Oxide Nanoparticles Research Articles

ADVANCES IN NANOMATERIALS AS LUBRICANT ADDITIVES: A SYSTEMIC REVIEW

The paper provides an overview of the significance of nanomaterials as additives, in the tribological performance of lubricants. This review describes the ascendancy of different nanoparticles such as carbon-based nanoparticles, metallic nanoparticles, oxide nanoparticles, sulphide nanoparticles, nanocomposites, hybrid and bimetallic nanoparticles in lubricants. The study also evaluates the underlying principles of lubricant-nanoparticle interactions and their effects on wear prevention and friction reduction. The key parameters including particle morphology, particle size, weight concentration, and functionalization of the particle surface, that determine the friction and wear characteristics are discussed. Also, the science behind surface interaction and various mechanisms involved in friction and wear modification is described. The review highlights the prospect of various nanomaterials in the field of lubrication and facilitates development of advanced nanolubricants with superior tribological properties, that attributes to the reduction in energy consumption and improved performance.

Surface Gold Atoms Determine Peroxidase Mimic Activity in Gold Alloy Nanoparticles.

The development of peroxidase mimic nanocatalysts is relevant for oxidation reactions in biosensing, environmental monitoring and green chemical processes. Several nanomaterials have been proposed as peroxidase mimic, the majority of which consists of noble metals and oxide nanoparticles (NPs). Yet, there is still limited information about how the change in the composition influences their catalytic activity. Here, the peroxidase mimic behaviour of gold NPs is compared to a traditional nanoalloy as Au-Ag and to the Au-Fe and the Au-Co nanoalloys, which were not tested before as oxidation catalysts. Since the alloys of gold with iron and cobalt are thermodynamically unstable, laser ablation in liquid (LAL) is exploited for the synthesis of these NPs. Using LAL, no chemical stabilizers or capping agents are present on the NPs surface, allowing the evaluation of the oxidation behaviour as a function of the alloy composition. The results point to the importance of surface gold atoms in the catalytic process, but also indicate the possibility of obtaining active nanocatalysts with a lower content of Au by alloying it with iron, which is earth-abundant, non-toxic and low cost. Overall, Au nanoalloys are worth consideration as a more sustainable alternative to pure Au nanocatalysts for oxidation reactions.

Activating colloidal synthesized Au catalyst by the electrochemical strategy: Gas atmosphere, electrolyte and electrochemical technique

Organic ligands are necessarily used to stabilize nanoparticles (NPs) in colloid synthesis, and the presence of these ligands in most cases can have adverse effects on heterogeneous nanocatalysis. Therefore, it is crucial to develop efficient methods to remove ligands and study the removal mechanism. In this article, we developed a combined electrochemical method (chronoamperometry (CA) + cyclic voltammetry (CV)), which can completely and efficiently remove thiol ligand from Au NPs to produce cleaned Au/C catalyst. Using the oxygen reduction reaction (ORR) activity as the evaluation criterion for ligand removal, we found that gas atmosphere (O2) plays an important role in the removal process, while the acidity and alkalinity of electrolyte have no effect on the removal efficiency. A proposed thiol ligand removal mechanism along with Au degradation is presented. The results of CA activation at an oxidation constant potential (1.7 V) indicate that oxidation of thiol alone cannot remove thiol ligand. Only if a reduction constant potential of 0.2 V is further applied, the ORR activity of Au/C catalyst will increase, indicating that both the oxidation and reduction processes of Au NPs are crucial for ligand removal. Although the CA method (with an upper potential of 1.7 V and a lower potential of 0.2 V) can efficiently remove the majority of thiol ligand, complete removal of thiol ligand requires further CV activation. Based on the relevant results, a combined electrochemical method (CA + CV) is established. Developing standardized methods for removing ligands on the surface of catalysts is important for obtaining efficient catalysts and is also important for the reproducibility of catalytic results.

Engineered metal nanoparticles for precision drug delivery: Pioneering the future of medicine: Mini review

AbstractMetal nanoparticles (NPs) have emerged as crucial components in precision drug delivery, presenting innovative opportunities to significantly enhance therapeutic efficacy and targeting accuracy. This review investigates recent developments in the engineering of metal NPs, emphasizing their distinctive properties and novel applications in drug delivery systems. A comprehensive analysis is performed on gold, silver, iron, and zinc oxide NPs, emphasizing their exceptional physicochemical properties and enhanced drug‐loading capacities. These features collectively enable the development and implementation of targeted and controlled drug delivery systems, indicating a new era of advanced therapeutic approaches. This review article accomplishes this by reflecting on the transformative potential of metal NPs, envisioning heightened efficacy, minimized side effects, and improved patient outcomes within the dynamic landscape of drug delivery platforms.

Antibacterial and Antitumoral Potentials of Phytosynthesized Silver/Silver Oxide Nanoparticles Using Tomato Flower Waste.

This study presents the phytosynthesis of silver-based nanoparticles using tomato flower waste extracts for the first time in the literature. The determination of total polyphenolic and flavonoid contents in the extracts showed high gallic acid equivalents (6436-8802 mg GAE/kg dm) and high quercetin equivalents (378-633 mg QE/kg dm), respectively, dependent on the extraction method. By the Ultra Performance Liquid Chromatography technique, 14 polyphenolic compounds were identified and quantified in the tomato flower waste extracts. The abundant phenolic compounds were caffeic acid (36,902-32,217 mg/kg) and chlorogenic acid (1640-1728 mg/kg), and the abundant flavonoid compounds were catechin (292-251 mg/kg) and luteolin (246-108 mg/kg). Transmission electron microscopy of the nanoparticles revealed a particle size range of 14-40 nm. Fourier Transform infrared spectroscopy and X-ray diffraction studies confirmed the phytosynthesis of the silver/silver oxide nanoparticles. These findings hold significant results for the antibacterial and antitumoral potential applications of the obtained nanoparticles, opening new areas for research and development and inspiring further exploration. The impact of this research on the field of metallic nanoparticle phytosynthesis is substantial, as it introduces a novel approach and could lead to significant advancements in the field.

Foliar Uptake and Distribution of Metallic Oxide Nanoparticles in Maize (Zea mays L.) Leaf.

The foliar uptake of Fe3O4, Cr2O3, CuO, and ZnO nanoparticles (NPs) by maize (Zea mays L.) was studied in a lab-scale experiment. The significant increase of Fe concentrations in leaves exposed to Fe3O4 was observed in both stomatal closing and stomatal opening treatments, suggesting the presence of a nonstomatal uptake. In parallel treatments with equal doses of Fe3O4 (∼200 nm), Cr2O3 (∼300 nm), CuO (∼30 nm), and ZnO (∼40 nm) (20-200 μg), the retention percentage of Fe in the leaves (21.0-69.0%) was higher than that of Cr, Cu, and Zn (0.5-14.0%). The steric hindrance effect seems more important for NPs of >200 nm, while hydrophobic surface and negative charge promote the foliar uptake of NPs smaller than 200 nm. The accumulation of NPs in the cuticle was observed through dark-field hyperspectral microscopy. Cr2O3, Fe3O4, and CuO NPs were difficult to penetrate the cuticle. In comparison, ZnO further migrated and distributed within the extracellular space of epidermal and mesophyll cells of the exposed leaf, possibly due to its comparatively higher solubility and hydrophilicity. The findings highlight the potential of the nonstomatal uptake, which might be a critical route for metallic oxide NPs to enter the food chain.

A New Approach to Single‐Step Fabrication of TiOx‐CeOx Nanoparticles

Mixed metal oxide (MMO) nanoparticles (NPs) are hybrids consisting of two or more nanoscale metal oxides. Advantages of MMO NPs over single metal oxides include improved catalytic activity, enhanced electrical and magnetic properties, and increased thermal stability due to the synergy of the different oxide components. This study presents a novel fabrication route for TiO2‐CeO2 NPs enriched with oxygen vacancies using a Haberland‐type gas aggregation cluster source. The NPs, deposited from different segmented Ti/Ce targets under varying O2 addition, were examined with respect to final composition, morphology, and Ti, Ce surface oxidation states. Particle formation mechanisms are proposed for the observed morphologies. Additionally, available O2 during deposition and its impact on the formation of defective sites were investigated. Defective sites in TiO2‐CeO2 NPs were analyzed using transfer to X‐ray photoelectron spectroscopy and transmission electron microscopy without contact to ambient oxygen. The incorporation of Ce to the target exhibits synergistic effects on the synthesis process. Segmented Ti/Ce targets enable the deposition of a broad range of mixed oxide NPs with diverse compositions and morphologies at considerably enhanced deposition rates, which is vital for practical applications. The presented fabrication approach is expected to be applicable for a broad variety of MMO NPs.

Interfacial contact-driven enhanced environmental photocatalysis of CdS-loaded OH-functionalized carbon nanotubes with low biotoxicity

CdS is a promising visible-light-driven photocatalyst, but it is highly toxic. Therefore, exploring alternatives that minimize toxicity while maintaining its photocatalytic properties is crucial. Carbon allotropes have been suggested as eco-friendly scaffolds for making high-performance photocatalysts with a small amount of toxic but visible light-responsive CdS additive to reduce environmental risk. However, it is unclear how small amounts of CdS in the nanocomposite can avoid a threat to environmental safety, and the role of surface functional groups on the physical interfaces for photocatalysis has not been sufficiently elucidated. Here, we used OH-functionalized carbon nanotubes (CNT-OH) as a support for CdS nanoparticles (NPs) and investigated the effect of CdS loading on photocatalytic activity and toxicity. Comprehensive microscopy coupled with machine learning-assisted spectroscopy revealed that electronic structure alterations occur uniquely at heterojunctions where CdS NPs contact CNT-OH, uncovering them as being catalytically active. Notably, the CNT-OH loaded by only 3 wt% CdS NPs resulted in a highly enhanced photocatalytic activity comparable to pure CdS NPs for selective oxidation of 2,5-hydroxymethylfurfural and degradation of 4-chlorophenol. These findings provide insight into heterocontact engineering using visible light-responsive catalysts and functionalized platforms to develop environmentally benign photocatalysts with high performance.

Adsorptive potential of dispersible chitosan-coated biogenic iron oxide nanocomposite for enhanced anti-bacterial activity against gram-positive and gram-negative bacterial pathogens

The use of various biomaterials, such as plants or microbes, to create nanoparticles (NPs), is seen as a viable strategy in green nanotechnology. The synthesis of low-cost, energy-efficient, nontoxic, ecologically acceptable metallic nanoparticles has recently become a critical topic. The biosynthesis of iron oxide NPs using pomegranate peel extract has been investigated. Biogenic iron oxide NPs were coated with highly porous chitosan as a supporting material to enhance applicability of NPs for wastewater remediation. Biogenic magnetic NPs and its composite were characterized by scanning electron microscope, X-ray diffraction, and Fourier Transformer Infrared spectroscopy (FTIR). Our study focused on the ability of biogenic magnetite Fe3O4 NPs and its bio-composite for removal of As+5 ions from wastewater. Adsorption isotherms were obtained using metal ion concentrations ranging from 5 to 25 mg/L. The Langmuir adsorption model was validated by our data. The reaction kinetics of the adsorption process were pseudo-second order. Interestingly, the bio-composite achieved 90% As+5 removal at pH4. In addition, the prepared nanocomposite was characterized using various analytical techniques to confirm its physicochemical properties. The adsorptive capacity of the nanocomposite was evaluated by studying the removal of pollutants and contaminants from aqueous solutions. Additionally, the antibacterial activity of the nanocomposite was assessed against a panel of clinically relevant Gram-positive and Gram-negative bacterial strains, including Staphylococcus epidermidis (RCMB 9241, ATCC 12228), Staphylococcus saprophyticus (RCMB 010028, ATCC 15305), Enterococcus faecalis (RCMB 010052), Streptococcus salivarius (ATCC 13415), Escherichia coli (RCMB 010052, ATCC 25922), Salmonella enterica serovar Typhimurium (RCMB 006(1), ATCC 14028) and Pseudomonas aeruginosa (ATCC 27853). Our findings have important implications in the field of low-cost, easy, and environmentally friendly water bioremediation.

Single and combined effects of titanium (TiO2) and zinc (ZnO) oxide nanoparticles in the rainbow trout gill cell line RTgill-W1.

Understanding the environmental impact of nanoparticle (NP) mixtures is essential to accurately assess the risk they represent for aquatic ecosystems. However, although the toxicity of individual NPs has been extensively studied, information regarding the toxicity of combined NPs is still comparatively rather scarce. Hence, this research aimed to investigate the individual and combined toxicity mechanisms of two widely consumed nanoparticles, zinc oxide (ZnO NPs) and titanium dioxide (TiO2 NPs), using an in vitro model, the RTgill-W1 rainbow trout gill epithelial cell line. Sublethal concentrations of ZnO NPs (0.1µgmL-1) and TiO2 (30µgmL-1) and a lethal concentration of ZnO NPs causing 10% mortality (EC10, 3µgmL-1) were selected based on cytotoxicity assays. Cells were then exposed to the NPs at the selected concentrations alone and to their combination. Cytotoxicity assays, oxidative stress markers, and targeted gene expression analyses were employed to assess the NP cellular toxicity mechanisms and their effects on the gill cells. The cytotoxicity of the mixture was identical to the one of ZnO NPs alone. Enzymatic and gene expression (nrf2, gpx, sod) analyses suggest that none of the tested conditions induced a strong redox imbalance. Metal detoxification mechanisms (mtb) and zinc transportation (znt1) were affected only in cells exposed to ZnO NPs, while tight junction proteins (zo1 and cldn1), and apoptosis protein p53 were overexpressed only in cells exposed to the mixture. Osmoregulation (Na + /K + ATPase gene expression) was not affected by the tested conditions. The overall results suggest that the toxic effects of ZnO and TiO2 NPs in the mixture were significantly enhanced and could result in the disruption of the gill epithelium integrity. This study provides new insights into the combined effects of commonly used nanoparticles, emphasizing the importance of further investigating how their toxicity may be influenced in mixtures.

Chitosan-coated iron(III) oxide nanoparticles and tungsten disulfide quantum dots-immobilized Fiber-based WaveFlex Biosensor for Staphylococcus Aureus bacterial detection in real food samples

The research proposes and investigates an extraordinarily sensitive, label-free WaveFlex biosensor utilizing optical fiber technology for the detection of Staphylococcus aureus (S. aureus), a common foodborne bacterium. The WaveFlex biosensor (plasmon Wave based Flexible optical fiber Biosensor) is based on a novel flexible tapered single-mode fiber structure, utilizing gold nanoparticles (AuNPs) to trigger the phenomenon of localized surface plasmon resonance (LSPR). Additionally, the sensitivity is further enhanced using chitosan-coated iron(III) oxide nanoparticles (Fe3O4–CS NPs) and tungsten disulfide quantum dots (WS2-QDs). The optical fiber surface is functionalized with antibodies to achieve specific detection of S. aureus. For S. aureus concentrations at 1 × 108 CFU/mL (colony-forming units per milliliter), the sensor's maximum sensitivity of 2.74 nm/lg (CFU/mL), and a detection limit (LOD) of 6.67 CFU/mL. This ultra-sensitive biosensor holds great potential for widespread applications in various fields, including disease detection, medical diagnostics, and food safety inspection.

Novel Synthesis and Biophysical Characterization of Zinc Oxide Nanoparticles Using Virgin Coconut Oil.

One of the primary concerns in the field of green synthesis of nanoparticles (NPs) utilizing plant materials is the scarcity of high purity, challenges in achieving large-scale production, and limited global accessibility. Hygienic preparation and safe storage of plant extracts are also considerable challenges in this field. So, an investigation was started to overcome these limitations. Virgin coconut oil (VCO) in its purest form is available commercially all over the world. Also, it has high medicinal value with excellent biomedical applications. Very limited work has been reported on oils as bio reducers and stabilizers. In those reports, they used a few chemicals as mediators in the processes of synthesis and cleaning. So, to the best of our knowledge, for the first time, zinc oxide (ZnO) NPs were synthesized using VCO as a reducing and capping agent with zero chemical mediators. A comprehensive investigation of the structural, microstructural, and optical properties was reported. X-ray diffraction confirms the formation of VCO-ZnO NPs with an average crystallite size of 32.81 nm in a hexagonal structure. UV characteristics confirm quantum confinement through a well-defined SPR near 223 nm with fwhm of 67 nm and a direct band gap at 3.96 eV. FTIR reveals the capping of VCO through carboxylic functional groups, particularly the -COO- group of coconut oil at 1770 cm-1 with a shift of about 30 cm-1 compared to plain VCO. TEM confirms the polycrystalline nature with nearly spherical and 10-22 nm particle size. The zeta potential of -15.4 ± 5.0 mV signifies the stability and antiagglomeration properties. FESEM with EDS results confirms morphological excellence, the purity level of synthesized NPs (99.5%), and the prominent scalability of NPs (84.38% yield). Finally, as-synthesized VCO-ZnO NPs showed very good antioxidant (IC50 78.991, 51.464, and 4.677 μg/mL in DPPH, ABTS, and FRAP assays, respectively), anti-inflammatory (IC50 22.42 μg/mL in protein denaturation), antimicrobial (MIC 0.156 mg/mL for Pseudomonas and 0.316 mg/mL for S. aureus), and antidiabetic properties (IC50 88.45 and 147.67 μg/mL for α-amylase and α-glucosidase assays, respectively).

Advances in antibacterial activity of zinc oxide nanoparticles against Staphylococcus aureus (Review).

Nanoparticles (NPs) are one of the promising strategies to deal with bacterial infections. As the main subset of NPs, metal and metal oxide NPs show destructive power against bacteria by releasing metal ions, direct contact of cell membranes and antibiotic delivery. Recently, a number of researchers have focused on the antibacterial activity of zinc oxide nanoparticles (ZnO NPs) against Staphylococcus aureus (S. aureus). Currently, there is a lack of a comprehensive review on ZnO NPs against S. aureus. Therefore, in this review, the antibacterial activity against S. aureus of ZnO NPs made by various synthetic methods was summarized, particularly the green synthetic ZnO NPs. The synergistic antibacterial effect against S. aureus of ZnO NPs with antibiotics was also summarized. Furthermore, the present review also emphasized the enhanced activities against S. aureus of ZnO nanocomposites, nano-hybrids and functional ZnO NPs.

Experimental investigation on an innovative serpentine channel‐based nanofluid cooling technology for modular lithium‐ion battery thermal management

AbstractMany nations have committed to becoming carbon neutral by 2050 as a means of addressing the global warming challenge. To achieve carbon neutrality, transportation is one of the most essential and important tasks. Energy‐efficient pure electric vehicles (EVs) and hybrid electric vehicles (HEVs) with green energy power are being developed in response to the worldwide energy and environmental crises, as the potential replacements for the current generation of combustion‐engine automobiles. EVs require batteries more than ever before. In this perspective, lithium‐ion batteries (LIBs) stand out as remarkable energy storage technologies and have been widely used due to their numerous impressive benefits. Owing to LIBs sensitivity to temperature, EVs typically use the battery thermal management system (BTMS). The working temperature span of a lithium‐ion battery in an electric car is 15°C–35°C, which is achieved by the use of a BTMS. The production of internal heat during charging and discharging also affects how well lithium‐ion batteries work. A battery heat control system is therefore required. The temperature of the LIB pack might be efficiently controlled by liquid‐cooled systems in discharge and charge scenarios. Based on Al2O3 nanofluid (NF), the current experimental study suggests a novel active cooling technology for regulating the heat produced by the 18650‐format lithium‐ion batteries. A thorough analysis is conducted on the impact of charge/discharge C‐rates, Al2O3 nanoparticle (NP) volume fractions, inflow coolant velocity, and intake liquid temperature on the thermal efficiency of the LIB pack. By incorporating aluminum oxide NPs into the water at varying volume fractions of 0.3%, 0.5%, and 1%, the LIB pack's maximum temperature was significantly reduced by 7.9%, 18.09%, and 19.56%, respectively. With increase in mass flow rate of coolant from 0.0290 to 0.5810 kg/s, the maximum temperature has been substantially reduced by 3.7%–8.6%. Results show that using higher fluid inflow temperature significantly increased both the highest experienced temperature and temperature diversity throughout the discharge operation by about, 6°C and 5°C, respectively. The outcomes of the study indicate that NFs exhibit superior cooling performance compared to conventional coolants such as water and ethylene glycol.

Interaction between Enzymatic Detergent and Textile Metals/Metal Oxide Nanoparticles

Introduction: Nanoparticles are used in industrial products, such as textiles, to induce novel properties, such as antibacterial, antistatic, UV blocking, self-cleaning properties, wrinkle resistance, and water and oil repellent. Moreover, using enzymes (protease, lipase, amylase, and cellulase) is widespread in detergent industries for washing conditions. Methods: This research examines the interactions between metal (Ag) and metal oxide nanoparticles (TiO2 and ZnO NPs) and amylase, cellulase, protease, and lipase as detergent enzymes and their impacts on enzyme activity. Using a central composite design, a total of 320 experiments under different conditions were conducted to determine the extent of change in enzyme activity. Results indicated that lipase had the lowest activity under interaction with silver nanoparticles, while cellulase and protease were most affected by interactions with Ag NPs and a-TiO2. Results: The surface response of the examined parameters showed the most effect from the interaction time and temperature and the enzyme/nanoparticle ratio and temperature parameters. This research result demonstrated that physical, chemical, and biological differences existed between nanoparticle and enzyme interface. Conclusion: The findings can be used to improve the interaction between nanoparticles and detergent enzymes in washing conditions, aiming to retain their traits.

A Comparative Evaluation of Antifungal and Physical Properties When Nanoparticles Are Incorporated Into the Tissue Conditioner: An In Vitro Study.

Objective The objective of this in vitrostudy was to comparatively evaluate the antifungaland physical properties of tissue conditioner incorporated with nanoparticles (NPs) of different types and concentrations. Materials and methods A total of 198 tissue conditioner samples were used in this study. The samples were categorized into a control group, namely, tissue conditioner without NPs (Group 1), and test groups, namely, tissue conditioner incorporated with zinc oxide (ZnO) NPs (Group 2) andmagnesium oxide (MgO) NPs (Group 3). The antifungal properties and surface roughness of the samples were evaluated. The groups were further subdivided into seven subgroups: control (without NPs), 5% ZnO NPs, 10% ZnO NPs, 15% ZnO NPs, 3% MgO NPs, 5% MgO NPs, and 7% MgO NPs by weight. Surface roughness was measured using an optical profilometer,and antifungal activity was measured in terms of the diameter of the inhibition zone (DIZ) using the well diffusion method over seven days. Results The result showed that the 5%ZnO NPs subgroup had the lowest mean surface roughness, whereas the 15% ZnO NPs subgroup had the highest antifungal activity. Increasing the concentration of NPsincreased the antifungal property, and there was a steady decrease in DIZ from day one to day seven in all test groups. Conclusion Our results showed that the incorporation of various concentrations of ZnO and MgO NPs into tissue conditioner samples positively affected their physical and antifungal properties. The highest antifungal activity was found in the 15% ZnO NPs subgroup, and the lowest surface roughness was found in the 5% ZnO NPs subgroup.

A novel electrochemical aptasensor based on NrGO-H-Mn3O4 NPs integrated CRISPR/Cas12a system for ultrasensitive low-density lipoprotein determination.

Atherosclerosis cardiovascular disease (ASCVD) has become one of the leading death causes in humans. Low-density lipoprotein (LDL) is an important biomarker for assessing ASCVD risk level. Thus, monitoring LDL levels can be an important means for early diagnosis of ASCVD. Herein, a novel electrochemical aptasensor for determination LDL was designed based on nitrogen-doped reduced graphene oxide-hemin-manganese oxide nanoparticles (NrGO-H-Mn3O4 NPs) integrated with clustered regularly interspaced short palindromic repeats and associated proteins (CRISPR/Cas12a) system. NrGO-H-Mn3O4 NPs not onlyhave alarge surface area and remarkable enhancedelectrical conductivity but also the interconversion of different valence states of iron in hemin can provide an electrical signal. Nonspecific single-stranded DNA (ssDNA) was bound to NrGO-H-Mn3O4 NPs to form a signaling probe and was immobilized on the electrode surface. The CRISPR/Cas12a system has excellent trans-cleavage activity, which can be used to cleave ssDNA, thus detaching the NrGO-H-Mn3O4 NPs from the sensing interface and attenuating the electrical signal. Significant signal change triggered by the target was ultimately obtained, thus achieving sensitive detection of the LDL in range from 0.005 to 1000.0nM with the detection limit of 0.005nM. The proposed sensor exhibited good stability, selectivity, and stability and achieved reliable detection of LDL in serum samples, demonstrating its promising application prospects for the diagnostic application of LDL.

Comparative Study of Antioxidant Activity of Dextran-Coated Iron Oxide, Gold, and Silver Nanoparticles Against Age-Induced Oxidative Stress in Erythrocytes.

Erythrocytes undergo several changes during human aging and age-related diseases and, thus, have been studied as biomarkers of the aging process. The present study aimed to explore the antioxidant ability of metal and metal oxide nanoparticles (NPs) such as iron oxide (Fe3O4), gold (Au), and silver (Ag) to mitigate age-related oxidative stress in human erythrocytes. Metal and metal oxide NPs behave like antioxidative enzymes, directly influencing redox pathways and thus have better efficiency. Additionally, biopolymer coatings such as dextran enhance the biocompatibility of these NPs. Therefore, dextran-coated Fe3O4, Au, and Ag NPs were synthesized using wet chemical methods and were characterized. Their hemocompatibility and ability to protect erythrocytes from age-induced oxidative stress were investigated. The Fe3O4 and Au NPs were observed to protect erythrocytes from hydrogen peroxide and age-induced oxidative damage, including decreased antioxidant levels, reduced activity of antioxidative enzymes, and increased amounts of oxidative species. Pretreatment with NPs preserved the morphology and membrane integrity of the erythrocyte. However, Ag NPs induced oxidative stress in erythrocytes similar to hydrogen peroxide. Therefore, dextran-coated Fe3O4 and Au nanoparticles have the potential to be employed as antioxidant therapies against age-related oxidative stress.

Photocatalytic Activity of Zinc Oxide Nano Particules and Boric Acid for Bleaching Process on Cotton Fabric

In this study, a photocatalytic process was applied as an alternative to conventional hydrogen peroxide bleaching on 100% cotton fabric. The effects of ZnO nanoparticles and boric acid as catalysts were investigated. Additionally, the synergistic impact of boric acid on the well-known bleaching effect of titanium dioxide nanoparticles was explored. Unlike existing literature, the study uniquely addressed whether the photocatalytic process, without the use of any catalyst, has a specific effect, particularly in whitening, on the color spectrum. All conducted photocatalytic processes on cotton fabrics were compared with conventional hydrogen peroxide bleaching in terms of color spectra (CIE L*, a*, b*, whiteness indexes) besides the SEM, SEM-EDX, and FTIR-ATR characterization tests. Moreover, XRD, SEM, and FTIR-ATR analysis results of ZnO nanoparticles were also shared in this study. This research is believed to shed light on future studies by evaluating more environmentally friendly pre-treatment processes in textile industry.

Highly active iron oxide@NC catalyst derived from the iron acetate/polyacrylonitrile threads: Driving nitroarene conversion to value‐added amines

AbstractChemoselective reduction of nitroarenes to corresponding arylamines is a significant reaction in the chemical industry. However, in the presence of other reducible groups, including halogenated nitrobenzene, nitrobiphenyl, and nitroquinoline in the same molecule of nitroaromatics, the control of chemoselectivity remains challenging. Here, a facile fabrication of a heterogeneous iron‐based catalyst is reported as a potential alternative to precious metal catalysts for the chemoselective reduction of nitroarenes. The pyrolysis of iron acetate/polyacrylonitrile (PAN) template under an inert atmosphere furnishes active Fe3O4 nanoparticles (NPs) encapsulated in nitrogen‐doped (N‐doped) carbon layers, which can provide more catalytic active sites (Fe3O4/PAN@800). Notably, non‐precious iron oxide NPs supported on N‐doped carbon support prevent aggregation, thereby enhancing the catalytic activity. The sustainable and reusable Fe3O4/PAN@800 catalyst, having only 0.8% metal content as demonstrated by x‐ray photoelectron spectroscopy, delivers excellent yields of corresponding amines from differently functionalized nitroarenes. Hydrogenation of a series of structurally functionalized nitroarenes produced excellent yields of anilines, which serve as building blocks and intermediates for fine and bulk chemicals. Hydrogenation of 2‐chloro‐3‐nitropyridine, 2‐nitro‐1,1′‐biphenyl, ortho‐nitroaniline, and 4‐aminophenyl acrylonitrile yielded respective anilines up to 99%. The active sites of Fe3O4 have magnetic performance, hence, the catalyst can be easily recovered using a magnet and reused for at least five cycles without significant loss of catalytic activity. Therefore, the easily prepared, cost‐effective, and reusable Fe3O4/PAN@800 catalyst presented in this study shows potential for applications in the selective reduction of aromatic nitro compounds. Consequently, this study potentially establishes a guideline for the facile preparation of abundant transition‐non‐noble metal‐based reusable supported catalysts for various applications in the chemical industry.