Search Results (5,528)

Titanium-based perovskites have garnered significant attention for photocatalytic applications, particularly in the field of environmental remediation through the degradation of synthetic dyes and pharmaceuticals in aqueous solutions. This review paper aims to explore the synthesis methods, crystal structures, photoactivity, and photocatalytic performance of titanium-based perovskites in degrading synthetic dye and pharmaceutical effluents in water. The unique advantages of titanium-based perovskites as photocatalysts, associated with their high redox potentials and excellent optical and electrical properties, are highlighted. Their limitations in visible light absorption and photocatalytic efficiency due to rapid charge carrier recombination are also discussed. Several strategies to overcome these limitations, such as surface modifications of the photocatalysts, metal and non-metal doping, the introduction of structure defects, the formation of heterojunctions with electron-accepting materials, and the deposition of plasmonic metal nanoparticles are systematically examined. This review also provides an overview of the photocatalytic degradation of dyes and pharmaceuticals as emerging contaminants, utilizing titanium-based perovskites as photocatalysts, to highlight their efficiency and potential for real-word applications. By covering research findings, current knowledge, and future perspectives, this review aims to stimulate advancements in the design and application of titanium-based perovskite photocatalysts. Full article

Background/Objectives: Silver nanoparticles (AgNPs) are highly valuable nanomaterials due to their unique optical and physicochemical properties. AgNPs have a lot of promise as contrast-enhancing and diagnostic agents in image-guided treatment. With a focus on their incorporation into image-guided and theranostic approaches, this narrative review attempts to assess the current function of AgNPs in imaging diagnostics. Methods: Using major scientific databases, such as PubMed, Web of Science, and Scopus, a narrative literature review has been conducted with an emphasis on recent preclinical and experimental research examining AgNP-based systems for diagnostic imaging applications. The design of the NPs, surface functionalization, imaging modality, and diagnostic performance of the evaluated studies were analyzed. Results: Due to their surface plasmon resonance and tunable physicochemical properties, AgNPs show great promise in a variety of imaging techniques, such as optical imaging, computed tomography (CT), and multimodal platforms, according to the reviewed literature. Functionalized AgNPs emerged as agents in image-guided therapy due to their improved target selectivity, enhanced imaging contrast, and signal amplification in tissues. Conclusions: AgNPs are appealing nanoscale platforms for image-guided methods and imaging diagnostics. Despite their encouraging preclinical results, some key issues, such as toxicity, biocompatibility, and clinical translation, remain critical. AgNP-based therapeutic and diagnostic systems will need to overcome these constraints in the future. Full article

A flexible paper-based surface-enhanced Raman scattering substrate with a hydrophobic surface was fabricated through a simple route. The Ag nanoparticle was modified on filter paper through the in situ growth method. The hydrophobic filter paper/Ag substrate was prepared via soaking in 10⁻⁸ g/mL of 1-dodecanethiol with a 12 h growth time. The hydrophobic filter paper/Ag substrate exhibits excellent flexibility and hydrophobic properties with a contact angle of 130.2°. The diffusion of the aqueous solution was significantly suppressed on the hydrophobic filter paper/Ag substrate. The hydrophobic filter paper/Ag substrate could simultaneously improve the SERS signal and fluorescence of the analyte, and that was successfully used for detecting thiram from edible oil with a limit of detection at 1.8 × 10⁻⁸ M and monitoring melamine in aqueous solution. The hydrophobic filter paper/Ag substrate is a flexible, economical, and convenient method for detecting harmful ingredients from oil by SERS. Full article

NS4A plays a role in forming the flavivirus replication complex, which inhibits apoptosis in host cells by inducing autophagy, thereby promoting viral replication. The host protein ENO1 interacts with NS4A, but the precise mechanism underlying this interaction and its role in viral replication remain unclear. In this study, we identified ZIKV NS4A^1–73 as a key regulator of replication and infection cycles in both temporal and spatial dimensions. Through surface plasmon resonance (SPR) analysis, we demonstrated that ENO1 directly interacts with NS4A^1–73. This critical binding inhibits the enzymatic activity of ENO1 and reduces cellular lactate and ATP production. Our findings suggest that ZIKV NS4A may effectively impede cellular metabolism by targeting the host factor ENO1, thus disrupting the glycolytic process. This insight could open new avenues for targeting ZIKV and similar viruses in therapeutic strategies. Full article

Biosensors have emerged as a rapidly evolving area of research, offering transformative potential across biomedical diagnostics, environmental monitoring, and pharmaceutical applications. Among the diverse range of biosensing technologies, graphene-based surface plasmonic resonance (SPR) biosensors have attracted particular interest due to their exceptional sensitivity, scalability for mass production, and cost-effective fabrication processes. This study explores the operational principles and current design methodologies of graphene-based SPR biosensors, with a special emphasis on the role of electrolyte gating and its impact on sensor performance. Furthermore, the influence of graphene’s quantum capacitance is investigated as a critical parameter for improving the accuracy and reliability of performance predictions in the proposed sensor configuration. Computational analysis of sensitivity and key performance metrics was conducted. Notably, key performance metrics of the sensor improved upon incorporating quantum capacitance effects into the simulation framework. At a β₂-microglobulin concentration of 0.00118 g/L, the sensitivity increased to 174 GHz·g/L, the figure of merit reached 0.55 L/g, the quality factor was 0.01, the signal-to-noise ratio (SNR) rose to 0.008, and the detection accuracy (DA) reached 0.08 L/THz, demonstrating the significant impact of quantum capacitance on the sensor’s performance. These findings highlight the potential of quantum-electrostatic considerations to enhance the precision and efficacy of graphene-based SPR biosensors, paving the way for the development of next-generation biosensing platforms with improved analytical capabilities. Unlike conventional graphene SPR biosensors, which primarily detect refractive index changes near the graphene surface, our model explicitly considers the electrostatic effect of biomolecules on graphene’s Fermi energy. By modelling β2-microglobulin as a charged species, we compute the resulting electric double layer and incorporate quantum capacitance in series. This amplifies the charge-induced modulation of graphene’s optical conductivity, and, combined with a graphene perfect absorber design, leads to enhanced plasmonic resonance shifts. Consequently, our approach achieves higher sensitivity and more precise detection of biomolecular interactions compared to traditional simulations. Full article

The development of reproducible and stable plasmon-free substrates for surface-enhanced Raman scattering (SERS) is critical for practical applications in analytical chemistry. Transition metal dichalcogenides (TMDCs) have emerged as promising candidates due to their unique electronic properties, yet their performance is often constrained by the chemical inertness of their pristine basal planes. This work presents a systematic comparison of crystalline flakes and nanoparticles of tungsten diselenide (WSe₂) and tungsten ditelluride (WTe₂), prepared via liquid-phase ultrasonic exfoliation and non-equilibrium femtosecond pulsed laser ablation in liquid (PLAL), respectively. The results demonstrate that nanoparticle-based substrates consistently outperform their flake-based counterparts, achieving enhancement factors in the range of ${10}^4$. The superior performance of the nanoparticles is hypothesized to originate from the synthesis-induced defects and high-curvature regions in the nanoparticles shell which facilitates efficient, defect-mediated charge transfer between the substrate and the analyte. At the same time, the inner polycrystalline volume conserves the important characteristics of the bulk counterparts like excitons in semiconducting WSe₂ and broadband absorption in semimetallic WTe₂, which unblocks the tunable photothermal colloidal response. The study establishes morphology engineering through non-equilibrium synthesis as a powerful and generalizable strategy for designing high-performance, dual-function colloidal platforms, offering a pathway toward robust and reproducible analytical systems. Full article

Biosensors have evolved significantly since their invention in the mid-twentieth century. From a simple electrochemical device to the current inclusion of AI, these sophisticated tools are capable of label-free, real-time multiplex detection. To make these sensing systems even more powerful, the incorporation of DNA origami has allowed this technology to become extremely precise, recognisable, and programmable to a range of molecules. This paper systematically summarises the incorporation of DNA origami with biosensors such as fluorescence, surface-enhanced Raman spectroscopy (SERS), surface plasmon resonance (SPR), and electrochemical sensors as well as approaches that are used to design DNA origami nanostructures. These tools allow a range of targets to be detected, ranging from small molecules to larger biological species. Collectively, these studies demonstrate that DNA origami-based biosensors provide high sensitivity; precise spatial control; and rapid, modular detection capabilities. Furthermore, their versatility enables applications across a diverse range of sectors. However, key challenges including limited reproducibility, structural instability, photobleaching, and non-specific binding continue to hinder their widespread adoption. This review proposes future directions aimed at overcoming key limitations, including enhancing biocompatibility and structural stability, to support the development of more advanced and clinical point-of-care-applicable biosensors. Full article

This study demonstrates how synthesis conditions and bacterial cellulose (BC) functionalization influence the physicochemical properties and antibacterial performance of BC membranes containing green-synthesized silver nanoparticles (AgNPs). Mint and avocado-seed extracts enabled AgNP formation in aqueous media but differed in composition. UV–Vis screening across pH and temperature revealed inefficient synthesis at acidic pH, whereas higher temperatures produced broader localized surface plasmon resonance (LSPR) bands. Neutral conditions generated the most intense and narrow LSPR signals. Under optimized conditions (pH 7, 23 °C), AgNPs were confirmed by TEM, and their colloidal properties differed between extracts: mint-derived particles exhibited smaller hydrodynamic diameters and lower polydispersity than avocado-derived AgNPs. Two BC functionalization strategies were evaluated: immersion in pre-formed AgNP dispersions and in situ synthesis within the BC matrix. In situ membranes displayed stronger and better-defined LSPR peaks. Agitation released nanoparticles from all BC-AgNP membranes, with smaller species released from in situ systems. Antibacterial assays against E. coli showed greater bactericidal activity for in situ membranes. Avocado-derived in situ BC-AgNPs produced larger inhibition halos and prevented bacterial regrowth in liquid culture. Overall, in situ green synthesis within BC provides an effective route to robust and sustainable antibacterial BC membranes. Full article

Self-powered photodetectors have attracted widespread attention in Internet of Things applications due to their low power consumption and high sensitivity. In this study, plasmonic self-powered poly(3-hexylthiophene)/zinc oxide (P3HT/ZnO) heterojunction photodetectors incorporating silver triangular nanoplates (AgTNPs) were fabricated using sol–gel and spin-coating techniques. The experimental results demonstrate that the incorporation of AgTNP nanostructures significantly enhances the photoelectric conversion efficiency of the plasmonic P3HT/AgTNPs/ZnO photodetectors across both the ultraviolet and visible spectral regions. The responsivity enhancement ratio of the plasmonic devices reached its maximum under illumination at a wavelength of 525 nm. Compared with the reference P3HT/ZnO device, the responsivity values of the P3HT/AgTNPs-1/ZnO and P3HT/AgTNPs-2/ZnO devices increased by factors of 3.24 and 4.21, respectively. The optimal P3HT/AgTNPs-2/ZnO device exhibited responsivity values of 9.49, 10.80, and 10.47 mA/W under irradiation at wavelengths of 440 nm, 460 nm, and 525 nm, respectively. The mechanism of performance enhancement induced by the plasmonic AgTNPs is also discussed. This work demonstrates that embedding triangular plasmonic metal nanoplates within semiconductor heterojunctions constitutes an effective strategy for performance enhancement, providing new insights for the rational design of high-performance optoelectronic devices. Full article

The temporal effects associated with surface plasmon polaritons (SPP) in a slab of conductive quantum material (metal, graphene, or semiconductor) are described as a quantum plasma. Exchange potentials associated with quantum degeneracy are included. We derive a new dispersion relation of SPP modes in a quantum plasma slab with finite size, which reduces to the previously known cases of a single plasma boundary and of a two-dimensional slab in the appropriate limits. A new SPP instability regime due to exchange quantum effects is demonstrated. The phenomenology of time refraction and time reflection is extended to SPP, and the frequency shifts and amplitude transformations due to a time boundary are derived. Finite time boundary effects and arbitrary temporal changes of the medium are also considered. Full article

Biotemplated strategies inspired by natural architecture have emerged as an effective strategy to improve the performance of photocatalytic materials. In this work, TiO₂-based photocatalysts were synthesized using olive leaves as a biological template to reproduce their hierarchical microstructure and enhance photocatalytic hydrogen production. The artificial olive leaf (AOL) support was obtained through a biotemplated ion-exchange process followed by hydrolysis and calcination. It was then modified by photodeposition of Au or Pt nanoparticles. The materials were characterized by SEM, XRD, N₂ adsorption–desorption, UV–Vis spectroscopy, and XPS to evaluate their structural and optical properties. SEM confirmed the successful replication of both the external morphology and internal architecture of the olive leaf, while XRD revealed low crystallinity with anatase as the only TiO₂ phase. Optical characterization showed a reduced band gap (~2.97 eV), and extended absorption toward the visible region, with Au nanoparticles exhibiting a plasmonic band at ~550 nm, whereas Pt enhanced light-harvesting efficiency. XPS indicated the presence of oxygen vacancies and Ti³⁺ species that promote metal–support interactions. Photocatalytic glycerol photoreforming showed a strong enhancement in hydrogen production after noble metal incorporation, reaching up to 14-fold under UV irradiation and 23-fold under simulated solar light for the Pt-modified catalyst, highlighting the synergy between biotemplated structuring and noble metal deposition. Full article

This study uses a bismuth ferrite (BiFeO₃) and MXene (Ti₃C₂Tx) to design a surface plasmon resonance (SPR) biosensor for the sensitivity enhancement at a 633 nm wavelength. Here, MXene serves as a biorecognition element (BRE) layer to ensure stable and reliable biomolecule adsorption. The MXene is a family of two-dimensional (2D) materials with metallic-like conductivity, a large surface area that can attach biomolecules, and improve biocompatibility. The addition of a conductive 2D MXene layer and a high-index BiFeO₃ dielectric layer greatly improves light–matter interaction and evanescent field penetration at the sensing interface. Strong plasmonic coupling is indicated by the reflectance analysis, which shows a distinct and consistent shift in the resonance angle as analyte RI increases. This study examined the sensitivity at optimized Ag and BiFeO₃ layer thickness. At an Ag of 39 nm and BiFeO₃ of 3 nm thickness, the maximal sensitivity of 340.68°/RIU with a remarkable figure of merit (FoM) of 47.38/RIU is obtained. The overall detection accuracy (DA) and FoM are significantly improved by the large sensitivity enhancement, despite a slight increase in full width at half maximum (FWHM). Furthermore, the penetration depth (PD) of 198.50 nm (at RI:1.330) and 199.52 nm (at RI:1.335) is attained with the proposed structure. Due to its high sensitivity, reusability, and reproducibility, the SPR biosensor has the potential to be used in biochemical, environmental, and medical detection. Full article

Accurate permittivity characterization at terahertz frequencies is important for material analysis and device design, yet it remains challenging for small-volume samples and compact test structures. In this work, a terahertz permittivity sensor based on a spoof surface plasmon polariton (SSPPs) transmission line coupled to a backside split-ring resonator (SRR) is proposed and numerically studied. The SSPPs line is patterned on the top side of the substrate, while the SRR is etched on the backside, with the sample loaded into the SRR gap. The SSPPs mode penetrates through the substrate and excites the SRR, producing a pronounced transmission notch. Changes in the sample permittivity modulate the effective capacitance of the resonator, resulting in a monotonic shift in the notch center frequency. For relative permittivities from 1 to 8, the notch center frequency decreases from 152.1 GHz to 117.8 GHz, corresponding to a total shift of 34.3 GHz and an average sensitivity of about 4.90 GHz/ε_r. The minimum S₂₁ remains within approximately −23.80 to −21.56 dB, while the Q-factor stays in the range of 94.33–108.23, indicating good spectral readability. Tolerance analysis further shows that the resonance frequency is sensitive to critical structural dimensions and layer alignment, and practical implementation is therefore more suitable for single-device calibrated frequency-shift sensing. These results demonstrate the feasibility of the proposed dual-layer SSPPs–SRR configuration for compact permittivity sensing in the terahertz regime. Full article

Structurally complex plasmonic nanoarchitectures represent an emerging class of nanomaterials with properties that extend beyond those of conventional spherical nanoparticles. Their distinctive structural motifs generate dense near field electromagnetic hot spots, expand interfacial surface area, and create biophysical environments at the nano–bio interface that can actively engage cellular signaling networks relevant to neural regeneration and aging. Despite growing interest in these platforms, a systematic, omics-guided synthesis that links nanoparticle structural features to transcriptomic programs and regenerative outcomes has been lacking. In this review, we summarize recent advances in high complexity plasmonic nanoparticle engineering and integrate published omics-based evidence of their cellular effects, organizing the discussion. Across these studies, transcriptomic analyses of nanoparticle treated neural systems consistently highlight three convergent biological themes: mitigation of oxidative stress and activation of antioxidant pathways, suppression of neuroinflammatory signaling, and induction of neuronal developmental and plasticity programs. Collectively, the omics-guided findings synthesized here suggest that structural complexity in plasmonic nanoarchitectures is not merely a synthetic achievement but a tunable determinant of cellular state, with important implications for the rational design of regenerative nanomedicines targeting neurodegenerative diseases and age-related neuronal decline. Full article

Detecting changes in the permittivities of materials has important applications in electronic information, materials science, biomedicine, and many other fields. However, existing detection methods are limited by factors such as sample thickness and resonance intensity, making it difficult to achieve sensitive dielectric constant detection at desired frequency bands. This paper proposes a method for detecting the dielectric constant changes in samples based on destructive interference of spoof surface plasmon polaritons (SSPPs) in a dual-path transmission structure, which forms a characteristic absorption peak at the SSPPs’ cutoff frequency. Specifically, by utilizing the dependence of the SSPPs’ phase on the periodic unit, a constant π phase difference is formed at the cutoff frequency through the periodic unit number difference between the two paths, resulting in a cutoff frequency absorption peak. When the sample is coated on the SSPPs’ dual-path structure, the boundary conditions are altered, leading to a cutoff frequency shift, thereby enabling dielectric constant detection at the specified frequency. Simulation results show that, with proper structural design, the normalized characteristic frequency shift reaches 10.8%/${\epsilon }_S$ and further demonstrates dramatic robustness against initial phase difference, sample thickness and sample loss. In summary, this work provides a novel high-precision and high-robustness method for detecting dielectric constant changes in samples at specified frequencies. Full article