Search Results (201)

This study presents the development of a TiO₂ nanowire-based electrochemical sensor for the selective and sensitive detection of hydrogen peroxide (H₂O₂) under neutral pH conditions, with a particular focus on its application in analyzing plant stress. The sensor exhibited a linear detection range of 0–0.5 mM, a sensitivity of 0.0393 mA · mM⁻¹, and a detection limit of 2.8 μM in phosphate-buffered saline solution (PBS, pH 7.4). This work’s main novelty lies in the systematic investigation of the relationship between TiO₂ nanostructure morphology, which is controlled by hydrothermal synthesis parameters, and the resulting sensor performance. Interference studies confirmed excellent selectivity in the presence of common electroactive species found in plant samples, such as NaCl, KNO₃, glucose, citric acid, and ascorbic acid. Real sample analysis using barley plant extracts grown under salt stress and treated with Fe₃O₄ nanoparticles confirmed the sensor’s applicability in complex biological matrices, enabling accurate quantification of endogenously produced H₂O₂. Endogenous H₂O₂ concentrations were found to range from near-zero levels in control and Fe₃O₄-only treated plants, to elevated levels of up to 0.36 mM in salt-stressed samples. These levels decreased to 0.25 and 0.15 mM upon Fe₃O₄ nanoparticle treatment, indicating a dose-dependent mitigation of stress. This finding was supported by genome template stability (GTS) analysis, which revealed improved DNA integrity in Fe₃O₄-treated plants. This study takes an integrated approach, combining the development of a nanostructured sensor with physiological and molecular stress assessment. The urgent need for tools to detect stress at an early stage and manage oxidative stress in sustainable agriculture underscores its relevance. Full article

In this study, we report the synthesis and characterization of a novel NH₂-MIL-101(Fe) magnetic composite, developed via in situ formation of NH₂-MIL-101(Fe) in the presence of Fe₃O₄ nanoparticles embedded within a chloropropyl-modified mesoporous silica layer. This hybrid composite retains the high adsorption capacity of NH₂-MIL-101(Fe) while benefiting from the easy magnetic separation enabled by Fe₃O₄ nanoparticles. The mesoporous silica forms a protective porous coating around the magnetic nanoparticles, significantly enhancing its chemical stability and preventing clumping. Beyond protection, the mesoporous silica layer provides a high-surface-area scaffold that promotes the uniform in situ growth of NH₂-MIL-101(Fe). Functionalization of the silica surface with chloride groups enables strong electrostatic interactions between the magnetic component and metal organic framework (MOF), ensuring a homogeneous and stable hybrid structure. The new composite’s capacity to remove Pb(II) and Cd(II) ions from aqueous solutions was systematically investigated. The adsorption data showed a good fit with the Langmuir isotherm model for both ions, the maximum adsorption capacities calculated being 214.6 mg g⁻¹ for Pb(II) and 181.6 mg g⁻¹ Cd(II). Furthermore, the kinetic behavior of the adsorption process was accurately described by the pseudo-second-order model. These findings confirm the effectiveness of this composite for the removal of Pb(II) and Cd(II) ions from aqueous solutions, demonstrating its potential as an efficient material for environmental remediation. The combination of magnetic recovery, high adsorption capacity, and stability makes this novel composite a promising candidate for heavy metal removal applications in water treatment processes. Full article

Antistatic and anti-flame biodegradable polymer composites were developed by melt-blending polybutylene succinate (PBS) with epoxy resin, polybutylene adipate-co-terephthalate (PBAT), and MgO particles. The composite films were prepared using a two-roll mill and an extrusion-blown film machine. Plasma and sparking techniques were used to improve the antistatic properties of the composites. The PBS/E1/PBAT/MgO 15% composite exhibited an improvement in V-1 rating of flame retardancy, indicating an enhancement in the flame retardancy of biodegradable composite films. The tensile strength of the PBS/PBAT blend increased from 19 MPa to 25 MPa with the addition of 1% epoxy due to the epoxy reaction increasing compatibility between PBS and PBAT. The PBS/E1/PBAT and PBS/E1/PBAT blends with MgO 0, 0.5, and 1% showed increases in the contact angle to 80.9°, 83.0°, and 85.7°, respectively, because the epoxy improved the reaction between PBS and PBAT via the MgO catalyst effect. Fourier-transform infrared spectroscopy confirmed the reaction between the epoxy groups of the epoxy resin and the carboxyl end groups of PBS and PBAT by new peaks at 1246 and 1249 cm⁻¹. Plasma technology (sputtering) presents better antistatic properties than the sparking process because of the high consistency of the metal nanoparticles on the surface. This composite can be applied for electronic devices as sustainable packaging. Full article

Arsenic and heavy metal contamination in water presents serious environmental and public health challenges, requiring effective treatment technologies. Titanium dioxide (TiO₂) nanoparticles offer promising adsorption potential due to their high surface area, mesoporosity, and chemical stability. This study investigates the removal of As(V), Cd(II), Cu(II), and Pb(II) by TiO₂ under environmentally relevant conditions (pH 3 and 7), commonly encountered in industrial and natural waters. TiO₂ was characterized using SEM, XRD, FTIR, BET, and pH_pzc analysis, confirming a mesoporous structure with mixed anatase/rutile phases. Adsorption followed Elovich kinetics, with the Langmuir model providing the best fit to the isotherm data. At pH 3, adsorption capacities (q_m) were of the following order: Pb(II) 30.80 mg g⁻¹ > Cd(II) 10.02 mg g⁻¹ > As(V) 8.45 mg g⁻¹ > Cu(II) 2.73 mg g⁻¹; at pH 7, they were as follows: Cd(II) 26.75 mg g⁻¹ > Pb(II) 26.20 mg g⁻¹ > As(V) 8.50 mg g⁻¹ > Cu(II) 5.05 mg g⁻¹. These results highlight a pH-dependent mechanism involving both chemisorption and physisorption. Principal Component Analysis (PCA) revealed that physicochemical properties, particularly electronegativity, significantly influenced removal efficiency. TiO₂ showed high, selective, and pH-responsive adsorption properties, supporting its use in sustainable water treatment. Future work should address nanoparticle recovery, regeneration, and performance under continuous flow conditions. Full article

The widespread use of lead (Pb) has led to serious environmental and human health problems worldwide. The application of oxide nanoparticles (CeO₂ NPs) in alleviating abiotic stress in plants has received extensive attention. In this study, 50 mg·L⁻¹ CeO₂ NPs can improve Pb resistance and promote rice growth. Specifically, this study observed that CeO₂ NPs increased the activity of antioxidant enzymes peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX), but the difference did not reach a significant level. At the same time, CeO₂ NPs upregulated antioxidant metabolites alpha-linolenic acid, linoleic acid, ferulic acid, and kaempferol under Pb stress. In addition, CeO₂ NPs upregulated multiple defense response-related genes, such as OsOPR1 and OsPR10a; RPR10a, and improved rice carbon flow and energy supply by upregulating sucrose and D-glucose. The results of this study provided technical support for alleviating Pb stress in rice. Full article

Excessive levels of heavy metal pollutants in the environment pose significant threats to human health and ecosystem stability. Consequently, the accurate and rapid detection of heavy metal ions is critically important. A AgNPs@CeO₂/Nafion composite was prepared by dispersing nano-ceria (CeO₂) in a Nafion solution and incorporating silver nanoparticles (AgNPs). The morphology, microstructure, and electrochemical properties of the modified electrode materials were systematically characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and cyclic voltammetry (CV). By leveraging the oxygen vacancies and high electron transfer efficiency of CeO₂, the strong adsorption capacity of Nafion, and the superior conductivity of AgNPs, an AgNPs@CeO₂/Nafion/GCE electrochemical sensor was developed. Under optimized conditions, trace Pb²⁺ in water was detected using square wave anodic stripping voltammetry (SWASV). The sensor demonstrated a linear response for Pb²⁺ within the concentration range of 1–100 μg·L⁻¹, with a detection limit of 0.17 μg·L⁻¹ (S/N = 3). When applied to real water samples, the method achieved recovery rates between 93.7% and 110.3%, validating its reliability and practical applicability. Full article

Heavy metal contamination of water is a critical environmental problem due to its toxicity and persistence in ecosystems. In this study, magnetic hydrogel spheres composed of carboxymethylated starch modified with poly(1-vinylimidazole) (CMS-g-PVI) and polyvinyl alcohol (PVA), combined with Fe₃O₄ nanoparticles, were synthesized and characterized to evaluate their efficiency in adsorbing metal ions such as Cu²⁺, Pb²⁺, and Cd²⁺. Structural characterization by FT-IR spectroscopy confirmed the successful integration of all functional components into the hydrogel matrix. Additionally, scanning electron microscopy (SEM) revealed a rough and porous surface morphology favorable for adsorption and an average bead diameter of 3.2 mm, influenced by the stirring rate during synthesis. Adsorption studies demonstrated maximum capacities of 82.4 mg·g⁻¹ for Cu²⁺, 66.5 mg·g⁻¹ for Pb²⁺, and 51.8 mg·g⁻¹ for Cd²⁺, with optimal removal efficiencies at pH 6.2 and 5.7. From a theoretical perspective, density functional theory (DFT) calculations using the B3LYP/6-311+G(d,p) method allowed the optimization of molecular structures and analysis of electronic properties. The total dipole moment (TDM) of the CMS-g-PVI/PVA system reached 20.81 Debye. A significant reduction in the HOMO-LUMO energy gap was observed upon metal adsorption, with values of 0.0308 eV for Cu²⁺, 0.0175 eV for Pb²⁺, and 0.0235 eV for Cd²⁺, confirming strong interactions between the hydrogel matrix and the metal ions. The combined experimental and computational approach provides a comprehensive understanding of the adsorption mechanisms and supports the development of efficient materials for water decontamination. Full article

Biochar (BC) is a widely studied economic and environment-friendly material. However, its application is limited by its underdeveloped pore structure, small specific surface area, low degree of graphitization, and difficulty in being separated from liquids during the application process. Raw cotton contains almost 100% cellulose and has a high yield for preparing biochar. A novel type of magnetic biochar composite was prepared by the impregnation–calcination method using cotton and iron nitrate nonahydrate(Fe(NO₃)₃·9H₂O). The material was characterized using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, thermogravimetric analysis (TG), and specific surface area testing (BET). The results show that Fe_xO_y nanoparticles with a uniform morphology and an average particle size of less than 20 nm are embedded in the composite; the saturation magnetization strength of the composite material reaches 21.6 emu/g; and compared to the original biochar, the composite material has a larger specific surface area (326 m²/g). As an adsorbent, the composite material has a fast removal rate for Pb²⁺ of 95% in 50 min. The Langmuir model calculation results show that the maximum adsorption capacity of the composite for Pb²⁺ is 252.7 mg/g. Fe_xO_y-BC easily achieves solid–liquid separation and can be recycled for Pb²⁺ wastewater treatment through adsorption–desorption–regeneration. Full article

This study investigates the development of advanced radiation shielding materials incorporating bismuth oxide (Bi₂O₃) nanoparticles (NPs) into polymethyl methacrylate (PMMA) composites, comparing efficacy against I-131 gamma radiation. The NPs exhibit a 1.53-fold reduction in z-average diameter and a significantly higher surface area than Bi₂O₃, ensuring superior dispersion and structural uniformity within the PMMA matrix. These characteristics, validated through SEM, EDX, and XRD analyses, contribute to enhanced gamma radiation attenuation, leveraging the high atomic number and density of Bi₂O₃. Mechanical evaluations reveal that increasing Bi₂O₃-NPs concentrations enhances ductility but reduces tensile strength, likely due to nanoparticle agglomeration and stress concentration. Radiation shielding performance, assessed using XCOM and Phy-X/PSD simulations, demonstrates a direct correlation between Bi₂O₃ content and attenuation efficiency. Notably, composites with 75% Bi₂O₃ content exhibit attenuation properties comparable to, or exceeding, those of PbO₂, achieving superior shielding efficacy at reduced thicknesses across various photon interaction mechanisms. These findings position Bi₂O₃ NPs-enhanced PMMA composites as promising lightweight high-performance alternatives to lead-based shields. By addressing toxicity and environmental concerns associated with lead, this work emphasizes the potential of high-Z nanomaterials in advancing radiation protection applications. This study highlights a transformative approach to designing safer and more efficient shielding solutions, contributing to the next generation of radiation protection materials. Full article

Zinc has attracted significant attention as a versatile material with potential applications in various fields, particularly in biomedical engineering. Despite its desirable characteristics, such as biodegradability and biocompatibility, the inherently low mechanical strength of zinc has been a major limitation for its broader use in clinical applications. To address this issue and enhance its mechanical performance without compromising its biocompatibility, a novel composite material was developed by mixing zinc oxide (ZnO) with zinc (Zn). ZnO is widely recognized for its high chemical stability, non-toxicity, and antimicrobial properties, making it an excellent additive for biomedical materials. In this study, Zn-ZnO nanocomposites were fabricated by uniformly dispersing ZnO nanoparticles into molten zinc using an ultrasonic processor. The uniform distribution of ZnO nanoparticles within the zinc matrix was confirmed, and the resulting nanocomposites demonstrated remarkable improvements in mechanical properties. Specifically, the hardness and tensile strength of the Zn-ZnO nanocomposites were increased by approximately 90% and 160%, respectively, compared to pure zinc. To evaluate the biodegradation behavior of the materials, both pure zinc and Zn-ZnO nanocomposite samples were immersed in phosphate-buffered saline (PBS) at 37 °C, simulating physiological conditions. The degradation rate was assessed by measuring the weight loss of the material over time. The biodegradation rate of the Zn-ZnO nanocomposites was found to be nearly identical to that of pure zinc under identical conditions, indicating that the addition of ZnO did not adversely affect the degradability of the material. These findings suggest that Zn-ZnO nanocomposites offer a promising solution for biomedical applications by combining improved mechanical properties with maintained biodegradability and biocompatibility. Full article

Near-infrared persistent luminescence (PersL) nanoparticles (NPs) have great potential in biomedical applications due to their ability to continuously emit tissue-penetrating light. Despite numerous reports on the distribution, biological safety and other consequences of PersL NPs in vitro and in vivo, there has been a lack of studies on the optical properties of these NPs in the physiological environment. In light of this, we investigated the effects of short-term immersion of the prominent Cr³⁺-doped ZnGa₂O₄ (CZGO) NPs in a simulated physiological environment for up to 48 h. This paper reports the changes in the structural and optical properties of CZGO NPs after their immersion in a phosphate-buffered saline (PBS) solution for pre-determined time intervals. Interestingly, the luminescence intensity and lifetime noticeably improved upon exposure to the PBS media, which is unusual among existing nanomaterials explored as bioimaging probes. After 48 h of immersion in the PBS solution, the CZGO NPs were approximately twice as bright as the non-immersed sample. X-ray spectroscopic techniques revealed the formation of ZnO, which results in an improvement in observed luminescence. Full article

This study is focused on the fabrication and characterization of various dual waveguides through femtosecond (fs) laser irradiation of GeO₂-based glass samples. The objective of the present work is to develop diverse waveguide configurations, namely straight, S-bend and Y-shaped waveguides within GeO₂–PbO glasses embedded with silver nanoparticles, utilizing a double-guide platform, for photonic applications such as resonant rings and beam splitters. Enhanced guidance was observed with a larger radius of curvature (80 mm) among the two distinct S-bend waveguides produced. The maximum relative propagation loss was recorded for the S-bend waveguide with a 40 mm radius, while the minimum loss was noted for the Y-shaped waveguide. In the latter configuration, with an opening angle of 5° and a separation of 300 µm between the two arms, an output power ratio of 50.5/49.5 between the left and right arms indicated promising potential for beam splitter applications. During the study, the quality factor (M²) of the proposed architectures was measured and the 80 mm S-bend configuration presented the best symmetry between the x and y axes; in the case of the Y configuration the similarity between the M² values in both axes, for the first and second arms, indicates comparable light guidance. Full article

In this study, magnetic carbon nanopolymers (Fe₃O₄/C@PM) were synthesized by suspension polymerization using magnetic carbon nanoparticles as the matrix, 2-thiophene formaldehyde and acrylamide as the monomers, and ethylene glycol dimethacrylate (EGDMA) as the crosslinking agent. The obtained material was characterized using multiple techniques, including scanning electron microscopy (SEM), infrared spectroscopy (FTIR), X-ray diffraction (XRD), N₂ adsorption–desorption, and thermogravimetric analysis (TGA). The adsorption effects of Zn²⁺, Cd²⁺, and Pb²⁺ in the mixed solution were evaluated using magnetic carbon nanoparticles (Fe₃O₄/C) and Fe₃O₄/C@PM as adsorbents. The adsorption isotherms, kinetic models, and cyclic regeneration of various metal ions, including Zn²⁺, Cd²⁺ and Pb²⁺, were studied. The results showed that the Fe₃O₄/C@PM maintained a slightly aggregated spherical morphology similar to Fe₃O₄/C and exhibited excellent adsorption capacity for all of Zn²⁺, Cd²⁺, and Pb²⁺, with maximum adsorption capacities of 343.3, 250.7, and 177.6 mg·g⁻¹, respectively. The adsorption mechanisms were mainly based on the chemical interactions between metal ions and functional groups on the surface of polymers. The kinetic study revealed that the adsorption process followed a pseudo-second-order kinetic model. When Fe₃O₄/C@PM was reused five times, its adsorption rates for Zn²⁺, Cd²⁺, and Pb²⁺ remained above 81%, indicating its great potential for the treatment of wastewater containing Zn²⁺, Cd²⁺, and Pb²⁺. Full article

The development of efficient catalysts for water electrolysis is crucial for advancing the low-carbon transition and addressing the energy crisis. This work involves the fabrication of graphene-based catalysts for the oxygen evolution reaction (OER) by integrating NiFe-LDH and PbO₂ onto graphene using plasma treatment. The plasma process takes only 30 min. Graphene’s two-dimensional structure increases the available reaction surface area and improves surface electron transport. Plasma treatment further improves catalyst performance by facilitating nanoparticle attachment and creating carbon defects and sulfur vacancies. Density functional theory (DFT) calculations at the PBE provide valuable insights into the role of vacancies in enhancing catalyst performance for OER. The catalyst’s conductivity and electronic structure are greatly impacted by vacancies. While modifications to the electronic structure increase the kinetics of charge transfer, the vacancy structure can produce more active sites and improve the adsorption and reactivity of OER intermediates. This optimization of intermediate adsorption and electronic properties leads to increased overall OER activity. The catalyst NiFe-PbO₂/S/rGO-45, synthesized through plasma treatment, demonstrated an overpotential of 230 mV at 50 mA·cm⁻² and a Tafel slope of 44.26 mV dec⁻¹, exhibiting rapid reaction kinetics and surpassing the OER activity of commercial IrO₂. With its excellent performance, the prepared catalyst has broad prospects in commercial applications such as water electrolysis and air batteries. Full article

Prussian blue nanoparticles (PBNPs) have been identified as a promising candidate for biomimetic peroxidase (POD)-like activity, specifically due to the metal centres (Fe³⁺/Fe²⁺) of Prussian blue (PB), which have the potential to function as catalytically active centres. The decoration of PBNPs with desired functional polymers (such as amino- or carboxylate-based) primarily facilitates the subsequent linkage of biomolecules to the nanoparticles for their use in biosensor applications. Thus, the elucidation of the catalytic POD mimicry of these systems is of significant scientific interest but has not been investigated in depth yet. In this report, we studied a series of poly(ethyleneimine) (PEI)-mediated PBNPs (PB/PEI NPs) prepared using various synthesis protocols. The resulting range of particles with varying size (~19–92 nm) and shape combinations were characterised in order to gain insights into their physicochemical properties. The POD-like nanozyme activity of these nanoparticles was then investigated by utilising a 3,3′,5,5′-tetramethylbenzidine (TMB)/H₂O₂ system, with the catalytic performance of the natural enzyme horseradish peroxidase (HRP) serving as a point of comparison. It was shown that most PB/PEI NPs displayed higher catalytic activity than the PBNPs, with higher activity observed in particles of smaller size, higher Fe content, and higher Fe²⁺/Fe³⁺ ratio. Furthermore, the nanoparticles demonstrated enhanced chemical stability in the presence of acid, sodium azide, or high concentrations of H₂O₂ when compared to HRP, confirming the viability of PB/PEI NPs as a promising nanozymatic material. This study disseminates fundamental knowledge on PB/PEI NPs and their POD-like activities, which will facilitate the selection of an appropriate particle type for future biosensor applications. Full article