AgNP Treatment Research Articles

The role of silver nanoparticles in the reluctance of colisepticemia in broiler chickens

This study aims to determine the influence of silver nanoparticles ( Ag-NPs ) on performance, clinical and pathological pictures, virulence gene expression, and electron microscopy of experimentally induced Escherichia coli infection (colisepticemia) in broiler chickens. One-day-old chickens (n = 120) were segregated into 4 equal groups (1–4) with 3 replicates of 10 birds each. Birds were fed mash diet in 3 phases: starter (1–14 d), grower (15–28 d), and finisher (29–35 d). Chickens of the first 3 groups (T1, T2, T3) were fed Ag-NPs in the following dietary levels: 4, 6, and 8 mg/kg diet, respectively, while chickens of the fourth group (C) were fed a basal diet. All groups were individually infected by crop gavages with 0.5 mL/bird of PBS containing 3 × 10 8 CFU/mL of E. coli serogroup O78 for 2 successive days. In vitro Ag-NPs had a potent inhibitory effect against E. coli growth in pure form only (2,000 mg). In vivo study revealed that treatment of colisepticemic broiler chickens at a low dose (4 mg/kg diet) improved performance, reduced both gross and histopathological lesion scores, and virulence genes. It also altered the electron microscopic profile of the inoculated E. coli in the examined liver tissue. Severe negative effect was recorded on supplementation of the higher dose of Ag-NPs (8 mg/kg diet) that resulted in major effects on all the measured parameters except the gene expression analysis. Ag-NPs treatment with a dose of 4 mg/kg diet could play an optimistic role in the impedance of colisepticemia in broiler chickens.

Interaction of Differently Coated Silver Nanoparticles With Skin and Oral Mucosal Cells.

Silver nanoparticles (AgNP) can be found in different consumer products and various medical devices due to their excellent biocidal properties. Despite extensive scientific literature reporting biological effects of AgNP, there is still a lack of scientific evidence on how different surface functionalization affects AgNP interaction with the human skin and the oral epithelium. This study aimed to investigate biological consequences following the treatment of HaCaT and TR146cells with AgNP stabilized with negatively charged sodium bis(2-ethylhexyl)-sulfosuccinate (AOT), neutral polyvinylpyrrolidone (PVP), and positively charged poly-l-lysine (PLL). All AgNP were characterized by means of size, shape and surface charge. Interactions with biological barriers were investigated invitro by determining cell viability, particle uptake, oxidative stress response and DNA damages following AgNP treatment. Results showed a significant difference in cytotoxicity depending on the surface coating used for AgNP stabilization. All three types of AgNP induced apoptosis, oxidative stress response and DNA damages in cells, but AOT- and PVP-coated AgNP exhibited lower toxicity than positively charged PLL-AgNP. Considering the number of data gaps related to the safe use of nanomaterials in biomedicine, this study highlights the importance of particle surface functionalization that should be considered during design and development of future AgNP-based medical products.

Combination of Chlorhexidine and Silver Nanoparticles: an Efficient Wound Infection and Healing Control System

Purulent wounds are associated with microbial persistence that alters healing and can lead to septic complications. Infected wound management includes use of antibacterial agents for providing fast and complete bacterial elimination with no adverse effects on tissue repair. The performance of chlorhexidine (Ch) irrigation as the main strategy for purulent wound treatment is still under debates and stimulates further development of antimicrobial strategies. In this study, the effects of silver nanoparticles (AgNP) on infected wound microbiology and healing were assessed in vitro and in vivo. AgNPs provided high antibacterial activity at the minimal inhibitory concentration (MIC) of 1.25 μg/mL for E. coli and P. aeruginosa, and 2.5 μg/mL for S. aureus. At the same time assessment of AgNPs, cytotoxicity in fibroblast culture demonstrated high cytocompatibility in concentrations 5 times higher than MIC. These data agreed with in vivo studies with purulent wound modeling followed by use of three treatment options: Ch-, AgNP, and Ch+AgNP wound dressings. It was shown that AgNP treatment effectively decreased the microbial contamination but had only slight effect on wound healing parameters. In contrast, Ch+AgNP combination was associated with significant acceleration of wound clearance and closure related with early M2 macrophage polarization and an enhanced healing process. In conclusion, adding of AgNPs to chlorhexidine treatment improves infected wound healing through acceleration of bacteria elimination and M2 macrophage polarization. Synergic effects of AgNPs and chlorhexidine could be a promising option for optimizing infected wound management.

Role of Biogenic Silver Nanoparticles on Hyperhydricity Reversion in Dianthus chinensis L. an In Vitro Model Culture

Hyperhydricity (HH) is one of the major problems in plant tissue culture. Increased frequency (75%) of HH in the cultures of. Dianthus chinensis L. cultivar telstar scarlet raised from nodal segments on agar (0.85%) gelled, benzyladenine (2.5 µM) supplemented Murashige and Skoog (MS) medium was noticed in the third subculture onwards. To reduce HH and to resume normal growth, the addition of silver nitrate is routinely recommended in the culture medium. However, the impact of biogenic silver nanoparticles (AgNPs) on HH reversion has not been well investigated. In this study, biogenic AgNPs prepared from leaf extract of D. chinensis were used to control HH in D. chinensis cultures. The characterization of bioynthesized AgNPs has been done by UV–Vis spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction analysis, energy-dispersive X-ray spectrum, transmission electron microscopy, and atomic force microscopy. Higher water content or addition of ethylene precursor, ethephon, in culture medium induced plantlet with unhealthy, pale green, glassy shoots (HH). Due to the biological activity of Ag+ ions and water regulating mechanism, AgNPs treatment on hyperhydric explant (4 weeks) resulted in high retroversion coupled with reduced relative water content. Supplementation of 100 µg L−1 AgNPs in MS medium significantly reduced the percentage of HH to 13.3%, in contrast to control (100%). Addition of AgNPs effectively reduced hydrogen peroxide (H2O2) content (50%) characterized by green, healthy shoots with proper stomata in contrast to hyperhydric shoots. The gene expression pattern of 1-aminocyclopropane-1-carboxylase synthase (ACS1) and 1-aminocyclopropane-1-carboxylic acid oxidase (ACO1) showed reduced expression after the retroversion of microshoots in 100 µg L−1 AgNPs medium compared to hyperhydric shoot. The relative gene expression profile of ACS1 and ACO1 at 100 µg L−1 AgNPs treatment was 9.8 and 1.8-fold over normal shoots (1), respectively. Inter simple sequence repeat (ISSR) analysis on AgNPs directed HH reverted shoots showed genetic stability thus proved safe to adopt this technique to produce true to type plants. Combined manipulation, coordination of water permeability, and anti-ethylene activity of AgNPs were responsible for effective HH reversion. These finding will put forward the future utilization of bioencapsulated AgNPs in plant tissue culture and agriculture practices.

ANTIBACTERIAL INFLUENCE OF SILVER NANOPARTICLES ON MULTI-RESISTANT STRAINS OF K. PNEUMONIAE ISOLATED AT HOSPITALS

Introduction. Overuse and misuse of antibiotics in humans, animals, and agriculture has led to the widespread rise of antibiotic resistance and strengthened nosocomial pathogenes' impact. Klebsiella pneumoniae became an increasing threat to public health. Nanomaterials are promising alternatives to conventional antibiotics in the fight against multi-resistant germs. Silver nanoparticles are well-known metallic nanoparticles with antimicrobial activity. Our research aimed to evaluate the spreading of K. pneumonia resistant to antibiotics at hospital and assess the effectiveness of Ag NPs against multi-resistant clinical strains of K. pneumoniae. Material and methods. K. pneumoniae strains were isolated and identified with the use of conventional bacteriological techniques. Susceptibility of the microorganisms was assessed to inhibitors of β-lactamases, carbapenems, macrolides, oxazolidinones, and other groups of antibiotics with use Kirby-Bauer disk diffusion method. The capability of AgNPs to inhibit attachment and multiplication of the K. pneumoniae multi-resistant strains was tested with the use of serial microdilution method, resazurin assay, and SEM. Results. K. pneumoniae was isolated from 13.7% of samples predominantly at the microbial association (97.5%). The microorganisms were resistant to five or more antibiotics in 73.2% of cases. AgNPs possess antimicrobial activity against tested strains at concentrations varied from 1.25 µg/ml to 2.5 µg/ml and kill all germs in 3 hours of incubation. AgNPs inhibited biofilm formation at initial stages and destroyed the mature (2 days) biofilm with Ag NPs treatment at concentrations 20-40 µg/ml. The effectiveness of mature K. pneumoniae biofilm treatment with AgNPs depended on biofilm age. The SEM images of the two-days biofilm reveal lysis of the bacterial cells after the cocultivation with Ag NPs but SEM analysis detected the maintaining of the three-dimensional structure in the case of a five-day biofilm after cocultivation with AgNPs. Conclusions. The distribution of K. pneumonia among patients with laryngeal pathology and its sensitivity to eleven antibiotics were examined. There was revealed the high rate of K. pneumonia multi-resistant strains. Ag NPs have strong antibacterial and anti-biofilm potential against multi-resistant K. pneumoniae. Therefore, our results highlight that the Ag NPs have promising antimicrobial and anti-biofilm abilities against multi-resistant clinical strains of K. pneumoniae.

Performance, intestinal microbial population, immune and physiological responses of broiler chickens to diet with different levels of silver nanoparticles coated on zeolite

The aim of this study was to evaluate the effects of different levels of silver nanoparticles (Ag-NPs) coated on zeolite on performance, gastrointestinal microflora, heterophile to lymphocyte ratio and humoral immune system responses of broiler chickens. Three hundred seventy-five chicks (Cobb 500) in a completely randomised design were distributed to five diets: 1) basal diet, 2) basal diet containing 1% zeolite and 3, 4 and 5) basal diet containing 1% zeolite coated with 25, 50 and 75 ppm Ag-NPs. Performance traits were recorded and blood samples were taken to determine antibody response against Newcastle on day 14, infectious bursal disease on day 21 and serum immunoglobulins (Igs) were determined on day 42. Heterophile to lymphocyte ratio was evaluated on days 28, 35 and 42. The result showed that feed conversion ratio (FCR) was significantly decreased in Ag-NP treatments compared with control group (p < .05). Total anaerobic bacteria and the population of Escherichia coli in ileum and caecum were decreased (p < .05). The highest number of lactobacillus was observed in NS50 (p < .05). Antibody response against Gumboro was decreased as well as the amount of IgY antibody in Ag-NPs treatments. Significant differences were observed in heterophile to lymphocyte ratio on day 28 and 35 and the highest amount was observed in NS50 group (p < .05). In conclusion, although this study showed that using Ag-NP dietary coated on zeolite could improve gut microflora, but Ag-NPs could also have side effects on the immune mechanism of broiler chickens. Highlights Silver nanoparticles (Ag-NPs) coated on zeolite improved feed efficiency at different levels. Ag-NPs (50 ppm) coated on zeolite reduced Escherichia coli number and decreased lactobacillus number. Ag-NPs (50 ppm) coated on zeolite decreased antibody response against Gumboro and amount of IgY antibodies.

Validation of Three Different Sterilization Methods of Tilapia Skin Dressing: Impact on Microbiological Enumeration and Collagen Content.

Tilapia fish skin has demonstrated promise as a stable and practical biological dressing to be used in wound and burn management. However, the appropriate sterilization technique of the Tilapia fish skin is crucial before its clinical application. The standard sterilization technique must eliminate harmful pathogens but maintain the structural and biochemical properties that could compromise the dressing function. This study investigated and compared the efficiency of three sterilizing agents; chlorhexidine gluconate 4% (CHG), povidone iodine 10% (PVP-I), and silver nanoparticles (25 μg/mL) (AgNPs), at three different times (5, 10, and 15 min) on Tilapia fish skin based on the microbial count, histological and collagen properties. Among the sterilization procedures, AgNPs showed rapid and complete antimicrobial activity, with a 100% reduction in microbial growth of the fish skin throughout the treated times. Furthermore, AgNPs did not impair the cellular structure or collagen fibers content of the fish skin. However, CHG and PVP-I caused alterations in the collagen content. This study demonstrated that the AgNPs treatment of Tilapia fish skin provided sterile skin while preserving the histological properties and structural integrity. These findings provide an efficient and quick sterilization method suitable for Tilapia fish skin that could be adopted as a biological dressing.

Human Intestinal Tissue Explant Exposure to Silver Nanoparticles Reveals Sex Dependent Alterations in Inflammatory Responses and Epithelial Cell Permeability.

Consumer products manufactured with antimicrobial silver nanoparticles (AgNPs) may affect the gastrointestinal (GI) system. The human GI-tract is complex and there are physiological and anatomical differences between human and animal models that limit comparisons between species. Thus, assessment of AgNP toxicity on the human GI-tract may require tools that allow for the examination of subtle changes in inflammatory markers and indicators of epithelial perturbation. Fresh tissues were excised from the GI-tract of human male and female subjects to evaluate the effects of AgNPs on the GI-system. The purpose of this study was to perform an assessment on the ability of the ex vivo model to evaluate changes in levels of pro-/anti-inflammatory cytokines/chemokines and mRNA expression of intestinal permeability related genes induced by AgNPs in ileal tissues. The ex vivo model preserved the structural and biological functions of the in-situ organ. Analysis of cytokine expression data indicated that intestinal tissue of male and female subjects responded differently to AgNP treatment, with male samples showing significantly elevated Granulocyte-macrophage colony-stimulating factor (GM-CSF) after treatment with 10 nm and 20 nm AgNPs for 2 h and significantly elevated RANTES after treatment with 20 nm AgNPs for 24 h. In contrast, tissues of female showed no significant effects of AgNP treatment at 2 h and significantly decreased RANTES (20 nm), TNF-α (10 nm), and IFN-γ (10 nm) at 24 h. Smaller size AgNPs (10 nm) perturbed more permeability-related genes in samples of male subjects, than in samples from female subjects. In contrast, exposure to 20 nm AgNPs resulted in upregulation of a greater number of genes in female-derived samples (36 genes) than in male-derived samples (8 genes). The ex vivo tissue model can distinguish sex dependent effects of AgNP and could serve as a translational non-animal model to assess the impacts of xenobiotics on human intestinal mucosa.

Are silver nanoparticles better than triclosan as a daily antimicrobial? Answers from the perspectives of gut microbiome disruption and pathogenicity

As an alternative to triclosan (TCS), the widespread use of silver nanoparticles (AgNPs) in daily products shows genuine potential. However, information regarding whether AgNPs are substantially better than TCS in their potential disruption of the gut microbiome and health effects is lacking. Using a simulator of the human intestinal microbial ecosystem (SHIME), we systemically compared the effects of TCS and AgNPs (at 1 μg/L and 30 μg/L) on the human gut microbiome in terms of changes in gut homeostasis, microbial community structure, antibiotic resistance profiles and abundances of opportunistic pathogens. Generally, TCS exerted more severe effects than AgNPs on gut disturbances (i.e., decreased production of short-chain fatty acids, increased contents of ammonium and total bile acids, and increased β-glucosidase activities) in a dose-dependent manner, whereas no clear dose effect was observed for the AgNP treatment because of potential nanoparticle transformation. The more serious effect of TCS than AgNPs on the microbiota composition was indicated by the dynamic increase in the Firmicutes/Bacteroidetes ratio determined using 16S rDNA sequencing. Metagenomic analyses revealed a more pronounced effect of TCS than AgNPs on the selection and dissemination of multiple resistance genes to antibiotics, TCS, and even Ag via the enrichment of genes encoding efflux pumps and mobile genetic elements. Consequently, the overgrowth of opportunistic pathogens was observed upon TCS exposure due to an imbalanced microbiome, in contrast to a slight increase in the abundance of some beneficial bacteria (i.e., Bifidobacterium) induced by the AgNP treatment. In conclusion, from the perspective of effects on gut health, AgNPs may prevail over TCS to some extent. However, the stress and potential selection of Ag resistance indicates the need for targeted surveillance of AgNP commercialization for daily use.

Size-Dependent Bioactivity of Silver Nanoparticles: Antibacterial Properties, Influence on Copper Status in Mice, and Whole-Body Turnover.

PurposeThe ability of silver nanoparticles (AgNPs) of different sizes to influence copper metabolism in mice is assessed.Materials and MethodsAgNPs with diameters of 10, 20, and 75 nm were fabricated through a chemical reduction of silver nitrate and characterized by UV/Vis spectrometry, transmission and scanning electronic microscopy, and laser diffractometry. To test their bioactivity, Escherichia coli cells, cultured A549 cells, and C57Bl/6 mice were used. The antibacterial activity of AgNPs was determined by inhibition of colony-forming ability, and cytotoxicity was tested using the MTT test (viability, %). Ceruloplasmin (Cp, the major mammalian extracellular copper-containing protein) concentration and enzymatic activity were measured using gel-assay analyses and WB, respectively. In vitro binding of AgNPs with serum proteins was monitored with UV/Vis spectroscopy. Metal concentrations were measured using atomic absorption spectrometry.ResultsThe smallest AgNPs displayed the largest dose- and time-dependent antibacterial activity. All nanoparticles inhibited the metabolic activity of A549 cells in accordance with dose and time, but no correlation between cytotoxicity and nanoparticle size was found. Nanosilver was not uniformly distributed through the body of mice intraperitoneally treated with low AgNP concentrations. It was predominantly accumulated in liver. There, nanosilver was included in ceruloplasmin, and Ag-ceruloplasmin with low oxidase activity level was formed. Larger nanoparticles more effectively interfered with the copper metabolism of mice. Large AgNPs quickly induced a drop of blood serum oxidase activity to practically zero, but after cancellation of AgNP treatment, the activity was rapidly restored. A major fraction of the nanosilver was excreted in the bile with Cp. Nanosilver was bound by alpha-2-macroglobulin in vitro and in vivo, but silver did not substitute for the copper atoms of Cp in vitro.ConclusionThe data showed that even at low concentrations, AgNPs influence murine copper metabolism in size-dependent manner. This property negatively correlated with the antibacterial activity of AgNPs.

Virucidal activity of silver nanoparticles against Banana bunchy top virus (BBTV) in banana plants

BackgroundBanana bunchy top virus (BBTV) is a destructive viral disease in many countries including Egypt; it causes severe economic losses in banana crop. Recently, nanotechnology was used to generate resistance against plant viruses. The main purpose of this study was to use silver nanoparticles (AgNPs) as antiviral agents against BBTV. In this research, three different concentrations of AgNPs (40, 50 and 60 ppm) were applied by foliar spray post-BBTV inoculation. In addition, photopigments, oxidative enzymes, proline and phenolic compounds were determined. Besides, Random amplified polymorphic DNA (RAPD) and Sequence-related amplified polymorphism (SRAP) markers were used to evaluate the genotoxicity of AgNPs as antiviral factors against BBTV, compared with the control plants.ResultsIn the current study, it was observed that banana plants infected with BBTV and treated with 50 ppm AgNPs have not shown any external symptoms where the rate of infection was 36%. On the other hand, banana plants treated with 50 ppm AgNPs after viral infection gave a significant increase in dry weight and leaf area, compared with BBTV infected banana plants (viral control). Our study showed that 50 ppm AgNPs treatment post-virus inoculation induced non-significantly and significant changes in chlorophyll (a and b) and carotenoids, respectively, compared with healthy and nano-controls. In contrast, phenol, proline and oxidative enzymes were significantly increased in all plants treated with 50 ppm AgNPs post-virus inoculation, compared with the healthy control. Our findings observed that the banana plants sprayed with 50 ppm AgNPs after BBTV infection induced a few changes at the genomic DNA level in the banana plants, whereas both RAPD and SRAP markers scored nearly the same polymorphism 36.99 and 37.5%, respectively. So, genotoxicity induced by banana plants treated with 50 ppm AgNPs post-BBTV inoculation was low.ConclusionsIt is evident from the study results the role of AgNPs as a novel, safe and effective antiviral agent against BBTV. These results should be taken into consideration in future for the use of AgNPs for plant viruses management.

Anti-Influenza Effect of Nanosilver in a Mouse Model.

The present study assesses copper metabolism of the host organism as a target of antiviral strategy, basing on the “virocell” concept. Silver nanoparticles (AgNPs) were used as a specific active agent because they reduce the level of holo-ceruloplasmin, the main extracellular cuproenzyme. The mouse model of influenza virus A infection was used with two doses: 1 LD50 and 10 LD50. Three treatment regimens were used: Scheme 1—mice were pretreated 4 days before infection and then every day during infection development; Scheme 2—mice were pretreated four days before infection and on the day of virus infection; Scheme 3—virus infection and AgNP treatment started simultaneously, and mice were injected with AgNPs until the end of the experiment. The mice treated by Scheme 1 demonstrated significantly lower mortality, the protection index reached 60–70% at the end of the experiment, and mean lifespan was prolonged. In addition, the treatment of the animals with AgNPs resulted in normalization of the weight dynamics. Despite the amelioration of the infection, AgNP treatment did not influence influenza virus replication. The possibility of using nanosilver as an effective indirectly-acting antiviral drug is discussed.

Alterations in reproductive parameters and gene expression in Balb/c mice testes after exposure to silver nanoparticles.

Silver nanoparticles (AgNPs) have become one of the most common nanomaterials in various commercial products; however, its potential toxicity to the male reproductive system and the possible mechanisms remains unknown. Our study aimed to investigate the toxicity of silver nanoparticle (AgNPs) in the testis and to elucidate its possible mechanisms. We exposed 6-week-old Balb/c male mice to AgNP daily [0 (control), 30 or 125mg/kg BW] for 90days. The histological structure, sperm production and levels of reproductive hormones were assessed; we also observed apoptotic cell nuclei and the ultrastructural characteristics of the testis. Microarray analyses were used to identify differentially expressed genes, and dysregulated apoptosis-related genes and protein were also analysed. Our results indicated that 125mg/kg AgNP changed testis morphology and decreased sperm production. AgNP treatment also increased apoptosis of germ cells and induced the presence of swollen or dissolved mitochondria in the testis. Microarray analysis showed the expression of 383 genes was altered by AgNP treatment, with apoptosis-related genes showing the greatest changes. Furthermore, we verified dysregulated apoptosis-related genes and proteins (caspase3 and Myc). These results demonstrated that AgNP induced changes of testis morphology, sperm production and apoptosis-related genes, suggested this process maybe associated with apoptosis.

β-sitosterol Mediated Silver Nanoparticles Induce Cytotoxicity in Human Colon Cancer HT-29 Cells.

Background:Silver nanoparticles (AgNP) are commonly used metallic nanoparticles in health care systems. Colon cancer incidence is increasing worldwide. In this study, AgNP was synthesized using β-sitosterol and its cytotoxic potential was evaluated in human colon cancer (HT-29) cells.Methods:Characterization of AgNP was analyzed by TEM and spectrophotometry analysis. HT-29 cells were treated with different concentrations (2, 4, 6, 8 and 10 ng/ml) of AgNPs and cytotoxicity was evaluated by MTT assay. The apoptosis was analyzed by the flow cytometry. The expression of p53 protein was analyzed by western blotting.Results:β-sitosterol mediated AgNP are spherical in shape and induced concentration-dependent cytotoxicity in HT-29 cells. AgNP caused apoptosis related morphological changes as evidenced by annexin positive staining. AgNP treatments also induced the p53 expression in HT-29 cells.Conclusion:Our present result suggests that β-sitosterol mediated AgNP induce apoptosis in colon cancer cells and this finding may pave the way for further experimental analysis in vivo.

Phyto-Mediated Synthesis of Silver Nanoparticles Using Terminalia chebula Fruit Extract and Evaluation of Its Cytotoxic and Antimicrobial Potential.

The increasing interest in developing potent non-toxic drugs in medicine is widening the opportunities for studying the usage of nanostructures in the treatment of various diseases. The present work reports a method for a facile and an eco-friendly synthesis of silver nanoparticles (AgNPs) using Terminalia chebula fruit extract (TCE). The obtained AgNPs was characterized by using different spectroscopic and microscopic techniques. The analysis of the results revealed that the as-obtained AgNPs have spherical morphology with an average diameter of 22 nm. Furthermore, the preliminary bioactivity evaluations revealed that the bio-conjugation of AgNPs, using TCE, significantly enhanced the antibacterial and anti-breast cancer potentials of the latter. The antibacterial activity of the as-prepared AgNPs showed that B. subtilis was more sensitive towards the AgNPs, followed by P. aeruginosa; while, E. coli and S. mutans showed comparatively minimal sensitivity toward the AgNPs. The IC50 values of TCE, AgNPs and TCE + AgNPs treatment of MCF-7 were found to be 17.53, 14.25 and 6.484 µg/mL, respectively. Therefore, it can be ascertained that the bio-conjugation may provide a headway with regard to the therapeutic employment of T. chebula, upon mechanistically understanding the basis of observed antibacterial and anticancer activities.

Mitophagy–lysosomal pathway is involved in silver nanoparticle-induced apoptosis in A549 cells

With the increasing use of silver nanoparticles (AgNPs) in biological materials, the cytotoxicity caused by these particles has attracted much attention. However, the molecular mechanism underlying AgNP cytotoxicity remains unclear. In this study, we aimed to systematically investigate the toxicity induced by AgNP exposure to the lung adenocarcinoma A549 cell line at the subcellular and signaling pathway levels and elucidate the related molecular mechanism. The survival rate of cells exposed to AgNPs at 0, 20, 40, 80, and 160 μg/mL for 24 or 48 h decreased in a dose- and time-dependent manner. AgNPs induced autophagy and mitophagy, determined by the transmission electron microscopy investigation and upregulation of LC3 II/I, p62, PINK1, and Parkin expression levels. AgNP treatment induced lysosomal injury, including the decline of lysosomal membrane integrity and increase in cathepsin B level. The decreased in mitochondrial membrane potential, along with upregulation of cytochrome c, caspases 9 and 3, and BAX/BCL2, further suggested that mitochondrial injury were involved in AgNP-induced apoptosis. In addition, mitochondrial injury may further lead to excessive production of reactive oxygen species and oxidative/ antioxidant imbalance. The results suggested that AgNPs could regulate autophagy via mitochondrial and lysosome injury in A549 cells. The information of the molecular mechanism will provide an experimental basis for the safe application of nanomaterials.

Potential Application of Silver Nanoparticles Encapsulated in Branched Amphiphilic Peptide Capsules to Circumvent Antibiotic Resistance in Methicillin-Resistant Staphylococcus Aureus: A Research Protocol

Introduction: Antibiotic resistance is a major global health concern as many fatalities occur each year due to severe infections associated with it, such as sepsis. This research protocol hopes to address the issue of antibiotic resistance in methicillin-resistant Staphylococcus aureus (MRSA) by using an alternative antibiotic therapy. Silver nanoparticles (AgNPs), which have antibiotic properties and low antibiotic resistance potential, will be administered in conjunction with stable and biocompatible branched amphiphilic peptide capsules (BAPCs). Surface functionalized ligands will be attached to the peptide capsules to target iron receptors essential to MRSA survival. By targeting its iron receptors, the bacteria will be unable to mutate in such a way that would attenuate its uptake of this antibiotic. Methods: Testing will begin in vitro on MRSA cultures to assess the minimum inhibitory concentration of the various AgNP treatment groups. Constraints determining the minimum inhibitory concentration include a minimum 3-hour delay in bactericidal effect from application, and a 95% eradication efficacy. Drug efficacy will be evaluated via ex vivo and in vivo mice experiments, with off-target toxicity effects measured via BAPC targeted immunohistochemistry, and both serological and organ-based tests. Repeated in vivo treatments will be performed against a control to measure the relative antibiotic resistance advantages this treatment proposes. As this protocol requires the use of mice, ethics approval from the Canadian Council on Animal Care will be obtained prior to experimentation. Results: It is expected that the AgNPs will be successfully encapsulated within the structurally-sound BAPCs and that the AgNPs will eradicate a significant amount of the MRSA present in the human body with minimal side effects. The in vitro, ex vivo and in vivo tests are likely to yield results that demonstrate that the most effective protocol in eradicating MRSA is to use AgNPs in BAPCs in conjunction with a vancomycin treatment. The proposal will likely satisfy the criteria for appropriate AgNP doses, which includes bactericidal effect in a time frame of hours, over 95% efficacy, and statistically significant reproducibility. Discussion: Successful BAPC mediated delivery of AgNPs prove the potential for targeted antibiotic application against multidrug bacteria with lower risk of antibiotic resistance compared to conventional antibiotics. This proof of concept protocol demonstrates the potential for applying rational design of BAPCs as a delivery vector. Certain limitations, including off-target toxicity and redundant targeting are issues to be cognizant of and controlled. Conclusion: This novel therapy can be considered as a preliminary step in overcoming antibiotic resistance. With appropriate modifications to the functional ligands attached to the BAPCs, the proposed drug mechanism could be applied to treat other bacterial strains.

Green Synthesis of Silver Nanoparticles Using Mushroom Flammulina velutipes Extract and Their Antibacterial Activity Against Aquatic Pathogens

In recent years, the biosynthesized silver nanoparticles (AgNPs) have been projected as an alternative to traditional antibiotics for their superior antimicrobial properties and significant inhibition of the biofilm formation. Particularly, it is found that the effectiveness of AgNPs varies greatly with the biomaterial used in their synthesis. Mushrooms are natural resources for excellent antioxidants and bioactive compounds. Nevertheless, there are few reports on the application of mushrooms in AgNPs biosynthesis. In this study, AgNPs were successfully synthesized using Flammulina velutipes extract as reductants and stabilizing agents. The following analyses of UV-visible spectroscopy showed typical absorbance peak at 450 nm. Transmission electron microscope analysis indicated that the prepared AgNPs were monodispersed spheres with an average size of approximately 22 nm. X-ray diffraction analysis confirmed the face-centered cubic (fcc) crystalline structure of metallic silver. Furthermore, the synthesized AgNPs exhibited high stability and antibacterial activities against 6 aquatic pathogens. A subsequent challenge experiment showed that the prepared AgNPs significantly reduced the mortality rate of Ruditapes philippinarum clam infected with Vibrio parahaemolyticus. Notably, AgNPs treatment could inhibit the biofilm formation of the pathogen, indicating that the extracellular synthesis of AgNPs using mushroom can be developed into a novel effective antimicrobial agent to overcome the multidrug-resistant microorganisms in aquaculture. This study will open a new way for edible mushroom processing and wide application in aquaculture.

Silver nanoparticles induce genetic, biochemical, and phenotype variation in chrysanthemum

Despite the tremendous progress in breeding, novel and user-friendly techniques of plant improvement are desirable. The study aimed to analyze the usefulness of silver nanoparticles (AgNPs) in the breeding of chrysanthemum: one of the top ornamental plant species. In vitro regeneration of adventitious shoots from internodes of chrysanthemum ‘Lilac Wonder’ was induced on the modified Murashige and Skoog (MS) medium supplemented with 0.6 mg L−1 6-benzylaminopurine (BAP), 2 mg L−1 indole-3-acetic acid (IAA) and AgNPs at 0, 5, 10 and 20 ppm concentration. The efficiency of callogenesis and caulogenesis were analyzed after 10 weeks of culture. The concentration of chlorophylls, carotenoids, and phenolic compounds in shoots and calli were estimated. Plants obtained from 20 ppm AgNPs treatment were additionally analyzed on the genetic level using randomly amplified polymorphic DNA (RAPD) and inter simple sequence repeats (ISSR) markers. In vitro rooted shoots were acclimatized in the glasshouse and subjected to biochemical and phenotype stability evaluation. AgNPs at the highest concentration (20 ppm) suppressed both callogenesis and caulogenesis in vitro. The concentration of metabolites in callus was stable, regardless of AgNPs treatment, except for carotenoids which production was enhanced by 20 ppm AgNPs. In contrast, the content of chlorophyll a and b in shoots varied depending on AgNPs treatment. Polymorphic loci were detected in 12 and 9 AgNPs-treated-plants by RAPD and ISSR markers, respectively (one of which was common to both marker systems). Rooting and acclimatization were fully successful in all experimental combinations. Phenotype alternations were detected in six plants; one from 10 ppm AgNPs treatment and five from 20 ppm treatment. They included variation in pigment content (anthocyanins and carotenoids) and/or inflorescence shape. Interestingly, only two plants revealed both genetic and phenotype polymorphisms. No genetic or phenotype variation was detected in the control plants. In conclusion, AgNPs can be used in chrysanthemum breeding.

Silver Nanocarriers Targeted with a CendR Peptide Potentiate the Cytotoxic Activity of an Anticancer Drug

AbstractSilver nanoparticles (AgNP) can be tracked in cells and tissues by optical imaging and isotopic fingerprinting. AgNPs are particularly useful as endocytosis probes as they can be rapidly dissolved with a biocompatible etching solution to eliminate extracellular NPs.Here, affinity‐targeted AgNPs are evaluated as therapeutic carriers of a potent cytotoxic compound, monomethyl auristatin E (MMAE). AgNPs are coated with MMAE via a lysosomal protease cathepsin B sensitive linker and functionalized with a prototypic CendR peptide (RPARPAR) that targets neuropilin‐1 (NRP‐1). This gives the AgNPs dual tumor specificity as both cathepsin B and NRP‐1 are overexpressed in many types of solid tumors. Cellular imaging, flow cytometry, viability assays, and high‐performance liquid chromatography‐mass spectrometry (HPLC‐MS) analysis show that the RPARPAR–MMAE–AgNPs are internalized and induce apoptotic cell death in NRP‐1‐positive PPC‐1 prostate cancer cells while sparing NRP‐1‐negative M21 melanoma cells. Furthermore, in a mixed culture of PPC‐1 and M21 cells, RPARPAR–MMAE–AgNP treatment selectively eliminates NRP‐1‐positive PPC‐1 cells. The study demonstrates that affinity‐targeted AgNPs can be used as carriers to selectively deliver and potentiate the activity of cytotoxic compounds in vitro, and that treatment with a biocompatible etching solution can be used to control the internalization and, thus, the cytotoxicity of these AgNPs.