced up to 40% as compared to base fluid water. The study demonstrates the advantage of an eco-friendly, low cost, and highly stable hybrid heat transfer fluid as a potential candidate for a medium-flux DASC system. [ABSTRACT FROM AUTHOR]

Throughout the central nervous system, the spinal cord plays a very important role, namely, transmitting sensory and motor information inwardly so that it can be processed by the brain. There are many different ways this structure can be damaged, such as through traumatic injury or surgery, such as scoliosis correction, for instance. Consequently, damage may be caused to the nervous system as a result of this. There is no doubt that optical devices such as microscopes and cameras can have a significant impact on research, diagnosis, and treatment planning for patients with spinal cord injuries (SCIs). Additionally, these technologies contribute a great deal to our understanding of these injuries, and they are also essential in enhancing the quality of life of individuals with spinal cord injuries. Through increasingly powerful, accurate, and minimally invasive technologies that have been developed over the last decade or so, several new optical devices have been introduced that are capable of improving the accuracy of SCI diagnosis and treatment and promoting a better quality of life after surgery. We aim in this paper to present a timely overview of the various research fields that have been conducted on optical devices that can be used to diagnose spinal cord injuries as well as to manage the associated health complications that affected individuals may experience. [ABSTRACT FROM AUTHOR]

Transition metal complexes, such as the low‐spin bis (phenylterpyridine) (A) and bis (pyridylterpyrazine)iron (II) (B) complexes, provide didactic chromophore species for demonstrating the Raman, resonance Raman, and the surface‐enhanced Raman scattering (SERS) behavior in coordination chemistry, as well as for elucidating the nature of inner‐sphere and outer‐sphere association with plasmonic nanoparticles. Their electrostatically stabilized ion pairs with citrate–gold nanoparticles have been studied in an aqueous solution, from the pronounced changes in the plasmonic band at 540 nm. Complex A, lacking any coordinating site, can only generate outer‐sphere complexes with citrate–gold nanoparticles, but they are stable enough to give a strong SERS response, even at 10−8 M. At 10−6 M, agglomeration accompanies the decrease of the electrostatic repulsion, resulting in a sharp decay of the plasmon resonance band at 540 nm. This is followed by the rise of a plasmon coupling band above 700 nm. However, at 10−4 M, the excess of the complex in the adsorption layer produces a reverse effect, decreasing agglomeration. The observed Raman spectra are essentially similar for the several concentrations employed because the outer‐sphere interaction implies a SERS electromagnetic mechanism. In contrast, complex B exhibits several pyridine and pyrazine N‐atoms available to form inner‐sphere‐associated species. A selective enhancement of the SERS signals is observed at 10−8 M, clearly indicating a chemical mechanism, consistent with a bridging mode. At 10−6 M and above, the agglomeration leads to a plasmon coupling band at 800 nm, while the SERS response indicates a change in the binding modes dictated by the excess of the complexing molecules. [ABSTRACT FROM AUTHOR]

Tailorable chiral plasmonic nanostructures have attracted great interest due to their potential applications in photonics and sensing. However, there are limited straightforward fabrication routes to modulate the morphology of chiral materials with an external stimulus. Here, a helical assembly of gold nanospheres (AuNSs) is successfully obtained via self‐assembly using glycopeptide helical nanofibers as templates based on electrostatic interactions. The assembly morphology can be readily tailored from short debris to single‐/double‐ and multiple helical threads by changing pHs, resulting in well‐controlled modulation of circular dichroism (CD) in the visible range. Further, this tunable assembly and corresponding chiroptical properties are fully reversible in the pH range from 6 to 10. The electromagnetic simulation revealed how the structural geometries of AuNS helices changed the electromagnetic field propagation pattern to facilitate corresponding chiral optical properties. This approach is a unique and facilely obtained example of chiral nanomaterials with in situ tailoring morphology and chiral properties through external stimulus, demonstrating a potential application for biosensing. [ABSTRACT FROM AUTHOR]

Planar light concentrators are potential applications for solar thermal conversion, in which the intensity of the electric field will exhibit strongly non-uniform characteristics. However, previous research has long ignored the solar absorption performance of plasmonic nanoparticles in the focused electric field. In this work, we use the finite element method (FEM) to study the optical behaviors of a single nanoparticle and multiple nanoparticles in the focused electric field formed by vertically and inwardly imposing the initial incident light on a quarter cylindrical surface. The results show that the focused electric field can significantly improve the solar absorption abilities compared with the parallel one for all the nanoparticles due to the local near-electric field enhancement caused by the aggregation of the free electrons on the smaller zone. Further studies on the focused electric field reveal that the plasmon heating behavior of Au spheres presents a rising trend with the decrease in inter-particle spacing, as the gap is less than the radius of Au spheres. As the number of nanoparticles increases along the focal line, the absorption power of the center nanoparticles gradually tends to be stable, and it is much lower than that of a single nanoparticle. As the nanoparticles are arranged along the y and z directions, the heterogeneity of the electric field makes the optical properties uneven. Notably, the strongest electric field appears slightly close to the incident surface rather than on the focal line. [ABSTRACT FROM AUTHOR]

Gold nanoclusters (Au NCs) have been attractive photosensitizers for many light-driven catalytic reactions due to their discrete electronic structure in the visible region. However, due to their ultrasmall sizes, they possess low stability; often, metal oxide and mesoporous supports are used to stabilize these nanoclusters. In this study, plasmonic Ag@SiO2 nanotriangle (NT) light antennas are used as supports, and the optical interactions between silver nanotriangles and Au NCs are comprehensively investigated. The Ag@SiO2–Au nanocomposite is synthesized by coating Au NCs on Ag@SiO2 using a branched polyethylenimine (BPEI) linker. Upon coating Au NCs on Ag@SiO2, the photoluminescence (PL) peak of Au NCs also blue-shifts while displaying faster decay in their excited state lifetimes, suggesting that the Ag NTs and Au NCs are optically coupled. To understand these interactions, different amounts of Ag@SiO2 NTs are added to Au NCs, and a decrease in the PL intensity of the Au NCs is observed. Using Stern–Volmer analyses, we reveal that this PL quenching is dynamic, and the energy from Au NCs is resonantly transferred to silver nanotriangles. Further, by employing Ag NTs with different surface plasmon resonance (SPR) peaks, we show that the shift in the Au NCs PL is dependent on the spectral overlap. By varying the SiO2 shell thickness from 7 to 31 nm and keeping the same degree of spectral overlap, we demonstrate that the PL quenching is distance dependent. The PL quenching in samples containing thick SiO2 (∼31 nm) reveals that the quenching occurs beyond the Förster resonance energy transfer (FRET) radius (∼20 nm) and suggests that the mechanism involves nanosurface/nanovolume energy transfer (NSET/NVET) that has been previously observed in hybrid plasmonic systems. These hybrid Ag@SiO2–Au nanocomposites have great potential for photocatalytic applications; therefore, a deeper understanding of energy transfer dynamics is critical for their growth in catalysis. [ABSTRACT FROM AUTHOR]

Plasmonic nanorods exhibit unique optical properties due to their ability to support localized surface plasmon resonances (LSPR). These nanorods are highly valued for applications in sensing, imaging, and medical therapies because of their tunable optical behavior and strong electromagnetic field enhancement. In this study, a seed-mediated approach was utilized to synthesize and purify gold nanorods (GNRs), with a focus on their integration in the LSPR sensor chips. The synthesis was begun with the preparation of small gold nanoparticles as seeds, followed by the growth of nanorods in a carefully controlled environment. UV-visible spectroscopy confirmed the formation of GNRs, revealing two plasmonic peaks, with the transverse peak at 523 nm and the longitudinal peak at 800 nm after 24 hours of aging. Further, the self-assembled monolayer of the GNRs on glass substrate achieved using a thiol-functionalized linker, 3-mercaptopropyltrimethoxysilane (MPTMS), and ionic strength modulation with NaCl. For optimal stabilization and alignment of the nanorods on the glass substrate, the ideal incubation time for the glass substrates in the colloidal gold nanoparticle solution was determined to be 24 hours. This duration was made the most effective configuration of the LSPR sensor chip, with improved stability and sensitivity for plasmonic applications. [ABSTRACT FROM AUTHOR]

Au trisoctahedrons (TOHs) with sharp tips and high-index facets have exceptional properties for diverse applications, such as plasmon-enhanced spectroscopies, catalysis, sensing, and biomedicine. However, the synthesis of Au TOHs remains challenging, and most reported synthetic methods are time-consuming or involve complex steps, hindering the exploration of their potential applications. Herein, we present a facile and fast approach to prepare Au TOHs with high uniformity and good control over the final size and shape, all within less than 10 min of synthesis, for surface-enhanced Raman spectroscopy (SERS) and refractive index sensing. The size of the Au TOHs can be easily tailored over a wide range, from 39 to 268 nm, allowing a tuning of the plasmon resonance at wavelengths from visible to near-infrared regions. The exposed facets of the Au TOHs can also be varied by controlling the growth temperatures. The wide tunability of size and exposed facets of Au TOHs can greatly broaden the range of their applications. We have also encapsulated Au TOHs with zeolite imidazolate framework (ZIF-8), obtaining core–shell hybrid structures. With the ability to tune Au TOH size, we further assessed their SERS performances in function of their size by detecting 2-NaT in solution, exhibiting enhancement factors of the order of 105 with higher values when the LSPR is blue-shifted from the laser excitation wavelength. Au TOHs have been also compared for refractive index sensing applications against Au nanospheres, revealing Au TOHs as better candidates. Overall, this facile and fast method for synthesizing Au TOHs with tunable size and exposed facets simplifies the path toward the exploration of properties and applications of this highly symmetrical and high-index nanostructure. [ABSTRACT FROM AUTHOR]

The global burden of colorectal cancer is significant and the limitations of conventional treatments like radiotherapy and chemotherapy require novel approaches to manage the colorectal neoplasia. This review explores the theranostic integration of quantum dots and plasmonic nanoparticles and its potential in overcoming the challenges of diagnosing and treating colorectal neoplasia. Quantum dots (QDs) facilitate fluorescence imaging and targeted delivery, enabling precise detection and localized therapy because of QD’s unique optoelectronic properties. Furthermore, their potential to improve targeted cancer cell destruction while protecting normal tissue can be observed in their utilization in photodynamic therapy. Plasmonic nanoparticles are a non-invasive approach to tumour ablation which induces a photothermal effect by leveraging localized surface plasmon resonance. A theranostic platform that incorporates QDs and plasmonic nanoparticles can provide simultaneous imaging and treatment capabilities, facilitating real-time monitoring of treatment response and improved therapeutic outcomes with minimized side effects. However, QDs and plasmonic nanoparticles have several challenges related to the nanoparticle design, biocompatibility and lack of clinical translation. By overcoming these challenges, the full potential of the theranostic integration can be realized. This review highlights opportunities for further study and development while underscoring the promising role of theranostic integration in transforming the therapy of colorectal neoplasia.

Cetyltrimethylammonium bromide (CTAB), a surfactant commonly used in the synthesis of gold nanorods (AuNR), presents challenges owing to cytotoxicity in biological applications, limiting their biomedical applicability, particularly in cancer therapy. This study introduces a straightforward methodology for the effective removal of CTAB by utilizing a combination of ligand replacement and surface bioconjugation processes that efficiently eliminates CTAB and simultaneously functionalizes nanorods with hyaluronic acid (HA) to enhance biocompatibility and introduce targeting capabilities toward cancer cells. The surface chemistry modification of CTAB-capped and CTAB-free AuNR, before and after the functionalization with HA, was scrutinized by UV–visible, surface-enhanced Raman scattering (SERS), attenuated total reflectance (ATR) Fourier-transform infrared (FTIR), and X-ray photoelectron (XPS) spectroscopies. The surface charge, size, and morphology of the different plasmonic nanoparticles were characterized by zeta potential, dynamic light scattering (DLS), and transmission electron microscopy (TEM). The photothermal response was assessed by laser irradiation and thermal camera measurements. Proof-of-work in vitro cellular experiments of cytotoxicity and oxidative stress were carried out on prostate cancer cells, PC-3, overexpressing the CD44 cell surface receptor specifically recognized by HA, in comparison with the CD44-negative murine fibroblasts (3T3 cell line) by MTT and MitoSOX assays, respectively. Cellular uptake and organelle alteration were scrutinized by confocal laser scanning microscopy (LSM), while the perturbative effects on cell migration were studied by optical microscopy (wound scratch assay). The study’s findings offer a promising pathway to tune the gold nanorod properties in cancer treatment by reducing cytotoxicity and enhancing targeted therapeutic efficacy, as well as in the control of scar tissue formation.

Secreted proteins mediate essential physiological processes. With conventional assays, it is challenging to map the spatial distribution of proteins secreted by single cells, to study cell-to-cell heterogeneity in secretion, or to detect proteins of low abundance or incipient secretion. Here, we introduce the "FluoroDOT assay," which uses an ultrabright nanoparticle plasmonic-fluor that enables high-resolution imaging of protein secretion. We find that plasmonic-fluors are 16,000-fold brighter, with nearly 30-fold higher signal-to-noise compared with conventional fluorescence labels. We demonstrate high-resolution imaging of different secreted cytokines in the single-plexed and spectrally multiplexed FluoroDOT assay that revealed cellular heterogeneity in secretion of multiple proteins simultaneously. Using diverse biochemical stimuli, including Mycobacterium tuberculosis infection, and a variety of immune cells such as macrophages, dendritic cells (DCs), and DC-T cell co-culture, we demonstrate that the assay is versatile, facile, and widely adaptable for enhancing biological understanding of spatial and temporal dynamics of single-cell secretome.

The ability of Plasmonic nanoparticles (PNPs) to efficiently convert absorbed light energy into localized heat has made them a popular choice for photothermal medical applications. However, during the photothermal process, the diffusion of localized heat can lead to temperature management challenges. To address this issue, researchers have developed a new generation of PNPs incorporating optical phase transition materials, allowing for tunable photothermal responses without altering the geometry. This tunability is achieved through rapid changes in optical and thermal properties during phase transitions. In this study, we conducted a numerical analysis on the photothermal response of a VO2@Au smart nanoshell in both tumor and healthy liver tissue under irradiation with a nanosecond (5 ns) pulsed laser. To obtain the temperature profile, we solved a coupling problem between electromagnetism and thermodynamics.

The constantly growing global demand for clean energy forces the development of technologiesproducing efficient and renewable energy sources. One direction of development is thin-film photovoltaicsystems that allow for the efficient conversion of solar energy to electrical or chemical energy andtheir usage in production of hydrogen, which is one of the most promising elements for storing greenenergy. The efficiency of photovoltaic systems is determined, among others factors, by properties ofa semiconductor in which light is absorbed and electron-hole pairs are generated. The efficiency ofthis process can be increased by using surface plasmon resonance induced on metallic nanoparticleslocated on the surface or inside the active material. Collective oscillations of the electron plasma excitedin the nanoparticle lead to trapping and enhancement of the electromagnetic field, which, resonantlyscattered to the active layer, increases the absorption in the cell. The selection of the material, size andshape of the nanoparticles allows spectral tuning of the absorption in the system. This study aims toimprove the efficiency of electrochemical cells with copper oxide electrodes by incorporating silvernanoparticles doped with palladium. The nanoparticles were prepared using physical vapour deposition.The fabricated structures were optically characterised by spectrophotometry and SE M microscopy.The conducted research demonstrates an increase in cell efficiency depending on the shape and sizeof the applied nanoparticles. The best results were obtained for systems subjected to post-depositionannealing, resulting in improved chemical stability and optical response of nanoparticles.Keywords: plasmonics, photoelectrochemical cells, plasmonic nanoparticles

Ultrafast laser processing possesses unique outlooks for the synthesis of novel nanoarchitectures and their further applications in the field of life science. It allows not only the formation of multi-element nanostructures with tuneable performance but also provides various non-invasive laser-stimulated modalities. In this work, we employed ultrafast laser processing for the manufacturing of silicon–gold nanocomposites (Si/Au NCs) with the Au mass fraction variable from 15% (0.5 min ablation time) to 79% (10 min) which increased their plasmonic efficiency by six times and narrowed the bandgap from 1.55 eV to 1.23 eV. These nanostructures demonstrated a considerable fs laser-stimulated hyperthermia with a Au-dependent heating efficiency (~10–20 °C). The prepared surfactant-free colloidal solutions showed good chemical stability with a decrease (i) of zeta (ξ) potential (from −46 mV to −30 mV) and (ii) of the hydrodynamic size of the nanoparticles (from 104 nm to 52 nm) due to the increase in the laser ablation time from 0.5 min to 10 min. The electrical conductivity of NCs revealed a minimum value (~1.53 µS/cm) at 2 min ablation time while their increasing concentration was saturated (~1012 NPs/mL) at 7 min ablation duration. The formed NCs demonstrated a polycrystalline Au nature regardless of the laser ablation time accompanied with the coexistence of oxidized Au and oxidized Si as well as gold silicide phases at a shorter laser ablation time (<1 min) and the formation of a pristine Au at a longer irradiation. Our findings demonstrate the merged employment of ultrafast laser processing for the design of multi-element NCs with tuneable properties reveal efficient composition-sensitive photo-thermal therapy modality. [ABSTRACT FROM AUTHOR]