Activity of Silver Nanoparticles against Staphylococcus spp

Staphylococcus aureus biofilm: Formulation, regulatory, and emerging natural products-derived therapeutics

Staphylococcus aureus can readily form biofilm which enhances the drug-resistance, resulting in life-threatening infections involving different organs. Biofilm formation occurs due to a series of developmental events including bacterial adhesion, aggregation, biofilm maturation, and dispersion, which are controlled by multiple regulatory systems. Rapidly increasing research and development outcomes on natural products targeting S. aureus biofilm formation and/or regulation led to an emergent application of active phytochemicals and combinations. This review aimed at providing an in-depth understanding of biofilm formation and regulation mechanisms for S. aureus, outlining the most important antibiofilm strategies and potential targets of natural products, and summarizing the latest progress in combating S. aureus biofilm with plant-derived natural products. These findings provided further evidence for novel antibiofilm drugs research and clinical therapies.

Local anesthetics as a tool for Staphylococcus spp. control: a systematic review

The objective of this work was to carry out a systematic review on the effectiveness of local anesthetics as antimicrobial agents against Staphylococcus spp. Searches were performed in the PubMed, Web of science, Scopus, Embase and Lilacs databases. As inclusion criteria, complete original articles, with in vitro experimental tests with the application of selected anesthetics and bacteria of the genus Staphylococcus spp. This review followed the methodological checklist for writing papers reporting systematic reviews by the PRISMA statement. The risk of bias was assessed according to the JBI critical appraisal checklist. Analysis was performed using an anesthetic-moderated simple linear regression model. This systematic review was registered by the Open Science Framework-OSF ( https://doi.org/10.17605/OSF.IO/C5JM7 ). Initially, 1141 articles were found, of which, after careful selection, 52 articles were analyzed. Lidocaine was the most commonly used anesthetic, being evaluated in 35 of the articles. S. aureus ATCC 25923 was the standard microorganism in 17 articles. The impact of the anesthetic concentration in relation to the antimicrobial effect was evaluated and the results showed that there was no statistically significant difference. (F [5, 12] = 0.688 p = 0.642), even when taking into account the moderator effect of anesthetics individually. Therefore, although the antimicrobial effect of local anesthetics was demonstrated in 82.7% of the studies evaluated, great heterogeneity of the results was found, which made it impossible to carry out a meta-analysis and make recommendations based on the evidence.

Green Approach for Synthesis of Silver Nanoparticles with Antimicrobial and Antioxidant Properties from Grapevine Waste Extracts

The present work aims to study the possibilities of developing silver nanoparticles using natural extracts of grape pomace wastes originating from the native variety of Fetească Neagră 6 Șt. This study focused on investigating the influence of grape pomace extract obtained by two different extraction methods (classical temperature extraction and microwave-assisted extraction) in the phytosynthesis process of metal nanoparticles. The total phenolic content of the extracts was assessed using the spectrophotometric method with the Folin-Ciocâlteu reagent, while the identification and quantification of specific components were conducted through high-performance liquid chromatography with a diode array detector (HPLC-DAD). The obtained nanoparticles were characterized by UV-Vis absorption spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM), along with assessing their antioxidant and antimicrobial properties against Gram-positive bacteria. The data collected from the experiments indicated that the nanoparticles were formed in a relatively short period of time (96 h) and, for the experimental variant involving the use of a 1:1 ratio (v/v, grape pomace extract: silver nitrate) for the nanoparticle phytosynthesis, the smallest crystallite sizes (from X-ray diffraction-4.58 nm and 5.14 nm) as well as spherical or semispherical nanoparticles with the lowest average diameters were obtained (19.99-23 nm, from TEM analysis). The phytosynthesis process was shown to enhance the antioxidant properties (determined using the DPPH assay) and the antimicrobial potential (tested against Gram-positive strains) of the nanoparticles, as evidenced by comparing their properties with those of the parent extracts; at the same time, the nanoparticles exhibited a selectivity in action, being active against the Staphylococcus aureus strain while presenting no antimicrobial potential against the Enterococcus faecalis strain.

Humic Polyelectrolytes Facilitate Rapid Microwave Synthesis of Silver Nanoparticles Suitable for Wound-Healing Applications

This article describes the one-pot microwave synthesis of silver nanoparticles (AgNPs) assisted with natural polyelectrolytes-humic substances (HS). The humic polyelectrolytes served both as chemical reductants for silver ions and as end-capping agents for AgNPs. Three commercially available sodium humates extracted from lignites and leonardite and one sodium fulvate isolated from natural brown water seeped through peat deposits were used in this study. The dynamics of the growth rate of AgNPs was characterised by UV-VIS spectroscopy by measuring the intensity of surface plasmon resonance at 420 nm. Transmission electron microscopy was used to characterise the size and morphology of AgNPs. Dynamic light scattering was used to determine size distributions of the synthesised AgNPs in the solutions. It was established that both conventional and microwave syntheses assisted with the coal humates produced small-size AgNPs in the range from 4 to 14 nm, with the maximum share of particles with sizes of (6 ± 2) nm by TEM estimates. The peat fulvate yielded much larger NPs with sizes from 10 to 50 nm by TEM estimates. DLS measurements revealed multimodal distributions of AgNPs stabilised with HS, which included both single NPs with the sizes from 5 to 15 nm, as well as their dominating aggregates with sizes from 20 to 200 nm and a smaller portion of extra-large aggregates up to 1000 nm. The given aggregates were loosely bound by humic polyelectrolyte, which prevented the coalescence of AgNPs into larger particles, as can be seen in the TEM images. The significant acceleration in the reaction time-a factor of 60 to 70-was achieved with the use of MW irradiation: from 240 min down to 210-240 s. The coal humate stabilised AgNPs showed antimicrobial properties in relation to S. aureus. A conclusion was made regarding the substantial advantages of microwave synthesis in the context of time and scaling up for the large-scale production of AgNP-HS preparations with antimicrobial properties suitable for external wound-healing applications.

Multifaceted Assessment of Porous Silica Nanocomposites: Unraveling Physical, Structural, and Biological Transformations Induced by Microwave Field Modification

In response to the persistent challenge of heavy and noble metal environmental contamination, our research explores a new idea to capture silver through porous spherical silica nanostructures. The aim was realized using microwave radiation at varying power (P = 150 or 800 W) and exposure times (t = 60 or 150 s). It led to the development of a silica surface with enhanced metal-capture capacity. The microwave-assisted silica surface modification influences the notable changes within the carrier but also enforces the crystallization process of silver nanoparticles with different morphology, structure, and chemical composition. Microwave treatment can also stimulate the formation of core-shell bioactive Ag/Ag2CO3 heterojunctions. Due to the silver nanoparticles' sphericity and silver carbonate's presence, the modified nanocomposites exhibited heightened toxicity against common microorganisms, such as E. coli and S. epidermidis. Toxicological assessments, including minimum inhibitory concentration (MIC) and half-maximal inhibitory concentration (IC50) determinations, underscored the efficacy of the nanocomposites. This research represents a significant stride in addressing pollution challenges. It shows the potential of microwave-modified silicas in the fight against environmental contamination. Microwave engineering underscores a sophisticated approach to pollution remediation and emphasizes the pivotal role of nanotechnology in shaping sustainable solutions for environmental stewardship.

MXSGD alleviates CsA-induced hypoimmunity lung injury by regulating microflora metabolism

Context

Ma Xing Shi Gan Decoction (MXSGD) is a traditional remedy for treating lung injuries that was developed by the Typhoid and Fever School of Pharmaceutical Biology. It has antitussive and expectorant effects, anti-inflammatory, antiviral, regulates the body's immunity, etc.

Aim

The aim of this study is to investigate whether MXSGD can ameliorate cyclosporine A (CsA)-induced hypoimmunity lung injury by regulating microflora metabolism. Methods: Establishment of a model for CsA-induced hypoimmunity lung injury. Using 16S rRNA high-throughput sequencing and LC-MS, the effects of MXSGD on gut flora and lung tissue microecology of mice with CsA-induced hypoimmunity were investigated.

Results

MXSGD was able to preserve lung tissue morphology and structure, reduce serum inflammatory marker expression and protect against CsA-induced lung tissue damage. Compared to the model, MXSGD increased beneficial gut bacteria: Eubacterium ventriosum group and Eubacterium nodatum group; decreased intestinal pathogens: Rikenellaceae RC9 intestinal group; reduced the abundance of Chryseobacterium and Acinetobacter, promoted the production of Lactobacillus and Streptococcus, and then promoted the lung flora to produce short-chain fatty acids. MXSGD was able to enhance the expression of serum metabolites such as Americine, 2-hydroxyhexadecanoylcarnitine, Emetine, All-trans-decaprenyl diphosphate, Biliverdin-IX-alpha, Hordatin A and N-demethyl mifepristone in the CsA-induced hypoimmunity lung injury model.

Conclusion

MXSGD can restore gut and lung microbiota diversity and serum metabolite changes to inhibit inflammation, ameliorate CsA-induced hypoimmunity lung injury.

Silver/Graphene Oxide Nanostructured Coatings for Modulating the Microbial Susceptibility of Fixation Devices Used in Knee Surgery

Exploring silver-based and carbon-based nanomaterials' excellent intrinsic antipathogenic effects represents an attractive alternative for fabricating anti-infective formulations. Using chemical synthesis protocols, stearate-conjugated silver (Ag@C18) nanoparticles and graphene oxide nanosheets (nGOs) were herein obtained and investigated in terms of composition and microstructure. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterizations revealed the formation of nanomaterials with desirable physical properties, while X-ray diffraction (XRD) analyses confirmed the high purity of synthesized nanomaterials. Further, laser-processed Ag@C18-nGO coatings were developed, optimized, and evaluated in terms of biological and microbiological outcomes. The highly biocompatible Ag@C18-nGO nanostructured coatings proved suitable candidates for the local modulation of biofilm-associated periprosthetic infections.

Research on Pachymaran to Ameliorate CsA-Induced Immunosuppressive Lung Injury by Regulating Microflora Metabolism

Pachymaran (PCP), the major medicinal constituent of Poria cocos, has a regulatory effect on immunosuppressive lung injury, but its mechanism of action with respect to gut microorganisms and their metabolites is not clear. The aim of this study was to investigate the protective effect of PCP against immunosuppressive lung injury caused by cyclosporine A (CsA), and to reveal its possible mechanism of action via the comprehensive analysis of 16S rRNA and LC-MS. We demonstrated that PCP was effective at alleviating CsA-induced immunosuppressive lung injury by restoring the organ indices and lung tissue morphology and structure. PCP significantly altered the composition of the gut and lung microbiota in mice with CsA-induced immunosuppressive lung injury by increasing the number of beneficial bacteria from the Eubacterium nodatum group, Eubacterium ventriosum group, Akkermansia, and Ruminococcus, and reducing the pathogenic Rikenellaceae RC9 gut group to fulfill its immunomodulatory role. In lung tissue microecology, PCP intervention significantly reduced the abundance of Chryseobacterium, Lawsonella, Paracoccus, and Sediminibacterium and increased the abundance of Alloprevotella. The LC-MS results showed that PCP alleviated the CsA-induced immunosuppression of lung tissue injury. The model serum metabolite Americine decreased the expression of PC(O-18:1(4Z)/0:0). Our results suggest that PCP may be involved in regulating the composition, function, and metabolism of the gut and lung microbiota to reverse CsA-induced immunosuppressive lung injury.

Integration of ZnO nanorods with silver ions by a facile co-precipitation for antimicrobial, larvicidal, and ovicidal activity

BACKGROUND

Infectious diseases prompted by micro-organisms such as fungi, parasites, or microbes, have influenced many countries' public health causing death. Scientists declared that metal oxide composites have various advantages in the medical field such as the antimicrobial feature has freshly been revealed as well as its role in suppressing mosquito population.

METHODS

In this work silver doped zinc oxide nanorods (Ag/ZnO NRs, 10 wt.%) were prepared by simple chemical route, and their microstructural characteristics were investigated by XRD, EDX, SEM, and TEM techniques. The antimicrobial, larvicidal, and ovicidal of the synthesized nanocomposites were examined.

RESULTS

The synthesized nanocomposite exhibited binary phase of crystallite size 112 nm was calculated from Williamson-Hall method. EDX spectrum revealed the purity of the composite consists of Zn, O, and Ag elements. The SEM and TEM micrographs showed the particles in nanorods with high density on the surface. The energy gap [Formula: see text] was evaluated from the UV-Vis absorbance in the range from 2.90 [Formula: see text] 3.08 eV inside the visible spectrum. The antimicrobial activity of the nanorods was examined against Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis) with inhibition zones 10.5 and 14.5 mm, respectively. Whereas gram-negative bacteria (Escherichia coli, Salmonella Typhimurium, and Pseudomonas aeruginosa) were 14 and 17 mm, respectively. Further, Candida albicans was investigated with inhibition zone 7.5 mm. Besides, the insecticidal impact of the nanocomposite against Culex pipiens larvae was performed at 30 mg/l causing 100% larval mortality with LC50 (11.78 mg/l). The micrograph images showed deformations in the larval body as well as egg resulting in zero egg hatchability.

CONCLUSION

The findings approved that synthesized nanorods have a significant impact on controlling pathogens that impart different diseases to humans and the environment.

In vitro investigation of silver nanoparticles synthesized using Gracilaria veruccosa - A seaweed against multidrug resistant Staphylococcusaureus

In recent years, the biosynthesis of silver (Ag) nanoparticles has attracted a great deal of interest for applications in biomedicine and bioremediation. In the present study, Gracilaria veruccosa extract was used to synthesize Ag nanoparticles for investigating their antibacterial and antibiofilm potentials. The color shift from olive green to brown indicated the synthesis of AgNPs by plasma resonance at 411 nm. Physical and chemical characterization revealed that AgNPs of 20-25 nm sizes were synthesized. Detecting functional groups, such as carboxylic acids and alkenes, suggested that the bioactive molecules in the G. veruccosa extract assisted the synthesis of AgNPs. X-ray diffraction verified the s purity and crystallinity of the AgNPs with an average diameter of 25 nm, while DLS analysis showed a negative surface charge of -22.5 mV. Moreover, AgNPs were tested in vitro for antibacterial and antibiofilm efficacies against S. aureus. The minimum inhibitory concentration (MIC) of AgNPs against S. aureus was 3.8 μg/mL. Light and fluorescence microscopy proved the potential of AgNPs to disrupt the mature biofilm of S. aureus. Therefore, the present report has deciphered the potential of G. veruccosafor the synthesis of AgNPs and targeted the pathogenic bacteria S. aureus.

Functionalization of 3D Printed Scaffolds Using Polydopamine and Silver Nanoparticles for Bone-Interfacing Applications

The prevention of bacterial colonization and the stimulation of osseointegration are two major requirements for bone-interfacing materials to reduce the incidence of complications and promote the restoration of the patient's health. The present investigation developed an effective, two-step functionalization of 3D printed scaffolds intended for bone-interfacing applications using a simple polydopamine (PDA) dip-coating method followed by the formation of silver nanoparticles (AgNPs) after a second coating step in silver nitrate. 3D printed polymeric substrates coated with a ∼20 nm PDA layer and 70 nm diameter AgNPs proved effective in hindering Staphylococcus aureus biofilm formation, with a 3000-8000-fold reduction in the number of bacterial colonies formed. The implementation of porous geometries significantly accelerated osteoblast-like cell growth. Microscopy characterization further elucidated homogeneity, features, and penetration of the coating inside the scaffold. A proof-of-concept coating on titanium substrates attests to the transferability of the method to other materials, broadening the range of applications both in and outside the medical sector. The antibacterial efficiency of the coating is likely to lead to a decrease in the number of bacterial infections developed after surgery in the presence of these coatings on prosthetics, thus translating to a reduction in revision surgeries and improved health outcomes.

Antibacterial activity of metallic-core gold and silver nanoparticles against some animal pathogens

The current work aimed to find substitutes for antibiotics because of the side effects of antibacterial agents and the expansion of bacterial resistance to these agents. The scope of this study was to evaluate the antibacterial activity of gold and silver nanoparticles (AuNPs and AgNPs) against selected animal pathogens (Staphylococcus aureus, Klebsiella pneumonia, Streptococcus pneumoniae, Escherichia coli, Bacillus abortus and Mycobacterium bovis). The synthesized nanoparticles were distinguished by scanning electron microscopy (SEM) analysis and tested for antibacterial activity with the broth microdilution method, well diffusion assay, and minimum bactericidal concentration procedure. Results showed that both AuNPs and AgNPs displayed good antibacterial activity against all tested bacteria. The strongest antibacterial action of AgNPS (18 mm) was contra E. coli. AuNPs displayed good antibacterial activity against S. aureus and B. bovis with a suppression area of 14 mm. Therefore, it is suggested that AgNPs and AuNPs could be effectively used against animal pathogens and may contribute to reducing antibiotic resistance. However, there is a need for further research on the in vivo toxicity and mechanisms of action of AuNPs and AgNPs.

Antibiofilm Effect of Silver Nanoparticles in Changing the Biofilm-Related Gene Expression of Staphylococcus epidermidis

Nowadays, antibiotic resistance is a major public health problem. Among staphylococci, infections caused by Staphylococcus epidermidis (S. epidermidis) are frequent and difficult to eradicate. This is due to its ability to form biofilm. Among the antibiotic substances, nanosilver is of particular interest. Based on this information, we decided to investigate the effect of nanosilver on the viability, biofilm formation and gene expression of the icaADBC operon and the icaR gene for biofilm and non-biofilm S. epidermidis strains. As we observed, the viability of all the tested strains decreased with the use of nanosilver at a concentration of 5 µg/mL. The ability to form biofilm also decreased with the use of nanosilver at a concentration of 3 µg/mL. Genetic expression of the icaADBC operon and the icaR gene varied depending on the ability of the strain to form biofilm. Low concentrations of nanosilver may cause increased biofilm production, however no such effect was observed with high concentrations. This confirms that the use of nanoparticles at an appropriately high dose in any future therapy is of utmost importance. Data from our publication confirm the antibacterial and antibiotic properties of nanosilver. This effect was observed phenotypically and also by levels of gene expression.

Ecotoxicity Study of New Composite Materials Based on Epoxy Matrix DER-331 Filled with Biocides Used for Industrial Applications

The impact of fillers in the epoxy oligomer on the test culture of the marine ecosystem was investigated. The content of additive—biocides—was selected based on the complex research using STAT-GRAPHICS^® Centurion XVI. The ecotoxicity of composite surfaces was determined in model systems using methods which are standard in eco-microbiology. The microorganism was identified by studying morphological, cultural, biochemical, and antigenic properties. Studies of the structure and the microrelief of the surfaces of composite materials were conducted using scanning electron microscopy (SEM) and X-ray energy dispersive spectroscopy. Based on comprehensive research, it was established that the composition of oxytetracycline with content of q = 1.5 wt% and nanosilver with a content of q = 0.075 wt% per 100 wt% of the DER-331 oligomer and 10 parts by the mass of the TETA hardener ensures the formation of a porous nano-heterogeneous structure of the coating, which leads to the acceleration of the release of silver ions from the surface of the polymer. The rational content of the complex additives of biocides ensures adhesion to the cell wall of bacteria with subsequent penetration into it and subsequent change to the cell membrane, its death, and, therefore, the suppression of the fouling process of metal structures.