Search Results (43)

In this work, ZnO nanoparticles were synthesized via a plant-mediated green route using Prosopis tamaulipana extract as a reducing and stabilizing agent and subsequently modified with silver to obtain Ag-modified ZnO powders. Structural and morphological characterization techniques confirmed the formation of nanocrystalline ZnO with a hexagonal wurtzite structure, submicrometric agglomerates composed of nanosized primary particles and a high degree of phase purity, indicating the effectiveness of the synthesis approach. The photocatalytic performance of the Ag-modified ZnO materials was evaluated under natural solar irradiation using methylene blue as a model organic contaminant in aqueous solution. Visual observations, together with absorbance, temperature and electrical conductivity measurements, demonstrated an effective and progressive degradation of the dye over a 5 h irradiation period. The observed increase in electrical conductivity under illumination was associated with enhanced charge carrier generation and improved separation efficiency, as well as the formation of reactive oxygen species, promoted by the presence of Ag as an electron sink. These results confirm that green-synthesized Ag-modified ZnO nanoparticles exhibit enhanced photocatalytic activity and are promising multifunctional materials for sustainable water sanitation applications. Full article

This work reports the synthesis, characterization, and photocatalytic performance of multifunctional spheres based on AgNP-doped TiO₂-Fe₃O₄ embedded in an alginate–chitosan biopolymeric matrix for the removal of organic contaminants from water. The composite powders exhibited a nanocrystalline structure composed of anatase TiO₂ (~20 nm) and magnetite (~25 nm), with homogeneously dispersed Ag nanoparticles, as observed by SEM. The spheres presented a mainly submicrometric particle size distribution (0.55–0.92 µm), favoring high surface area and colloidal stability. Under simulated solar irradiation, the material achieved efficient photocatalytic degradation of methylene blue, with a pseudo-first-order rate constant of 0.112 h⁻¹ and ~46% decolorization after 5 h. UV-Vis spectra showed progressive attenuation of the dye absorption band without accumulation of intermediates. Magnetic recovery tests confirmed rapid separation and reuse without performance loss. The enhanced activity is attributed to the synergistic interaction among plasmonic Ag, photocatalytic TiO₂, redox-active Fe₃O₄, and the adsorptive carbon–biopolymer matrix. The material exhibited strong antibacterial activity, achieving over 90% removal of fecal coliforms after 5 h of irradiation. Therefore, the developed AgNP-doped TiO₂-Fe₃O₄ spheres represent a sustainable, reusable, and efficient material for solar-assisted water sanitation. Full article

Luminescent organic–inorganic Cu(I) halide hybrid molecular crystals exhibit remarkable structural diversity and photophysical properties, but their application in aqueous environments is often limited by insufficient stability. Herein, we report portable and reusable photoluminescent sensors based on Cu(I)–I triethylenediamine derivatives [Cu₄I₆(pr-ted)₂] and [Cu₃I₅(bz-ted)₂] (pr-ted = 1-propyl-1,4-diazabicyclo[2.2.2]octan-1-ium; bz-ted = 1-benzyl-1,4-diazabicyclo[2.2.2]octan-1-ium). Their submicrometric particles exhibit intense UV-excited emissions and high photoluminescence quantum yields but limited water stability. To address this limitation, ultrasound sonication was employed to control particle size and produce stable suspensions that can be incorporated into polymeric matrices via 3D printing with photocurable resins or polylactic acid (PLA) films by drop-casting, yielding mechanically robust composites that retain their structural and optical properties. The devices used act as selective turn-off luminescent sensors for Fe³⁺ in aqueous media, with nanomolar detection limits (1.33–1.58 nM) below regulatory thresholds for drinking water. Moreover, [Cu₃I₅(bz-ted)₂] enables tetracycline detection in river water with a limit of detection of 0.038 nM. Mechanistic studies indicate that reversible photoinduced electron transfer is the primary quenching pathway, while composites maintain sensing performance over multiple reuse cycles. Full article

Titanium dioxide (TiO₂) nano- and submicrometric particles’ widespread use in different sectors raised concerns about human and environmental exposure. The validation of analytical methods is essential to ensure reliability in risk assessment studies. In this study, a single-particle inductively coupled plasma mass spectrometry (spICP-MS) method was validated for the detection, quantification, and dimensional characterization of TiO₂ particles in biological tissues. Tissue samples collected after exposure to TiO₂ particles underwent mild acidic digestion using a HNO₃/H₂O₂ mixture to achieve complete matrix decomposition while preserving particle integrity. The resulting digests were analyzed by ICP-MS operated in single-particle mode to quantify and size TiO₂ particles. Method validation was conducted according to ISO/IEC 17025:2017 and included linearity, repeatability, recovery, and detection limit assessments. The limit of detection for TiO₂ particles was 0.04 µg/g, and 55.7 nm was the size the detection limit. Repeatability was within 0.5–11.5% for both TiO₂ mass concentrations and particle size determination. The validated method was applied to tissues from inhalation-exposed subjects, showing TiO₂ levels of 80 ± 20 µg TiO₂/g and particle number concentrations of 5.0 × 10⁵ ± 1.2 × 10⁵ part. TiO₂/mg. Detected TiO₂ particles’ mean diameter ranged from 230 to 330 nm. The developed and validated spICP-MS method provides robust and sensitive quantification of TiO₂ particles in biological matrices, supporting its use in human biomonitoring and exposure assessment studies. Full article

The characterization of airborne submicrometric composite structures’ debris is a challenge in the field of environmental monitoring and control. The work presented here aims to develop a new quantitative method to measure elemental mass concentrations via particle sampling and Transmission Electron Microscopy—Energy-Dispersive X-ray Spectroscopy (TEM-EDS). The principle is to collect airborne particles on a porous TEM grid, then add a certain mass of reference particles, and compare the relative mass percentages of elements from reference and sample particles via EDS. Diverse pairs of airborne particles (RbCl, CsCl, NaCl, SrCl₂, Ga(NO₃)₃, braking particles) were deposited on one TEM grid, and the experimental elemental mass ratios were measured by EDS and compared with the theoretical values. Results show that the quantitative and homogeneous collection of reference particles, such as RbCl, on the TEM grid could be suitable. For all the tested conditions, the absolute deviations between the theoretical elemental mass ratios and the experimental ratios remain lower than 8%. Thus, the mass concentration of Fe from the braking aerosol is calculated as 107 µg/m³. Compared to the cumbersome real-time instrument, this new method for mass characterization appears to be convenient, and requires a short time of aerosol sampling at the workplace. This approach ensures safety and practicability when assessing, e.g., the exposure risk of hazardous materials. Full article

This study presents a multilayer magnetic Janus sub-micrometric particle (MMJSP) as a nanoreactor for lipase catalysis. The core of the nanoparticle is constructed from a core-shell Fe₃O₄@SiO₂ framework, which serves as a precursor for the sequential amino and aldehyde modifications using 3-aminopropyltriethoxysilane and benzaldehyde. Following localized etching and subsequent modification with N,N-dimethyldodecylamine, a Janus nanoparticle with distinct hydrophilic and hydrophobic domains is synthesized. The resulting MMJSP demonstrates a stable attachment to the reaction interface and significantly enhances lipase performance, exhibiting 1.4-fold and 1.6-fold enhancements in activity after immobilization during 1 h hydrolysis and 24 h esterification reactions, respectively. Additionally, the storage stability of the immobilized lipase is improved by 100% over a period of 30 days. Reusability assessments reveal that the immobilized enzyme retains 80.7% activity after 10 cycles of esterification and 80.6% after 50 cycles of hydrolysis, with the magnetic properties allowing for rapid separation and recovery of the immobilized enzyme. Full article

A Si/SiC/SiO₂ (53/44/3 wt.%) composite is evaluated as an anode material for Li-ion batteries. This material, a result of the high-energy ball-milling of a by-product of the carbothermal reduction of silica (Si slag), is predominantly made up of micrometric particles of amorphous or short-range order Si in which submicrometric SiC inclusions are dispersed. Its capacity is 860 mAh g⁻¹ (1.7 mAh cm⁻²) after 200 cycles in half-cell configuration and 1.6 mAh cm⁻² after 70 cycles in full-cell. The SiC component is not electroactive for lithiation but plays a key role in the electrode stability by preventing the formation of the c-Li₁₅S_i4 phase, known to accelerate electrode degradation. It is shown that capacity decay with cycling mainly originates from solid electrolyte interphase (SEI) growth rather than particle disconnections. Complementary wide angle X-ray scattering (WAXS) analyses confirm the SEI grows alongside cycling and allows for the highlighting of its major components, namely, Li₂CO₃ and LiF. The morphological evolution of the electrode upon cycling is studied by electrochemical dilatometry, operando optical microscopy, and focused ion beam (FIB) and broad ion beam (BIB) scanning electron microscopy (SEM). No particle cracking is observed. However, reconstructed 3D imaging of the electrodes before and after 10 and 200 cycles clearly shows that the particles progressively evolve a dendritic structure. The SEI grows on and within the particles and induces a significant decrease in the electrode’s porosity and an increase in its thickness. Full article

This study investigates the mechanochemical transformation of commercial vermiculites from Uganda and China, processed for 30 minutes (30 min), 8 hours (8 h), and 24 hours (24 h). Structural and textural modifications were analyzed using X-ray diffraction (XRD), thermogravimetric analysis (TGA), BET surface area measurements, and scanning electron microscopy (SEM). Characterization via X-ray diffraction (XRD), thermogravimetric analysis (TGA), BET surface area measurements, and scanning electron microscopy (SEM) revealed substantial structural and textural modifications. Crystallinity decreased significantly, from 66.37% to 3.47% in the Ugandan sample, whereas the three mixed-phase Chinese samples exhibited greater structural resilience, with final crystallinity ranging from 3.82% to 6.30%. Mechanochemical treatment induced mineral phase transformations, including hydrobiotite formation in the Ugandan sample and Fe₃Si, quartz, moganite, and NaMgH₃ in the Chinese samples. Particle size reduced significantly, reaching submicrometric dimensions after 24 h, with C1 showing the smallest mean size (0.39 µm). BET analysis showed an initial increase in specific surface area, peaking at 31.83 m²/g for C1 after 8 h, followed by a decrease due to pore collapse. The optimal treatment time varied by sample, with 30 min maximizing adsorption in C2 and C3, while 8 h was most effective for C1. These findings highlight mechanochemical treatment as a viable method for tuning vermiculite properties for applications in adsorption, catalysis, and composite materials. Full article

This review discusses the literature data on the synthesis, physicochemical properties, and cytotoxicity of composite nanoparticles bearing the mitochondrial protein cytochrome c (cytC), which can act as a proapoptotic mediator in addition to its main function as an electron carrier in the electron transport chain. The introduction of exogenous cytC via absorption of carrier particles, the phagocytosis of colloid particles of submicrometric size, or the receptor-mediated endocytosis of nanoparticles in cancer cells, initiates the process of apoptosis—a multistage cascade of biochemical reactions leading to complete destruction of the cells. CytC–carrier composite particles have the potential for use in the treatment of neoplasms with superficial localization: skin, mouth, stomach, colon, etc. This approach can solve the two main problems of anticancer therapy: selectivity and non-toxicity. Selectivity is based on the incapability of the normal cell to absorb (nano)particles, except for the cells of the immune system. The use of cytC as a protein that normally functions in mitochondria is harmless for the macroorganism. In this review, the factors limiting cytotoxicity and the ways to increase it are discussed from the point of view of the physicochemical properties of the cytC–carrier particles. The different techniques used for the preparation of cytC-bearing colloids and nanoparticles are discussed. Articles reporting the achievement of high cytotoxicity with each of the techniques are critically analyzed. Full article

Background/Objectives: This study investigates for the first time the use of the prilling technique in combination with solvent evaporation to produce nano- and submicrometric PLGA particles to deliver properly an active pharmaceutical ingredient. Curcumin (CCM), a hydrophobic compound classified under BCS (Biopharmaceutics Classification System) class IV, was selected as the model drug. Methods: Key process parameters, including polymer concentration, solvent type, nozzle size, and surfactant levels, were optimized to obtain stable particles with a narrow size distribution determined by DLS analysis. Results: Particles mean diameter (d₅₀) 316 and 452 nm, depending on drug-loaded cargo as Curcumin-loaded PLGA nanoparticles demonstrated high encapsulation efficiency, assessed via HPLC analysis, stability, and controlled release profiles. In vitro studies revealed a faster release for lower drug loadings (90% release in 6 h) compared to sustained release over 7 days for higher-loaded nanoparticles, attributed to polymer degradation and drug-polymer interactions on the surface of the particles, as confirmed by FTIR analyses. Conclusions: These findings underline the potential of this scalable technique for biomedical applications, offering a versatile platform for designing drug delivery systems with tailored release characteristics. Full article

Ir-based catalysts are the best in terms of activity and stability for oxygen evolution reactions (OERs) in proton exchange water electrolysis. Due to their cost, efforts have been made to decrease their load without a loss of activity. In this paper, Ir nanoparticles measuring 2–3 nm were loaded on TiO₂ anatase supports of submicrometric size in different amounts using the microwave polyol method to optimize their mass activity. Using anatase particles with a diameter of about 100 nm and titania nanotubes (TNTs), Ir/TiO₂ catalysts with Ir contents of 5, 10, 20, and 40 wt.% were synthesized and characterized via structural and electrochemical techniques. It was shown that the amount of Ir must be regulated to obtain continuous coverage on titania with strong Ir–TiO₂ interactions which, for the 100 nm diameter anatase, is limited to about 20 wt.%. A higher percentage of Ir over 40 wt.% can be dispersed over the TNTs. Exceeding one layer of coverage leads to a decrease in the catalyst’s utilization. Ir/TiO₂(10:90), Ir/TiO₂(20:80), and Ir/TiO₂(40:60) presented the highest pseudocapacitive currents per unit of Ir mass. The electrochemical active areas and mass activities for these later catalysts were also the highest compared to Ir/TiO₂(05:95), Ir/TNT(40:60), and the unsupported catalysts and increased from 40 to 10 wt.% Ir. They also presented the lowest overpotentials of about 300 mV at 10 mA cm⁻² for the OER, with Ir/TiO₂(10:90) presenting the best specific activities and surface turnover frequencies, thus showing that the size of the support can be regulated to decrease the Ir content of the catalyst without a loss of activity. Full article

Student sleepiness during classes is a frequently reported condition that can impair performance in the teaching–learning process and is even unsustainable for health. Although the environmental quality of the classroom may affect the students’ sleepiness, studies that exhaustively investigate the relationship between indoor environmental quality (IEQ) and sleepiness levels in classrooms are lacking. To this end, in the present paper, we carried out an experimental pilot study involving twenty-seven Italian adolescent students to determine the increase in their sleepiness rate during the school period utilizing the Epworth Sleepiness Scale (ESS). The analysis was performed in a classroom in which the indoor environmental quality was monitored, including measurements of the thermal comfort, sound pressure level, illuminance, carbon dioxide (CO₂) concentrations, and airborne particle concentrations (both sub-micrometric particles and PM₁₀). Three measurement days were considered. The results showed that student sleepiness significantly increased during the school period (Day 1 p = 0.00, Day 2 p = 0.03, and Day 3 p = 0.03). This increase was observed on measurement days characterized as having both perceived higher and lower thermal comfort and even in the presence of limited exposure to airborne particle concentrations, presenting an association with the high indoor concentration of CO₂ detected in the classroom (Day 1 between 978 and 3261 ppm; Day 2 between 1044 and 2338 ppm; Day 3 between 1116 and 2623 ppm), due to reduced ventilation rates and the students’ sleepiness. Thus, the findings suggest that adequate ventilation rates can limit the increase in the rate of sleepiness, indicating, from our pilot study, that recommendations of sustainable environmental practices through comprehensive feasibility studies can promote positive changes in indoor environments such as classrooms. Full article

This paper deals with the development and characterization of an Inconel 625 (IN625) reinforced with 2 wt.% of sub-micrometrical TiC particles produced by the laser powder bed fusion (LPBF) process. IN625 and IN625 2 wt.% TiC microstructural evolution was evaluated in the as-built, solution-annealed (2 h at 1150 °C), and prolonged heat-treated (2 h at 1150 °C + 100 h at 1000 °C) conditions. The IN625 and IN625 + TiC samples were successfully produced with low residual porosity (<0.15%). In the as-built conditions, both materials developed mainly columnar grains elongated to the building direction with melt pools, fine dendric structures, and small fractions of recrystallized grains. Some TiC segregations were observed in the composite, preferentially located at the melt pool boundaries. The heat treatments led to a different microstructural evolution between the base alloy and the composite. After solution annealing, the IN625 alloy was subjected to full recrystallization with a drastic reduction in hardness. Afterward, the prolonged thermal exposures for 100 h at 1000 °C provoked the formation of carbides, increasing the hardness. On the contrary, the composite retained the as-built microstructure with columnar grains in the solution-annealed and prolonged heat-treated conditions, revealing a limited formation and growth of carbides, thus resulting in a reduced hardness variation. The addition of TiC inside the IN625 enhanced the microstructural stability of the composite, preventing the recrystallization and the growth of phases occurring under prolonged thermal exposures. The current study therefore reported the effect of TiC particles on the microstructural stabilization of LPBFed IN625, with a peculiar focus on the prolonged thermal exposure at 1000 °C. Full article

Liposomes coated with chitosan by ionic gelation with tripolyphosphate (TPP-chitosomes) are interesting particles for stabilizing active compounds. However, the encapsulation condition must be optimized. The aim of this study was to optimize the encapsulation of phenolics and carotenoids of carrot pomace in TPP-chitosomes by using a Central Composite Design 2³ and response surface methodology. The independent variables were the phospholipid (0.8–4.2 mg/mL), chitosan (2.6–9.4 mg/mL), and carrot pomace (4–14 g/100 mL of ethanol) concentrations; the responses were the encapsulation efficiency in TPP-chitosomes (EE) of phenolics, a-carotene, and b-carotene and the particle size and zeta potential of the particles. The zeta potential ranged from +17 to +37 mV, indicating that the liposomes were coated with chitosan and that the particle sizes were in the nanometric to submicrometric scale. The optimized condition for encapsulating carotenoids was 2.5 mg/mL phospholipids, 6.0 mg/mL chitosan, and 12 g of carrot pomace/100 mL of ethanol. In this condition, the EE of phenolics and α- and β-carotene was 95%, 98%, and 99%, respectively. Therefore, TPP-chitosomes containing encapsulated phenolics and carotenoids, which can be obtained from agro-industrial by-products, have potential application as natural pigments in food or cosmetics. TPP-chitosomes can also be used to encapsulate other types of natural pigments. Full article

Background: Escalating global plastic production, expected to reach 34,000 million tons by 2050, poses a significant threat to human and environmental well-being, particularly in aquatic ecosystems. Microplastics (MP) and nanoplastics (NP), which originate from the degradation of plastics, are of concern due to their potential bioaccumulation and uptake of pollutants. This study addresses identification methods and focuses on insect meal, a raw material for aquaculture feed. Methods: By using different techniques, the study was able to detect MP and NP in insect meal samples. Chemical digestion with KOH at 60 °C efficiently removed organic matter without affecting the synthetic polymer polyethylene (PE). Filtration, confocal Raman microscopy, SEM, and TEM were used for comprehensive analysis, and integrity tests on PE films were performed using Raman and FTIR spectroscopy. The results showed the presence of PE microplastic particles in the insect meal, which was confirmed by correlative Raman and SEM mapping on a positively charged surface. In addition, the increased resolution of the Raman microscope identified submicrometric PE NP (800 nm). Transmission electron microscopy (TEM) with energy-dispersive X-ray spectroscopy (EDX) confirmed plastic-like structures in the insect meal, highlighting the presence of PE plastics characterized by irregular shapes and some agglomeration. The higher carbon concentration in the EDX analysis supported the plastic nature, which was also confirmed by Raman spectroscopy. Conclusions: The study provides a robust method for the detection of MP and NP in insect meal and provides valuable insight into the possible presence of plastics in insect-based aquafeeds. The combination of different analytical methods increases the reliability of the results and sets the stage for future investigations that could focus on the quantification of NP and the assessment of their potential environmental impact. Full article