Search Results (455)

Green synthesis of metal oxide nanoparticles (NPs) offers an eco-friendly, cost-effective alternative to conventional chemical and physical methods, minimizing energy use and hazardous reagents. This study demonstrates the biogenic production of manganese oxide (MnO) NPs using Catharanthus roseus flower extract as a reducing and capping agent, Comprehensive characterization via FTIR (Mn–O vibrations at 591–405 cm⁻¹ along the capping groups), XRD (confirms the cubic crystalline phase), FESEM (flaky, agglomerated sheets), EDX (Mn 62.37%, O 28.40% and C 9.23%), zeta potential (−0.3 mV), and TGA (33.7% phased mass loss to 985 °C) verified pure and stable MnO NPs. In vitro assays on L929 fibroblasts revealed dose-dependent MTT cytotoxicity (78.77% viability at 20 µg/mL to 39.97% at 100 µg/mL) yet enhanced scratch wound closure (−16.31% area reduction vs. −17.41% control), alongside potent antibacterial activity with highest inhibition zones of 15 mm against Klebsiella pneumoniae and Escherichia coli, and lowest of 4 mm against Pseudomonas aeruginosa at 40–100 µg/mL. These multifaceted properties highlight C. roseus-assisted MnO NPs’ promise for wound healing and antimicrobial applications, warranting dosage optimization and in vivo studies. Full article

The objective of this study is to develop a nanosized, visible-light-responsive photocatalyst with magnetic separability and recyclability for repeated use. Spinel ferrite nanoparticles, which are environmentally friendly, are promising candidates for achieving this goal. Spinel ferrite nanoparticles were synthesized via a low-temperature hydrothermal method to investigate their microstructural characteristics, magnetic properties, and photocatalytic performance. Initially, four ternary spinel ferrite (MFe₂O₄, where M = Mg, Mn, Co, and Zn) nanoparticles were compared in terms of their physical properties and photodegradation efficiencies of organic dye methylene blue (MB). Among them, the MgFe₂O₄ and ZnFe₂O₄ samples exhibited superior photocatalytic activity compared to the MnFe₂O₄ and CoFe₂O₄ samples. Subsequently, a systematic investigation of the Zn–Mg ferrite system (Zn_1−xMg_xFe₂O₄, x = 0 to 0.8 in increments of 0.2) was carried out. The results revealed that the x = 0.8 samples achieved the highest photodegradation efficiency of 99 for a 10 MB aqueous solution under visible-light irradiation for 90 min. This improved performance is attributed to formation of a heterojunction of Zn–Mg nanoferrite/Fe₂O₃, which promotes light harvesting and prevents photogenerated charge recommendation, thus significantly improving photocatalytic activity. Full article

Chronic wounds, particularly those complicated by infection, present significant challenges in clinical management. The microenvironment of these wounds is typically characterized by the accumulation of reactive oxygen species (ROS) and abnormal local pH levels, both of which impede the healing process. Baicalin (BA), a natural flavonoid, exhibits anti-inflammatory activity, ROS-scavenging capability, and pro-healing effects. In this study, hydrogels were synthesized through photoinitiated radical polymerization of methacrylic anhydride (MAA) and dopamine (DA)-modified chondroitin sulfate (ChSMA-DA), grafting degrees of MA and DA were 58%, 23%, MPDA@MnO₂ nanoparticles (NPs), and methacrylated gelatin (GelMA). The gelation time, microtopography, swelling behavior, and water retention of the hydrogels were investigated, along with their degradation, rheological properties, and photothermal effects. The results indicate that swelling ratio (SR) and water retention (WR) of optimal HG-MPDA@MnO₂-M sample were 5.7, 82.42%, exhibited responsive behavior upon weakly acidic environment with pH 6.5 and elevated ROS levels, and exhibited a stable photothermal effect (photothermal conversion efficiency was 22.7%) under 808 nm near-infrared (NIR) light. Following the incorporation of the drug model BA, the cumulative release percentage over 24 h under the combined stimulation of pH 6.5, 1 mmol·L⁻¹ H₂O₂, and 808 nm NIR was 81.1%, significantly higher than either factor alone. These hydrogels show promise as an injectable dressing for chronic wounds, effectively integrating the internal microenvironment of the wound tissue with external NIR to modulate drug release. Full article

Background/Objectives: Photodynamic therapy (PDT) is severely limited by the hypoxic tumor microenvironment, which restricts reactive oxygen species (ROS) generation and compromises therapeutic efficacy. To address this critical barrier, we engineered a multifunctional nanocomposite (Pha@FSMP) integrating oxygen supplementation, pH-responsive drug release, and magnetic targeting for enhanced PDT. Methods: The platform is constructed with a superparamagnetic Fe₃O₄ core, coated in amino-functionalized mesoporous silica (mSiO₂) loaded with MnO₂ as an oxygen-evolving catalyst, and surface-conjugated with the pH-responsive copolymer PEG-b-PAsp to encapsulate the hydrophobic photosensitizer Pha. We characterized its core physicochemical and functional properties, and evaluated its photodynamic efficacy via in vitro cellular assays and in vivo studies in a murine melanoma model. Results: In vitro assays demonstrated significant elevation of intracellular ROS levels and enhanced PDT-mediated cytotoxicity against B16-F10 melanoma cells. In vivo studies in a murine melanoma model confirmed potent tumor growth inhibition, metastasis suppression, and prolonged survival, accompanied by excellent biosafety. Conclusions: Collectively, this oxygen-augmented nanocomposite represents a promising strategy to overcome hypoxia-associated PDT resistance, offering a translatable platform for improved cancer therapy. Full article

A sustainable strategy was developed to valorize rabbit manure waste by synthesizing a porous quaternary Ni-Co-Zn-Fe layered double hydroxide/biochar nanocomposite (QL-RMB) for the efficient removal of Mn(VII) in the form of permanganate (MnO₄⁻) from aqueous solutions. The QL-RMB adsorbent exhibited a well-developed mesoporous structure with uniformly dispersed nanoparticles, achieving 73% MnO₄⁻ removal within 60 min under optimized conditions (pH 3.0; dosage 0.5 g L⁻¹). Adsorption followed pseudo-second-order kinetics and was best described by the Freundlich isotherm model (R² > 0.98), yielding a maximum Langmuir adsorption capacity (q_max) of 45.13 mg g⁻¹. Statistical physics modeling confirmed a multi-ionic, vertically oriented adsorption configuration, while thermodynamic analysis demonstrated that the process was spontaneous and exothermic, governed by electrostatic attraction, anion exchange, and surface complexation. The QL-RMB composite exhibited excellent MnO₄⁻ selectivity in the presence of competing ions (selectivity coefficients: 24.96 for Fe³⁺, 31.59 for Ni²⁺, 23.56 for Zn²⁺) and retained significant removal efficiency (73.96%) after five regeneration cycles. In a circular economy approach, the Mn (VII)-spent adsorbent (QL-RMB/Mn) was valorized as an electrocatalyst for urea electro-oxidation, achieving a current density of ~127.19 mA cm⁻² for pristine QL-RMB, which increased to ~217.07 mA cm⁻² after Mn(VII) adsorption (QL-RMB/Mn) in 1 M KOH/1 M urea. Batch scale-up studies revealed an efficiency of 42.55 g or 95% MnO₄⁻ removal from 50 L water, with a low estimated production cost of 0.0602 USD g⁻¹. Environmental sustainability was confirmed by the National Environmental Methods Index (NEMI), modified Green Analytical Procedure Index (Mo-GAPI), Eco-scale (score: 77), and Analytical GREEness (AGREE) assessment frameworks. Full article

Manganese (Mn) is an essential trace element crucial for antioxidant defense, metabolism, and neuronal function, yet both deficiency and excess may induce oxidative stress and organ-specific damage. This study investigated the effects of dietary manganese exclusion and replacement of standard MnCO₃ with Mn₂O₃ nanoparticles on redox status and oxidative damage in rats. Twenty-four male Wistar rats were divided into three groups: control (K) receiving 65 mg/kg Mn as MnCO₃, manganese-deficient (B), and nanoparticle-supplemented (N) receiving 65 mg/kg Mn as Mn₂O₃ nanoparticles. After 12 weeks, tissues were analyzed for oxidative stress markers and antioxidant enzyme activities. Manganese deficiency resulted in decreased plasma SOD activity, increased lipid peroxidation, and severe oxidative–nitrosative damage in the brain and jejunum, despite hepatic compensatory mechanisms. Mn₂O₃ nanoparticle supplementation enhanced hepatic and renal antioxidant capacity, reducing oxidative damage in these organs. However, nanoparticles induced pronounced neurotoxicity, characterized by GSH depletion, elevated DNA damage (8-OHdG), protein nitration (3-NT), and caspase activation in brain tissue. These findings demonstrate that while Mn₂O₃ nanoparticles offer improved bioavailability and hepatorenal benefits, they pose significant neurotoxic risks, necessitating caution in dietary supplementation strategies. Full article

Graphene-based composite materials have attracted much attention for a range of applications in various fields, including electronics, sensing, catalysis, energy storage and conversion. Single-step large-scale microwave plasma synthesis of graphene and nitrogen-doped graphene (N-graphene) composite materials has been demonstrated. The developed atmospheric pressure plasma method allows continuous synthesis of different graphene-based hybrids in a controllable and environmentally friendly manner. Control over the synthesis process, i.e., size, uniformity, surface distribution of the nanoparticles and graphene/N-graphene quality, was provided by adjusting plasma parameters and injection configuration. Protocols for the production of particular composites, i.e., graphene-MnO, N-graphene-MnO, N-graphene-MnS, and N-graphene-Fe_xO_y, have been established using methane and acetonitrile as precursors. A comprehensive physicochemical characterization of the produced composites was conducted using high-resolution transmission electron microscopy, scanning transmission electron microscopy, Raman spectroscopy, X-ray diffraction, and near-edge X-ray-absorption fine-structure and X-ray photoelectron spectroscopies. Full article

Treatment of postsurgical osteosarcoma remains one of the major challenges in orthopedic clinics. Conventional implants often fail to address complex pathological issues, including irregular bone defects, residual tumor cells, and delayed bone regeneration. Herein, this study reports a multifunctional shape-memory polyurethane (SMPU)/manganese dioxide (MnO₂) composite that provides adaptive support, antitumor activity, and osteogenic bioactivity. SMPU was synthesized by introducing 1,4-butanediol (BDO) and dimethylolpropionic acid (DMPA) as chain extenders at a specific ratio. Commercial MnO₂ nanoparticles were incorporated as both a photothermal agent and a bioactive component to achieve multifunctionality. As designed, a coordination system was formed between the polymer chains and MnO₂ nanoparticles within the composites. The influence of MnO₂ content was systematically investigated. Although increasing MnO₂ amounts improved photothermal and mechanical performance, excessive incorporation adversely affected the molecular structure and compromised the composite’s biocompatibility. By adjusting the MnO₂ content, the composites were demonstrated to possess robust mechanical performance, good shape-memory behavior, and controllable Mn²⁺ release. Additionally, the composites exhibited tunable photothermal performance under near-infrared (NIR) irradiation. Furthermore, in vitro studies confirmed that the composites containing 4 wt% MnO₂ could eliminate tumor cells via photothermal effects and promote the osteogenic differentiation of human bone marrow-derived mesenchymal stem cells (hBMSCs). Overall, the SMPU/MnO₂ composites had superior multifunction for treating irregular bone defects following bone tumor surgery. Full article

Micronutrient deficiencies and low nutrient-use efficiency remain critical constraints to sustainable crop production. This study tested the hypothesis that Zn- and Cu-doped MnFe₂O₄ spinel ferrite nanoparticles can function as an efficient multinutrient nanofertilizer to enhance fenugreek (Trigonella foenum-graecum L.) growth and physiological performance. Zn- and Cu-doped MnFe₂O₄ nanoparticles were synthesized via a sol–gel method and characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). The nanoparticles exhibited a cubic spinel structure with an average crystallite size of 27 nm and uniform incorporation of Zn and Cu within the MnFe₂O₄ lattice. Foliar application at different concentrations (100–500 mg/L) significantly improved seed germination, seed vigor, plant height, leaf number, stem thickness, biomass accumulation, and chlorophyll content compared with the untreated control. The 300 mg/L treatment consistently produced the greatest improvements, increasing plant height, biomass, and total chlorophyll content by more than 25–40% relative to control plants. Higher concentrations of T₅ resulted in diminished benefits, indicating a concentration-dependent response. These findings demonstrate that Zn- and Cu-doped MnFe₂O₄ nanofertilizer provides a balanced and bioavailable source of essential micronutrients, offering a promising nano-enabled strategy for improving nutrient use efficiency and sustainable fenugreek production. Full article

We present frequency- and magnetic field-dependent measurements of the complex dielectric permittivity ε*(f, H) of a kerosene-based ferrofluid, containing Mn₀.₆Fe₀.₄Fe₂O₄ nanoparticles, over 0.8–5 GHz and static fields up to ~91 kA/m. The imaginary part, ${\epsilon }_F^{″}$, shows a peak at a characteristic frequency that shifts towards higher frequencies with increasing H, revealing a magnetic field-dependent relaxation process, interpreted using the Maxwell–Wagner–Sillars model. The dielectrophoretic extraction of nanoparticles was evaluated via the squared electric field gradient, and a threshold, ${\left(\nabla E^2\right)}_{\min }$, dependent on particle size was determined. Below that threshold, Brownian forces dominate, so the ferrofluid acts as a homogeneous dielectric. For this case, the Clausius–Mossotti factor (CM) was calculated for ferrofluid droplets in air and in water as a function of frequency and magnetic field. In air, CM exhibits modest but systematic magnetic field dependence, indicating a magnetically modulated dielectric response at GHz frequencies. In contrast, when water is used as the reference medium, CM remains negative and essentially independent of H across the entire frequency range, suggesting that the high permittivity of water masks the magneto-dielectric effects in the ferrofluid. These findings provide insight into the interplay between the magnetic field and the permittivity of ferrofluids, with implications for high-frequency applications. Moreover, using a λ/4 antenna connected to a network analyzer, the existence of the dielectrophoretic force acting on a ferrofluid-impregnated textile thread at microwave frequencies was experimentally demonstrated. Full article

Engineering surfaces operating in harsh environments frequently require simultaneous resistance to abrasive wear and the minimization of interfacial adhesion. Achieving this dual functionality through a single surface modification strategy remains challenging. This study presents a novel hybrid approach combining bionic laser surface texturing with a polytetrafluoroethylene/polydimethylsiloxane/TiO₂ nanocomposite coating to synergistically enhance both wear resistance and hydrophobicity of 65Mn steel. Crescent-shaped micro-dimples, inspired by the exoskeleton of Procambarus clarkii, were fabricated via a femtosecond laser. A composite coating containing hydrophobically modified TiO₂ nanoparticles was subsequently deposited. Single-factor experiments identified effective parameter ranges. A four-factor, five-level central composite rotatable design combined with response surface methodology was employed to systematically optimize texture depth, texture spacing, TiO₂ mass fraction, and coating thickness. The results demonstrate that textures with a depth of less than 100 μm and spacing less than 400 μm effectively homogenize surface stress distribution. RSM analysis revealed that TiO₂ content and texture depth predominantly influence hydrophobicity, while texture spacing overwhelmingly controls wear mass loss. Significant interactions between coating and texture parameters were identified. The optimal parameter combination was determined as: 6% TiO₂, 40 μm coating thickness, 50 μm texture depth, and 250 μm texture spacing. Under these conditions, the surface achieved a superhydrophobic contact angle of 152.1° and a low-wear mass loss of 8.9 mg. Validation tests yielded values of 150.8° and 9.3 mg, respectively, confirming model reliability. The synergistic mechanism involves textures acting as debris reservoirs and stress distributors, while the coating provides a low-surface-energy, hardened top layer that minimizes adhesion and facilitates a rolling–sliding contact mode. This work provides a robust, optimized framework for designing multifunctional surfaces for demanding tribological applications. Full article

In this work, La_0.70Ca_0.25Sr_0.05MnO₃ perovskite nanoparticles were produced in large amounts (in a single batch) and were embedded into filaments for 3D printing alongside carbon fibers. The produced materials showed room-temperature magnetocaloric effects proportional to the quantity of encapsulated nanoparticles. Moreover, the thermal properties of 3D-printed pellets (produced using the composite filaments) were also analyzed and compared to standard filaments. Full article

Amyloidosis is characterized by the deposition of misfolded proteins as highly stable, insoluble β-sheet-rich fibrils, posing a major therapeutic challenge due to their resistance to degradation. Insulin-derived amyloidosis at subcutaneous injection sites is a clinically significant complication in patients with diabetes, leading to impaired insulin absorption, unpredictable glycemic control, substantially increased insulin dose requirements, and localized masses (amyloidomas) that may require surgical excision when symptomatic. In this study, we evaluated sodium oleate-functionalized magnetic nanoparticles (MNs) with a hydrodynamic diameter of 50 nm with a magnetite (iron oxide—Fe₃O₄) core as a targeted physical intervention to disrupt preformed insulin amyloid fibrils. The strategy exploits localized nanoscale hyperthermia generated by MNs under a high-frequency radiofrequency (RF) field (1.65 MHz). Fibril integrity and disassembly kinetics were assessed using Thioflavin T (ThT) fluorescence assays and fluorescence microscopy. RF-activated MNs induced rapid, concentration-dependent fibril disruption; notably, at 2 mg/mL MNs, near-complete disassembly was achieved within 15 min—a timeframe compatible with clinical procedures. Neither RF nor MNs alone produced significant effects, confirming a synergistic magnetothermal mechanism. These results provide a proof of concept for a minimally invasive, externally triggered approach to clear localized insulin amyloid deposits, offering promising potential as a novel therapeutic strategy for managing injection-site amyloidosis in diabetic patients, where current options remain limited and often inadequate. Full article

In this work, a novel nanostructured Mn₃O₄-based electrochemical sensor was developed for the determination of heavy metals in aqueous media. The Mn₃O₄ nanostructure was solvothermally synthesized in the sole presence of propylene glycol (PG). Under the specific synthetic conditions, PG provided surface coating and stabilization by decomposition products and/or residual PG molecules that have been adsorbed on Mn₃O₄ NPs surfaces, creating a thin organic layer. This imparts a negative surface charge (zeta potential), enhancing colloidal stability in dispersions and electrochemical performance. The physicochemical properties of the resulting NPs were characterized via X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Thermogravimetric Analysis (TGA), and Dynamic light scattering (DLS) and ζ-potential measurements, as well as SEM imaging of the modified electrode surface, confirming its successful formation and favorable structural properties. The LODs of Cd²⁺, Pb²⁺, Zn²⁺, and Cu²⁺ for their simultaneous determination are 2.9 μg·L⁻¹, 5.2 μg·L⁻¹, 7.1 μg·L⁻¹, and 2.5 μg·L⁻¹, respectively, with relative standard deviations of about 5.24%, 4.43%, 7.74%, and 4.53%, respectively. As a result of this study, a simple, sensitive, and reproducible electrochemical sensor based on a carbon paste electrode (CPE) modified with novel synthesized manganese nanoparticles and employing voltammetric techniques was applied in water and wastewater. Full article

This paper presents a comprehensive investigation into the synthesis, morphological characteristics, electrical conductivity, dielectric behavior, and electrocatalytic activity of perovskite-structured iron manganite (FeMnO₃), with a specific focus on its performance in the hydrogen evolution reaction (HER). FeMnO₃(FMO) nanoparticles (NPs) were synthesized using a sol–gel-type Pechini method and characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and field-emission scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (FESEM-EDS). XRD analysis confirmed the formation of a crystalline structure with cubic symmetry assigned to the Ia-3 space group, with an average crystallite size of 52.47 nm. FESEM images revealed a relatively uniform morphology with an average particle diameter of 55.84 nm. The redox and oxidation states of Fe and Mn can be studied by temperature-programmed oxidation (TPO-O₂) in order to understand oxygen uptake and metal oxidation processes occurring within the FMO lattice. The dielectric constant, dielectric loss, electric modulus and electrical conductivity were calculated as a function of frequency and temperature using a Novocontrol Alpha-A broadband dielectric spectrometer (Novocontrol system) coupled with the LCR-800 precision meter. The dielectric data reveal that the FMO has semiconducting behavior with dominant charge- or ionic-relaxation processes. The electrocatalytic activity toward the HER was evaluated using linear sweep voltammetry (LSV), with the working electrode modified by an FMO catalyst ink. The material exhibited significant catalytic activity within the HER potential range, and an increase in the number of cycles led to stabilized current and enhanced hydrogen evolution. These results highlight the stability of FeMnO₃ for hydrogen generation. Full article