Nanomaterials最新文献

Quantum dots combine advantages such as strong processability via solution methods, wide color gamut coverage, and precise emission color coordinates, making them highly promising for applications in optoelectronic devices. However, they face limitations such as insufficient fluorescence intensity and low far-field extraction efficiency. Plasmonic nanocavities based on metallic nanostructures offer an efficient platform for regulating light-matter interactions. In this study, we constructed a tilted plasmonic nanocavity structure composed of a silver nanocube, CdSe/CdS nanorods, and a single-crystal silver microplate. An Al₂O₃ isolation layer prepared via atomic layer deposition was used to control the nanocavity gap, precisely matching the plasmonic resonance mode with the 620 nm fluorescence emission of the quantum dots. This coupling system significantly enhances the radiative rate in the emission band and the electric field strength in the excitation band, achieving a 187-fold luminescence enhancement of the quantum dot. Additionally, leveraging the nano-antenna effect, the fluorescence exhibits upward directional emission. Experimental and simulation results confirm the high-efficiency enhancement and directional control of quantum dot fluorescence by the tilted nanocavity, providing new insights for the integrated application of quantum dots in displays, quantum communication, and other fields.

Photothermal therapy (PTT) is an emerging non-invasive treatment for cancer, offering targeted, localized therapy with minimal side effects. Its growing significance lies in its ability to precisely heat and destroy tumor cells while sparing surrounding healthy tissue. This study aimed to validate the δP1 approximation for simulating light propagation and thermal effects in biological tissues, particularly for photothermal therapy (PTT) applications. The model is applied to various scenarios, including homogeneous and heterogeneous tissue geometries with different optical properties and nanoparticle concentrations. The results are compared with analytical solutions, Monte Carlo results and experimental data to assess model accuracy. The δP1 approximation demonstrates superior performance compared to Beer-Lambert and Standard diffusion models, accurately predicting temperature distributions and capturing the influence of heterogeneous geometries. These findings highlight the potential of the δP1 model to significantly advance the field of PTT by providing reliable predictions for treatment planning and optimization.

The influence of a non-resonant intense laser field on the optical absorption and Raman scattering processes in ZnO/Mg_0.2Zn_0.8O quantum wells is theoretically investigated. It is shown that the dressing field significantly modifies the confinement potential and reshapes the electronic wave functions, leading to tunable shifts in intersubband transition energies and changes in the dipole matrix elements. These laser-induced effects produce notable variations in the absorption spectrum and strongly modulate the Raman differential cross section and Raman gain. Under the application of a non-resonant laser field, the Raman gain is enhanced by almost a factor of four, whereas off-resonant pumping results in much weaker, yet still field-dependent, responses. The results demonstrate that intense laser fields provide an effective tool to dynamically control the optical and Raman properties of ZnO-based quantum well structures.

Plasmonic nanostructures have been widely employed to improve upconversion luminescence performance; however, their impact on excitation pathways under multi-wavelength excitation is not yet fully understood. In this work, we constructed hybrid systems composed of gold nanorod arrays and NaYF₄:Yb³⁺/Ln³⁺ (Ln = Er³⁺, Tm³⁺) upconversion nanoparticles to systematically investigate upconversion behavior under dual-wavelength excitation at 808 and 976 nm. Contrary to the expected synergistic enhancement, our experimental results demonstrate that dual-wavelength excitation in the plasmonic hybrid structures produces different responses of upconversion emission. Measurements dependent on excitation power, along with the analysis of emission intensity ratio, indicate that plasmonic coupling under dual-wavelength excitation significantly enhances dissipative pathways that compete with upconversion processes. Notably, these effects strongly depend on the intrinsic energy-level structure of the lanthanide ions. In the Er³⁺-doped system, excitation at 808 nm facilitates population of higher-lying excited states, but the overall upconversion gain remains limited. In contrast, in the Tm³⁺-doped system, plasmonic coupling markedly amplifies stimulated emission and cross-relaxation processes, causing rapid depletion of high-energy state populations and substantial suppression of luminescence. These findings elucidate the competition between upconversion and dissipation processes governing plasmon-assisted upconversion under dual-wavelength excitation and provide a physical foundation for manipulating upconversion luminescence using multiple wavelengths.

The development of anisotropic gold nanostructures supporting localized surface plasmon (LSP) resonances in the near-infrared (NIR) biological window is of great interest for diagnostic and therapeutic nanotechnologies. Here, we report gold open-shell nanoparticles (AuOSNs), a symmetry-broken nanoshell architecture exhibiting strong NIR surface-enhanced Raman scattering (SERS) activity. AuOSNs were fabricated via a surfactant-free strategy combining bottom-up silica sphere assembly with a simple top-down gold deposition process, without using highly cytotoxic surfactants such as cetyltrimethylammonium bromide (CTAB). Boundary element method (BEM) simulations revealed that the asymmetric open-shell geometry induces NIR LSP resonances with pronounced electromagnetic field localization near the opening edges, depending on excitation configuration. Consistent with these predictions, extinction spectra of AuOSNs dispersed in water showed an LSP resonance peak at ~793 nm, close to the 785 nm excitation wavelength for SERS. In aqueous dispersion, AuOSNs modified with 4-mercaptobenzoic acid (4-MBA) exhibited strong SERS activity with enhancement factors of ~10⁶. Furthermore, polyethylene glycol (PEG)-modified MBA/AuOSNs showed negligible cytotoxicity in vitro. SERS imaging confirmed that PEG/MBA/AuOSNs enable visualization of HeLa cells via characteristic MBA SERS signals. These results demonstrate that surfactant-free AuOSNs provide a biocompatible platform for NIR-excited SERS sensing and cellular imaging, highlighting their potential in plasmonic bioimaging applications.

The rapid expansion of the coal chemical industry has led to a growing demand for effective treatment of high salinity wastewater, particularly the concentrated brine streams targeted for zero liquid discharge (ZLD) management. Conventional treatment technologies face significant challenges under such extreme conditions, underscoring the urgency of developing innovative and energy-efficient alternatives. Interfacial solar steam generation (ISSG) has emerged as a promising approach for concentrated brine treatment owing to its rapid evaporation rates, low carbon footprint, and high solar thermal energy utilization. Nevertheless, the long-term stability of solar evaporators remains limited by photothermal material degradation, excessive heat loss, and salt accumulation-all of which constitute major bottlenecks preventing large-scale implementation of ISSG in ZLD systems. This review first outlines the fundamental principles, advantages, and practical constraints of interfacial solar evaporation. It then highlights recent advances in high-performance solar evaporators featuring broadband light absorption, efficient solar thermal conversion, suppressed heat dissipation, robust anti-salt fouling behavior, and sustained operational durability. These emerging designs substantially improve the feasibility of ISSG and provide promising pathways for the clean, efficient, and sustainable treatment of concentrated brine in the coal chemical industry.

Multi-walled carbon nanotubes (MWCNTs) are increasingly incorporated into industrial and consumer products, raising concerns about potential carcinogenicity because their physicochemical properties vary widely among materials. Although Mitsui-7 has been classified as possibly carcinogenic to humans (IARC, Group 2B), the carcinogenic potential of domestically manufactured MWCNTs and the determinants underlying material-specific differences remain insufficiently characterized. Here, we applied an adverse outcome pathway (AOP)-oriented integrated testing strategy (ITS) to compare four domestically manufactured MWCNTs with Mitsui-7 using human bronchial epithelial BEAS-2B cells. Acute responses were assessed by measuring cytotoxicity and intracellular reactive oxygen species (ROS). Exposure concentrations for long-term studies were selected using range-finding assays, and cells were then exposed for four weeks at non-cytotoxic concentrations. Following chronic exposure, transformation-related phenotypes were evaluated using anchorage-independent growth, anchorage-dependent clonogenicity, wound healing migration, and Transwell-Matrigel invasion assays, and tumorigenic potential was examined in xenograft models using colony-derived cells. Highly aggregated MWCNTs elicited stronger oxidative stress and were associated with increased proliferation/clonal expansion, enhanced anchorage-independent colony formation, and increased tumor formation in vivo, whereas other materials showed more limited or endpoint-specific responses. Overall, the results indicate that MWCNT-associated carcinogenic potential is material-dependent rather than a uniform class effect and support the utility of an AOP-aligned ITS for nanosafety assessment and hazard differentiation of carbon-based nanomaterials.

Silver nanoparticles were biosynthesized using the culture supernatant of Staphylococcus sp. YRA, a strain isolated from Colombian mining sediments. Synthesis was optimized at 1 mM AgNO₃, pH 7, 40 °C and 7 μg/mL extract, producing spherical, protein-capped AgNPs with primary sizes in the tens-of-nanometers range (~35-90 nm by SEM), while DLS indicated larger hydrodynamic diameters (~250-320 nm) consistent with aggregation in suspension (ζ-potential -16.6 mV). These nanoparticles remained stable over 6 months. Characterization by UV-Vis, SEM, AFM, EDS and FTIR confirmed extracellular protein-mediated reduction and capping. The AgNPs showed antibacterial activity against multidrug-resistant clinical isolates (Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Salmonella bongori, Enterococcus spp.), with inhibition zones of 8-16 mm at 400-1000 μg/mL. Biofilm formation was reduced by >50% at 700 μg/mL in both Gram-positive and Gram-negative strains. In Phaseolus vulgaris (P. vulgaris), low concentrations (5-100 μg/mL) increased growth and chlorophyll content, while 500 μg/mL caused moderate inhibition. FTIR analysis identified amide and thiol groups from bacterial enzymes as capping agents. These results suggest Staphylococcus sp. YRA as a bacterial platform for AgNPs production with antibiofilm activity against MDR pathogens and acceptable phytotoxicity profile for potential applications.

The applications of nanofluids are widely beneficial in heat transmission and cooling systems. Nanofluid viscosity and thermal conductivity have a substantial effect on heat transfer applications and on devices such as solar and geothermal systems. Machine learning models enable faster, less expensive modeling of nanofluid thermophysical properties. These models are secure for future studies and in the development of nanotechnology. In this review, shape, size, temperature, and volume concentration are considered as inputs to develop several machine learning methods, such as artificial neural networks, support vector regression, decision trees, and random forests. These models were analyzed by comparing their R² values, and the results indicated that machine learning-based models generally exhibited more reliable performance than the other approaches. The observation in this review was that thermal conductivity increases with temperature and volume fractions, whereas viscosity decreases with size, temperature, and volume fractions. To determine the optimal nanoparticle type, size, and concentration for specific applications such as data center cooling and high-heat-flux electronics, future research may employ ML-based optimization techniques.

As a widely used catalyst class, transition metal oxides (TMOs) face the challenges of detrimental nanoparticle agglomeration. The newly developing two-dimensional (2D) covalent triazine frameworks (CTFs) offer a promising solution as catalyst supports, capable of yielding composites with excellent dispersibility and synergistic catalytic enhancement. Building on this, and employing a hydroxylation functional modification strategy, this article introduces a binary oxide system to construct a CTF/CuO-NiO composite that exhibits excellent catalytic performance for the thermal decomposition of ammonium perchlorate (AP). Specifically, polyvinyl alcohol (PVA) was first employed to introduce -OH anchoring sites onto the CTF surface. A subsequent co-precipitation yielded a uniform dispersion of CuO-NiO nanoparticles across the functionalized CTF support. DSC analysis revealed that incorporating merely 2 wt% of the CTF/CuO-NiO composite into AP significantly alters its high-temperature decomposition (HTD) peak temperature, shifting it from 404.6 °C to 332.1 °C. This work highlights the construction of a binary oxide system through an effective dispersion strategy to enhance the synergistic catalytic performance of CTF-based composites.