Search Results (53)

Background/Objectives: Optimizing synthesis parameters is essential to ensure the quality and stability of nanostructures. This study aimed to optimize the synthesis of selenium nanoparticles (SeNPs) by chemical reduction, using sodium selenite (Na₂SeO₃), ascorbic acid (AA), and polyvinyl alcohol (PVA) at different concentrations, volumes, and molar ratios. The effects of reduction time, purification steps, and variations in the concentration of the precursor and reducing agent, as well as in the volume of the stabilizer, on the characteristics of SeNPs were investigated to ensure their long-term stability, maintenance of their properties, and biological applicability. Methods: The SeNPs were analyzed by UV/Vis absorption spectroscopy, Dynamic Light Scattering (DLS), and Transmission Electron Microscopy (TEM), and were also evaluated for antifungal activity against the SC5314 strain of Candida albicans. Results/Conclusions: Monodisperse SeNPs were obtained under high concentrations of Na₂SeO₃ and AA, short reduction time, higher volumes of PVA (2–4 mL), and purification at 24.300× g, presenting a spherical morphology, hydrodynamic diameter of 137.0–171.7 nm, dry diameter of 20–120 nm, polydispersity index of 0.049–0.306, Zeta potential of −7.79 to −19.6 mV, and stability for up to 180 days. In the absence or presence of 1 mL of PVA, the SeNPs were predominantly amorphous. Regarding biological activity, the SeNPs did not exhibit antifungal activity under the experimental conditions in the tested strain. Together, this study provides a comprehensive update on the synthesis of SeNPs under different conditions and their stability over time, contributing to the consolidation of knowledge in the field. Full article

Background/Objective: Resin-based composite (RBC) gained wide popularity in dentistry due to its excellent biocompatibility, superior aesthetics, and good bonding to enamel and dentine. However, they have several shortcomings, including mechanical insufficiency and shrinkage tendency. Many researchers have utilized nanoparticles (NPs) as a reinforcing filler for RBCs. This article focused on assessing the impact of three different nanoparticles, ZrO₂, TiO_2, and SiO_2, with concentrations of 3 wt% and 7 wt%, on the elastic modulus (E) and fracture toughness (K_IC) of one commercial light-activated dental resin composite. Methods: 140 rectangular specimens were constructed according to ISO 4049 with dimensions (25 × 2 × 5 ± 0.03 mm) and (25 × 2 × 2 ± 0.03 mm) for fracture toughness and elastic modulus, respectively. Specimens were categorized into four main groups based on nanofiller types. Control: plain without filler (CC) and three modified ones with ZrO₂ (ZC), TiO₂ (TC), and SiO₂ (SC). Furthermore, modified groups were divided into two subgroups according to nanofiller concentration, 3 and 7 wt% (ZC3, ZC7, TC3, TC7, SC3, and SC7), n = 10. Mechanical testing for fracture toughness was completed using a single-edge notched beam, while a three-point bending test was used for elastic modulus. Analysis of data was based on two-way ANOVA and Bonferroni post hoc (α = 0.05). Results: ZrO₂ provided the most substantial improvement in both E and K_IC, with the optimal performance observed at 3 wt% for stiffness and 7 wt% for toughness. TiO₂ groups also enhanced these properties at both concentrations; however, the gains were less pronounced compared to ZrO₂. SiO₂ improved mechanical performance at 3 wt%, but a higher loading of 7 wt% resulted in reduced values. Conclusions: Resin-based composite modified with 3 wt% of NPs tends to possess higher fracture toughness and modulus of elasticity. Fracture toughness enhancement was concentration-dependent with ZrO₂ NPs, where the best result was obtained with 7 wt%. Nanoparticle-reinforced composite, particularly ZrO₂, may be suitable for prosthodontic applications. Full article

Microglia-derived small extracellular vesicles (MGEVs) are key mediators of neuroimmune communication, yet their cross-species comparability and translational relevance remain poorly defined. Here, we establish a harmonized framework to compare the molecular and biochemical signatures of sEVs derived from immortalized mouse (BV2) and human (HMC3) microglial cells as well as assess their bioactivity on a human Schwann cell (HuSC) line. MGEVs were isolated via MISEV-aligned size-exclusion chromatography (SEC) and characterized by nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM), and immunoblotting for canonical EV markers CD9, CD63, CD81, TSG101. Human and mouse MGEVs exhibited similar morphology but displayed distinct membrane tetraspanin protein enrichment patterns. Functionally, mouse and human MGEVs attenuated HuSC migration while enhancing HuSC proliferation and their resistance to H₂O₂-induced oxidative stress, with human MGEVs providing stronger protective effects, suggesting they retain similar core functional properties. Short, non-coding-miRNA sequencing analysis identified 196 shared miRNAs (Spearman ρ = 0.72) with species-specific enrichment: human MGEVs-derived miRNAs favored regenerative and metabolic pathways, whereas mouse MGEVs-derived miRNAs aligned more so with inflammatory signaling. This study delivers the first integrated cross-species blueprint of MGEVs, revealing conserved neuroprotective actions alongside species-biased miRNA cargo that define translational boundaries and highlight human-relevant MGEV signatures for therapeutic innovation, therefore contributing to the importance of considering these differences in translational research. Full article

Zinc oxide (ZnO) is a widely studied photocatalyst for the degradation of organic pollutants in water, yet its conventional sol–gel synthesis often suffers from low yield and produces materials with low specific surface area. In this study, we tackled these limitations by synthesizing ZnO nanoparticles using a supercritical-CO₂-assisted sol–gel method (ZnO-scCO₂). The influence of the calcination temperature, precursor concentration, and solvent type on the synthesis of ZnO was systematically investigated, and the materials were characterized with a combination of techniques (XRD, SEM, N₂ physisorption, UV-Vis-DRS spectroscopy). The photocatalytic performance of the ZnO-scCO₂ materials was evaluated in the degradation of two probe pollutants (phenol and rhodamine B, 200 ppm), under UV and visible radiation. The scCO₂-assisted method in ethanol as the solvent allowed achieving at least a four-fold higher ZnO yield and two-fold higher surface area compared to the materials prepared with a conventional sol–gel route without scCO₂. These ZnO-scCO₂ nanoparticles consistently showed enhanced photocatalytic activity in the removal of phenol and rhodamine B compared to their counterparts synthesized without scCO₂ and compared to commercial ZnO. Among the screened synthetic parameters, the solvent in which ZnO was prepared proved to be the one with the strongest influence in determining the ZnO yield and its photocatalytic activity. The optimum results were obtained using 0.50 M zinc acetate as the precursor in 1-butanol as the solvent, and calcination at 300 °C. Full article

The reliance on carbon-based fuels remains a major contributor to greenhouse gas emissions, emphasizing the need for sustainable alternatives such as hydrogen. Sodium borohydride (NaBH₄), with a hydrogen content of 10.6 wt%, is a promising chemical hydrogen storage material capable of releasing four moles of H₂ per mole through hydrolysis; however, effective catalysts are essential for practical implementation. In this study, silver nanoparticles supported on glucose-derived carbon microspheres (AgSC) were synthesized and evaluated for catalytic NaBH₄ hydrolysis. Structural characterization (XRD, TEM, SEM, EDS) confirmed the uniform dispersion of metallic silver nanoparticles on the carbon support with no detectable Ag₂O phase. AgSC exhibited superior catalytic activity compared to unsupported Ag or bare carbon, achieving the highest hydrogen generation under neutral pH, elevated temperatures, and 835 µmol NaBH₄. The catalyst displayed an activation energy of 54 kJ mol⁻¹, turnover numbers (TONs) of 1.4 × 10⁵–1.9 × 10⁵, and turnover frequencies (TOFs) of 7.1 × 10⁴–9.3 × 10⁴ h⁻¹, demonstrating efficient utilization of active sites. pH-dependent studies revealed optimal hydrogen yield under neutral conditions, while acidic and basic media reduced performance due to surface poisoning and BH₄⁻ stabilization, respectively. Reusability tests showed only ~5% activity loss after five cycles. These findings establish AgSC as a stable, efficient, and recyclable catalyst for on-demand hydrogen generation, supporting sustainable clean fuel technologies. Full article

Co₃O₄ nanoparticles synthesized by solution combustion synthesis present a versatile platform for the development of porous nanostructures with tunable morphology and physicochemical properties. Synthesis conditions and parameters such as fuel type; fuel-to-oxidizer ratio and temperature control lead yielding; and Co₃O₄ NPs with fine particle size, surface area, and porosity result in enhancing their electrochemical and catalytic capabilities. This review evaluates present studies about SCS Co₃O₄ NPs to study how synthesis parameter modifications affect both surface morphology and material structure characteristics including porosity features, which make their improved performance ideal for lithium-ion batteries and supercapacitors. Moreover, the integration of dopants with carbon-based hybrid composites enhances material conductivity and stability by addressing both capacity fading and low electronic conductivity concerns. This review mainly aims to explore the significant relation between fundamental material design principles together with practical uses and provides predictions about future research advancements that aim to enhance the performance of Co₃O₄ NPs in next-generation energy and environmental technology applications. Full article

We have investigated for the first time the temperature, size, and ion-doping concentration dependence of the magnetic properties, band-gap energy, and specific heat of CuFeO₂ in both bulk materials and nanoparticles using a microscopic model (the s-d model) and Green’s function theory. Variations in the ionic radii of the dopant elements compared to those of the host ions introduce strain effects, which alter the exchange-interaction constants. Consequently, the influence of ion doping on the various properties of CuFeO₂ nanoparticles has been elucidated at a microscopic level. The magnetization exhibits an increase when CuFeO₂ is doped with Mn at the Fe site or Li and Ca at the Cu site, whereas doping with Sc or Mg at the Fe site leads to a decrease in magnetization. Regarding the band-gap energy, it increases upon doping with Mg and Sc at the Fe site, while doping with Mn at the Fe site or with Li and Ca at the Cu site results in a decrease. The temperature dependence of the specific heat reveals two distinct peaks, corresponding to the two magnetic phase-transition temperatures. The theoretical results show good qualitative agreement with experimental data, confirming the validity of the proposed model. Full article

Solution combustion synthesis (SCS) is often utilized to prepare crystalline nanoparticles of transition metal oxides, in particular Mn oxides. The structure and composition of the final product depend on the conditions of the synthesis, in particular on the composition of metal precursors, its molar ratio to the fuel component, and the mode of heating. In the present work, the study of chemical phenomena that may occur in the SCS process has been studied for the conventional nitrate–glycine synthesis of Mn oxide, as well as for nitrate–citrate–glycine and nitrate–citrate–urea synthesis. In the case of nitrate–glycine synthesis at a 1:1 fuel-to-salt ratio, the formation of a weak complex of Mn(II) and glycine provides the conditions for an instantaneous SCS reaction upon heating, resulting in slight sintering of final oxide nanoparticles. Partial hydrolysis of the Mn precursor during slow solvent evaporation results in the formation of a mixture of oxides, namely MnO and Mn₃O₄. Formation of MnO is completely suppressed when ammonium citrate is added into the initial mixture. Pure Mn₂O₃ oxide is obtained from nitrate–citrate synthesis, while the pure Mn₃O₄ phase is obtained in the case of nitrate–citrate–glycine and nitrate–citrate–urea synthesis, due to the higher temperature generated in the presence of additional fuel. In the presence of citrate, the SCS reaction is slower, resulting in stronger sintering of the nanoparticles. The study of the electrochemical properties of synthesized oxides demonstrates that SCS with the nitrate–citrate–urea mixture provides the highest charge capacitance in 1 M NaOH: 130 F/g at 2 A/g. The impedance characterization of materials allows us to propose a tentative mechanism of degradation of electrode materials during galvanostatic cycling. Full article

This study investigates the high-pressure structural and vibrational properties of nano-Sc₂O₃ using a combination of X-ray diffraction, Raman spectroscopy, and theoretical calculations. Nano-Sc₂O₃ maintains its cubic bixbyite structure up to 26.4 GPa, without evidence of phase transitions, contrasting with bulk Sc₂O₃, which transitions to a monoclinic phase around 25–28 GPa. Raman spectroscopy reveals a pressure-induced blue shift in the vibrational modes, indicating lattice compression, and the absence of new modes confirms the retention of the cubic symmetry. Theoretical predictions using density functional theory (DFT) closely match the experimental data, validating the computational approach we use to model the pressure-dependent vibrational behavior of nano-Sc₂O₃. Comparisons with previous studies seem to show that the nanoscale material exhibits enhanced structural stability compared to its bulk counterpart, likely due to size effects and surface energy contributions. These findings provide new insights into the behavior of nanomaterials under extreme conditions and highlight the potential applications of nano-Sc₂O₃ in high-pressure environments. Full article

This work describes the preparation of highly homogeneous thermoplastic starches (TPS’s) with the addition of 0, 5, or 10 wt.% of maltodextrin (MD) and 0 or 3 wt.% of TiO₂ nanoparticles. The TPS preparation was based on a two-step preparation protocol, which consisted in solution casting (SC) followed by melt mixing (MM). Rheology measurements at the typical starch processing temperature (120 °C) demonstrated that maltodextrin acted as a lubricating agent, which decreased the viscosity of the system. Consequently, the in situ measurement during the MM confirmed that the torque moments and real processing temperatures of all TPS/MD systems decreased in comparison with the pure TPS. The detailed characterization of morphology, thermomechanical properties, and local mechanical properties revealed that the viscosity decrease was accompanied by a slight decrease in the system homogeneity. The changes in the real processing temperatures might be quite moderate (ca 2–3 °C), but maltodextrin is a cheap and easy-to-add modifier, and the milder processing conditions are advantageous for both technical applications (energy savings) and biomedical applications (beneficial for temperature-sensitive additives, such as antibiotics). Full article

In this work, non-ordered and ordered CeO₂-based catalysts are proposed for CO₂ conversion to dimethyl carbonate (DMC). Particularly, non-ordered mesoporous CeO₂, consisting of small nanoparticles of about 8 nm, is compared with two highly porous (635–722 m²/g) ordered CeO₂@SBA-15 nanocomposites obtained by two different impregnation strategies (a two-solvent impregnation method (TS) and a self-combustion (SC) method), with a final CeO₂ loading of 10 wt%. Rietveld analyses on XRD data combined with TEM imaging evidence the influence of the impregnation strategy on the dispersion of the active phase as follows: nanoparticles of 8 nm for the TS composite vs. 3 nm for the SC composite. The catalytic results show comparable activities for the mesoporous ceria and the CeO₂@SBA-15_SC nanocomposite, while a lower DMC yield is found for the CeO₂@SBA-15_TS nanocomposite. This finding can presumably be ascribed to a partial obstruction of the pores by the CeO₂ nanoparticles in the case of the TS composite, leading to a reduced accessibility of the active phase. On the other hand, in the case of the SC composite, where the CeO₂ particle size is much lower than the pore size, there is an improved accessibility of the active phase to the molecules of the reactants. Full article

Zinc oxide (ZnO) nanoparticles are widely recognized for their distinctive properties and versatile applications across diverse technological domains. However, traditional methods of synthesizing ZnO nanoparticles are characterized by environmental incompatibility, high costs, and the necessity for precise process control to attain the intended particle dimensions and morphology. The present study utilized a chives extract as a sustainable and eco-friendly fuel in the solution combustion synthesized (SCS) process to produce ZnO nanoparticles. The investigation encompassed an analysis of the impact of the fuel-to-oxidizer (F/O) ratio on the synthesized ZnO nanoparticles’ size, morphology, and crystallinity. X-ray diffraction (XRD) results showed that the particle’s crystallite size increased significantly from 12 nm to 42 nm after decreasing the F/O ratio. Furthermore, electron microscopic imagery and FTIR spectroscopy outcomes indicated that modifications in the F/O ratio significantly influenced the SCS process parameters, forming particles with diverse morphologies, including spherical, pyramid-like, hexagonal, and hexagonal plate-like shapes. This research presents a straightforward, cost-efficient, and environmentally sustainable approach for producing ZnO nanoparticles with diverse morphologies, presenting a broad potential for various applications. Full article

Sodium citrate (SC) is sensitive to violet light illumination (VLI) and acts as a weak reductant. Conversely, gold (III) chloride trihydrate (GC) often acts as an oxidant in a redox reaction. In this study, the influences of colored light on the production of gold nanoparticles (AuNPs) in a mixture of gold (III) ions and citrate via VLI and the antibacterial photodynamic inactivation (aPDI) of Escherichia coli (E. coli) are determined under alkaline conditions. The diameter of AuNPs is within the range of 3–15 nm, i.e., their mean diameter is 9 nm; when citrate is mixed with gold (III) ions under VLI, AuNPs are formed via an electron transfer process. Additionally, GC mixed with SC (GCSC) inhibits E. coli more effectively under VLI than it does under blue, green, or red light. GCSC and SC are shown to inhibit E. coli populations by 4.67 and 1.12 logs, respectively, via VLI at 10 W/m² for 60 min under alkaline conditions. GCSC-treated E. coli has a more significant photolytic effect on anionic superoxide radical (${\mathrm{O}}_2^{•-}$) formation under VLI, as more ${\mathrm{O}}_2^{•-}$ is formed within E. coli if the GCSC-treated samples are subjected to VLI. The ${\mathrm{O}}_2^{•-}$ exhibits a greater effect in a solution of GCSC than that shown by SC alone under VLI treatment. Gold (III) ions in a GCSC system appear to act as an oxidant by facilitating the electron transfer from citrate under VLI and the formation of AuNPs and ${\mathrm{O}}_2^{•-}$ via GCSC photolysis under alkaline conditions. As such, the photolysis of GCSC under VLI is a useful process that can be applied to aPDI. Full article

This study investigates the potential of a hybrid nanofluid composed of MoS₂ and ZnO nanoparticles dispersed in engine oil, aiming to enhance the properties of a lubricant’s chemical reaction with the Soret effect on a stretching sheet under the influence of an applied magnetic field. With the growing demand for efficient lubrication systems in various industrial applications, including automotive engines, the development of novel nanofluid-based lubricants presents a promising avenue for improving engine performance and longevity. However, the synergistic effects of hybrid nanoparticles in engine oil remain relatively unexplored. The present research addresses this gap by examining the thermal conductivity, viscosity, and wear resistance of the hybrid nanofluid, shedding light on its potential as an advanced lubrication solution. Overall, the objectives of studying the hybrid nanolubricant MoS₂ + ZnO with engine oil aim to advance the development of more efficient and durable lubrication solutions for automotive engines, contributing to improved reliability, fuel efficiency, and environmental sustainability. In the present study, the heat and mass transformation of a Casson hybrid nanofluid (MoS₂ + ZnO) based on engine oil over a stretched wall with chemical reaction and thermo-diffusion effect is analyzed. The governing nonlinear partial differential equations are simplified as ordinary differential equations (ODEs) by utilizing the relevant similarity variables. The MATLAB Bvp4c technique is used to solve the obtained linear ODE equations. The results are presented through graphs and tables for various parameters, namely, M, Q, β, Pr, Ec, Sc, Sr, Kp, Kr, and ${\varphi }_2*$ (hybrid nanolubricant parameters) and various state variables. A comparative survey of all the graphs is presented for the nanofluid (MoS₂/engine oil) and the hybrid nanofluid (MoS₂ + ZnO/engine oil). The results reveal that the velocity profile diminished against the values of M, Kp, and β, and the temperature profile rises with Ec and Q, whereas Pr decreases. The concentration profile is incremented (decremented) with the value of Sr (Sc and Kr). A comparison of the nanofluid and hybrid nanofluid suggests that the velocity f′ (η) becomes slower with the augmentation of ${\varphi }_2*$ whereas the temperature increases when ${\varphi }_2*$ = 0.6 become slower. Full article

Polymeric nanoparticles (PNPs) are frequently researched and used in drug delivery. The degradation of PNPs is highly dependent on various properties, such as polymer chemical structure, size, crystallinity, and melting temperature. Hence, a precise understanding of PNP degradation behavior is essential for optimizing the system. This study focused on enzymatic hydrolysis as a degradation mechanism by investigation of the degradation of PNP with various crystallinities. The aliphatic polyester polylactide ([C₃H₄O₂]n, PLA) was used as two chiral forms, poly l-lactide (PlLA) and poly d-lactide (PdLA), and formed a unique crystalline stereocomplex (SC). PNPs were prepared via a nanoprecipitation method. In order to further control the crystallinity and melting temperatures of the SC, the polymer poly(3-ethylglycolide) [C₆H₈O₄]n (PEtGly) was synthesized. Our investigation shows that the PNP degradation can be controlled by various chemical structures, crystallinity and stereocomplexation. The influence of proteinase K on PNP degradation was also discussed in this research. AFM did not reveal any changes within the first 24 h but indicated accelerated degradation after 7 days when higher EtGly content was present, implying that lower crystallinity renders the particles more susceptible to hydrolysis. QCM-D exhibited reduced enzyme adsorption and a slower degradation rate in SC-PNPs with lower EtGly contents and higher crystallinities. A more in-depth analysis of the degradation process unveiled that QCM-D detected rapid degradation from the outset, whereas AFM exhibited delayed changes of degradation. The knowledge gained in this work is useful for the design and creation of advanced PNPs with enhanced structures and properties. Full article