Search Results (827)

The use of nanoparticles (NPs) synthesized from plant extracts is an alternative to conventional pesticides for the control of agricultural pests. This study aimed to optimize the conditions of synthesis of silver–zinc nanoparticles (Ag-ZnNPs) using extracts of Ocimum basilicum L. and Crotalaria longirostrata Hook. & Arn. and to evaluate their phytotoxic impact on maize seedlings. The Ag-ZnNPs (Ag-Zn nanoparticles) were synthesized by redox reaction between metal ions and reducing metabolites present in the extracts. A response surface methodology (RSM) with three factors (extract concentration, heating time and pressure) was applied to determine the optimal synthesis conditions. The phytotoxicity of nanoparticles (NPs) on maize seedlings was subsequently evaluated on root growth, oxidative stress enzymes (CAT, POD, and APX), and physiology of seedlings. Nanoparticles synthesized from C. longirostrata extract demonstrated superior properties, with an optimization of synthesis (R² = 95.3%) where the extract concentration (1:4 v/v; p < 0.01) was the critical factor influencing the reduction of metallic ions to nanoparticles. These NPs exhibited superior stability, smaller size (<100 nm), and zeta potential greater than 30 mV compared with O. basilicum extracts. Their NPs exhibited poorer optimization of synthesis (R² = 43.8%) without the effect of any of the variables evaluated. Essentially, C. longirostrata NPs showed no phytotoxic effects on maize seedlings’ physiological parameters and enhanced root growth (117.2 mm) without negatively affecting photosynthesis (PSII 70-81 FvFm). Ag-ZnNPs synthesized with C. longirostrata exhibited optimal stability and size, along with no observed possible phytotoxicity effects, unlike O. basilicum NPs, which cause stress on maize seedlings. Therefore, Crotalaria longirostrata NPs could represent a promising material for agricultural pest control, with no apparent adverse effect on maize crops. Full article

Inspired by their biocompatibility and thermoreversible gelation—transitioning from room temperature liquids to body temperature gels—Pluronic hydrogels were employed in this study to optimize intracanal penetration and ensure medicament stability. We developed a silver nanoparticle (AgNP)-loaded Pluronic gel (AgNPs-P-gel) as a biocompatible, easily removable intracanal medicament. Following PRILE 2021 guidelines, AgNPs-P-gels (F127/F68) were evaluated for gelation, AgNP release, and antibacterial activity against Enterococcus faecalis and Streptococcus mutans via minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and growth curves. Biofilms in bovine teeth were quantified using CFUs and scanning electron microscope (SEM) imaging. Biocompatibility was tested in L-929 fibroblasts using MTT assays and RT-qPCR for pro-inflammatory cytokines (IL-6, TNF-α, IL-1β). Removal efficacy from bovine canals was microscopically scored. The optimized formulation (20% F127, 7.5% F68) gelled at 34 °C with sustained release over 168 h. AgNPs-P-gel showed strong antibacterial activity (MIC: 25–50 µg/mL). In ex vivo models, 100 µg/mL AgNPs-P-gel (AgNPs-100-P-gel) reduced bacterial counts comparably to calcium hydroxide and chlorhexidine, but with lower cytotoxicity. Although inducing cytokine expression similar to conventional medicaments, AgNPs-P-gel demonstrated significantly superior removability. Thermoreversible AgNPs-P-gel offers sustained antimicrobial action, favorable biocompatibility, and superior removability, potentially improving endodontic disinfection predictability as a calcium hydroxide alternative. Full article

Green-synthesized silver nanoparticles (AgNPs) exhibit outstanding antibacterial and antioxidant potential for designing and developing nanomedicines and medical devices. Nephelium lappaceum or rambutan contains polyphenol-based phytochemicals, which suggests its suitability for the green synthesis of NPs. However, the lack of a systematic approach directly impacts the robustness and reproducibility of the process. Design of experiments can address these challenges in obtaining NPs with the desired quality profile. In this work, we demonstrated the advantages of a Plackett–Burman model in the semi-automated green synthesis of AgNPs using N. lappaceum peel extract. The extract concentration was the only significant factor affecting the particle size. The optimized NPs exhibited triangular and hexagonal morphologies and a hydrodynamic diameter of 80 nm after 24 h without a stabilizing agent, representing 1.2% prediction error according to the model’s equation. The in vitro antioxidant capacity was confirmed through the ABTS radical scavenging assay. The AgNPs displayed a minimum inhibitory concentration of 23.5 µg mL⁻¹ against Escherichia coli and Staphylococcus aureus. Overall, this work highlights the synergistic role between a DoE-assisted green synthesis, the phytochemicals from N. lappaceum peel extract, and the formed AgNPs, positioning this systematic approach as a sustainable and efficient process for novel antibacterial and antioxidant agents. Full article

The invasive fall armyworm (Spodoptera frugiperda) threatens Philippine crops, highlighting the need for sustainable pest management. This study therefore optimizes the green synthesis of silver nanoparticles (AgNPs) from water hyacinth (Eichhornia crassipes), an abundant and problematic aquatic weed, as a potential pest control tool. Methanolic leaf extracts were prepared under varying methanol concentrations, temperatures, and extraction times, and total phenolic content was quantified using the Folin–Ciocalteu method. SEM–EDX confirmed the formation of silver nanoparticles synthesized from Eichhornia crassipes (Ec-AgNPs), with particles observed at ≤100 nm. Optimal extraction occurred at 47 °C, 90% methanol, and 76 min, maximizing phenolic yield. Overall, results suggest phenolic content and extract volume influence nanoparticle size and stability, with larger extract volumes increasing agglomeration risk. Pesticidal efficacy was not evaluated; further work is needed to assess pest control performance. Full article

Silver nanoparticles (AgNP), which have a wide range of applications in technical and biological fields, are produced in hundreds of tons annually and are eventually released into water, air, and soil. In this study, the effects of AgNPs on Phanerochaete chrysosporium, a white-rot fungus that plays a key role in wood waste degradation, were investigated. The AgNP were synthesized at high temperature with gallic acid under different pH conditions: near-neutral pH (~7.5), notation AgNP@GA-1, and alkaline pH (~10.5), notation AgNP@GA-2, focusing on their ability to cope with oxidative stress. The samples were characterized by fine granularity (particle diameter of 12 and 11 nm, respectively), specific plasmonic features (characteristic band at 425 and 408 nm), hydrodynamic diameter of 93 and 133 nm, respectively, and Zeta potential of −34 to −44 mV, which gave them stability over a period of three months. The fungal cultures exposed to AgNP concentrations of 40–100 µL/mL (approximately 4–11 µg/mL) presented superoxide dismutase (SOD) activity, which increased by approximately 45% at 40 µL/mL for AgNP@GA-1 after 7 days, whereas AgNP@GA-2 decreased SOD activity by up to 40% at 60 µL/mL. Both AgNP types strongly stimulated catalase (CAT) biosynthesis, with two- to three-fold increased activity on the 7th day at 100 µL/mL. CAT activity remained significantly elevated for AgNP@GA-1 on the 14th day at 60–80 µL/mL, whereas for AgNP@GA-2 it decreased by 40–60% compared with the control. Variations in malondialdehyde content indicated moderate lipid peroxidation, suggesting relatively low cytotoxic effects on fungal cells. Overall, the results demonstrate that P. chrysosporium exhibits adaptive biochemical responses to AgNP-induced oxidative stress while maintaining metabolic functionality, highlighting the potential compatibility of AgNPs with white-rot fungi involved in environmental wood waste biodegradation processes. Full article

Titanium dioxide nanoparticles (TiO₂ NPs) are incorporated into automotive coatings to enhance durability, corrosion, UV resistance, and, in some formulations, photocatalytic self-cleaning. While the toxicology of pristine TiO₂ is well studied, the behavior of TiO₂ NPs embedded in polymer matrices and subjected to real-world aging, maintenance, and removal remains poorly characterized. This narrative review synthesizes 24 publications spanning the lifecycle of TiO₂ nano-enabled automotive coatings, from synthesis and formulation through application, in-service weathering, repair, refinishing, and end-of-life environmental fate. Upstream properties, such as coating functionality and performance, have been examined as determinants of later-life release, exposure, and fate. Across studies, dispersion state, interfacial compatibility, and surface modification—together with transformations such as agglomeration, photocatalysis, weathering, and eco-corona formation—shape particle stability, release, exposure relevance, and toxicological risk. Evidence indicates that sanding and accelerated weathering predominantly generate matrix-associated, polymer-fragment-dominated aerosols rather than pristine TiO₂ NPs, while NP-specific exposure measurements during spray application remain limited. Hazard data suggest matrix embedding may attenuate, but does not eliminate, biological responses relative to pure particles. Wastewater treatment plants and biosolids have been shown to act as sinks with potential for soil accumulation following sludge application. Regulatory frameworks rarely account for aging, transformation, and release, stressing the need for synchronized testing of aged materials and nano-specific exposure metrics to support safer-by-design coatings and risk governance. Full article

Cutaneous wound healing is a complex biological process often impaired by bacterial infections, especially by Staphylococcus aureus. To address this, alginate (ALG)/chitosan (CS) polyelectrolyte multilayer (PEM) films incorporating alginate-coated silver nanoparticles (ALG–AgNPs) were fabricated by layer-by-layer self-assembly. The films exhibited a porous, layered morphology with homogeneous distribution of ALG–AgNPs, hydrophilic surfaces (contact angle ≈ 55°), a high swelling degree (~175%), and a water vapor transmission rate of 1830 g m⁻²·day⁻¹. Thermal analyses showed similar degradation profiles up to 600 °C, with the ALG–AgNP film displaying lower moisture loss and higher dehydration temperature, consistent with enhanced ionic and coordination crosslinking (–NH₃⁺/–COO⁻ and Ag–O–C bonds). The release of Ag⁺ in PBS (pH 7.4) was ~3% after 24 h, following a Korsmeyer–Peppas mechanism (R² = 0.97, n < 0.5), and degradation, with ~40% mass loss in 6 days, indicated gradual matrix disintegration. Cytocompatibility studies revealed >80% viability for fibroblasts, keratinocytes, macrophages, and <2% hemolysis of red blood cells. Immune assays showed a tendency towards reduced TNF-α and IL-1β and regulated IL-6/IL-8 release. Antibacterial evaluations demonstrated a 5-log reduction in planktonic bacterial viability and >2-log reduction in adhesion, and an 11 ± 1 mm inhibition zone for S. aureus. These results demonstrate that ALG/CS–AgNP PEM films combine biocompatibility, antibacterial efficacy, controlled degradation, and structural stability, making them promising multifunctional scaffolds for the regeneration of infected skin wounds. Full article

Biocompatible nanocomposite hydrogels are emerging as versatile platforms in nanomedicine, particularly when natural proteins are used as both structural and chemical components. In this work, we report a green, simple, and rapid in situ synthesis of ultrasmall silver nanoparticles (uAgNPs) within a bovine serum albumin (BSA) hydrogel, in which albumin simultaneously acts as the reducing agent and three-dimensional scaffold. The confined reaction environment generated uniformly dispersed Ag nanostructures with diameters in the 4–40 nm range, as confirmed by DLS and TEM. High-resolution TEM revealed clear Face-Centered Cubic (FCC, 111) lattice fringes, demonstrating the crystalline nature of the embedded uAgNPs. Quantitative image analysis showed narrow size distributions and high circularities, consistent with cluster stabilization through protein–metal interactions. Rheological measurements further indicated that the incorporation of uAgNPs enhanced hydrogel stiffness and delayed yielding, reflecting a reinforcement effect mediated by the nanoparticles acting as additional cross-linking points. Moreover, when very small embedded uAgNPs are formed, the presence of emissive silver nanoclusters was found using fluorescence emission spectroscopy. Overall, our results show that BSA hydrogels provide an effective matrix for directing green uAgNP nucleation, ensuring high stability, controlled growth in less than 2 min, and improved mechanical properties. The resulting protein–nanoparticle composite constitutes a promising soft material for imaging, sensing, and other biomedical applications requiring stable, biocompatible nanoscale architectures. Full article

Microwave-assisted biosynthesis using marine Chlorella sp. extracts provides a green and efficient route for the production of silver nanoparticles (AgNPs). Compared with the conventional method (24 h), microwave-assisted synthesis reduces the reaction time to less than 7 min while producing smaller and more uniformly distributed nanoparticles. AgNPs were synthesized using extracts obtained with different solvents and directly compared with those produced via the conventional method to substantiate the efficiency of the microwave-assisted approach. UV–visible spectroscopy confirmed rapid nanoparticle formation, exhibiting surface plasmon resonance peaks in the range of 405 to 427 nm. TEM analysis revealed predominantly spherical AgNPs with particle sizes of approximately 10 to 20 nm. The XRD and FTIR analyses confirmed their crystalline structure and stabilization by algal-derived functional groups. The biological activities of the AgNPs were dependent on the extraction solvent. AgNPs synthesized using hexane extracts exhibited pronounced antibacterial activity, achieving minimum inhibitory concentrations as low as 0.31 µg/mL. In addition, the AgNP induced concentration-dependent cytotoxic effects in human breast cancer cell lines. IC₅₀ values, determined via dose–response analysis, ranged from 0.18 to 0.67 μg/mL in MDA-MB-231 cells and 1.70 to 8.42 μg/mL in MCF-7 cells. These results indicate a potent cytotoxic profile, with MDA-MB-231 cells exhibiting significantly higher sensitivity to the microwave-assisted formulations. Collectively, these findings highlight microwave-assisted algal-mediated biosynthesis as a sustainable and effective platform for generating bioactive AgNPs with promising antibacterial and anticancer potential. Full article

This study presents a straightforward process for producing a hybrid ternary composite of silver nanoparticles (Ag NPs), small graphene oxide (s-GO), and zirconia (ZrO₂) and its use as an electrode material for electrochemical sensing. The physico-chemical properties of the ternary composite were analyzed by means of field emission scanning electron microscopy (FE-SEM), ultraviolet-visible (UV-vis) and FTIR spectroscopy, X-ray Photoelectron Spectrometry (XPS) and contact angle (CA) measurements. The synthesized hybrid nanomaterial was employed as an electrode modifier in the fabrication of a modified screen-printed carbon electrode (SPCE) and used for the simultaneous electrochemical sensing of key environmental pollutants such as hydroquinone (HQ) and catechol (CAT). The developed sensor exhibited linearity in the range of 0–100 µM for both HQ and CAT, with sensitivity values of 2640 µA·mM⁻¹·cm⁻² for HQ and 5120 µA·mM⁻¹·cm⁻² for CAT. The limits of detection (LOD) were 1.5 µM for HQ and 0.72 µM for CAT, respectively. The synergistic enhancement of electron transfer kinetics, the increased electroactive surface area, the strong anti-interference capability, and excellent reproducibility and stability establish these modified electrodes as promising candidates for environmental monitoring and real sample analysis. Full article

Antimicrobial resistance (AMR) remains a serious public health concern, and methicillin-resistant Staphylococcus aureus (MRSA) continues to limit treatment options. This laboratory-based comparative study evaluated antibiotic resistance patterns and nanoparticle (NP) susceptibility among 110 S. aureus isolates recovered from human skin and soft tissue infections (n = 80) and camel milk (n = 30). Proteomic identification utilizing matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) was carried out for all isolates under study. Phenotypic differentiation between MRSA and methicillin-sensitive S. aureus (MSSA) was performed via the cefoxitin disk diffusion method, and antimicrobial susceptibility testing was carried out using the disk diffusion method as stated in international guidelines. Multidrug resistance (MDR) was defined by established criteria. The antibacterial activity of silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) was detected by broth microdilution to determine minimum inhibitory concentration values (MIC₅₀ and MIC₉₀). The ability to develop reduced susceptibility was evaluated through ten serial sub-inhibitory passages followed by stability testing without using nanoparticles. MRSA prevalence was 52.5% among human isolates and 70% among camel milk isolates. Overall, 56.4% of isolates met MDR criteria, with a significantly higher MDR rate among MRSA compared with MSSA. Both human and camel isolates showed similar resistance patterns. AgNPs exhibited strong antibacterial activity, with MIC₅₀ and MIC₉₀ values of 0.0078 mg/mL and 0.0156 mg/mL, respectively; nevertheless, AuNPs demonstrated higher MIC values. Response to NPs was similar between isolates, independent of methicillin resistance or MDR. Serial sub-inhibitory exposure resulted in increased MIC values in all tested isolates, and stable resistance persisted in 50% of cases. These results indicate ongoing MRSA circulation in human and animal settings and reinforce the need for careful and controlled use of NP-based antimicrobials. Full article

Conventional colorimetric lateral flow immunoassays (LFIAs) often suffer from insufficient sensitivity for detecting trace low-molecular-weight contaminants like mycotoxins. The development of colorimetric probes with a high molar extinction coefficient is therefore critical for enhancing detection performance. Although silver nanoparticles (AgNPs) exhibit an extremely high molar extinction coefficient, their practical application in LFIA is hindered by inherent chemical instability and suboptimal visual contrast. To address these limitations, we have engineered robust and high-performance polydopamine-functionalized AgNPs (Ag@PDA NPs) as advanced LFIA signal probes, which were successfully used for detecting aflatoxin B₁ (AFB₁) in maize. The multifunctional PDA nanoshell effectively shields the Ag core from oxidation and other destabilizing factors, ensuring superior long-term stability and significantly enhancing colorimetric contrast. Moreover, it improves the colloidal hydrophilicity, enabling faster and more uniform migration kinetics along the test strip. Leveraging these engineered properties, the developed assay achieved a limit of detection (LOD) of 0.23 ng mL⁻¹ for AFB₁ in buffer, representing a remarkable 2.17-fold sensitivity enhancement over conventional colloidal gold-based LFIAs. Validation in spiked maize samples confirmed high reliability, with recoveries ranging from 95.70% to 119.28% and precision (inter-/intra-assay CVs) below 13.03%. Full article

Background/Objectives: Hydrogels infused with silver nanoparticles (AgNPs) are widely used for their antibacterial properties, yet their stability, specifically upon contact with solid growth media (agar), remains poorly explored. This study compared two hydrogel matrices, anionic Carbopol 934 and non-ionic Pluronic F127, incorporating AgNPs of three different sizes. The evaluation focused on colloidal stability and antibacterial efficacy against Gram-positive and Gram-negative bacteria. Methods: In this study AgNPs (~20, ~55, and ~65 nm) were synthesised via a wet-chemical method and characterised by UV–visible spectroscopy, dynamic light scattering (DLS), and transmission electron microscopy (TEM). AgNPs were incorporated into Carbopol 934 and Pluronic F127 hydrogel matrices. Colloidal stability was monitored over four months of storage and upon contact with tryptic soy agar (TSA). Antibacterial activity was assessed using agar diffusion assays. Results: Showed that both hydrogel systems maintained AgNP stability during storage, comparable to aqueous suspensions. However, upon contact with TSA, aggregation of Carbopol–AgNP hydrogels occurred, whereas Pluronic–AgNP hydrogels remained stable. In antibacterial assays, both hydrogels produced larger zones of inhibition (ZOI) than AgNP suspensions against Gram-negative bacteria (E. coli, P. aeruginosa), with Carbopol–AgNP hydrogels demonstrating superior efficacy in an inverse size-dependent manner. Against Gram-positive bacteria (S. aureus, S. epidermidis), Pluronic–AgNP hydrogels initially showed larger ZOIs due to the polymer’s intrinsic antibacterial activity. However, after correcting for this baseline, Carbopol–AgNP hydrogels exhibited superior net efficacy, with S. epidermidis showing greater susceptibility than S. aureus. Conclusions: While both Carbopol 934 and Pluronic F127 stabilise AgNPs during storage, the matrix type significantly influences behaviour at the biological interface. Carbopol–AgNP hydrogels aggregate upon contact with solid agar yet deliver superior, size-dependent antibacterial activity compared to the stable but less potent Pluronic systems. Full article

This study investigates the development and characterization of bioactive films incorporating silver nanoparticles (AgNPs) into biocompatible polymers, namely alginate and chitosan, fabricated using two methods, spin-coating and drop-casting, and aiming to enhance their antimicrobial properties. Dynamic light scattering (DLS) and electrophoretic mobility (EM) of the film precursor solutions revealed significant changes in the nanoparticles’ size and Zeta potential (ZP), reflecting the influence of polymer coatings. Alginate contributed to high electrostatic stability due to its negative charge, while chitosan facilitated specific interactions with negatively charged surfaces. Raman spectroscopy revealed that spin-coating conditions did not successfully result in film formation, highlighting the need for further optimization. Therefore, subsequent characterization studies were conducted only for the films formed by drop-casting. Topographical and nanomechanical assessments of these drop-cast films, using atomic force microscopy (AFM) and force spectroscopy, demonstrated that AgNPs reduced adhesion and elasticity in alginate films, while increasing rigidity and adhesion in chitosan-based films. Antimicrobial tests confirmed the efficacy of AgNPs in both precursor solutions and polymer films, with chitosan-based films that retained structural integrity, which makes them suitable for prolonged applications, while alginate films displayed rapid gelation upon hydration, potentially advantageous in short-term applications. The findings underscore the potential of these biopolymer-AgNP composites in creating antimicrobial materials for food packaging, wound dressings, and other biomedical applications. However, challenges related to film deposition methods, such as spin-coating, require further optimization to improve film formation and reproducibility. Full article