Concentrations Of AgNPs Research Articles

Electrospun Chitosan/Polylactic Acid Nanofibers with Silver Nanoparticles: Structure, Antibacterial, and Cytotoxic Properties.

Electrospinning, a technique for creating fabric materials from polymer solutions, is widely used in various fields, including biomedicine. The unique properties of electrospun fibrous membranes, such as large surface area, compositional versatility, and customizable porous structure, make them ideal for advanced biomedical applications like tissue engineering and wound healing. By considering the high biocompatibility and well-known regenerative potential of polylactic acid (PLA) and chitosan (CH), as well as the versatile antibacterial effect of silver nanoparticles (AgNPs), this study explores the antibacterial efficacy, adhesive properties, and cytotoxicity of electrospun chitosan membranes with a unique nanofibrous structure and varying concentrations of AgNPs. Silver nanoparticles incorporated at concentrations of 25-50 μg/mL or above significantly enhanced the antibacterial effectiveness, especially against Staphylococcus aureus and Escherichia coli. Biocompatibility assessments using umbilical cord mesenchymal stem cells demonstrated the nontoxic nature of the membranes with an AgNP concentration of 12.5 μg/mL, underscoring their potential for biomedical applications. This study provides valuable insights into developing electrospun chitosan membranes as effective antimicrobial coatings for various biomedical uses, including wound healing patches and tissue engineering constructs for soft tissue replacement.

Genetic determinants of silver nanoparticle resistance and the impact of gamma irradiation on nanoparticle stability

BackgroundOne of the main issues facing public health with microbial infections is antibiotic resistance. Nanoparticles (NPs) are among the best alternatives to overcome this issue. Silver nanoparticle (AgNPs) preparations are widely applied to treat multidrug-resistant pathogens. Therefore, there is an urgent need for greater knowledge regarding the effects of improper and excessive use of these medications. The current study describes the consequences of long-term exposure to sub-lethal concentrations of AgNPs on the bacterial sensitivity to NPs and the reflection of this change on the bacterial genome.ResultsChemical methods have been used to prepare AgNPs and gamma irradiation has been utilized to produce more stable AgNPs. Different techniques were used to characterize and identify the prepared AgNPs including UV-visible spectrophotometer, Fourier Transform Infrared (FT-IR), Dynamic light scattering (DLS), and zeta potential. Transmission electron microscope (TEM) and Scanning electron microscope (SEM) showed 50–100 nm spherical-shaped AgNPs. Eleven gram-negative and gram-positive bacterial isolates were collected from different wound infections. The minimum inhibitory concentrations (MICs) of AgNPs against the tested isolates were evaluated using the agar dilution method. This was followed by the induction of bacterial resistance to AgNPs using increasing concentrations of AgNPs. All isolates changed their susceptibility level to become resistant to high concentrations of AgNPs upon recultivation at increasing concentrations of AgNPs. Whole genome sequencing (WGS) was performed on selected susceptible isolates of gram-positive Staphylococcus lentus (St.L.1), gram-negative Klebsiella pneumonia (KP.1), and their resistant isolates St.L_R.Ag and KP_R.Ag to detect the genomic changes and mutations.ConclusionsFor the detection of single-nucleotide polymorphisms (SNPs) and the identification of all variants (SNPs, insertions, and deletions) in our isolates, the Variation Analysis Service tool available in the Bacterial and Viral Bioinformatics Resource Center (BV-BRC) was used. Compared to the susceptible isolates, the AgNPs-resistant isolates St.L_R.Ag and KP_R.Ag had unique mutations in specific efflux pump systems, stress response, outer membrane proteins, and permeases. These findings might help to explain how single-nucleotide variants contribute to AgNPs resistance. Consequently, strict regulations and rules regarding the use and disposal of nano waste worldwide, strict knowledge of microbe-nanoparticle interaction, and the regulated disposal of NPs are required to prevent pathogens from developing nanoparticle resistance.

Green synthesis of silver nanoparticles from endophytic fungus Colletotrichum sp. with special emphasis on antibacterial, antioxidant and plant growth promoting potential

The creation of "microbial nanotechnology" for quick and large-scale manufacturing of nanoparticles would be possible with an effective biosynthesis method. Plumbago zeylanica L. is a medicinal plant from which the endophytic fungus Colletotrichum sp. was isolated and identified by 18S rDNA sequencing and microscopic studies. Cell filtrate of Colletotrichum sp. was employed to produce biological silver nanoparticles which acted as a reducing and stabilising agent during this process. The brown colour proved that silver nanoparticles (AgNPs) are being produced. In characterization of AgNPs, ultraviolet-visible spectroscopy revealed maximum absorption at 425 nm. From transmission electron microscopy and field emission scanning electron microscopic study the shape of the silver nanoparticle was found spherical with 10–30 nm diameters. The existence of elemental silver (peak) was verified by the silver signal in the energy-dispersive X?ray spectroscopy. Fourier-transform infrared analysis showed some major and minor shifts in the peaks of some chemical bonding. Synthesised AgNP had strong antibacterial action against pathogenic bacterial strains in 200 g/mL concentration and against Pseudomonas aeruginosa MTCC 741, it showed the highest inhibition. The AgNP concentration of 150 g/mL demonstrated the highest competency for antioxidant capabilities while ascorbic acid was used as the reference. Also, AgNP exhibited plant growth-promoting ability as in 40 mg/L concentration; it significantly enhanced the shoot and root growth, total soluble protein, sugar, and indole acetic acid content of P. zeylanica L. This AgNP can be useful in pharmaceutical industries and agriculture as nano fertilizers for all these purposes.

Embedment of Biosynthesised Silver Nanoparticles in PolyNIPAAm/Chitosan Hydrogel for Development of Proactive Smart Textiles.

A smart viscose fabric with temperature and pH responsiveness and proactive antibacterial and UV protection was developed. PNCS (poly-(N-isopropylakrylamide)/chitosan) hydrogel was used as the carrier of silver nanoparticles (Ag NPs), synthesised in an environmentally friendly manner using AgNO3 and a sumac leaf extract. PNCS hydrogel and Ag NPs were applied to the viscose fabric by either in situ synthesis of Ag NPs on the surface of viscose fibres previously modified with PNCS hydrogel, or by the direct immobilisation of Ag NPs by the dehydration/hydration of the PNCS hydrogel with the nanodispersion of Ag NPs in the sumac leaf extract and subsequent application to the viscose fibres. Compared to the pre-functionalised PNCS application method, the in situ functionalisation imparted much higher concentration of Ag NPs on the fibres, colouring the samples brown to brown-green. These samples showed more than 90% reduction in the test bacteria E. coli and S. aureus and provided excellent UV protection. In this case, the PNCS hydrogel acted as a reservoir for Ag NPs, whose release was based on a diffusion-controlled mechanism. Despite the Ag NPs decreasing the responsiveness of the PNCS hydrogel, the moisture management was still preserved in the modified samples. Accordingly, the PNCS hydrogel is a suitable carrier for biosynthesized Ag NPs to tailor the protective smart surface of viscose fibres.

Silver nanoparticle toxicity in rainbow trout: insights into physiological and molecular responses

Metallic nanoparticles, with their large surface area to volume ratio, are increasingly important in various life fields, but they can cause varying toxic effects on fish. This study investigates the toxicological effects of silver nanoparticles (AgNPs) on rainbow trout (Oncorhynchus mykiss), focusing on hematological, biochemical, antioxidant, and histopathological changes. Fish were exposed to varying concentrations of AgNPs (0.2, 0.8, and 1.4 mg/L) for 21 days. Hematological analysis revealed significant reductions in red blood cell (RBC) counts, hemoglobin (Hb), and hematocrit (HCT) at higher AgNPs concentrations, while white blood cell (WBC) counts increased, indicating immune system activation. Biochemical assays demonstrated dose-dependent decreases in total protein and albumin, alongside increased cholesterol and triglyceride levels, suggesting impaired liver function and disrupted lipid metabolism. Antioxidant enzyme activity (SOD, CAT, GST) initially increased at lower AgNPs concentrations but declined at higher exposures, indicating oxidative stress. Molecular analysis further supported these findings, with upregulation of oxidative stress-related genes (SOD1, CAT) and inflammatory markers (HSP70, IL-1β). Histopathological examinations revealed necrosis, hyperplasia, and lamellar fusion in the gills, along with significant liver damage, including vacuolation and Kupffer cell proliferation, particularly at the highest exposure. Behavioral assays showed erratic swimming and reduced feeding in fish exposed to higher AgNPs concentrations. This study highlights the dose-dependent toxic effects of AgNPs on rainbow trout and underscores the potential for long-term, possibly irreversible damage at higher exposure levels. These findings emphasize the need for stricter environmental regulations on nanoparticle use to mitigate their ecological impact.

Antimicrobial Responses to Bacterial Metabolic Activity and Biofilm Formation Studied Using Microbial Fuel Cell-Based Biosensors.

Simultaneous monitoring of antimicrobial responses to bacterial metabolic activity and biofilm formation is critical for efficient screening of new anti-biofilm drugs. A microbial fuel cell-based biosensor using Pseudomonas aeruginosa as an electricigen was constructed. The effects of silver nanoparticles (AgNPs) on the cellular metabolic activity and biofilm formation of P. aeruginosa in the biosensors were investigated and compared with the traditional biofilm detection method. The crystal violet staining results showed that the concentration of AgNPs being increased to 20 and 40 μg/mL had a slight and obvious inhibitory effect on biofilm formation, respectively. In comparison, the detection sensitivity of the biosensor was much higher. When the concentration of AgNPs was 5 μg/mL, the output voltage of the biosensor was suppressed, and the inhibition gradually increased with the AgNPs dose. AgNPs inhibited the activity of planktonic cells in the anolyte and the formation of biofilm on the anode surface, and it had a dose-dependent effect on the secretion of phenazine in the anolyte. The biosensor could monitor the impacts of AgNPs not only on biofilm formation but also on cell activity and metabolic activity. It provides a new and sensitive method for the screening of anti-biofilm drugs.

Stage-Specific Effects of Silver Nanoparticles on Physiology During the Early Growth Stages of Rice.

Silver nanoparticles (AgNPs), widely utilized nanomaterials, can negatively affect crop growth and development. However, it remains unclear whether crops exhibit similar responses to AgNPs stress at seed germination and seedling stages. In this study, rice seeds and seedlings were exposed to AgNPs, and their growth, photosynthetic efficiency, and antioxidant systems were recorded. demonstrated significant AgNPs accumulation in rice tissues, with notable higher accumulation in seedlings exposed to AgNPs after germination compared to AgNPs exposure during germination. The roots exhibited greater AgNPs accumulation than shoots across both stages. Exposure to AgNPs during the seed germination stage, even at concentrations up to 2 mg/L, did not significantly affect growth, physiological indices, or oxidative stress. In contrast, seedlings exposed to 1 and 2 mg/L AgNPs showed significant reductions in shoot length, biomass, nutrient content, and photosynthetic efficiency. At low AgNPs concentrations, the maximum relative electron transport rate (rETRmax) was significantly reduced, while the higher concentrations caused pronounced declines in the chlorophyll a fluorescence transient curves (OJIP) compared to the control group. Antioxidant enzyme activities increased in both leaves and roots in a dose-dependent manner, with roots exhibiting significantly higher activity, suggesting that roots are the primary site of AgNPs stress responses. In conclusion, rice responds differently to AgNPs exposure at distinct developmental stages, with the seedling stage being more susceptible to AgNPs-induced stress than the seed germination stage. These findings underscore the importance of considering growth stages when assessing the food safety and environmental risks associated with AgNPs exposure.

Antimicrobial and Antibiofilm Activity of Green Synthesized Silver Nanoparticles by Using In Vitro Grown Aloe vera L.

In this study, invitro grown Aloe vera L. tissues were used for AgNP synthesis. Adventitious root and callus tissues were grown in MS medium containing 1 mg/L IAA and 1 mg/L NAA. Using A. vera L. leaf, in vitro grown callus, and adventitious roots tissue extracts, AgNPs were synthesized. According to DLS analysis, PDI values and zeta potential values showed that AgNPs from adventitious root were more suitable in terms of size and surface charge. Characterization of adventitious root-derived AgNPs was performed by UV-Vis absorption spectrum, ICP/MS, SEM, FTIR, and XRD. According to HPLC results, catechin, gentisic acid, caffeic acid, coumaric acid, polydatin, coumarin, and ellagic acid were found in adventitious roots. Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC2 7853), MRSA (ATCC 33951) and Staphylococcus aureus (ATCC 6538) strains were used to determine the antibacterial and antibiofilm activity of AgNPs. The highest antibacterial activity was determined against P. aeruginosa. Lower concentrations of AgNPs caused changes in the structure of the biofilm formed by P. aeruginosa, which produced particularly strong biofilms, resulting in failure of biofilm maturation. Accordingly, AgNPs synthesized from Aloe vera L. adventitious roots had antibacterial and antibiofilm activity even at low concentrationsagainst the tested bacterial strains.

Lethal and Sublethal Toxicity of Nanosilver and Carbon Nanotube Composites to Hydra vulgaris-A Toxicogenomic Approach.

The increasing use of nanocomposites has raised concerns about the potential environmental impacts, which are less understood than those observed with individual nanomaterials. The purpose of this study was to investigate the toxicity of nanosilver carbon-walled nanotube (AgNP-CWNT) composites in Hydra vulgaris. The lethal and sublethal toxicity was determined based on the characteristic morphological changes (retraction/loss of tentacles and body disintegration) for this organism. In addition, a gene expression array was optimized for gene expression analysis for oxidative stress (superoxide dismutase, catalase), regeneration and growth (serum response factor), protein synthesis, oxidized DNA repair, neural activity (dopamine decarboxylase), and the proteasome/autophagy pathways. The hydras were exposed for 96 h to increasing concentrations of single AgNPs, CWNTs, and to 10% AgNPs-90% CWNTs, and 50% AgNPs-50% CNWT composites. Transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS) analysis revealed the presence of AgNPs attached to the carbon nanotubes and AgNP aggregates. The data revealed that the AgNP-CWNT composites were more toxic than their counterparts (AgNPs and CNWT). The sublethal morphological changes (EC50) were strongly associated with oxidative stress and protein synthesis while lethal morphological changes (LC50) encompassed changes in dopamine activity, regeneration, and proteasome/autophagic pathways. In conclusion, the toxicity of AgNP-CWNT composites presents a different pattern in gene expression, and at lower threshold concentrations than those obtained for AgNPs or CWNTs alone.

Chemical and thermal stability of different AgNP concentrations incorporated in 0.1% DMPT UPE resin

Purpose In response to the growing demand for a polymer with improved chemical and thermal stability in the construction sector, this study aims to thoroughly explore the characteristics of silver nanoparticles (AgNP) and their various concentrations. The primary goal is to determine the effect of these nanoparticles on the chemical and thermal stability of unsaturated polyester (UPE) resin doped with dimethyl-para-toluidine (DMPT) when exposed to high temperatures. Design/methodology/approach Silver nanoparticles were first synthesized from the chemical reaction between silver nitrate and trisodium citrate before its addition to the resin. The nanocomposites were thoroughly examined using advanced analytical methods such as Fourier transform (FTIR), Raman spectroscopy and scanning electron microscope to determine chemical stability. Thermal stability tests were carried out using thermogravimetric analysis, differential thermal analysis and derivative thermogravimetry methods; viscosity and peak exotherm were also examined. Findings The data shows that increasing nanoparticle concentration improves resin chemical stability, reduces peak exotherm duration and increases viscosity. Clearly, only 1.5% AgNP concentration outperformed neat UPE resin, while 0.5% and 1% AgNP concentrations fall short in terms of thermal stability. Originality/value The enhanced resin highlights the subtle influence of nanoparticle addition, which has a greater impact on the chemical structure of the composite rather than its thermal properties.

STUDY OF SILVER NANOPARTICLES BIOACCUMULATION IN CULTURED RED AND GREEN SEAWEED

The bioaccumulation of polyvinylpyrrolidone-coated silver nanoparticles (PVP-AgNPs) in Palmaria palmata and Ulva sp. seaweed was investigated by ICP-MS and SP-ICP-MS (determination of nanoparticles and size distribution after an enzymatic extraction). Seaweeds were exposed to 0.1 and 1.0 mg L-1 of PVP-AgNPs of small particle size (15 nm) for 28 days. They were cultured in 40-L seawater tanks and nanoparticles were mixed with growing media and the phytoplankton used for feeding. Bioaccumulation changed with the type of seaweed and was not proportional to the concentration. Palmaria palmata and Ulva sp. reached the maximum total Ag concentration at 14 and 21 days of exposure to 1.0 mg L-1, respectively. The Ag concentrations measured (until 0.79 ± 0.06 μg g-1 w.w.) were much smaller than those found in previous studies after short-term exposure (up to 48 h) under laboratory conditions, probably due to the presence of organic matter in the growing media. The maximum concentrations of AgNPs were achieved at 14 and 28 days for Palmaria palmata and Ulva sp., respectively, with most frequent sizes of approximately 20 nm. The size values measured by SP-ICP-MS agreed with TEM sizes in the enzymatic extracts. No changes were observed in the concentrations of most metals (Co, Cr, Cu, Mo, Ni, Rb and V) in exposed seaweed; only a decrease of Cd and Pb at the dose of 1 mg L-1 in Palmaria was observed. Studies simulating the real marine environment are important to estimate bioaccumulation and safety, which change depending on the type of seaweed and nanoparticle.

Mechanical characteristics and antibacterial activity against Staphylococcus aureus of sustainable cellulosic paper coated with Ag and Cu modified ZnO nanoparticles

In this study, zinc oxide (ZnO) nanoparticles were prepared and modified using a wet chemical method with different concentrations of Ag and Cu nanoparticles. The objective was to improve the mechanical, optical, and antibacterial properties of the coated paper by using the prepared pigments. The long-term antimicrobial effects of the coated paper were evaluated over 25 years. The successful synthesis of a hexagonal structure of ZnO nanoparticles decorated with spherical Ag and Cu nanoparticles ranging from 20 to 50 nm was confirmed using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and transmission electron microscopy (TEM). By increasing the concentrations of Ag and Cu from 0.01% to 1.0%, the mechanical properties of the coated paper were enhanced. The tensile strength reached a maximum of 6.77 kN/m and 7.03 kN/m, elongation increased to 1.69% and 1.70%, tensile energy absorption improved to approximately 77 and 80 J/m2, and burst strength rose to 218 and 219 kPa, respectively. The use of Ag-modified ZnO maintains the optical properties, while Cu-modified ZnO reduces brightness and whiteness without affecting opacity. The antimicrobial inhibition activity was improved with higher silver (Ag) and copper (Cu) content. The formulations containing 1% Ag/ZnO and 1%Cu/ZnO showed long-lasting antibacterial effects against gram-positive Staphylococcus aureus bacteria. Even after 25 years of aging, they maintained inhibition rates of 92.2% and 62.2%, respectively. The molecular docking and GeneMANIA analysis revealed the potential of ZnO, Ag-modified ZnO, and Cu-modified ZnO nanoparticles to disrupt the S. aureus cell wall biosynthesis pathway by targeting the MurA enzyme and associated cell wall synthesis genes.

Antimicrobial effect of silver nanoparticles as a potential healing treatment for wounds contaminated with Staphylococcus aureus in wistar rats

Currently, the main challenges associated with conventional treatments for complex wounds include antibiotic resistance, persistent infections, delayed healing, pain and discomfort, lesion recurrence, and limited patient adherence. Silver nanoparticles (AgNPs) have demonstrated potential for bacterial control in contaminated wounds while promoting tissue regeneration. The aim of this study was to evaluate the bactericidal activity of AgNPs in wounds contaminated and non-contaminated with S. aureus. An aqueous suspension of AgNPs at a concentration of 117 μg/mL was synthesized by reducing silver nitrate in a medium containing tannic acid and sodium citrate. The resulting nanoparticles were spherical, with an average diameter of 24.3 ± 0.18 nm, a polydispersity index (PDI) of 0.25 ± 0.013, and a ζ-potential of −60.0 ± 3.07 mV. The bactericidal effect of AgNPs was observed at concentrations of 58.5 μg/mL for Escherichia coli and 6.74 μg/mL for S. aureus and Pseudomonas aeruginosa. Fibroblast viability (L929 cells) was maintained at confluence with AgNPs concentrations ranging from 0.1 μg/mL to 7.3 μg/mL. On the 7th day post-wound induction, animals treated with AgNPs exhibited 90 % re-epithelialization along with effective microbiological control. Histological analysis revealed a significant increase in fibroblast production in the treated groups compared to controls (p < 0.01). These results indicate that AgNPs hold promise for topical applications in bacterial control and wound healing.

Silver Nanoparticles Reduce Anthracnose Severity and Promote Growth of Bean Plants (Phaseolus vulgaris)

The present study aimed to evaluate the effect of silver nanoparticles (AgNPs) on the development of Colletotrichum lindemuthianum, the progression of anthracnose symptoms, and the growth of common bean plants. For this purpose, the fungal mycelial growth and conidial germination were assessed at AgNP concentrations of 0, 10, 30, and 50 mg·L−1 after seven days of incubation, as well as at 0, 0.1, 0.5, 1, 10, 30, and 50 mg·L−1 after 72 h, respectively. Bean plants of the IPR Uirapuru cultivar were sprayed at the V3 growth stage with AgNPs at 0, 10, 30, or 50 mg·L−1, either two days before, on the day of, or two days after inoculation. Conidial germination and appressoria melanization were measured on the leaf discs collected 24, 48, and 72 h after inoculation, and disease severity was assessed at 7 and 12 days post-inoculation. Another set of bean plants grown under the same conditions was used to evaluate growth promotion by AgNPs. For this, the plants were sprayed twice (with a seven-day interval), starting at the V3 growth stage, with AgNPs at 0, 10, 30, or 50 mg·L−1. Seven days after the second treatment, plant length and the fresh and dry weights of shoots and roots were measured, and the foliar pigments were quantified. The AgNPs did not reduce mycelial growth but completely inhibited the germination of C. lindemuthianum conidia. The severity of anthracnose decreased with the AgNPs in a dose- and application time-dependent manner, with the highest reduction (90%) observed when applied on the same day as an inoculation at 50 mg·L−1. This was strongly linked to a 70% decline in conidia germination and appressorium melanization on bean leaves. AgNPs at 50 mg·L−1 promoted plant growth by increasing the total length by 3%, as well as the fresh weights of bean shoots and roots by 17% and 90%, respectively, but did not affect the content of leaf pigments.

Phytogenic Silver Nanoparticles from Callicarpa macrophylla and their Biological Activities

In the present investigation, the phytogenic synthesis of silver nanoparticles (AgNPs) was carried out with Callicarpa macrophylla which possess multiple functional properties. The absorbance peak of the resultant AgNPs was found to be between 300 and 800 nm, with the highest absorbance at 436 nm. The phytocomponents accountable for facilitating the synthesis were determined through the utilization of Fourier-transform infrared (FTIR) analysis, which unveiled the presence of hydroxyl, amide, aldehyde, and alkene moieties. The crystal structure of the AgNPs was investigated via X-ray diffraction (XRD) analysis, which exhibited diffraction intensities at the 2-theta angle, signifying the presence of a well-defined crystalline structure of AgNPs. The polydispersity of the AgNPs was observed under a transmission electron microscope (TEM), with an average particle size of 10 to 60 nm. The AgNPs exhibited moderate antibacterial activity against Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus. The sprouting percentage of Pisum sativum, Vigna radiata, and Macrotyloma uniflorum seeds was assessed with notable observation of increase in length of root size was maximum at AgNPs concentrations of 5 mg/mL and 2 mg/mL for Pisum sativum and Vigna radiata, respectively. However, in the case of Macrotyloma uniflorum, the highest germination rate was observed at a concentration of 10 mg/mL. Similarly, shoot length was highest in all seeds at 10 mg/mL. Furthermore, the AgNPs showed significant dye degradation capabilities, with the highest degradation rate for safranin (58%), followed by methylene blue (35%), and the least degradation observed with crystal violet (21%). Overall, the studies confirm the multi applicative properties of AgNPs synthesized from Callicarpa macrophylla.

Assessment of the Antimicrobial Efficacy and Mechanical Properties of Glass Ionomer Cement (GIC) Incorporating Silver Nanoparticles In Varying Concentrations for Pediatric Dental Applications

ABSTRACT Background: Glass ionomer cement (GIC) is widely used in pediatric dentistry due to its fluoride-releasing properties and strong adhesion to tooth structure. However, enhancing its antimicrobial efficacy remains a challenge. Incorporating silver nanoparticles (AgNPs) has been proposed as a solution to increase the antimicrobial properties of GIC without compromising its mechanical strength. Materials and Methods: This study investigated the effects of integrating varying concentrations of AgNPs into GIC on its antimicrobial efficacy against common oral pathogens and its mechanical properties. Three concentrations of AgNPs (0.5%, 1%, and 1.5% by weight) were evaluated. Antimicrobial activity was assessed using the agar diffusion test against Streptococcus mutans and Lactobacillus acidophilus. Mechanical properties, including compressive strength and wear resistance, were measured using standardized tests. Thirty pediatric patients were randomly assigned to receive dental treatments using one of the three modified GIC formulations. Results: The GIC modified with 1% AgNPs demonstrated optimal antimicrobial activity, showing a significant inhibition zone increase of 25% against S. mutans and 20% against L. acidophilus compared to the control. The compressive strength of the GIC was maintained, with the 1% AgNP formulation achieving a compressive strength of 220 MPa, comparable to the control (215 MPa). Wear resistance slightly decreased as the concentration of AgNPs increased. Conclusion: The addition of 1% AgNPs to GIC significantly enhances its antimicrobial properties without adversely affecting its mechanical strength. This formulation holds potential for improving the effectiveness of pediatric dental restorations by reducing the risk of secondary caries.

Mechanisms of ROS-induced mitochondria-dependent apoptosis in Phaeodactylum tricornutum under AgNPs exposure

IntroductionNanomaterials such as silver nanoparticles (AgNPs) have gained widespread application across various fields. However, the large-scale production and application of AgNPs have raised concerns about their distribution in the environment and potential pollution issues.MethodsThis study investigates the toxic effects of AgNPs on the diatom Phaeodactylum tricornutum by employing electron microscopy for cellular observation, quantifying apoptotic cell numbers, and measuring antioxidant indicators. The research examines how varying concentrations of AgNPs induce stress in P. tricornutum and the specific mechanisms of the toxic effect.ResultsThe findings reveal that AgNPs induce apoptosis in P. tricornutum cells by triggering a mitochondria-mediated pathway, marked by a decrease in mitochondrial membrane potential and the activation of caspase enzymes. Additionally, AgNP exposure results in an overproduction of reactive oxygen species (ROS) within the algal cells, leading to lipid peroxidation of the cell membrane and a consequent increase in malondialdehyde (MDA) levels. This oxidative stress response induces the upregulation of antioxidant enzyme activities in an attempt to mitigate the excessive ROS.DiscussionROS is identified as the primary factor responsible for inducing mitochondria-mediated apoptosis. The research results will provide a theoretical basis for understanding the toxic effects and mechanisms of AgNPs on marine microalgae.

In vivo assessment of topically applied silver nanoparticles on entire cornea: comprehensive FTIR study

Silver nanoparticles (AgNPs) have gained attention in medicine for their potent antibacterial, antiviral, and anti-inflammatory properties. The use of silver nanoparticles in ophthalmic solutions raises concerns regarding potential toxicity of nanoparticles to ocular tissues, such as the cornea, conjunctiva, and retina, which necessitates further toxicity assessments aiding in the development of safer ophthalmic solutions. This study investigates the impact of AgNPs on corneal tissue using ophthalmic investigations, Fourier transform infrared (FTIR) spectroscopy, and chemometric analyses. Three concentrations of AgNPs (0.48 µg/mL, 7.2 µg/mL, and 15.5 µg/mL) were topically applied twice daily for 10 days, synthesized biologically by reducing silver nitrate with almond kernels water extract. Corneas, obtained by cutting 2–3 mm below the ora serrata, were analyzed with FTIR spectroscopy and subjected to chemometric analyses. Results reveal AgNPs’ influence on constituents with OH and NH groups, affecting corneal lipids and reducing the lipid saturation index. AgNPs alter both bulk and interfacial water, leading to changes in corneal hydration thus modifying corneal physico-chemical properties. The influence extends to the water environment around proteins and lipids, releasing bound water from phospholipids and disrupting hydrogen bonding networks around proteins. In conclusion, the applied AgNPs concentrations can be linked to dry eye onset.

Green synthesis of silver nanoparticle by Hyoscyamus muticus L. extract and study of its effect on tomato infected with Meloidogyne javanica

In this study, the aqueous leaf extract of Hyoscyamus muticus L Plant leaf was prepared using three methods: maceration (MAC), microwave-assisted extraction (MAE), and ultrasonic-assisted extraction (UAE). Then, the extracts were used to synthesize silver nanoparticles (Ag NPs) in an environmentally friendly approach. The characterization of the synthesized Ag NPs was carried out by various techniques. The XRD results confirmed the successful synthesis of nano-sized Ag crystals with spherical structure. The SEM images showed the formation of Ag NPs, which were smaller than 75 nm. The UV–Vis studies showed an obvious absorption peak for Ag NPs between 400 and 500 nm, with a clear peak around 450 nm for all samples. The elemental analysis using the EDS technique confirmed the presence of silver in the synthesized Ag NPs. Furthermore, the effect of different concentrations of Ag NPs was investigated on hatching and second-stage juvenile (J2s) mortality of Meloidogyne javanica, under controlled conditions. The results showed that increasing concentrations of Ag NPs led to higher percentages of inhibition of egg hatching and J2s mortality. Additionally, the Ag NPs synthesized by ultrasonic-assisted extraction with lower lethal concentration were found to be more toxic to M. javanica than the extract prepared by soaking. According to the results, Ag NPs showed a stronger inhibitory effect on M. javanica egg hatching and J2s mortality compared to the total extracts and chemically synthesized Ag NPs. Also, the lowest LC50 was observed for the Ag NPs synthesized using the plant extract as: UAE > MAE (180 w) > MAE (90 w) > MAC methods. The highest inhibition of egg hatch occurred at 0.5% v/v of Ag NPs after 72 h and remained consistent after 120 h.

Insight into Antiviral Activity of Ag/TiO2 Nanocomposites Against Influenza H1N1 Virus and Its Antiviral Mechanism.

Synthesis and characterization of silver (Ag)/titanium dioxide (TiO2) nanocomposite (ATA) to investigate its antiviral activity against the H1N1 influenza virus and antiviral mechanisms. A water-dispersible ATA was prepared by a photocatalytic reduction process from AgNO3 and TiO2. The characterization of ATA was performed by ultraviolet-visible spectroscopy, X-ray diffraction, high-resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy. The antiviral activities and the antiviral mechanism of ATA were investigated in detail by light microscopy, transmission electron microscopy and biological techniques such as cell cytotoxicity, 50% tissue culture infectious dose detection, western blot and reverse transcription-polymerase chain reaction. These results showed the successful synthesis of ATA nanocomposite with uniform particle size and distribution. It demonstrated the highly efficient antiviral activity of ATA in a dose- and time-dependent manner, as indicated by the reduction of viral titer and the reduction of cytopathic effects caused by viral infection. In the presence of ATA, the structure of the H1N1 influenza virus is directly destroyed and even disintegrated, with the damaged surface membrane proteins and fuzzy contour. It reduces the infection efficiency of influenza by suppressing the activity and expression of hemagglutinin and neuraminidase. The results of mechanistic studies suggested that ATA nanocomposite primarily interferes with virus attachment to viral receptors on the cell surface. Our study suggests that ATA may be a good antiviral candidate against the influenza virus. Compared with AgNPs alone, our synthesized ATA nanocomposites can achieve similar viral inactivation rates using only a much smaller concentration of AgNPs, greatly reducing the amount of AgNPs and their potential side effects. It has great practical value for attaching ATA to the high-efficiency particulate air network in the air purifier, which can kill the virus attached to it and limit its spread.