Search Results (140)

Environmental contamination is a critical global concern, primarily due to detrimental greenhouse gas (GHG) emissions, especially carbon dioxide (CO₂), which significantly contribute to climate change. Moreover, the presence of harmful heavy metals like Ni, Cd, Cu, Hg, and Pb in soil and water ecosystems has led to poor water quality. Noble metal nanoparticles (MNPs), for instance, Pd, Ag, Pt, and Au, have emerged as promising solutions for addressing environmental pollution. However, the practical utilization of MNPs faces challenges as they tend to aggregate and lose stability. To overcome this issue, the reverse double-solvent method (RDSM) was utilized to synthesis melamine-based porous polyaminals (POPs) as a supportive material for the in situ growing of silver nanoparticles (Ag NPs). The porous structure of melamine-based porous polyaminals, featuring aminal-linked (-HN-C-NH-) and triazine groups, provides excellent binding sites for capturing Ag⁺ ions, thereby improving the dispersion and stability of the nanoparticles. The resulting material exhibited ultrafine particle sizes for Ag NPs, and the incorporation of Ag NPs within the porous polyaminals demonstrated a high surface area (~279 m²/g) and total pore volume (1.21 cm³/g), encompassing micropores and mesopores. Additionally, the Ag NPs@POPs showcased significant capacity for CO₂ capture (2.99 mmol/g at 273 K and 1 bar) and effectively removed Cu (II), with a remarkable removal efficiency of 99.04%. The nitrogen-rich porous polyaminals offer promising prospects for immobilizing and encapsulating Ag nanoparticles, making them outstanding adsorbents for selectively capturing carbon dioxide and removing metal ions. Pursuing this approach holds immense potential for various environmental applications. Full article

Nb₂O₅ (niobia) coatings were prepared by spin coating of niobium sol, synthesized using niobium chloride as the precursor and ethanol and water as solvents, followed by high-temperature annealing. Doping of the films was achieved by incorporating commercially available SiO₂ (Ludox) and noble metal nanoparticles (NPs) into the sol prior to its deposition. Various sizes of Pt (5 and 30 nm), Ag (10, 20, and 40 nm), and Au (5, 10, and 20 nm) NPs were used to enhance sensing behavior of coatings. After annealing, films were subjected to chemical etching to remove the silica phase. This process generated porosity within the films, which in turn enabled the tailoring of both their optical and sensing properties. It was demonstrated that both the type and size of the incorporated nanoparticles significantly influenced the sensing behavior. The most effective enhancement was observed with the addition of 10 nm AuNPs. Optical characterization indicated that 10 nm AuNPs had a minimal effect on the optical properties. In contrast, doping with 20 nm AuNPs led to a reduction in the refractive index and an increase in Urbach energy. No significant alteration in the optical band gap due to doping was observed. Full article

Multidrug-resistant (MDR) biofilm infections characterized by densely packed microbial communities encased in protective extracellular matrices pose a formidable challenge to conventional antimicrobial therapies and are a major contributor to chronic, recurrent and device-associated infections. These biofilms significantly reduce antibiotic penetration, facilitate the survival of dormant persister cells and promote horizontal gene transfer, all of which contribute to the emergence and persistence of MDR pathogens. Metal nanoparticles (MNPs) have emerged as promising alternatives due to their potent antibiofilm properties. However, conventional synthesis methods are associated with high costs, complexity, inefficiency and negative environmental impacts. To overcome these limitations there has been a global push toward the development of sustainable and eco-friendly synthesis approaches. Recent advancements have demonstrated the successful use of various plant extracts, microbial cultures, and biomolecules for the green synthesis of MNPs, which offers biocompatibility, scalability, and environmental safety. This review provides a comprehensive overview of recent trends and the latest progress in the green synthesis of MNPs including silver (Ag), gold (Au), platinum (Pt), and selenium (Se), and also explores the mechanistic pathways and characterization techniques. Furthermore, it highlights the antibiofilm applications of these MNPs emphasizing their roles in disrupting biofilms and restoring the efficacy of existing antimicrobial strategies. Full article

The aim of this study was to produce a coating for protective glass glued to touch displays with high antibacterial effectiveness. This paper presents the structural, mechanical, optical, and antibacterial properties of a TiO₂:Ag–Pt coating prepared by dual reactive DC and RF magnetron sputtering. Characterization techniques used include XRD, TEM with EDS, SEM, AFM, nanoindentation for hardness and Young’s modulus, wettability tests, and optical property analysis. The coating exhibited columnar crystals with a width of 30–50 nm. Crystals of anatase, rutile, silver, and platinum with a size of up to 3 nm were identified. The coating deposited on glass had a concentration of 5.0 ± 0.2% at. Ag and 4.4 ± 0.1% at. Pt. The value of the optical band gap energy, corresponding to the direct transition, was 3.36 eV, while Urbach’s energy was in the order of 500 meV. The hydrophilic coating had a roughness RMS = 1.8 ± 0.2 nm, hardness HV = 6.8 ± 0.5 GPa, and Young’s modulus E = 116 ± 8 GPa. A unique combination of the phase composition of the TiO₂:Ag–Pt coating, metallic Ag and Pt nanoparticles in a ceramic matrix of anatase and rutile crystallites resulted a >90% reduction of Staphylococcus aureus bacteria. This antibacterial effect was attributed to the activation of the doped semiconductor under visible light via plasmon resonance of the Ag and Pt nanoparticles, as well as a light-independent antibacterial action due to Ag⁺ ion release. In contrast, commercial antibacterial coatings typically achieve only around 60% bacterial reduction. Full article

Bacterial infections are the primary cause of mastitis in dairy cattle. Fungal mastitis occurs in 1–12% of cases. Antibiotic therapy, the standard treatment for mastitis, has led to antibiotic-resistant bacteria, reducing treatment efficacy and increasing fungal mastitis occurrence. Antibiotics lack biocidal effects on fungi, which often exhibit resistance to antifungal agents. This study evaluated the antifungal properties of nanoparticles (NPs) against Candida albicans, Candida glabrata, Candida parapsilosis, Diutina rugosa var. rugosa, Diutina catenulata, and Diutina rugosa. Tested NPs included gold (AuNPs), silver (AgNPs), copper (CuNPs), iron with hydrophilic carbon coating (FeCNPs) (1.56–25 mg/L), and platinum (PtNPs) (0.625–10 mg/L), along with their complexes. Minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) at 0.75–25 mg/L for AuNPs, AgNPs, CuNPs, and FeCNPs and 0.313–10 mg/L for PtNPs, as well as fungal sensitivity to standard antifungals, were determined. Each strain showed different sensitivities depending on the NPs used and their concentrations. C. glabrata was the most resistant to nanoparticles, while D. catenulata was the most susceptible. PtNPs and FeCNPs showed no or weak biocidal properties. Some mycotic-resistant strains were sensitive to nanoparticles. This study indicates a high in vitro antifungal potential for the application of nanoparticles, especially AgCuNPs, as a new effective non-antibiotic agent for the prevention and control of mycotic mastitis in dairy cattle. Full article

Background: Nanomedicine has shown significant promise in advancing cancer diagnostics and therapeutics. In particular, nanoparticles (NPs) offer potential for overcoming limitations associated with conventional therapies, such as off-target toxicity and side effects. Among the various NPs, silver nanoparticles (AgNPs) have garnered attention due to their cytotoxic and genotoxic properties in cancer cells. However, despite their potential, the optimization of AgNPs efficacy often necessitates combination strategies with other therapeutic agents. This study explores the potential of AgNPs integrated with Zr-based metal-organic frameworks (MOFs) UiO-66 for drug delivery, to enhance cancer therapy. Methods: We decorated amino-terephthalic based UiO-66-NH₂ with AgNPs and loaded it with the chemotherapeutic agent cisplatin (Cis-Pt) to make the UiO-66-NH₂@AgNPs@Cis-Pt. A preliminary MTT assay was conducted to evaluate the cytotoxic effects of the nanocomposite on several glioblastoma and other tumour cell lines, including U251, U87, GL261, HeLa, RKO, and HepG2. Results: Our results demonstrate that UiO-66-NH₂@AgNPs@Cis-Pt and its combinations exhibit enhanced cytotoxicity compared to individual components such as AgNPs and Cis-Pt. Conclusions: This work offers preliminary insights into the potential of AgNP-functionalized MOFs as effective drug and delivery platforms, particularly in the context of combination therapy for cancer treatment. Full article

The extraction of metallic nanoparticles (MNPs) from waste electrical and electronic equipment (WEEE) has gained extensive attention from researchers for eco-friendly, reliable, and sustainable alternative protocol over the traditional linear economic approach (make-use-dispose) for boosting the circular economy. A plethora of MNPs including metals/metal oxide nanoparticles having a size dimension ranging from 1–100 nanometers (nm) have been extracted from these WEEE by using different chemical, physical, and biological methods. Recovery of certain precious MNPs can be achieved by dismantling and recycling electronic waste items in the form of gold (Au), platinum (Pt), zinc oxide (ZnO), silver (Ag), and copper oxide (CuO). These MNPs provide a huge range of applications such as antibacterial, therapeutic, target drug delivery, and biotechnological applications. This comprehensive review provides in-depth knowledge of the synthesis of MNPs using different techniques from WEEE and delves into their potential applications in biomedical fields with in-depth mechanisms. This article also discussed global challenges and opportunities in this area for adopting the concept of circular economy to conserve natural resources for future generations and hence create a greener environment and protect our planet. Full article

(1) Context: Cancer is still a major problem worldwide, and traditional therapies like radiation and chemotherapy often fail to alleviate symptoms because of side effects, systemic toxicity, and mechanisms of resistance. Beneficial anticancer effects that spare healthy tissues are made possible by the distinctive redox characteristics of noble metal complexes, especially those containing palladium, gold, silver, and platinum. (2) Methods: The redox processes, molecular targets, and therapeutic uses of noble metal complexes in cancer have been the subject of much study over the last 20 years; novel approaches to ligand design, functionalization of nanoparticles, and tumor-specific drug delivery systems are highlighted. (3) Results: Recent developments include Pt(IV) prodrugs and terpyridine-modified Pt complexes for enhanced selectivity and decreased toxicity; platinum complexes, like cisplatin, trigger reactive oxygen species (ROS) production and DNA damage. Functionalized gold nanoparticles (AuNPs) improve targeted delivery and theranostic capabilities, while gold complexes, particularly Au(I) and Au(III), inhibit redox-sensitive processes such as thioredoxin reductase (TrxR). (4) Conclusions: Ag(I)-based compounds and nanoparticles (AgNPs) induce DNA damage and mitochondrial dysfunction by taking advantage of oxidative stress. As redox-based anticancer medicines, noble metal complexes have the ability to transform by taking advantage of certain biochemical features to treat cancer more effectively and selectively. Full article

Over the years, the ammonia concentration in water streams and the environment is increasing at an alarming rate. Many membrane-based processes have been studied to alleviate this concern via adsorption and filtration. On the other hand, ammonia electro-oxidation is an approach of particular interest owing to its energetic and environmental benefits. Thus, a plausible alternative to combine these two paths is by using an electroconductive membrane (ECM) to complete the ammonia oxidation reaction (AOR). This combination of processes has been studied very limitedly, and it can be an area for development. Herein, we developed a multilayered membrane with hydrophilic and electrocatalytic properties capable of completing the AOR. The porosity of carbon black (CB) particles was embedded in the polymeric support (CBES) and the active side was composed of a triple layer consisting of polyamide/CB/Pt nanoparticles (PA:CB:Pt). The CBES increased the membrane porosity, changed the pores morphology, and enhanced water permeability and electroconductivity. The deposition of each layer was monitored and corroborated physically, chemically, and electrochemically. The final membrane CBES:PA:VXC:Pt reached higher water flux than its PSF counterpart (3.9 ± 0.3 LMH), had a hydrophilic surface (water contact angle: 19.8 ± 0.4°), and achieved the AOR at −0.3 V vs. Ag/AgCl. Our results suggest that ECMs with conductive material in both membrane layers enhanced their electrical properties. Moreover, this study is proof-of-concept that the AOR can be succeeded by a polymeric FO-ECMs. Full article

Metal–organic frameworks (MOFs) have emerged as versatile materials with remarkably high surface areas and tunable properties, attracting significant attention for various applications. In this work, the modification of a UiO-66 MOF with metal nanoparticles (NPs) is investigated for the purpose of enhancing its photocatalytic activity for CO₂ reduction to liquid fuels. Several NPs (Au, Cu, Ag, Pd, Pt, and Ni) were loaded into the UiO-66 framework and employed as photocatalysts. The synergistic effects of plasmonic resonance and MOF characteristics were investigated to improve photocatalytic performance. The synthesized materials were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS), confirming the successful integration of metal NPs onto the UiO-66 framework. Morphological analysis revealed distinct distributions and sizes of NPs on the UiO-66 surface for different metals. Photocatalytic CO₂ reduction experiments demonstrated enhanced activity of plasmonic MOFs, yielding methanol and ethanol. The findings revealed by this study provide valuable insights into tailoring MOFs for improved photocatalytic applications through the incorporation of plasmonic metal nanoparticles. Full article

The biosynthesis of silver nanoparticles using plant extracts is a promising field of research because of the useful biomedical applications of metal nanoparticles. In this study, the antibacterial and antioxidant properties of silver nanoparticles biosynthesized with the aqueous leaf extract of Pergularia tomentosa were defined using a simple, eco-friendly, consistent, and cost-effective method. The leaf extract of Pergularia tomentosa (PT) served as a capping and reducing agent to biosynthesize silver nanoparticles. The effects of several parameters, such as the concentration of AgNO₃, ratio of AgNO₃ to extract, pH, and incubation time, were examined to optimize the synthesis process. In total, 5 mM of AgNO₃, a 1:0.06 ratio of AgNO₃ to Pergularia tomentosa extract, pH 9.0, and reaction mixture incubation for 24 h were found to be the ideal parameters for biosynthesizing silver nanoparticles (AgNPs). UV–visible spectroscopy, X-ray diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FTIR), and scanning electron microscopy were used to characterize the biosynthesized Pergularia tomentosa silver nanoparticles (PT-AgNPs). Gram-positive bacteria (Staphylococcus aureus and Bacillus cereus) and Gram-negative bacteria (Salmonella enteritides and Escherichia coli) were used to test the PT-AgNPs’ antibacterial activity. The presence of different functional groups was determined using FTIR. The AgNPs were hexagon shaped. The nanoparticles were more toxic against S. enteritides than both B. cereus and E. coli. In antioxidant analyses, the AgNPs were found to be as strong at free radical scavenging as gallic acid (standard), with IC₅₀ values of 0.69 and 22.30 μg/mL for DPPH and ABTS radicals, respectively. Interestingly, the PT-AgNPs displayed increased anti-inflammatory activity compared with the P. tomentosa leaf extract (79% vs. 59% at 500 µg/mL). The PT-AgNPs did not display any cytotoxicity against the MCF-7 cell line at the MIC. In conclusion, silver nanoparticles fortified with Pergularia tomentosa extract exhibited potential as effective antibacterial, anti-inflammatory, and antioxidant agents, suggesting their viability as alternatives to commercially available products. Full article

This work aims at the effects of anion-exchange membranes (AEMs) and ionomer binders on the catalyst electrodes for anion-exchange membrane fuel cells (AEMFCs). In the experiments, four metal catalysts (nano-grade Pt, PtRu, PdNi and Ag), four AEMs (aQAPS-S8, AT-1, X37-50T and X37-50RT) and two alkaline ionomers (aQAPS-S14 and XB-7) were used. They were verified through several technical parameters examination and cell performance comparison for the optimal selection of AMEs. The bimetallic PdNi nanoparticles (PdNi/C) loaded with Vulcan XC-72R carbon black were used as anode electrodes by using the wet impregnation method, and Ag nanoparticles (Ag/C) were used as the catalyst cathode. It was found that the power density and current density of the X37-50RT are higher than the other three membranes. Also, alkaline ionomers of XB-7 had better performance than aQAPS-S14. The efficiency was improved by 32%, 155% and 27%, respectively, when compared to other membranes by using the same catalyst of PdNi/C, Ag/C and Pt/C. The results are consistent with the membrane ion conductivity measurements, which showed that the conductivity of the X37-50RT membrane is the highest among them. The conductivity values for hydroxide ions (OH⁻) and bromide ions (Br⁻) are 131 mS/cm and 91 mS/cm, respectively. These findings suggest that the properties (water uptake, swelling rate and mechanical) of the anion-exchange membrane (AEM) can serve as a key reference for AEM fuel cell applications. Full article

Electric heating is frequently employed to treat volatile organic compounds (VOCs) through catalytic combustion. However, it is associated with problems such as slow heating, high energy consumption, and low efficiency. This study explores PdPt/Al₂O₃ catalysts for igniting methanol (MeOH) through H₂ catalytic combustion, providing internal on-site heating of catalyst active sites. It also investigates VOCs’ abatement using H₂-ignited-MeOH combustion without H₂ and external heating. Bimetallic catalysts enhance activity and reduce thermal aging. Hydrogen gas (H₂) can initiate the MeOH combustion at room temperature with the addition of very small amounts, even below its low explosive limit of 4%. This process optimizes MeOH ignition at approximately 350 °C, even when the concentration of H₂ is as low as 0.01%. This method enhances combustion kinetics, converting MeOH and VOCs into CO₂ and water. Catalytic performance is independent of PdPt nanoparticle sizes in fresh and spent catalysts, represented in XRD and STEM. Using hydrogen as an igniting agent provides a clean, effective method to initiate catalytic reactions, addressing traditional challenges and enhancing VOCs’ decomposition efficiency. Full article

Nitrobenzene (NB) is one of the nitro-aromatic compounds that is extensively used in various chemical industries. Despite its potential applications, NB is considered to be a toxic compound that has significant hazardous effects on human health and the environment. Thus, it can be said that the NB level should be monitored to avoid its negative impacts on human health. In this vein, the electrochemical method has emerged as one of the most efficient sensing techniques for the determination of NB. The sensing performance of the electrochemical techniques depends on the electro-catalytic properties and conductivity of the electrode materials. In the past few years, various electrode materials, such as conductive metal ions, semiconducting metal oxides, metal–organic frameworks, and two-dimensional (2D) materials, have been used as the electrode material for the construction of the NB sensor. Thus, it is worth summarizing previous studies on the design and synthesis of electrode materials for the construction of the NB sensor. In this mini-review article, we summarize the previous reports on the synthesis of various advanced electrode materials, such as platinum (Pt) nanoparticles (NPs), silver (Ag) NPs, carbon dots (CDs), graphene, graphitic carbon nitride (g-C₃N₄), zinc stannate (ZnSnO₃), cerium oxide (CeO₂), zinc oxide (ZnO), and so on. Furthermore, the impacts of different electrode materials are systematically discussed for the sensing of NB. The advantages of, limitations of, and future perspectives on the construction of NB sensors are discussed. The aim of the present mini-review article is to enhance the knowledge and overall literature, working towards the construction of NB sensors. Full article

The process of noble metal nanoparticle synthesis is complex and consists of at least two steps: slow nucleation and fast autocatalytic growth. The kinetics of these two processes depends on the reductant “power” and the addition of stabilizers, as well as other factors (e.g., temperature, pH, ionic strength). Knowing these parameters, it is possible to synthesize materials with appropriate physicochemical properties, which can be simply adjusted by the type of the used metal, particle morphology and surface property. This, in turn, affects the possibility of their applications in various areas of life, including medicine, catalysis, engineering, fuel cells, etc. However, in some cases, the standard route, i.e., the chemical reduction of a metal precursor carried out in the batch reactor, is not sufficient due to problems with temperature control, properties of reagents, unstable or dangerous intermediates and products, etc. Therefore, in this review, we focused on an alternative approach to their chemical synthesis provided by microreactor systems. The use of microreactors for the synthesis of noble metal nanomaterials (e.g., Ag, Au, Pt, Pd), obtained by chemical reduction, is analyzed, taking into account investigations carried out in recent years. A particular emphasis is placed on the processes in which the use of microreactors removed the limitations associated with synthesis in a batch reactor. Moreover, the opportunities and challenges related to the synthesis of noble nanomaterials in the microreactor system are underlined. This review discusses the advantages as well as the problems of nanoparticle synthesis in microreactors. Full article