Search Results (333)

Gold nanoparticles (AuNPs) are of significant interest due to their unique properties and applications in biomedicine. While hyaluronic acid (HA) has been used to modify pre-formed AuNPs, its thiolated derivative (HA−SH) has been less explored for the direct synthesis and stabilization of AuNPs. This study investigates the use of thiolated hyaluronic acid as a key component in the synthesis of AuNPs. A series of HA-AuNPs (HA-AuNP1-4) were synthesized by reacting HA-SH with HAuCl₄ at different mass ratios. The resulting nanoparticles were characterized using UV-Vis spectroscopy, scanning/transmission electron microscopy (SEM/STEM), X-ray photoelectron spectroscopy (XPS), photon cross-correlation spectroscopy (PCCS), and zeta potential measurements. The chemical transformations of the thiol ligand were studied using NMR spectroscopy. The morphologies and sizes of AuNPs depended on the HA-SH-to-HAuCl₄ ratio, ranging from icosahedral and triangular particles (≥146 nm) to quasi-spherical particles with a bimodal distribution (6–7 nm and 45–60 nm). XPS confirmed the presence of metallic gold (Au⁰) and a Au−S bond, while NMR and XPS revealed the partial oxidation of thiol groups to sulfonic acid. Zeta potential measurements showed that lower HAuCl₄ concentrations resulted in higher negative charge (up to −41.5 mV), enhancing colloidal stability. This work demonstrates a versatile approach to the synthesis of hyaluronic acid-based gold nanomaterials with tunable properties for potential biomedical applications. Full article

Insufficient harvesting of visible photons, limited adsorption, and fast recombination of photogenerated electron-hole pairs restrict the application of graphitic carbon nitride (g-C₃N₄). Here, we propose a straightforward solid-phase synthesis method for fabricating 2D/2D graphitic carbon nitride/reduced graphene oxide (SCN/GR) hybrid photocatalysts. The synthesis process involves the thermal condensation of three precursors: dicyandiamide (as the g-C₃N₄ source), NH₄Cl (as a pore-forming agent), and graphene oxide (GO, which is in situ reduced to rGO during thermal treatment). The incorporation of reduced graphene oxide (rGO) into the g-C₃N₄ matrix not only narrows the bandgap of the material but also expedites the separation of photogenerated carriers. The photocatalytic activity of the SCN/GR hybrid was systematically evaluated by degrading ciprofloxacin in aqueous solution under different light conditions. The results demonstrated remarkable degradation efficiency: 72% removal within 1 h under full-spectrum light, 81% under UV light, and 52% under visible light. Notably, the introduction of rGO significantly improved the visible light absorption capacity of g-C₃N₄. Additionally, SCN/GR exhibits exceptional cyclic stability, maintaining its structural integrity and photocatalytic properties unchanged across five successive degradation cycles. This study offers a simple yet effective pathway to synthesize 2D/2D composite photocatalysts, which hold significant promise for practical applications in water treatment processes. Full article

The efficient degradation of antibiotics in pharmaceutical wastewater remains a critical challenge against environmental contaminants. Conventional photocatalysts face potential limitations such as narrow visible-light absorption, rapid carrier recombination, and reliance on precious metal cocatalysts. This review investigates the coordination structure of MXene as a cocatalyst to synergistically enhance photocatalytic antibiotic degradation efficiency and the coordination structure modification mechanisms. MXene’s tunable bandgap (0.92–1.75 eV), exceptional conductivity (100–20,000 S/cm), and abundant surface terminations (-O, -OH, -F) enable the construction of Schottky or Z-scheme heterojunctions with semiconductors (Cu₂O, TiO₂, g-C₃N₄), achieving 50–70% efficiency improvement compared to pristine semiconductors. The “electron sponge” effect of MXene suppresses electron-hole recombination by 3–5 times, while its surface functional groups dynamically optimize pollutant adsorption. Notably, MXene’s localized surface plasmon resonance extends light harvesting from visible (400–800 nm) to near-infrared regions (800–2000 nm), tripling photon utilization efficiency. Theoretical simulations demonstrate that d-orbital electronic configurations and terminal groups cooperatively regulate catalytic active sites at atomic scales. The MXene composites demonstrate remarkable environmental stability, maintaining over 90% degradation efficiency of antibiotic under high salinity (2 M NaCl) and broad pH range (4–10). Future research should prioritize green synthesis protocols and mechanistic investigations of interfacial dynamics in multicomponent wastewater systems to facilitate engineering applications. This work provides fundamental insights into designing MXene-based photocatalysts for sustainable water purification. Full article

Titanium (Ti)-based implants are widely used for bone injuries but suffer from poor bioactivity. To address this, we propose an innovative synergistic approach that combines laser melting deposition (LMD) for the fabrication of titanium-based supports with laser direct writing via two-photon polymerization (LDW via TPP) for their functionalization with 3D polymeric microstructures. We functionalized Ti surfaces fabricated by LMD using Ti (99.85 wt.%) and TiC powders (79.95 wt.% Ti, 20.05 wt.% C), with 3D microstructures obtained by LDW via TPP. The 3D microstructures were made of IP-Dip photopolymer and comprised 64 vertical microtubes arranged in five layers (10 to 170 μm tall, >94% porosity). When seeded with MG-63 osteoblast-like cells, the Ti-based surfaces functionalized with 3D polymeric microstructures promoted 3D cells’ spatial organization. Moreover, the cells seeded on functionalized Ti-based surfaces showed earlier organic matrix synthesis (day 7 vs. day 14) and mineralization (higher deposits of calcium and phosphorus, starting from day 7), as compared with the cells from non-functionalized Ti. In addition, the traction forces exerted by the cells on the 3D microstructures, determined using FEBio Studio software, were of the order of hundreds of µN, whereas if the cells would have been seeded on extracellular matrix-like materials, the traction forces would have been of only few nN. These results point towards the major role played by 3D polymeric microarchitectures in the interaction between osteoblast-like cells and Ti-based surfaces. Overall, the functionalization of Ti-based constructs fabricated by LMD with 3D polymeric microstructures made by LDW via TPP significantly improved Ti bioactivity. Full article

Developing detectors to enhance the timing resolution of positron emission tomography scanners can help reduce radioactive doses absorbed by patients and improve spatial resolution in medical imaging. Time resolution may be enhanced in heterostructures comprising a heavy scintillator for attenuation of 511 keV γ-quanta, as well as a fast scintillator converting recoiled electrons from the heavy scintillator to prompt light photons. In this study, ZnO films as fast scintillators with different thicknesses were obtained on substrates of a heavy bismuth germanate (Bi₄Ge₃O₁₂, BGO) scintillator using several film preparation techniques, such as spray-coating, drop-casting, and spin-coating. The design of heterostructures combined the key advantage of a low-cost film preparation technique with environmentally friendly and available precursors. This work proposes synthesis methods of highly nanocrystalline ZnO films on BGO, where a film thickness ranges from 6 to 18 μm. All ZnO studied films exhibit exciton luminescence peaked in UV (353 nm) and defect luminescence in the green (657 nm) range under 325 nm excitation. The best coincidence time resolution of 158 ± 8 ps was obtained with BGO@ZnO heterostructures fabricated by the spray-coating. The proposed approach allowed obtaining BGO@ZnO heterostructures for potential use as ultrafast scintillation detectors. Full article

Carbon dots (CDs) derived from renewable biomass are emerging as sustainable alternatives to traditional nanomaterials for applications in bioimaging, sensing, and photonics. In this study, we reported a one-step synthesis of photoluminescent CDs from Laurus nobilis leaves particularly spread in the Mediterranean area. The resulting nanoparticles (NPs) exhibited average diameters of 3–5 nm and high colloidal stability in water. Structural analysis by X-Rays Diffraction revealed the presence of amorphous graphitic domains, while infrared spectroscopy confirmed oxygenated functional groups on the CD surface. Spectrofluorimetric analysis showed excitation-dependent blue–green emission with a maximum at 490 nm that can be applied also as label agents for cells. The environmental sustainability of the synthetic procedure was evaluated through a Life Cycle Assessment (LCA), highlighting that the current impacts were primarily associated with electricity consumption, due to the laboratory-scale nature of the process. These impacts are expected to decrease significantly with future scale-up and process optimization. Full article

This study investigates the synthesis and characterization of boron-modified nanotubular titania (NTO) arrays fabricated via a single-step anodizing process with varying concentrations of boric acid (BA). Following anodization, a reductive heat treatment was applied to facilitate the crystallization of the anatase phase in the boron-modified NTO. The effect of the BA concentration on the structural, morphological, and photoelectrochemical (PEC) properties of the NTOs was systematically explored through scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), luminescence, and UV-Vis spectrometry. The introduction of boron during anodization facilitated the formation of sub-bandgap states, thereby enhancing the light absorption and electron mobility. This study revealed the optimal BA concentration that yielded a 3.3-fold enhancement of the PEC performance, attributed to a reduction in the bandgap energy. Notably, the highest incident photon-to-current conversion efficiency (IPCE) was observed for NTO samples anodized at a 0.10 M BA concentration. These findings underscore the promise of boron-modified NTOs for advanced photocatalytic applications, particularly in solar-driven water-splitting processes. Full article

Aqueous singlet oxygen (¹O₂) sensitization is of high interest due to its wide application in bio-imaging and photodynamic therapy. For organic photosensitizers like porphyrin derivatives, surfactant-assisted micelles have been intensively explored for dispersing hydrophobic sensitizers in aqueous phase; however, they can suffer from poor long-term stability. In this work, palladium octaethylporphyrin (PdOEP)-embedded silica particles were prepared with assistance from Tween micelles, and their corresponding application in aqueous ¹O₂ sensitization was explored. With assistance from Tween 80 at a >3 mg/mL concentration, superior (>95%) solubilization of PdOEP was observed in aqueous solution, leading to a high ¹O₂ quantum yield (Φ_Δ ≈ 93%). By optimizing the synthesis conditions, >95% of micellar PdOEP was embedded into silica particles, exhibiting comparable Φ_Δ (up to 70%) to micellar systems by effectively suppressing PdOEP aggregation in particles. The PdOEP-embedded silica particles exhibited dramatically enhanced long-term stability (more than one year) compared to corresponding micelles with a half-life of ~38 days. In addition, aqueous ¹O₂ sensitization by PdOEP-embedded silica particles was demonstrated upon two-photon excitation in a near-infrared regime (λ_ex = 1030 nm), highlighting the great potential of this method for future biological applications. Full article

Nanophotonics, the study of light–matter interactions at the nanometer scale, has emerged as a transformative field that bridges photonics and nanotechnology. Using engineered nanomaterials—including plasmonic metals, high-index dielectrics, two-dimensional (2D) materials, and hybrid systems—nanophotonics enables light manipulation beyond the diffraction limit, unlocking novel applications in sensing, imaging, and quantum technologies. This review provides a comprehensive overview of recent advances (post-2020) in nanophotonic materials, fabrication methods, and their cutting-edge applications. We first discuss the fundamental principles governing nanophotonic phenomena, such as localized surface plasmon resonances (LSPRs), Mie resonances, and exciton–polariton coupling, highlighting their roles in enhancing light–matter interactions. Next, we examine state-of-the-art fabrication techniques, including top-down (e.g., electron beam lithography and nanoimprinting) and bottom-up (e.g., chemical vapor deposition and colloidal synthesis) approaches, as well as hybrid strategies that combine scalability with nanoscale precision. We then explore emerging applications across diverse domains: quantum photonics (single-photon sources, entangled light generation), biosensing (ultrasensitive detection of viruses and biomarkers), nonlinear optics (high-harmonic generation and wave mixing), and integrated photonic circuits. Special attention is given to active and tunable nanophotonic systems, such as reconfigurable metasurfaces and hybrid graphene–dielectric devices. Despite rapid progress, challenges remain, including optical losses, thermal management, and scalable integration. We conclude by outlining future directions, such as machine learning-assisted design, programmable photonics, and quantum-enhanced sensing, and offering insights into the next generation of nanophotonic technologies. This review serves as a timely resource for researchers in photonics, materials science, and nanotechnology. Full article

The synthesis of Fe₃O₄ and ε-Fe₂O₃ nanoparticles (hereafter referred to as Fe₃O₄ NPs and ε-Fe₂O₃ NPs, respectively) was conducted in an eco-friendly manner using FeCl₃·6H₂O as the primary reactant. The experiment was conducted by subjecting the sample to an aqueous solution of FeCl₂·4H₂O at a temperature of 80 °C for a duration of 45 min, with the inclusion of apricot kernel shell extract (AKSE) as a natural reducing agent. The synthesized Fe₃O₄ NPs and ε-Fe₂O₃ NPs were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The optical properties of Fe₃O₄ NPs and ε-Fe₂O₃ NPs were examined, with the band gap energy estimated using the Kubelka–Munk formula. The results demonstrated a band gap of E_g (Fe₃O₄ NPs) = 2.59 eV and E_g (ε-Fe₂O₃ NPs) = 2.75 eV, thereby confirming their semiconductor behavior. The photoconductivity of Fe₃O₄ NPs and ε-Fe₂O₃ NPs was analyzed as a function of photon energy. For Fe₃O₄ NPs, photoconductivity exhibited an increase between 1.37 eV and 6.2 eV prior to reaching a state of stability. A comparable trend was observed for ε-Fe₂O₃ NPs, with an increase from 1.35 eV to 6.22 eV, followed by stabilization. Furthermore, the extinction coefficient (k) was determined. For Fe₃O₄ NPs, k ranged from 39 to a maximum of 300, while for ε-Fe₂O₃ NPs, it varied from 37 to a maximum of 280. A higher k value indicates strong light absorption, rendering these nanoparticles highly suitable for photothermal and sensing applications. Full article

Metal–organic frameworks (MOFs), particularly ZIF-8, have emerged as promising materials due to their high porosity, tunability, and chemical stability. In this study, we report the synthesis of ZnFe₂O₃-doped ZIF-8 composites with 10 wt% loading via a solvothermal method to enhance their optical and photocatalytic performance. Structural analyses confirmed the successful incorporation of ZnFe₂O₃ without disrupting the ZIF-8 framework. Optical studies revealed enhanced absorption in the visible range, a narrowed bandgap (4.26 eV vs. 4.37 eV for pristine ZIF-8), and an increased extinction coefficient, indicating superior light-harvesting potential. The photocatalytic activity was evaluated by methylene blue (MB) degradation under visible light, where the 10 wt% ZnFe₂O₃-ZIF-8 composite achieved 90% degradation efficiency, outperforming pristine ZIF-8 (67.8%). The catalyst also demonstrated excellent recyclability over five cycles and a proposed degradation mechanism involving ·OH and ·O₂⁻ radical formation. These findings demonstrate the potential of highly doped ZnFe₂O₃@ZIF-8 composites for environmental remediation and photonic applications. Full article

The mechanism for the upscale deposition of energy into the atmosphere from molecules and photons up to organized wind systems is examined. This analysis rests on the statistical multifractal analysis of airborne observations. The results show that the persistence of molecular velocity after collision in breaking the continuous translational symmetry of an equilibrated gas is causative. The symmetry breaking may be caused by excited photofragments with the associated persistence of molecular velocity after collision, interaction with condensed phase surfaces (solid or liquid), or, in a scaling environment, an adjacent scale having a different velocity and temperature. The relationship of these factors for the solution to the Navier–Stokes equation in an atmospheric context is considered. The scale invariant version of Gibbs free energy, carried by the most energetic molecules, enables the acceleration of organized flow (winds) from the smallest planetary scales by virtue of the nonlinearity of the mechanism, subject to dissipation by the more numerous average molecules maintaining an operational temperature via infrared radiation to the cold sink of space. The fastest moving molecules also affect the transfer of infrared radiation because their higher kinetic energy and the associated more-energetic collisions contribute more to the far wings of the spectral lines, where the collisional displacement from the central energy level gap is greatest and the lines are less self-absorbed. The relationship of events at these scales to macroscopic variables such as the thermal wind equation and its components will be considered in the Discussion section. An attempt is made to synthesize the mechanisms by which winds are generated and sustained, on all scales, by appealing to published works since 2003. This synthesis produces a view of the general circulation that includes thermodynamics and the defining role of turbulence in driving it. Full article

Dye-sensitized solar cells (DSSCs) are promising alternatives for power generation due to their environmental friendliness, cost effectiveness, and strong performance under diffused light. Conversely, their low spectral response in the ultraviolet (UV) region significantly obliterates their overall performance. The so-called luminescent down-shifting (LDS) presents a practical solution by converting high-energy UV photons into visible light that can be efficiently absorbed by sensitizer dyes. Herein, a conventional solid-state technique was applied for the synthesis of an LDS, europium (II)-doped barium orthosilicate (BaSiO₃:Eu²⁺) material. The material exhibited strong UV absorption, with prominent peaks near 400 nm and within the 200–300 nm range, despite a weaker response in the visible region. The estimated optical bandgap was 3.47 eV, making it well-suited for UV absorbers. Analysis of the energy transfer mechanism from the LDS material to the N719 dye sensitizer depicted a strong spectral overlap of $2\times {10}^{10}{\mathrm{M}}^{-1}{\mathrm{c}\mathrm{m}}^{-1}{\mathrm{n}\mathrm{m}}^4$, suggesting efficient energy transfer from the donor to the acceptor. The estimated Förster distance was approximately $6.83\mathrm{n}\mathrm{m}$, which matches the absorption profile of the dye-sensitizer. Our findings demonstrate the potential of BaSiO₃:Eu²⁺ as an effective LDS material for enhancing UV light absorption and improving DSSC performance through increased spectral utilization and reduced UV-induced degradation. Full article

The first chlorido platinum(II) complex with a cyclometallated 1,3-bis(pyridin-2-yl)benzene ligand, Pt(bpyb)Cl, was prepared in 1999. Four years later, its luminescent properties were discovered. Since then, a huge number of studies have been dedicated to the synthesis and characterization of related complexes, and to their application in photonics, optoelectronics, bioimaging, and photodynamic therapy. The present review concerns the main results obtained in the last five years by our research group in Milan. After a brief introduction on Pt(bpyb)Cl complexes, we illustrate our recent investigations to show the Milanese contribution to the rapid growth of this platinum family. Full article

Musculoskeletal (MSK) disorders remain a major global cause of disability, with diagnostic complexity arising from their heterogeneous presentation and multifactorial pathophysiology. Recent advances across imaging modalities, molecular biomarkers, artificial intelligence applications, and point-of-care technologies are fundamentally reshaping musculoskeletal diagnostics. This review offers a novel synthesis by unifying recent innovations across multiple diagnostic imaging modalities, such as CT, MRI, and ultrasound, with emerging biochemical, genetic, and digital technologies. While existing reviews typically focus on advances within a single modality or for specific MSK conditions, this paper integrates a broad spectrum of developments to highlight how use of multimodal diagnostic strategies in combination can improve disease detection, stratification, and clinical decision-making in real-world settings. Technological developments in imaging, including photon-counting detector computed tomography, quantitative magnetic resonance imaging, and four-dimensional computed tomography, have enhanced the ability to visualize structural and dynamic musculoskeletal abnormalities with greater precision. Molecular imaging and biochemical markers such as CTX-II (C-terminal cross-linked telopeptides of type II collagen) and PINP (procollagen type I N-propeptide) provide early, objective indicators of tissue degeneration and bone turnover, while genetic and epigenetic profiling can elucidate individual patterns of susceptibility. Point-of-care ultrasound and portable diagnostic devices have expanded real-time imaging and functional assessment capabilities across diverse clinical settings. Artificial intelligence and machine learning algorithms now automate image interpretation, predict clinical outcomes, and enhance clinical decision support, complementing conventional clinical evaluations. Wearable sensors and mobile health technologies extend continuous monitoring beyond traditional healthcare environments, generating real-world data critical for dynamic disease management. However, standardization of diagnostic protocols, rigorous validation of novel methodologies, and thoughtful integration of multimodal data remain essential for translating technological advances into improved patient outcomes. Despite these advances, several key limitations constrain widespread clinical adoption. Imaging modalities lack standardized acquisition protocols and reference values, making cross-site comparison and clinical interpretation difficult. AI-driven diagnostic tools often suffer from limited external validation and transparency (“black-box” models), impacting clinicians’ trust and hindering regulatory approval. Molecular markers like CTX-II and PINP, though promising, show variability due to diurnal fluctuations and comorbid conditions, complicating their use in routine monitoring. Integration of multimodal data, especially across imaging, omics, and wearable devices, remains technically and logistically complex, requiring robust data infrastructure and informatics expertise not yet widely available in MSK clinical practice. Furthermore, reimbursement models have not caught up with many of these innovations, limiting access in resource-constrained healthcare settings. As these fields converge, musculoskeletal diagnostics methods are poised to evolve into a more precise, personalized, and patient-centered discipline, driving meaningful improvements in musculoskeletal health worldwide. Full article