Search Results (246)

Photocatalytic water sterilization has emerged as a promising sustainable technology for addressing microbial contamination across diverse sectors including healthcare, food production, and environmental management. This review examines the fundamental mechanisms and recent advances in photocatalytic water sterilization, with a particular emphasis on the differential bactericidal pathways against Gram-negative and Gram-positive bacteria. Gram-negative bacteria undergo a two-step inactivation process involving initial outer membrane lipopolysaccharide (LPS) degradation followed by inner membrane disruption, whereas Gram-positive bacteria exhibit simpler kinetics due to direct oxidative attacks on their thick peptidoglycan layer. Escherichia coli has long been used as the gold standard in photocatalytic sterilization studies owing to its aerobic nature and suitability for the colony-counting method. In contrast, Lactobacillus casei, a facultative anaerobe, can be cultured statically and evaluated rapidly using turbidity-based optical density measurements. Therefore, both organisms serve complementary roles depending on the experimental objectives—E. coli for precise quantification and L. casei for rapid, practical assessments of Gram-positive bacterial inactivation under laboratory conditions. We also describe sterilization using light alone while comparing it to photocatalytic sterilization and then discuss two innovative suspension-based photocatalyst systems: polystyrene bead-supported TiO₂/SiO₂ composites offering balanced reactivity and separability and magnetic TiO₂-SiO₂/Fe₃O₄ nanoparticles enabling rapid magnetic recovery. Future research directions should prioritize enhancing visible-light efficiency using metal-doped TiO₂ such as Cu-doped systems; improving catalyst durability; developing new applications of photocatalysts, such as protecting RO membranes; and validating scalability across diverse industrial and medical water treatment applications. Full article

Humic acids (HAs) are widely used as adsorbents or carriers, yet they still lack oxygenic functional groups under certain conditions. Modification via catalytic oxidation under mild conditions is an ideal method to increase the oxygenic functional groups in HAs—if simple catalyst separation could be realized. Here, we report the use of CuO nanoparticles supported by Fe₃O₄ magnetic nanospheres as magnetic catalytic systems (MCSs) that could catalyze HA modification via Fenton oxidation. These MCSs can be easily magnetically separated from the products. The content of carboxyl groups increased from 2.45% to 10.47% after reaction, while the yield of modified HAs remained approximately 100%. These results indicate that oxidation with MCSs could be a potential method for HA modification. Full article

Multimodal nanocomposites that combine optical and magnetic functionalities are of great interest for applications such as imaging and temperature sensing. Ternary CuInS₂ (CIS)-based quantum dots (QDs) offer low toxicity, strong near-infrared (NIR) emission, and high photostability, making them promising for optical nanothermometry and imaging. In this study, CIS QDs were synthesized using an aqueous cysteine-mediated approach. Manganese ferrite (MnFe₂O₄) nanoparticles were prepared as the magnetic component due to their non-toxicity and superparamagnetic properties. To integrate both functionalities, QDs and magnetic nanoparticles (MNPs) were encapsulated in silica and then combined to form multimodal CIS/MnFe₂O₄/SiO₂ nanocomposites. The structure and morphology of the materials were characterized by TEM and XRD, while their optical properties were examined using UV–Vis, photoluminescence (PL) spectroscopy. This design ensured optical isolation, preventing fluorescence quenching while maintaining colloidal stability. The obtained composites exhibited PL in the NIR region and a thermosensitivity of 2.04%/°C. TEM analysis confirmed uniform silica shell formation and successful integration of both components within the composite. The materials also retained the superparamagnetic behavior of MnFe₂O₄, making them suitable for combined optical and magnetic functionalities. These results demonstrate the potential of CIS/MnFe₂O₄/SiO₂ nanocomposites as multifunctional platforms for optical imaging, temperature monitoring, and magnetically modulated effects. Full article

The removal of synthetic dyes from industrial effluents remains challenging due to their chemical stability and poor biodegradability. Here we engineer metal-doped carbon dots (CDs) as heterogeneous Fenton-like catalysts and elucidate how dopant identity governs structure–activity relationships and reactive oxygen species (ROS) pathways. Fe-, Cu-, Zn- and Mg-doped CDs were prepared via a one-pot hydrothermal route and comprehensively characterised by TEM, FTIR, XPS and zeta-potential analysis. The resulting nanoparticles displayed narrow size distributions (10.2–15.2 nm) and dopant-dependent surface chemistries and charges. Catalytic tests with methylene blue (MB) and rhodamine B (RB) show that Fe-doped CDs deliver the highest activity toward MB degradation (k = 0.0218 min⁻¹), attributable to efficient Fe²⁺/Fe³⁺ redox cycling coupled with hydroxyl-rich surfaces that promote H₂O₂ activation. Zn-doped CDs achieve complete RB decolourisation under Fenton-like conditions, which we ascribe to their higher surface charge and abundant oxygenated sites that enhance pollutant adsorption and ROS generation. Cu- and Mg-doped CDs exhibit intermediate and dopant-specific performances consistent with their respective redox and adsorption characteristics. Collectively, these results establish clear correlations between dopant chemistry, surface functionality, and ROS formation routes, providing mechanistic guidance for the rational design of carbon-based Fenton catalysts for sustainable water remediation. Full article

Natural convection enhanced by magnetic fields and nanofluids has broad applications in thermal management systems. This study investigates magnetohydrodynamic (MHD) natural convection in a wavy trapezoidal cavity containing centrally located heated square obstacles, filled with various nanofluids Cu–H₂O, Fe₃O₄–H₂O, and Al₂O₃–H₂O. A uniform magnetic field is applied horizontally, and the effects of key parameters such as Rayleigh number, Ra (10³–10⁶), Hartmann number, Ha (0–50), and nanoparticle volume fraction, φ (0.00, 0.02, 0.04) are analyzed. The numerical simulations are performed using the finite element method, incorporating a wavy upper boundary and slanted sidewalls to model realistic enclosures. Results show that an increasing Rayleigh number enhances heat transfer, while a stronger magnetic field reduces convective flow. Among the nanofluids, Cu–H₂O demonstrates the highest Nusselt number and ecological coefficient of performance (ECOP), whereas Fe₃O₄–H₂O exhibits superior performance under stronger magnetic fields due to its magnetic nature. Entropy generation, S_T decreases with increasing Ra and φ, indicating reduced thermodynamic irreversibility. These results provide insights into designing energy-efficient enclosures using nanofluids under magnetic control. Full article

Background: Minimally invasive hyperthermia and regenerative therapies require materials that deliver precise, localized heat without compromising biocompatibility. Most conventional polymers are thermally insulating and challenging to control in vivo, motivating this review. Objectives: We aimed to (i) examine the use of thermally enhanced biopolymers in hyperthermia-based therapies, (ii) appraise evidence from clinical and preclinical studies, (iii) identify and classify principal applications in regenerative medicine. Methods: A PRISMA-guided systematic review (2020–2025) with predefined inclusion/exclusion criteria was conducted and complemented by a bibliometric analysis using VOSviewer for mapping and visualization. Results: Modifying biopolymers—via functionalization with photothermal or magnetic nanoagents (Au; Fe₂O₃/Fe₃O₄/CoFe₂O₄; CuS; Ag; MXenes, e.g., Nb₂C), crosslinking strategies, and hybrid formulations—significantly increased thermal conductivity, enabling localized hyperthermia and controlled drug release. In vitro and in vivo studies showed that europium-doped iron oxide nanoparticles embedded in chitosan generated heat efficiently while sparing healthy tissues, underscoring the need to balance biocompatibility and thermal performance. Hydrogel systems enriched with carbon nanomaterials (graphene, carbon nanotubes) and matrices such as GelMA, PNIPAM, hyaluronic acid, and PLA/PLGA demonstrated tissue compatibility and effective thermal behavior; graphene was compatible with neural tissue without inducing inflammation. Conclusions: Thermally conductive biopolymers show growing potential for oncology and regenerative medicine. The evidence supports further academic and interdisciplinary research to optimize safety, performance, and translational pathways. Full article

Green synthesis represents a sustainable, reliable, and eco-friendly approach for producing various materials and nanomaterials, including metal and metal oxide nanoparticles. This environmentally conscious method has garnered significant attention from materials scientists. In recent years, interest in plant-mediated nanoparticle synthesis has grown markedly, owing to advantages such as enhanced product stability, low synthesis costs, and the use of non-toxic, renewable resources. This review specifically focuses on the green synthesis of metal oxide nanoparticles using plant extracts, highlighting five key oxides: TiO₂, ZnO, WO₃, CuO, and Fe₂O₃, which are prepared through various plant-based methods. The release of toxic effluents like synthetic dyes into the environment poses serious threats to aquatic ecosystems and human health. Therefore, the application of biosynthesized nanoparticles in removing such pollutants from industrial wastewater is critically examined. This paper discusses the synthesis routes, characterization techniques, green synthesis methodologies, and evaluates the photocatalytic performance and dye degradation mechanisms of these plant-derived nanoparticles. Full article

This study investigates the formation of hydroxyl radicals (OH radicals) in cavitation bubble plasma-treated water (CBPTW) using a chemical probe method. CBPTW samples were prepared with different electrode materials (W, Fe, Cu, and Ag), and the chemical scavenger was added two minutes after the completion of cavitation and plasma treatments. The concentrations of metal ions and hydrogen peroxide (H₂O₂) generated in the CBPTW were also measured over time. This study reveals a novel mechanism whereby metal nanoparticles and ions released from electrodes catalyze the continuous generation of hydroxyl radicals in CBPTW, which has not been fully addressed in previous studies. The results suggest a continuous generation of OH radicals in CBPTW prepared with W, Fe, and Cu electrodes, with the amount of OH radicals produced in the order Cu > Fe > W. The study reveals a correlation between OH radical production and electrode wear, suggesting that the continuous generation of OH radicals in CBPTW results from the catalytic decomposition of H₂O₂ by metal nanoparticles or ions released from the electrodes. It should be noted that cavitation bubble plasma (CBP) is fundamentally different from sonochemistry. While sonochemistry utilizes ultrasound-induced cavitation to generate radicals, CBP relies on plasma discharge generated inside cavitation bubbles. No ultrasound was applied in this study; therefore, all observed radical formation is attributable exclusively to plasma processes rather than sonochemical effects. However, the precise mechanism of continuous OH radical formation in CBPTW remains unclear and requires further investigation. These findings provide new insights into the role of electrode materials in continuous OH radical generation in cavitation bubble plasma treated water, offering potential applications in water purification and sterilization technologies. Full article

Endocytic uptake and lysosomal localization are suggested to be the key mechanisms underlying the toxicity of metal oxide nanoparticles (MONPs), with dissolution in the acidic milieu driving the response. In this study, we aimed to investigate if MONPs of varying solubility are similarly sequestered intracellularly, including in lysosomes and the role of the acidic lysosomal milieu on toxicity induced by copper oxide (CuO) nanoparticles (NPs), nickel oxide (NiO) NPs, aluminum oxide (Al₂O₃) NPs, and titanium dioxide (TiO₂) NPs of varying solubility in FE1 lung epithelial cells. Mitsui-7 multi-walled carbon nanotubes (MWCNTs) served as contrasts against particles. Enhanced darkfield hyperspectral imaging (EDF-HSI) with fluorescence microscopy was used to determine their potential association with lysosomes. The v-ATPase inhibitor Bafilomycin A1 (BaFA1) was used to assess the role of lysosomal acidification on toxicity. The results showed co-localization of all MONPs with lysosomes, with insoluble TiO₂ NPs showing the greatest co-localization. However, only acute toxicity induced by soluble CuO NPs was affected by the presence of BaFA1, showing a 14% improvement in relative survival. In addition, all MONPs were found to be associated with large actin aggregates; however, treatment with insoluble TiO₂ NPs, but not soluble CuO NPs, impaired the organization of F-actin and α-tubulin. These results indicate that MONPs are sequestered similarly intracellularly; however, the nature or magnitude of their toxicity is not similarly impacted by it. Future studies involving a broader variety of NPs are needed to fully understand the role of differential sequestration of NPs on cellular toxicity. Full article

The excessive use of conventional fertilizers has led to low nutrient-use efficiency and significant environmental challenges. To address these limitations, this study aimed to evaluate the effects of Fe₂O₃ and CuO nanoparticles (NPs) as potential nanofertilizers, on the soil chemical composition, nutrient fractionation, enzyme activity, and Lepidium sativum L. growth. The results of the study showed that Fe₂O₃-NPs improved nitrogen bioavailability and enhanced plant biomass, particularly at low to moderate doses. CuO-NPs, in contrast, reduced nitrogen and phosphorus mobility and showed phytotoxic effects at high concentrations. Enzyme activity was suppressed at high NP levels, likely due to oxidative stress. Nutrient fractionation revealed the increased immobilization of phosphorus and the moderate mobilization of potassium and copper, depending on NP type. Based on the results, Fe₂O₃-NPs show potential as a nanofertilizer for enhancing soil fertility and plant growth in sandy loam soils, whereas CuO-NPs require caution due to toxicity risks. Future research should focus on long-term environmental impact, optimal NP concentrations, and their interaction with soil microbial communities. Full article

Aiming to address the key challenges of poor enzyme stability, difficult recovery, and difficult synergistic optimization of catalytic efficiency in high-value conversion of biomass, this study utilizes mineralization self-assembly technology to combine laccase with Fe₃O₄@SiO₂-PMIDA-Cu²⁺ composite, constructing magnetic laccase nanoflower (MLac-NFs) materials with a porous structure and superparamagnetism. This synthetic material can efficiently catalyze the selective oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). The characterization results indicated that MLac-NFs exhibit optimal catalytic activity (63.4 U mg⁻¹) under conditions of pH 6.0 and 40 °C, with significantly enhanced storage stability (retaining 94.26% of activity after 30 days of storage at 4 °C). Apparent kinetic analysis reveals that the substrate affinity and maximum reaction rate of MLac-NFs were increased by 38.3% and 439.6%, respectively. In the laccase–mediator system (LMS), MLac-NFs mediated by 30 mM TEMPO could achieve complete conversion of HMF to FDCA within 24 h. Moreover, due to the introduction of magnetic nanoparticles, the MLac-NFs could be recovered and reused via an external magnetic field, maintaining 53.26% of the initial FDCA yield after six cycles. Full article

In the present research, a novel magnetic adsorbent was developed via the sol–gel method by coating CuFe₂O₄ nanoparticles on biochar sourced from brewed tea waste. The synthesized adsorbent was utilized for the removal of Ni(II) ions from aqueous media. The adsorption efficiency of Ni(II) ions was assessed under crucial experimental conditions such as initial solution pH, contact time, adsorbent dosage, and initial Ni(II) concentration. The adsorbent exhibited rapid adsorption kinetics, achieving equilibrium in approximately 15 min, and maintained high efficiency across a wide pH range. Adsorption experiments were conducted for Ni(II) solutions at their natural pH (5.6) to minimize chemical usage and enhance process simplicity. An impressive maximum adsorption capacity of 232.6 mg g⁻¹ was recorded, outperforming many previously reported adsorbents. Furthermore, desorption studies demonstrated nearly 100% recovery of Ni(II) ions using 1.0 M HCl solution, indicating excellent regeneration potential of the adsorbent. Additionally, the prediction performance of an artificial neural network (ANN) model was evaluated to predict Ni(II) removal efficiency based on experimental variables, showing strong agreement with experimental data. Isotherm and kinetic models were also applied to the data to estimate the adsorption mechanisms. These findings demonstrate the promise of CuFe₂O₄-modified tea waste biochar for sustainable water treatment applications. Full article

Environmental sustainability and responsible resource utilization are critical global challenges. In this work, we present a sustainable and circular-economy-based approach for synthesizing CuFe₂O₄ nanoparticles by directly utilizing copper oxide minerals sourced from Chilean mining operations. Copper sulfate (CuSO₄) was extracted from these minerals through acid leaching and used as a precursor for nanoparticle synthesis via both chemical co-precipitation and microwave-assisted methods. The influence of different precipitating agents—NaOH, Na₂CO₃, and NaF—was systematically evaluated. XRD and FESEM analyses revealed that NaOH produced the most phase-pure and well-dispersed nanoparticles, while NaF resulted in secondary phase formation. The microwave-assisted method further improved particle uniformity and reduced agglomeration due to rapid and homogeneous heating. Electrochemical characterization was conducted to assess the suitability of the synthesized CuFe₂O₄ for supercapacitor applications. Cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) measurements confirmed pseudocapacitive behavior, with a specific capacitance of up to 1000 F/g at 2 A/g. These findings highlight the potential of CuFe₂O₄ as a low-cost, high-performance electrode material for energy storage. This study underscores the feasibility of converting primary mined minerals into functional nanomaterials while promoting sustainable mineral valorization. The approach can be extended to other critical metals and mineral residues, including tailings, supporting the broader goals of a circular economy and environmental remediation. Full article

Heavy metal contamination in natural waters and soils poses a significant environmental challenge, necessitating efficient and sustainable water treatment solutions. This study presents the computational design of low-density polyethylene (LDPE) films functionalized with iron oxide (Fe₃O₄) nanoparticles (NPs) for enhanced water purification applications. Composite materials containing 5%, 10%, and 15% were synthesized and characterized in terms of adsorption efficiency, surface morphology, and reusability. Advanced molecular modeling using BIOVIA Pipeline was employed to investigate charge distribution, functional group behaviour, and atomic-scale interactions between polymer chains and metal ions. The computational results revealed structure–property relationships crucial for optimizing adsorption performance and understanding geochemically driven interaction mechanisms. The LDPE/Fe₃O₄ composites demonstrated significant removal efficiency of Cu²⁺ and Ni²⁺ ions, along with favourable mechanical properties and regeneration potential. These findings highlight the synergistic role of mineral–polymer interfaces in water remediation, presenting a scalable approach to designing multifunctional polymeric materials for environmental applications. This study contributes to the growing field of polymer-based adsorbents, reinforcing their value in sustainable water treatment technologies and environmental protection efforts. Full article

Tomatoes are a fundamental part of the daily diet, rich in carbohydrates, vitamins, minerals, carotenoids, and polyphenols. Nonetheless, optimal fruit yield and quality typically depend on the application of synthetic agrochemicals. However, the irrational use of these agrochemicals has caused various environmental problems. Therefore, it is necessary to develop alternatives to conventional agrochemical products. Applying nanomaterials as fertilizers in tomato production is emerging as a promising approach, with documented improvements in germination, vegetative development, and fruit yield. Therefore, we present a comprehensive review of recent developments (2015–2024) in the application of nanomaterials in tomato crops, with a particular emphasis on the significance of nanomaterial characteristics in their role as fertilizers. Several types of nanomaterials, such as ZnO, Ag, TiO₂, Si, hydroxyapatite, P, Zn, Se, CuO, Cu, Fe, Fe₂O₃, CaO, CaCO₃, and S, have been evaluated as fertilizers for tomato crops, with ZnO nanoparticles being the most extensively studied. However, it is pertinent to conduct further research on the less-explored nanomaterials to gain a deeper understanding of their effects on seed germination, plant growth, and fruit quality and quantity. Full article