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Silver-Gold Bimetallic Alloy versus Core-Shell Nanoparticles: Implications for Plasmonic Enhancement and Photothermal Applications
摘要： Bimetallic plasmonic nanoparticles enable tuning of the optical response and chemical stability by variation of the composition. The present numerical simulation study compares Ag-Au alloy, Ag@Au core-shell, and Au@Ag core-shell bimetallic plasmonic nanoparticles of both spherical and anisotropic (nanotriangle and nanorods) shapes. By studying both spherical and anisotropic (with LSPR in the near-infrared region) shapes, cases with and without interband transitions of Au can be decoupled. Explicit comparisons are facilitated by numerical models supported by careful validation and examination of optical constants of Au-Ag alloys reported in literature. Although both Au-Ag core-shell and alloy nanoparticles exhibit an intermediary optical response between that of pure Ag and Au nanoparticles, there are noticeable differences in the spectral characteristics. Also, the effect of the bimetallic constitution in anisotropic nanoparticles is starkly different from that in spherical nanoparticles due to the absence of Au interband transitions in the former case. In general, the improved chemical stability of Ag nanoparticles by incorporation of Au comes with a cost of reduction in plasmonic enhancement, also applicable to anisotropic nanoparticles with a weaker effect. A photothermal heat transfer study confirms that increased absorption by the incorporation of Au in spherical Ag nanoparticles also results in an increased steady state temperature. On the other hand, anisotropic nanoparticles are inherently better absorbers, hence better photothermal sources and their photothermal properties are apparently not strongly affected by the incorporation of one metal in the other. This study of the optical/spectral and photothermal characteristics of bimetallic Au-Ag alloy versus core-shell nanoparticles provides a detailed physical insight for the development of new taylor-made plasmonic nanostructures.
关键词： Localized Surface Plasmon Resonance (LSPR),Au@Ag core-shell,Ag-Au alloy,Ag@Au core-shell,Bimetallic plasmonic nanoparticles,Photothermal applications
更新于2025-09-23 15:21:01
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Benign prostatic hyperplasia treatment using plasmonic nanoparticles irradiated by laser in a rat model
摘要： Objective: In the current study we have stimulated the efficacy of plasmonic nanoparticles (NPs) by laser hyperthermia to achieve a less invasive method for tumor photothermal therapy of benign prostatic hyperplasia (BPH). Methods: The levels of apoptosis on induced BPH in rats were assessed after treatment and revealed and recorded by various assayed. Moreover, the expression of caspases was considered to demonstrate the apoptotic pathways due to laser induced plasmonic NPs. Results: In the Laser + NPs group prostate size of induced BPH decreased. Laser + NPs also decreased prostate specific antigen in comparison with the BPH groups. Furthermore, Laser + NPs attenuated BPH histopathologic indices in the rats. Laser + NPs induced apoptosis in prostatic epithelial cells via caspase-1 pathway. Conclusions: Altogether, the approach and findings from this study can be applied to introduce the laser irritated NPs method as a novel and less invasive therapy for patients suffering from BPH.
关键词： Photothermal therapy,Caspase,Laser,Benign prostatic hyperplasia,Apoptosis,Plasmonic nanoparticles
更新于2025-09-23 15:21:01
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Recent advances of plasmonic nanoparticle-based optical analysis in homogeneous solution and at the single-nanoparticle level
摘要： Plasmonic nanoparticles with special localized surface plasmon resonance (LSPR) characters have been widely applied for optical sensing of various targets. With the combination of single nanoparticle imaging techniques, dynamic information of reactions and biological processes is obtained, facilitating the deep understanding of their principle and design of outstanding nanomaterials. In this review, we summarize the recently adopted optical analysis of diverse analytes based on plasmonic nanoparticles in both homogeneous solution and single-nanoparticle level. A brief introduction of LSPR is first discussed. Colorimetric and fluorimetric homogeneous detection examples by using different sensing mechanisms and strategies are provided. Single plasmonic nanoparticle-based analysis is concluded in two aspects: visualization of chemical reactions and understanding of biological processes. The basic sensing mechanisms and performances of these systems are introduced. Finally, this review highlights the challenges and future trend of plasmonic nanoparticle-based optical analysis system.
关键词： Plasmonic nanoparticles,Single-nanoparticle level,Fluorimetric assays,Chemical reactions,Localized surface plasmon resonance (LSPR),Optical analysis,Homogeneous solution,Colorimetric assays,Biological processes
更新于2025-09-23 15:21:01
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Sensitive and Rapid Cancer Diagnosis with Immunoplasmonic Assay Based on Plasmonic Nanoparticles: Toward Fine-Needle Aspiration Cytology
摘要： Fine-needle aspiration cytology is a minimally invasive diagnostic strategy. However, collected specimens have to undergo a series of complex preparation steps, thus limiting the use of fine-needle aspiration cytology as a diagnostic approach for cytopathologists. In this study, we propose a cytology approach, easily adaptable to conventional one, by employing plasmonic biomarkers (gold(red_scattering), silver/gold(blue_scattering), and silver/gold(green_scattering) nanoparticles), each having a well-defined optical feature. Plasmonic nanoparticles, incubated with the suspension cells, are fully visible and differentiable on the cell membranes under the darkfield lateral RGB (Red-Green-Blue) side-illumination microscopy. The post-fabrication of plasmonic nanoparticles by the conjugation of a specific antibody (anti-human epidermal growth factor receptor 2: HER2) directly allows to visualize the selectively recognized antigens of the suspension cells (MDA-MB-453++HER2 and Jurkat-HER2) in co-cultures and individual cultures by using the side-illumination compared to the conventional dark-field visualization protocol. We also incubate two cancer cell lines (trypsinized MDA-MB-231++CD44 and MDA-MB-453++HER2) with anti-CD44 and anti-HER2 functionalized plasmonic nanoparticles, and nano-immunoplasmonic and immunofluorescence assays show a good agreement with each other for the recognition of expressed antigens (CD44 and HER2). Our results demonstrate a remarkable potential of plasmonic nanoparticles for a simple and rapid examination of small population of cells from collected specimens by using nano-immunoplasmonic approach and the side-illumination microscopy.
关键词： Fine-needle aspiration cytology,Plasmonic nanoparticles,Plasmonic biomarkers,Cancer diagnosis,Immunoplasmonic Assay,Side-illumination microscopy
更新于2025-09-23 15:19:57
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On the Role of Plasmonic Nanoparticles on the Photocatalytic of TiO <sub/>2</sub> Nanoparticles for Visible-Light Photoreduction of Bicarbonate
摘要： The potential application of anatase titanium dioxide (TiO2) nanoparticles for solar fuel generation has been recently attracting many attentions due to its excellent chemical stability. Nevertheless, the fast charge recombination during photoexcitation process may often reduce the photocatalytic activity. This work presents the role of plasmonic Au nanoparticles on enhancing the photocatalytic activity of TiO2 nanoparticles for a visible-light-driven conversion of bicarbonate to formate. Here, two types of nano-sized Au and TiO2 heterostructures, i.e., Au-TiO2 Janus nanostructures and core-shell Au@TiO2 nanostructures were successfully prepared and characterized using UV-Vis and HR-TEM. Results demonstrated that Au-TiO2 Janus nanostructures had a superior photocatalytic activity compared to TiO2 nanoparticles and core-shell Au@TiO2 nanostructures. This photocatalytic enhancement is believed due to the presence of surface plasmon resonance (SPR) phenomenon in Au nanoparticles that provides a Fermi energy level, which could prevent the charge recombination process during photoexcitation.
关键词： Visible-Light Photoreduction,Bicarbonate,Plasmonic Nanoparticles,Photocatalytic,TiO2 Nanoparticles
更新于2025-09-23 15:19:57
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Cellulose paper support with dual-layered nanoa??microstructures for enhanced plasmonic photothermal heating and solar vapor generation
摘要： Plasmonic nanoparticles, such as gold nanoparticles (AuNPs), have been actively applied in solar vapor generation for seawater desalination and water purification, owing to their photothermal heating performances. Such nanoparticles have been frequently anchored within porous supporting materials to ensure easy handling and water absorption. However, there has been limited progress in improving the transport efficiency of light to nanoparticles within porous supports to achieve more effective photothermal heating. Here, we show an enhanced light absorption of AuNPs by supporting on a cellulose paper with tailored porous structures for efficient photothermal heating. The paper consists of AuNP-anchored cellulose nanofibers and cellulose pulp as the top and bottom layers, respectively, which provides dual-layered porous nano-microstructures in the perpendicular direction. Then, the bottom layer with pulp-derived microstructures reflects the transmitted light back to AuNPs within the top layer, which improves their light absorptivity. Thus, under 1 sun illumination, the dual-layered paper demonstrates superior performance in photothermal heating (increases from 28 °C to 46 °C) and solar vapor generation (1.72 kg m?2 h?1) compared with the single-layered AuNP-anchored cellulose nanofiber paper even at the same AuNP content. Furthermore, the water evaporation rate per AuNP content of the dual-layered paper is more than 2 times higher than those of the state-of-the-art AuNP-anchored porous materials under the same light irradiation. This strategy enables the efficient use of precious plasmonic nanoparticles for further development of solar vapor generation.
关键词： gold nanoparticles,Plasmonic nanoparticles,cellulose paper,nano-microstructures,photothermal heating,solar vapor generation
更新于2025-09-23 15:19:57
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Tailored Engineering of Bimetallic Plasmonic Au@Ag Core@Shell Nanoparticles
摘要： A distinctive synthetic method for the efficient synthesis of multifunctional bimetallic plasmonic Au@Ag core@shell nanoparticles (NPs) with tunable size, morphology, and localized surface plasmon resonance (LSPR) using Triton X-100/hexanol-1/deionized water/cyclohexane-based water-in-oil (W/O) microemulsion (ME) is described. The W/O ME acted as a “true nanoreactor” for the synthesis of Au@Ag core@shell NPs by providing a confined and controlled environment and suppressing the nucleation, growth, agglomeration, and aggregation of the NPs. High-resolution transmission electron microscopic analysis of the synthesized Au@Ag core@shell NPs revealed an “unusual core@shell” contrast, and the selected area electron diffraction and Moiré patterns showed that Au layers are paralleled to Ag layers, thus indicating the formation of Au@Ag core@shell NPs. Interestingly, the UV?visible spectrum of the Au@Ag core@shell NPs exhibited enthralling plasmonic properties by introducing a high-frequency quadrupolar LSPR mode originated from the isolated Au@Ag NPs along with a low-frequency dipolar LSPR mode originated from the coupled Au@Ag NPs. The effective plasmonic enhancement of the Au@Ag core@shell NPs is attributed to the extreme enhancement of the localized electromagnetic field by coupling of the localized surface plasmons of the Au core and Ag shell. The mechanisms for the nucleation and growth of Au@Ag core@shell NPs in W/O ME have been proposed. A unique electron transfer phenomenon between the Au core and Ag shell is elucidated for better understanding and manipulation of the electronic properties, which evinced the development of Au@Ag core@shell NPs through suppression of the galvanic replacement reaction.
关键词： localized surface plasmon resonance,Au@Ag core@shell,bimetallic plasmonic nanoparticles,electron transfer phenomenon,water-in-oil microemulsion
更新于2025-09-23 15:19:57
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Thermoplasmonica??Activated Hydrogel Based Dynamic Light Attenuator
摘要： This work describes the morphological, optical, and thermo-optical properties of a temperature-sensitive hydrogel poly(N-isopropylacrylamide-co-N-isopropylmethacrylamide) [P(NIPAm-co-NIPMAm]) film containing a specific amount of gold nanorods (GNRs). The light-induced thermoplasmonic heating of GNRs is used to control the optical scattering of an initially transparent hydrogel film. A hydrated P(NIPAm-co-NIPMAm) film is optically clear at room temperature. When heated to temperatures over 37 °C via light irradiation with a resonant source (λ = 810 nm) to the GNRs, a reversible phase transition from a swollen hydrated state to a shrunken dehydrated state occurs. This phenomenon causes a drastic and reversible change in the optical transparency from a clear to an opaque state. A significant red shift (≈30 nm) of the longitudinal band can also be seen due to an increased average refractive index surrounding the GNRs. This change is in agreement with an ad hoc theoretical model which uses a modified Gans theory for ellipsoidal nanoparticles. Morphological analysis of the composite film shows the presence of well-isolated and randomly dispersed GNRs. Thermo-optical experiments demonstrate an all-optically controlled light attenuator (65% contrast ratio) which can be easily integrated in several modern optical applications such as smart windows and light-responsive optical attenuators.
关键词： gold nanorods,active plasmonics,optical attenuators,polymers,optical transparency,hydrogels,plasmonic nanoparticles
更新于2025-09-23 15:19:57
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Photothermal response of plasmonic nanofillers for membrane distillation
摘要： Light-to-heat conversion in plasmonic nanoparticles (NPs) inside polymeric membranes is beneficial for improving the efficiency of membrane distillation for seawater desalination. However, the physical mechanisms ruling photothermal membrane distillation are unclear yet. Here, we model the plasmonic photothermal light-to-heat conversion from Ag, Au, and Cu nanofillers in polymeric membranes for membrane distillation. Photothermal effects in the cases of isolated metallic NPs and their assembly are investigated considering size effects and excitation sources. The increasing content of metallic NPs improves the efficiency of the light-to-heat conversion. For a polymeric membrane, filled with 25% Ag NPs, our model well reproduces the experimental temperature increase of 10 K. Specifically, we find that Ag NPs with a radius of around 30–40 nm are favorite candidates for membrane heating with excitation energy in the visible/near-UV range. The incorporation of a term associated with heat losses into the heat transfer equation well reproduces the cooling effect associated with vaporization at the membrane surface. Compared to Ag NPs, Au and Cu NPs show a broadened absorption cross section and their resonance has a nonlinear behavior with varying the excitation energy, better matching with sunlight radiation spectrum.
关键词： photothermal conversion,membrane distillation,seawater desalination,plasmonic nanoparticles,light-to-heat conversion
更新于2025-09-23 15:19:57
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Visible Light CO2 Reduction to CH4 Using Hierarchical Yolk@shell TiO2-xHx Modified with Plasmonic Au-Pd Nanoparticles
摘要： Engineering of advanced semiconductor photocatalysts for CO2 conversion to solar fuels is a promising strategy to solve the greenhouse effect and energy crisis. Herein, hierarchical urchin-like yolk@shell TiO2-xHx decorated with core/shell Au-Pd plasmonic nanoparticles (HUY@S-TOH/AuPd) have been prepared using a multi-step process and employed as advanced visible light active photocatalyst in CO2 conversion to CH4 with rate of 47 μmol/gcat.h (up to 126 μmol/gcat after 7h). Different engineered sites in this structure for high gas adsorption, powerful visible light activation and intense electron transportation are responsible for the observed high photocatalytic CO2 conversion efficiency. The present smart designing process can produce a considerable cooperation, not only to disclose the architectural engineering to improvement of photo-conversion efficiency, but also as a viable and appropriate photocatalytic process to sustainable energy production.
关键词： nanoarchitecture,Plasmonic nanoparticles,Photocatalysis,CO2 Conversion,Oxygen vacancy
更新于2025-09-23 15:19:57