Search Results (608)

Multifunctional drugs represent an emerging strategy for treating complex skin disorders and melanoma. A series of benzothiazole-based hybrids incorporating gallic and syringic acid moieties was synthesized and evaluated as multifunctional agents for skin-related applications. Six hydrazone (GAHYDR1–3) and acyl-hydrazone (GACIN1–3) derivatives were obtained and fully characterized. Hydroxylated compounds showed the strongest antioxidant activity, with GAHYDR1 and GACIN1 displaying low DPPH IC₅₀ values and high FRAP reducing power. UV–Vis studies revealed strong UVA–UVB absorption, with molar extinction coefficients comparable to or exceeding those of PBSA. Photoprotective evaluation showed SPF values up to 10.09 (GACIN2) and broad-spectrum behavior for selected derivatives. Antioxidant activity remained substantially stable over 3 months in solution. Antiproliferative assays against Colo38, A375, and HaCaT cell lines indicated generally low cytotoxicity toward non-tumor cells. Notably, GAHYDR3 exhibited selective activity against A375 melanoma cells (IC₅₀ = 8.75 µM; SI = 8.12). Overall, phenolic substitution emerged as a key determinant of biological activity, highlighting hydroxylated benzothiazole hybrids as promising antioxidant and photoprotective agents, with GAHYDR3 representing a potential lead for anti-melanoma development. Full article

To reveal the varieties and color genesis of emerald-green tourmaline crystals from Tanzania, a systematic study was conducted using conventional gemological tests, X-ray diffraction, Fourier-transform infrared spectroscopy, polarized ultraviolet–visible spectroscopy (UV–vis), X-ray photoelectron spectroscopy (XPS), low-temperature photoluminescence (PL) spectroscopy, and electron probe microanalysis (EPMA). The results indicate that the tourmaline is dravite. Its UV–vis absorption spectrum shows strong broad absorption bands at approximately 436 and 600 nm, with a pronounced transmission at 520 nm, which directly accounts for its emerald green color. Obvious polarized absorption was observed along and perpendicular to the c-axis. XPS and PL results confirm that chromium is present in the samples in the form of Cr³⁺. EPMA compositional analysis indicated a low Cr₂O₃ content of 0.804 wt.%; combined with crystal structural properties and spectral responses, these results suggest that Cr³⁺ preferentially occupies the Y site in the crystal structure and that d–d electronic transitions represent the underlying mechanism of its color formation. This study comprehensively illustrated the mineralogical and spectral properties of Cr-bearing dravite, providing fundamental data for further research on its genesis and gemological application. Full article

Chicken bile-mediated silver nanoparticles (Ag-NPs) were synthesized and evaluated via UV–Vis, SEM, FTIR, and XRD. The synthesis of Ag-NPs was validated by observing a color change that was visible to the naked eye and via UV–Vis spectroscopy. A peak at 435 nm in the UV–Vis spectrum suggest the formation of Ag-NPs. The FTIR spectrum indicated that Ag⁺ reduction into Ag-NPs may occur due to proteins that are present in chicken bile. The XRD results showed that the nanoparticles were crystalline in nature, with a crystallite size of 25 nm. The SEM images showed that spherical-shaped nanoparticles with an average size of 20–60 nm were formed. The effects of different parameters, such as extract concentration, pH, and temperature, on the shape and reaction rate of Ag-NPs were examined. The results showed that the formation of Ag-NPs increased substantially in basic medium and they were found to be more stable at 60 °C. The prepared Ag-NPs were evaluated for their antibacterial activity and photocatalytic efficiency in degrading Disperse Orange 1 (DOI) dye. The antibacterial assessment of the synthesized Ag-NPs showed significant antibacterial activity. Based on the photodegradation study, it was found that the synthesized Ag-NPs showed high activity and almost complete (97%) degradation of DOI within the first 100 min. Thus, the overall results reveal that the prepared Ag-NPs offer a better approach for remediating the aforementioned contaminants. Full article

The Huanggangliang area in Inner Mongolia is a major fluorite and polymetallic ore district in China. Its skarn-type deposit yields rare color-change fluorite, yet the coloration and photochromic mechanisms remain poorly studied. Five faceted samples were characterized by conventional gemological tests, EDXRF, UV-Vis, Raman, PL, TL, and FTIR to determine their composition, spectral features, and defects. The results indicate two distinct color-forming mechanisms. Group I is dominated by f-f transitions of rare-earth elements with color-center synergy, showing a strong gray-blue to blue-violet color change and a characteristic absorption peak at ~580 nm in the UV-Vis spectrum. Group II is dominated by high-concentration irradiated color centers. Its deep blue-violet color and weak color change are attributed to colloidal induced by long-term endogenous α, β, and γ irradiation from radioactive Th. The lack of additional Raman peaks and a broad UV-Vis absorption peak at ~595 nm, along with multiple UV color-center peaks, weak fluorescence, and thermoluminescence, all confirm the presence of high-concentration electron traps. This study establishes the composition–spectrum–color relationship, reveals the control of ore-fluid evolution on mechanism differentiation, and provides a scientific basis for identifying and analyzing color-change fluorite. Full article

The rising incidence of viral infections demands the creation of innovative, biocompatible antiviral drugs with broad-spectrum effectiveness. This study combines the green synthesis, optimization, and characterization of silver nanoparticles (AgNPs) utilizing Dacryodes edulis (D. edulis) extract, assessing their antiviral, and antimicrobial characteristics. AgNPs were synthesized through the bio-reduction of silver nitrate with D. edulis water extract as a reducing, capping and stabilizing agent. The synthesis was refined through a Design of Experiments methodology. The characterization techniques, UV-Vis, Fourier-transform infrared, transmission electron microscopy, and dynamic light scattering, validated the successful synthesis of AgNPs with an average size of 101.56 ± 28.22 nm (TEM) and 156 ± 0.81 nm (DLS), a polydispersity index of 0.34, and a zeta potential of −22 mV. High-resolution liquid chromatography–tandem mass spectrometry analysis identified some bioactive compounds which enhance the antimicrobial and antiviral properties of the samples. Enzyme kinetics experiments revealed substantial inhibitory efficacy against the SARS-CoV-2 papain-like protease (PL-pro), with AgNPs exhibiting a lower IC₅₀ (0.271 ± 0.051 mg/mL) than the D. edulis extract (0.337 ± 0.043 mg/mL). The AgNPs exhibited MIC of 0.063 mg/mL for E. coli, 0.125 mg/mL for S. aureus and 0.08 mg/mL for S. pyrogens. The corresponding MBC values were 0.125 mg/mL, 0.25 mg/mL and 0.31 mg/mL, respectively. The fungal strains C. glabrata and C. albicans displayed MIC of 0.63 mg/mL and 0.31 mg/mL, respectively, and MBC values of 0.63 mg/mL and 0.31 mg/mL, respectively. This study underscores the potential of D. edulis-derived AgNPs as a cost-efficient, environmentally sustainable, and highly bioactive antibacterial and antiviral nanomaterial, facilitating the advancement of nanotechnology-based therapies for viral infections. Full article

Water pollution caused by antibiotics is a growing problem. Therefore, photodegradation by efficient catalysts is an environmentally friendly technology that can effectively degrade organic pollutants in water. In this work, a method was innovatively used to prepare a ternary heterostructure of plasmon-enhanced Ag-CuO/TiO₂. The composite was synthesized through a facile stepwise strategy involving the formation of CuO nanorods, TiO₂ coating, and subsequent deposition of Ag nanoparticles on their surface using AgNO₃, enabling intimate interfacial contact among the different components. The prepared samples were characterized by XRD, HRTEM, XPS, and UV-Vis. The chemical composition of the composite Ag-CuO/TiO₂ showed a Cu/Ti atomic ratio of 2.58, as well as a Ag/Cu ratio of 0.91. The UV-Vis spectrum reveals the largest absorption peak at 550 nm for the composite Ag-CuO/TiO₂. The prepared Ag-CuO/TiO₂ composites were applied to the visible-light degradation of tetracycline hydrochloride, with the photocatalytic degradation rate reaching 80.7% under the optimal conditions within 60 min, which is significantly better than CuO and CuO/TiO₂ without silver nanoparticles. Capture experiments indicated that h⁺ are involved during the course of the photodegradation and that h⁺ are the main active substances. Furthermore, the proposed mechanism for the photodegradation of the Ag-CuO/TiO₂ composites is given. It has potential applications in the treatment of organic pollutants in water. Full article

According to the National Cancer Institute, approximately 3.9 billion people worldwide suffer from non-communicable oral diseases, with head and neck cancer patients experiencing exacerbated oral mucositis primarily from radiotherapy. This condition manifests as painful, debilitating mucosal lesions, necessitating effective antimicrobial interventions. This study developed and characterized stable mouthwash formulations containing green-synthesized silver nanoparticles (AgNPs) derived from Baccharis trimera (carqueja) extract for the management of oral mucositis, evaluating their physicochemical stability, antimicrobial efficacy, and biosafety. AgNPs formation was confirmed by color change to brown and a surface plasmon resonance band at 407 nm (UV-Vis), with dynamic light scattering revealing a monomodal hydrodynamic diameter of ~25 nm and stable dispersion; scanning electron microscopy showed spherical particles of 25–35 nm. Four formulations (22–85 ppm AgNPs) in a commercial vehicle exhibited excellent stability over 60 days at 5 °C and 25 °C, maintaining near-neutral pH (~7), low surface tension (<5 mN/m), and unchanged spectral profiles, with no phase separation under centrifugation or thermal stress (up to 70 °C). Antimicrobial assays via broth microdilution demonstrated broad-spectrum activity for the 85 ppm formulation: MICs of 125 µg/mL (S. epidermidis, E. faecalis), 62.5 µg/mL (E. coli, P. aeruginosa), and 250 µg/mL (S. aureus), with MBC of 125 µg/mL (bactericidal) against P. aeruginosa; no activity against C. albicans (MIC > 500 µg/mL). Against human oral microbiota (n = 4 volunteers), it reduced bacterial growth by 14–156% relative to controls (e.g., −5% to 156% inhibition). Cytogenotoxicity tests (A. cepa) confirmed non-toxicity (mitotic index 79–93% of control, low cellular alteration index). These findings establish the carqueja-mediated instant green AgNPs mouthwash as a stable, potent antimicrobial agent, poised to mitigate mucositis-related infections and enhance the quality of life of cancer patients. Full article

Zinc–antimony–boro–germanate glasses highly doped with Sm₂O₃ were synthesized by the conventional melt-quenching method. Their structural, optical, and luminescent properties were systematically investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), diffuse reflectance UV–Vis (DR-UV–Vis), and photoluminescence (PL) spectroscopy. XRD analysis confirmed the amorphous nature of all prepared samples. XPS measurements were used to examine the surface chemical composition of the Sm₂O₃-doped glasses, with particular focus on verifying samarium incorporation and identifying its oxidation state after synthesis, since Sm ions act as the luminescent centers in these materials. For the sample containing the highest Sm₂O₃ concentration, the DR-UV–Vis spectrum exhibited ten absorption bands assigned to intra 4f electronic transitions. Based on these data, the nephelauxetic and bonding parameters were determined, indicating that increasing Sm₂O₃ content enhances the ionic character of the bonds within the glass network. PL spectra revealed three characteristic emission bands associated with Sm³⁺ luminescent centers. The emission intensity reached a maximum at 3 mol% Sm₂O₃, while further increases in samarium content led to luminescence quenching. The most intense emission band was in the yellow–orange region of the visible spectrum, highlighting the potential of these materials for yellow–orange-emitting solid-state laser applications. The excitation spectra show that the optical response is strongly dependent on concentration, with a sample doped with 3 mol% Sm₂O₃ exhibiting the highest excitation efficiency. The dominant excitation band centered near 402 nm, together with weaker bands in the blue region, indicating that these glasses are promising candidates for near-UV-pumped orange-emitting photonic devices. Full article

In response to the increasingly severe issue of heavy metal pollution in water, this paper proposes a method for the robust quantitative analysis of copper ions in purified water and real water samples based on the feature-level fusion of ultraviolet-visible absorption (UV-Vis) spectra and fluorescence spectra, combined with the Extreme Gradient Boosting (XGBoost) algorithm. Specifically, this study introduces a feature-level fusion strategy to overcome the limitations of single-spectrum detection, while the optimized XGBoost algorithm is employed to model the complex non-linear relationships that are difficult to capture using traditional linear regression methods. An optimization algorithm is introduced to fine-tune the model’s hyperparameters, thereby enhancing its predictive performance. Using the coefficient of determination (R²) and root mean square error (RMSE) as evaluation metrics, rapid and accurate detection of copper ions in water is achieved. Experimental results show that, for standard solutions, the optimized XGBoost model achieves a coefficient of determination of 0.9915 and a root mean square error of 2.6663 mg/L; for actual water samples, the optimized XGBoost model achieved a coefficient of determination of 0.9892 and RMSE of 1.2738 mg/L. This demonstrates the model’s strong generalization ability in overcoming the physical limitations of optical probes. This method effectively identifies and quantifies copper ions in water samples, demonstrating good accuracy and stability. Full article

While both Urbach tails and dangling bonds are known to be present in a-Si films, the current literature lacks parametrization that simultaneously accounts for both types of defects using only transmittance spectra, reflectance spectra, or spectroscopic ellipsometry. To address this issue, we performed parametrizations of three magnetron-sputtered a-Si thin films deposited on glass substrates at different low pressures of argon gas, using only their measured UV–Vis–NIR transmittance spectra T(λ = [300, 2500] nm) and different dispersion models. We preprocessed T(λ) by suppressing both general and bandpass noise to yield the spectrum T_d(λ). The films were parametrized from T_d(λ) using two versions of the Tauc–Lorentz–Urbach dispersion model and the universal dispersion model (UDM) of Franta. The most accurate parametrization was achieved employing UDM including Urbach tail and three subgap oscillators. JDOS and the dielectric function ε(E) were computed by this UDM, and it was concluded that these three oscillators correspond to electron transitions via two bands of dangling bonds. The respective DOS is similar to the DOS previously reported for a-Si:H, but not to a-Si, indicating a relatively low density of dangling bonds in our a-Si films. Record low parametrization errors are achieved, which confirms the accuracy of these results. Full article

In most amorphous materials, the concentration of Urbach tail states is larger than the concentration of dangling bond states. However, absorption accounting for the Urbach tail while disregarding the dangling bonds is commonly used or derived by spectroscopic characterizations of amorphous films from a single spectrum, mostly due to the insufficient accuracy of such characterizations. This paper proposes an advanced envelope method (AEM) for transmittance spectrum T(λ), aiming to resolve this problem. The novelties in AEM are: improved preprocessing of T(λ), extending the envelopes deeper into the region of strong absorption (RSA), enhanced determination of the refractive index n(λ) in the region of weak absorption, optimization of both n(λ) and the extinction coefficient k(λ) in RSA, as well as analysis of the types of electron transitions and calculation of their energy gaps. Three single magnetron sputtered a-Si films deposited on glass substrates are characterized by AEM, and three other relevant methods that disregard deep-levels. The best accuracy is achieved when these films are characterized by AEM. It is demonstrated that the absorption coefficient α(λ) of each of these films distinguishes electron transitions via dangling bond states from those via tails states, and the DOS corresponds to the Mott–Davis model of amorphous materials. Full article

Licania tomentosa leaf extract was used to synthesize zinc oxide nanoparticles (ZnO NPs) which were systematically analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Visible (UV-Vis) and Fourier transform infrared (FT-IR) spectroscopies and energy-dispersion X-ray spectroscopy (EDS) methods. Based on XRD scans, the green NPs have an average crystallite size of 15.9 nm as estimated using the Scherrer equation and have a roughly spherical shape with an average diameter of 25.15 ± 1.2 nm as calculated from SEM data. As estimated from the Tauc plot based on UV-Vis absorption spectra, ZnO NPs have a small band gap of 3.0 eV. The biosynthesized ZnO NPs were effectively utilized for the photodegradation of methylene blue (MB) and crystal violet (CV) dyes under UV illumination with resulting MB and CV degradation efficiencies of ~94% and ~81% after 60 min and 70 min, with pH = 12 and pH = 10, respectively. Different experimental parameters such as NPs quantity, experimental pH, light intensity and initial concentration of dyes were varied to test the performance of the catalyst. Furthermore, efficient recycling of the catalyst was demonstrated. We also undertook antimicrobial studies of the green ZnO NPs. The ZnO NPs demonstrated broad-spectrum antimicrobial efficacy against Escherichia coli ATCC 35218, Enterococcus faecalis ATCC 29737, Klebsiella pneumoniae ATCC 700603, Pseudomonas aeruginosa ATCC 27853, P. aeruginosa B3, Staphylococcus aureus ATCC 29213, and S. aureus SA01, with the minimum inhibitory concentration (MIC) and the inhibitory concentrations associated with 50% effect (IC50) values ranging from 250 to 2000 µg/mL and 7.74 to 283.14 µg/mL, respectively. The nanoparticles also significantly inhibited biofilm formation by E. faecalis ATCC 29737, P. aeruginosa ATCC 27856, and S. aureus SA03. The antimicrobial efficiency of the ZnO NPs against Escherichia coli ATCC 25922 and Staphylococcus aureus SA03 isolates was also assessed using the disk diffusion assays. Taken together, our results reveal that the biosynthesized ZnO NPs are promising multifunctional materials with potential applications in antimicrobial treatments, biofilm control, and photocatalytic remediation. Full article

Silver nanoparticles (AgNPs) are widely recognized for their potent antibacterial properties and diverse biomedical applications. While conventional synthesis methods typically rely on chemical-reducing agents that may pose risks to human health and the environment, this study proposes an eco-friendly green synthesis approach utilizing porcine skin extracts. The extracts were prepared through thermal treatment and filtration to serve as a biological reducing agent. Successful synthesis was validated using dynamic light scattering, Fourier transform infrared (FTIR) spectroscopy, UV–Vis spectroscopy, and scanning electron microscopy (SEM). Furthermore, the antimicrobial efficacy of the synthesized AgNPs was evaluated against multidrug-resistant microorganisms, demonstrating significant growth inhibition across various antibiotic-resistant strains. These findings suggest that porcine skin—a readily available bioresource—is a promising precursor for the sustainable production of AgNPs with broad-spectrum antimicrobial potential. Full article

Green synthesis is an eco-friendly, simple, and cost-effective process for the synthesis of metal nanoparticles from plant extracts that are rich in bioactive compounds. In the current study, the antioxidant potential and total soluble polyphenol content (TPC) of different parts of Ligusticum mutellina (L.) Crantz were evaluated using DPPH (2,2-diphenyl-1-picrylhydrazyl) and FRAP (ferric reducing antioxidant power) assays, and the results indicated that the seed extract was the most active plant part. HPLC analysis indicated the presence of phenolic compounds such as gallic acid, protocatechuic acid, and catechin, which may contribute to the reduction and stabilization of AgNPs. Silver nanoparticles (AgNPs) were synthesized from the aqueous seed extract of L. mutellina. The formation of nanoparticles was confirmed by UV–Vis spectroscopy, FT-IR analysis, powder X-ray diffraction (PXRD), and transmission electron microscopy (TEM). The UV–Vis spectrum indicated a surface plasmon resonance peak at around 411 nm, and PXRD analysis indicated an average crystallite size of around 13 nm. TEM analysis revealed predominantly spherical nanoparticles with an average size of 25.36 ± 10.76 nm. The synthesized AgNPs exhibited strong antibacterial activity against Gram-positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria. Overall, the results demonstrate that L. mutellina seed extract represents an effective natural source of reducing and stabilizing agents for green nanoparticle synthesis and highlight the potential of the obtained AgNPs as environmentally friendly antimicrobial materials. Full article

Fluoroquinolones (FQLs) are synthetic derivatives of the quinolone class, originally developed from the nalidixic acid scaffold. FQLs are widely used in human and animal medicine due to their broad spectrum of activity against Gram-positive and Gram-negative bacteria. Their strong bactericidal properties result from the inhibition of bacterial DNA transcription and replication. However, inappropriate use of these antibiotics often leads to toxic side effects, environmental pollution, and the development of antibiotic resistance in bacteria. Recently, numerous methods for determination of FQLs in various matrices have been developed using separation techniques such as high-performance liquid chromatography and capillary electrophoresis. In recent years, analytical procedures have employed a range of detection methods, including UV–Vis spectrophotometry, electrochemiluminescence, mass spectrometry, and fluorescence. Most of these procedures involve some form of extraction during the sample preparation step. This report summarizes the development of FQL determination methods over the last five years and may assist in selecting an appropriate procedure for a given sample matrix. Full article