In response to the persistent challenge of heavy and noble metal environmental contamination, our research explores a new idea to capture silver through porous spherical silica nanostructures. The aim was realized using microwave radiation at varying power (P = 150 or 800 W) and exposure times (t = 60 or 150 s). It led to the development of a silica surface with enhanced metal-capture capacity. The microwave-assisted silica surface modification influences the notable changes within the carrier but also enforces the crystallization process of silver nanoparticles with different morphology, structure, and chemical composition. Microwave treatment can also stimulate the formation of core–shell bioactive Ag/Ag2CO3 heterojunctions. Due to the silver nanoparticles’ sphericity and silver carbonate’s presence, the modified nanocomposites exhibited heightened toxicity against common microorganisms, such as E. coli and S. epidermidis. Toxicological assessments, including minimum inhibitory concentration (MIC) and half-maximal inhibitory concentration (IC50) determinations, underscored the efficacy of the nanocomposites. This research represents a significant stride in addressing pollution challenges. It shows the potential of microwave-modified silicas in the fight against environmental contamination. Microwave engineering underscores a sophisticated approach to pollution remediation and emphasizes the pivotal role of nanotechnology in shaping sustainable solutions for environmental stewardship.
Heavy metals and other organic pollutants burden the environment, and their removal or neutralization is still inadequate. The great potential for development in this area includes porous, spherical silica nanostructures with a well-developed active surface and open porosity. In this context, we modified the surface of silica spheres using a microwave field (variable power and exposure time) to increase the metal uptake potential and build stable bioactive Ag2O/Ag2CO3 heterojunctions. The results showed that the power of the microwave field (P = 150 or 700 W) had a more negligible effect on carrier modification than time (t = 60 or 150 s). The surface-activated and silver-loaded silica carrier features like morphology, structure, and chemical composition correlate with microbial and antioxidant enzyme activity. We demonstrated that the increased sphericity of silver nanoparticles enormously increased toxicity against E. coli, B. cereus, and S. epidermidis. Furthermore, such structures negatively affected the antioxidant defense system of E. coli, B. cereus, and S. epidermidis through the induction of oxidative stress, leading to cell death. The most robust effects were found for nanocomposites in which the carrier was treated for an extended period in a microwave field.
To functionalize the NiTi alloy, multifunctional innovative nanocoatings of Ag-TiO2 and Ag-TiO2 doped with hydroxyapatite were engineered on its surface. The coatings were thoroughly characterized, focusing on surface topography and key functional properties, including adhesion, surface wettability, biocompatibility, antibacterial activity, and corrosion resistance. The electrochemical corrosion kinetics in a simulated body fluid and the mechanisms were analyzed. The coatings exhibited hydrophilic properties and were biocompatible with fibroblast and osteoblast cells while also demonstrating antibacterial activity against E. coli and S. epidermidis. The coatings adhered strongly to the NiTi substrate, with superior adhesion observed in the hydroxyapatite-doped layers. Conversely, the Ag-TiO2 layers showed enhanced corrosion resistance.
This study investigates the degradation of six different types of absorbable surgical threads commonly used in clinical practice, focusing on their response to exposure to physiological fluids. The threads were subjected to hydrolytic and enzymatic degradation in physiological saline, bile, and pancreatic juice. Our findings demonstrate that bile and pancreatic juice, particularly when contaminated with bacterial strains such as Escherichia coli, Klebsiella spp., and Enterococcus faecalis, significantly accelerate the degradation process. Using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and tensile strength testing, we observed distinct differences in the chemical structure and mechanical integrity of the sutures. Principal component analysis (PCA) of the FTIR spectra revealed that PDS threads exhibited the highest resistance to degradation, maintaining their mechanical properties for a longer duration compared with Monocryl and Vicryl. These results highlight the critical role of thread selection in gastrointestinal surgeries, where prolonged exposure to bile and pancreatic juice can compromise the suture integrity and lead to postoperative complications. The insights gained from this study will contribute to improving the selection and application of absorbable threads in clinical settings.
Oral infections caused by antibiotic-resistant bacteria represent an emerging biomedical hazard and growing challenge for modern dentistry. To address this issue, Ag– and Cu–ZnO nanocomposites (NCs) were synthesized using ZnO carrier to combat the oral pathogens Streptococcus mutans and Streptococcus sobrinus. A comprehensive analysis of chemically synthesized metal oxide nanocomposites (MONCs) was performed, combining physicochemical characterization (TEM, XRD, ζ-potential, DLS, pH, and PFO/PSO kinetic models) with biological toxicity assessment (MIC, ATR–FTIR, SEM, and FAMEs) to better understand their antimicrobial mechanisms. The results confirmed that the synthesized nanoproducts fulfill the criteria for nanomaterials (NMs) (particle size < 100 nm). Among them, Ag–ZnO exhibited the highest antibacterial activity against both strains (MIC = 50 mg L−1). Kinetic modeling revealed faster and more efficient Ag ion release from Ag–ZnO NCs compared to Cu from Cu–ZnO NCs. Molecular analyses indicated strong MONC–bacterial interactions at the cell surface, leading to changes in protein secondary structures, alterations in lipid composition, and disruption of Gram-positive bacterial membranes. Additionally, Ag–ZnO inhibited chain and cluster formation in both bacterial species, while Cu–ZnO affected only S. sobrinus. Overall, Ag– and Cu–ZnO NCs show strong potential as antimicrobial agents against oral pathogens.
Rising triple-negative breast cancer (TNBC) cases and Candida infection risks during chemotherapy demand novel therapies, with metal-oxide nanocomposites emerging as a promising solution. In this study, we synthesized Ag-ZnO and Cu-ZnO nanocomposites as established quantitative links between their physicochemical properties, ion release behaviour, and biological activity, evaluating antifungal effects against Candida albicans (ATCC 90028) and Saccharomyces cerevisiae (ATCC 9763), and their anticancer potential against MDA-MB-231 cells (ATCC HTB-26). The results revealed Ag (~13–19 nm) and Cu (~4–8 nm) nanoparticles dispersed in a ZnO matrix, with XPS confirming mixed Ag0/Ag(I)/Ag(III) and Cu(I)/Cu(II) speciation. Ag-ZnO NC exhibited strong antifungal activity (MIC = 25 mg L−1) against both fungi, while Cu-ZnO NC was only effective (MIC = 100 mg L−1) against S. cerevisiae. Aqueous release of Ag+ was ~2.6-fold higher than Cu2+. Ag-ZnO NC induced marked ROS generation (~6-fold higher than S. cerevisiae) and dehydrogenase inhibition (6.6- and ~20-fold, respectively). ATR-FTIR linked species-specific susceptibility to cell-wall architecture. SEM confirmed membrane destabilization and perforation. In MDA-MB-231, necrotic fractions reached ~9% and >40% for Ag-ZnO and Cu-ZnO, respectively. Both metal oxide nanocomposites (MONCs) act through ion release, revealing a selectivity window, especially for Ag-ZnO. Further studies on non-cancerous cells, ion-release kinetics, uptake and in vivo validation are essential to establish a therapeutic index.