Antibacterial Activity Of Silver Nanoparticles Research Articles

Biosynthesis of Silver Based Nanoparticles Using Plant Leaves Extracts and Their Antibacterial Activities

The emergence of antibiotic-resistant bacteria is a major global public health concern. Antibacterial agents are one of the most exciting areas for the use of nanoparticles and have shown great potential as alternative antibacterial agents due to their outstanding physical and chemical properties. The biosynthesis and antibacterial activities of Silver Nanoparticles (AgNPs) could contribute to the development of innovative antimicrobial drugs with potential for a variety of medical applications. The X Ray Diffraction (XRD) results showed that the formed particles were pure silver nanoparticles with a cubic crystal structure and granular size. Fourier-transform infrared (FTIR) also showed that functional aggregates formed, and the thumb region confirmed the presence of silver nanoparticles. In addition, we investigated the Uv-Visible and biological activity of AgNPs. A study of the biological activity of gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli, and Klebsiella pneumonia) bacteria showed the importance of nano-silver particle biosynthesis.

Chitosan oligomer/silver nanoparticles/PCL composite electrospun membrane for severe burn wound healing

In the management of burn wounds, antimicrobial and wound healing properties are crucial. In this study, we prepared a three-layer electrospun poly(ε-caprolactone) (PCL) membrane for burn wound dressing. The hydrophobic electrospun PCL layer, embedded with silver nanoparticles (SNPs) (PCL-Ag), was coated with another layer of electrospun plasma-treated PCL-Ag to enhance the wettability of the membrane. This enhancement was to facilitate the absorption of the hydrophilic chitosan oligomer (COS) - the third layer of the dressing. The resultant membranes were characterised and tested for different properties to demonstrate their applicability as wound dressing materials. The combination of COS and SNPs of the fabricated membrane supports the healing process and reduces burn severity due to the healing capacity of COS and the antibacterial activity of SNPs, without compromising mechanical strength. We conducted several in vitro and in vivo experiments to evaluate its applicability for burn wound healing. The PCL-Ag/COS sample demonstrated outstanding in vitro biocompatibility and excellent antibacterial activity against Staphylococcus aureus strains. We used the membrane to treat burns on rabbits in the laboratory over 30 days, and consistently observed positive outcomes. This research offers insights into the development of bioactive dressings for wound healing and opens up opportunities for practical applications of COS-incorporated materials.

Antibacterial activity of silver nanoparticles synthesized from Citrus aurantium and its synergistic effect of the combination of silver nanoparticles with ampicillin against Proteus mirabilis

Abstract Background: Proteus mirabilis is one of the most infectious organisms that cause a various infections involving those of the skin, wounds, and urinary tract. This study describes the synthesis of silver nanoparticles (AgNps) and using it as an antibacterial agent. Objective: To determine the activity of AgNps and synergistic effect of combination of AgNps with ampicillin (AMP). Materials and Methods: Out of 205 samples, 32 isolated were identified as P. mirabilis and determine the inhibition zone by using AgNps and its combination with AMP. The AgNps were biosynthesized by Citrus aurantium and then characterized using Ultraviolet (UV)-visible spectroscopy, X-ray diffraction (XRD) and transmission electron microscope (TEM). The antibacterial activity of AgNps was done using well diffusion agar method and the activity was evaluated by calculating the increase in the inhibition zone and reduction in the bacterial growth. Results: The synthesized AgNps was first characterized by UV-visible spectroscopy which showed a peak between 400 and 500 cm–1. The color changes from clear yellow to red or brown color indicate the formation of AgNps. The particle size of AgNps was calculated and found to be 21.24 nm by XRD. The TEM images showed the presence of very regular particles in shape of nanospheres with a particle size in the range of 10–28 nm. Different concentrations (25, 50, 75, 100 µg/mL) were used for determining the activities of AgNps and the combination of AgNps with AMP, and the result showed that the most efficient in inhibition zone was at concentration 100 µg/mL. Conclusion: This study concluded that the green synthesized AgNps from C. aurantium leaves extract have most potential as antibacterial against P. mirabilis.

Green silver nanoparticles display protection against Clavibacter michiganensis subsp. michiganensis in tomato plants (Solanum lycopersicum L.)

The quarantined bacterium Clavibacter michiganensis subsp. michiganensis (Cmm) causes significant losses on tomato plants worldwide, therefore efforts to reduce its damage are imperative. The alternatives offered by nanotechnology in the near future to be applied for the control of Cmm should be studied. Hence, this study aimed to determine the antibacterial activity of silver nanoparticles (AgNPs) biosynthesized on Moringa (Mo) leaves against Cmm in tomato plants (Solanum lycopersicum L.) and the possible protective mechanisms associated. UV–vis, TEM and FTIR, elucidated some structural and physicochemical characteristics of biosynthesized AgNPs. The preventive and curative effect of Mo extract and Mo-AgNPs at 50 ppm against Cmm in tomato plants was evaluated. Cmm was inoculated in the stems of tomato plants with 1 × 109 UFC/mL. Biometric parameters, disease severity, PAL, CAT, SOD activities, H2O2 levels, as well as chalcone synthase and pr1a gene expression were measured in greenhouse during 29 days. The UV–vis spectrum revealed the maximum absorption at 330 nm. Mo-AgNPs (32 nm; quasi-spherical shape) exhibited antibacterial potential against Cmm decreasing the disease severity by 86.29 % at 29 days after the treatments were applied. Besides, the Mo extract decreased the disease severity in 72 %, both compared to the control, being these two treatments the most promising for controlling Cmm. The Mo extract in preventive and curative treatments had the highest numbers of leaves, 33.31 %. The enzymatic activity exhibited no discernible pattern when comparing healthy and diseased plants, measured 29 days after the confrontations. Gene expression suggested a role of SAR pathway in the protective treatment by Mo Ag-NPs. In conclusion, the application of AgNPs derived from Mo leaf extracts effectively reduces the disease severity caused by Cmm on tomato plants under greenhouse conditions.

Prompt antibacterial activity of silver nanoparticle decorated on HAp embedded NiFe2O4 nanocomposite (NiFe2O4@HAp-Ag) against pathogenic strains and investigation of its photocatalytic activity towards degradation of antibiotics

Local bacterial infection in clinics is still a difficult task and poses serious health threats to human. Systemic antibiotic administration typically results in negative side-effects and bacterial resistance and only has transient antibacterial activity. Several biomedical applications immensely prefer modified hydroxyapatite with excellent biocompatibility and antibacterial characteristics. Herein, we fabricate hydroxyapatite-embedded NiFe2O4 using in situ hydrothermal method and used as a support for silver nanoparticle onto its surface to achieve an effective biological response. The properties of the as-synthesized materials were characterized using several spectroscopic techniques which include X-ray diffraction spectroscopy, Fourier transform infrared spectroscopy, ultraviolet–diffuse reflectance spectroscopy spectroscopy, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, high resolution transmission electron microscopy. In addition, the magnetic behavior of these nanocomposites was examined using the vibrating sample magnetometer technique. This ternary nanocomposite exhibits potent antimicrobial activity against both Gram-negative bacteria (Pseudomonas aeruginosa and klebsiella pneumoniae) as well as Gram-positive bacteria (Staphylococcus aureus and Bacillus cereus). The MIC or minimum inhibitory concentration, MBC or minimum bactericidal concentration, the disc diffusion, bacterial growth rate, and inhibition rate tests were utilized for the examination of the antimicrobial effect of this synthesized nanocomposite against pathogenic strains. Along with this, we have also investigated its photocatalytic activity toward degradation of cefixime antibiotic under solar light and it shows excellent photodegradation performance. The fabricated nanocomposite demonstrated high reusability with good photostability. Notably, using magnetic decantation this prepared nanocomposite can be easily eliminated from the disinfected medium.

Synthesis of silver nanoparticles by aqueous extract of Zingiber officinale and their antibacterial activities against selected species

Abstract Silver nanoparticles have special plasmonic and antibacterial characteristics that make them efficient in a variety of commercial medical applications. According to recent research, chemically synthesized silver nanoparticles are harmful even in low concentrations. It was crucial to identify appropriate synthesis methods that may have low costs and be nontoxic to the environment. Zingiber officinale (ginger) extracts used to prepare silver nanoparticles were inexpensive and environmentally friendly, and the best physicochemical characteristics were analyzed. Silver nanoparticles were characterized by using UV-visible spectroscopy, Scanning electron microscopy (SEM), and X-ray diffraction (XRD). The surface Plasmon resonance peak at 425 nm was observed using UV-Visible spectroscopy. Scanning electron microscopy observed that the nanoparticles were spherical and ranged in size from 5 to 35 nm. The XRD pattern values of 2θ: 38.2o, 46.3o, and 64.58o are used to determine the planes (111), (200), and (220). The silver nanoparticle’s existence was verified by the face-centered cubic (FCC). Silver nanoparticles were found to have antibacterial efficacy against gram-positive Staphylococcus and gram-negative bacteria such as Pseudomonas aeruginosa, Klebsiella Aerogenes, Salmonella, Staphylococcus and Escherichia coli. The antibacterial activity of silver nanoparticles was observed using the agar well diffusion (AWD) method at three different concentrations (100 μg/ml, 75 μg/ml, and 50 μg/ml). The zone of inhibition measured against the bacterial strains pseudomonas Aeruginosa, Klebsiella aerogenes, Escherichia coli, Salmonella and Staphylococcus which were (18.4±1.25 mm, 16.9±0.74 mm, 14.8±1.25 mm), (16.8±0.96 mm, 14.6±0.76 mm, 14.0±1.15 mm), (19.7±0.76 mm, 18.2±0.66 mm, 15.4±1.15 mm), (16.6±0.67 mm, 14.2±0.23 mm, 12.8±0.78 mm) and (12±0.68 mm, 10±0.20 mm, 08±0.15 mm). These nanoparticles’ potent antibacterial properties may enable them to be employed as nanomedicines for a variety of gram-negative bacterial illness treatments.

Green Synthesis and Antibacterial Activity of Silver Nanoparticles Obtained from Moringa oleifera Seed Cake

In the present work, we report a simple, cost-efficient, and eco-friendly green method to synthesize silver nanoparticles with antimicrobial activity. An ethanolic extract from Moringa oleifera seed residue was used as a reducing and stabilizing agent in an aqueous solution of silver nitrate. The synthesized silver nanoparticles’ hydrodynamic radius, polydispersity index, and zeta-potential were evaluated by Dynamic Light Scattering. Scanning Electron Microscopy was employed to confirm the size and morphology of the nanoparticles. Synthesis of spherical particles with 127 ± 24 nm was confirmed. After sintering, the product of the synthesis was analyzed by X-ray diffraction. The X-ray diffraction pattern attributed to reflections of the (111), (200), (220), and (311) planes, which are characteristic of silver nanoparticles, confirms the successful synthesis of crystalline face-centered cubic nanoparticles. The antimicrobial activity of the bionanoparticles was tested against Escherichia coli BL21(DE3) cells and compared with the effect of a Moringa oleifera seed cake extract. Herein, we show that the growth of Escherichia coli is significantly affected by the addition of the synthesized bionanoparticles. Addition of the bionanoparticles inhibited the growth and lengthened the lag phase of the bacterial culture.

Green Synthesized Silver Nanoparticles Loaded in Polysaccharide Hydrogel Applied to Chronic Wound Healing in Mice Models.

The prevalence of chronic wounds is increasing owing to the expanding population and the growing number of individuals suffering from diabetes. Such a chronic wound continues to be a significant healthcare burden for diabetic patients because it frequently carries a high chance of limb loss due to amputation and reduces survival as a result. Development of innovative wound dressing materials with the potential to stop bacterial infections and accelerate the process of tissue regeneration is needed to increase the effectiveness of diabetic wound healing. In the current study, a co-polymerization process based on a free radical reaction was used to create a hydrogel of polysaccharides blend graft acrylamide (PsB-g-Am). Starch, chitosan, and alginate make up the polysaccharides blend (PsB). The produced hydrogel's structure was characterized using FTIR spectroscopy. The antibacterial activities of silver nanoparticles synthesized through the green method using garlic bulb (Allium sativum) is reported. The silver nanoparticles' physical characteristics were examined using scanning electron microscopy, transmission electron microscopy analysis, and UV-visible spectroscopy and they were found to range in size from 50 to 100 nm. The agar well diffusion technique is used to investigate the antibacterial characteristics. Inclusion of silver nanoparticles in the hydrogels demonstrated concentration-dependent antibacterial behavior against Gram-negative Klebsiella pneumoniae and Gram-positive Staphylococcus aureus during antimicrobial testing of the hydrogels. When hydrogels were applied to diabetic mice, the system was examined for its healing abilities, and positive therapeutic results were obtained in as little as 14 days. Thus, it can be inferred that graft copolymer of chitosan-AgNPs hydrogels can promote healing in chronic wounds over time and can be utilized as an alternative to conventional therapies for chronic wounds (such as those brought on by diabetes) in mouse models.

Therapeutic Effects of Co-administration of Silver Nanoparticles and Vitamin C on Vaginal Infection Caused by Group B Streptococcus

Background: Group B Streptococcus (GBS) is a bacterium commonly isolated from the vagina. Silver nanoparticles (SNPs) are potential antibacterial agents, and studies have shown their toxic effects. Vitamin C (VC) is an essential vitamin with a protective role against toxicological conditions. We aimed to the evaluation therapeutic effects of the co-administration of SNPs and VC on vaginal infection caused by GBS in mice models. Methods: Vaginitis model was established by intravaginal inoculation of GBS. The Co-administration of SNPs and VC was used to treat the infections. The antibacterial activity of SNPs was determined by the minimum inhibitory concentration. The toxicity of nanoparticles was measured by MTT assay. The microbial load and estrous cycle of mice during treatment were evaluated. Finally, blood samples and vaginal tissue sections were isolated and analyzed. Results: The results showed that SNPs have excellent effects on GBS, and the MIC was 512 ppm. Cell viability after exposure at 512 ppm of SNPs was 32.11% but after treatment with VC increased viability at 512 ppm of nanoparticles to 65.32%. In mice that received SNPs and VC at the same time, the bacteria were completely removed from the vagina, and estrus cycle returned to normal cycle. Analysis of the prepared blood samples and microscopic examination of the vaginal sections confirmed the results. Conclusion: SNPs have a potential antibacterial effect on GBS. But nanoparticles have toxic effects on mammalian cells. The simultaneous use of VC, as a powerful antioxidant, can completely eliminate this toxic effect of nanoparticles.

Preferential role of distinct phytochemicals in biosynthesis and antibacterial activity of silver nanoparticles

Biosynthesis of silver nanoparticles (AgNPs) by plant extracts and its antibacterial utilization has attracted great attention due to the spontaneous reducing and capping capacities of phytochemicals. However, the preferential role and mechanisms of the functional phytochemicals from different plants on AgNPs synthesis, and its catalytic and antibacterial performance remain largely unknown. This study used three widespread arbor species, including Eriobotrya japonica (EJ), Cupressus funebris (CF) and Populus (PL), as the precursors and their leaf extracts as reducing and stabilizing agents for the biosynthesis of AgNPs. A total of 18 phytochemicals in leaf extracts were identified by ultra-high liquid-phase mass spectrometer. For EJ extracts, most kinds of flavonoids participated in the generation of AgNPs by a reduced content of 5∼10%, while for CF extracts, about 15∼40% of the polyphenols were consumed to reduce Ag+ to Ag0. Notably, the more stable and homogeneous spherical AgNPs with smaller size (≈38 nm) and high catalytic capacity on Methylene blue were obtained from EJ extracts rather than CF extracts, and no AgNPs were synthesized from PL extracts, indicating that flavonoids are superior than polyphenols to act as reducer and stabilizer in AgNPs biosynthesis. The antibacterial activities against Gram-positive (Staphylococcus aureus and Bacillus mycoides) and Gram-negative bacteria (Pseudomonas putida and Escherichia coli) were higher in EJ-AgNPs than that in CF-AgNPs, which confirmed the synergistic antibacterial effects of flavonoids combined with AgNPs in EJ-AgNPs. This study provides a significant reference on the biosynthesis of AgNPs with efficient antibacterial utilization underlying effect of abundant flavonoids in plant extracts.

Photocatalytic degradation of methylene blue and antibacterial activity of silver nanoparticles synthesized from Camellia sinensis leaf extract

Green synthesis of silver nanoparticles (AgNPs) has attracted substantial interest and achievement due to their environmental friendliness, ease of manipulation, and potential for large-scale production. By using aqueous Camellia sinensis leaf extract, suspensions of AgNPs, which possess photocatalytic and biological activity, were successfully synthesized in this study. The reduction of silver ions to AgNPs was visually inspected via the colour of the reaction mixture, which was altered from pale yellow to reddish brown. The methods of characterization of the as-synthesized AgNPs were performed using Ultraviolet-Visible spectroscopy (UV-Vis), dynamic light scattering technique (DLS), and X-ray diffraction analysis (XRD). The surface plasmon resonance bands of AgNPs at 420-430 nm in UV-Vis spectra indicated the presence of silver particles at the nanoscale. The size of AgNPs was determined by DLS, ranging from 25 nm to 40 nm. XRD analysis showed that AgNPs were highly pure and crystalline. The antibacterial activity of AgNPs against Gram-positive and Gram-negative bacterial strains, including Staphylococcus aureus and Escherichia coli, respectively, was demonstrated by the disc diffusion method. The examination of the photocatalytic activity of AgNPs was conducted through methylene blue (MB) degrading experiments, and the MB degrading performance was approximately 95% within 72 h under sunlight.

Antibacterial Activity of Silver Nanoparticles Poguntano Herb Extract (Picria fel-terrae Lour) against Staphylococcus epidermidis

Green synthesis methods to synthesize nanoparticles using natural products can be used by utilizing plants or microorganisms. Poguntano (Picria fel-terrae Lour.) or leaf kukurang is a plant from the family Scrophulariaceae. This study aimed to determine the antibacterial activity of silver nanoparticles of Poguntano aqueous extract. The antibacterial activity of silver nanoparticle water extract bacteria Staphylococcus epidermidis with extract concentrations of 20 mg/mL (12.43 ± 0.12), 10 mg/mL (11.50 ± 0.10) and 5 mg/mL (10.43 ± 0.12) can inhibit bacterial growth, Staphylococcus epidermidis at a concentration of 10 mg/mL, absorbance values at wavelengths of 260 nm and 280 nm were higher than the absorbance values at a concentration of 5 mg/mL. Staphylococcus epidermidis biofilm inhibition test shows that the results of the absorbance or OD measurement in the biofilm inhibition test using the silver nanoparticle of Poguntano extract, the OD value at a concentration of 10 mg/mL (0.367± 0.57) showed a biofilm inhibition result of 45.24 % greater than the concentration of 5 mg/mL which is 0.510 ± 0.54 with a biofilm inhibition result of 23.77%, this indicates that the greater the attention of the extract, the smaller the biofilm formation of Staphylococcus epidermidis bacteria.

Antibacterial Activity of Silver nanoparticles Against Pathogenic Bacterial Isolates from Diabetic Foot Patients

Diabetic foot is a catastrophic complication of diabetes. This study included isolation and identification of three types of bacteria that cause diabetic foot ulcers, fifty-five isolates of Staphylococcus aureus, thirty-five isolates of Acinetobacter baumannii, and thirty isolates of Serratia marcescens. These isolates were obtained from diabetic foot patients at different private clinics in and around Baghdad and Medical City Hospital. The proportion of male patients was greater than females, and it was noted that the age group (51-68 years) was more ages affected by diabetic foot. These isolates showed high resistance to most of the antibiotics used, Staphylococcus aureus was resistant to Penicillin, Tetracycline, and Ciprofloxacin in the percentage of 100 %, 65 %, and 26 %, respectively. Acinetobacter baumannii, showed high resistance to Penicillin, at a percentage of 80%, and Ciprofloxacin at 60%. Serratia marcescens was resistant to most antibiotics that were used in this study, Tetracycline, Penicillin, Cefotaxime, and Amoxicillin in the percent of (100, 95, 91, 88,70, and 64) %, respectively. The chemical reduction method was used in this study to synthesize silver nanoparticles. The characterization of silver nanoparticles was done by Field Emission Scanning Electron Microscope, and transmission electron microscope, which showed particle sizes of 24.56 to 66.2 nm, which proved that silver nanoparticles had nano size and spherical shape. The result of antibacterial activity of silver nanoparticles and silver nitrate against Staphylococcus aureus bacteria showed the highest effect of silver nitrate than other bacteria tested in this study, the diameter of the inhibition zone reached 15.66mm. Likewise for silver nanoparticles where the diameter of the inhibition zone of highest effect reached 29.33mm for Staphylococcus aureus bacteria. The test of silver nanoparticles' ability to inhibit bacterial growth produced the greatest results for Staphylococcus aureus bacteria, which were inhibited after 60 minutes. Based on these research findings, silver nanoparticles have demonstrated their efficacy in this study against isolated bacteria from diabetic feet.

Antibacterial activity of silver nanoparticles created by one step nanosecond Nd: YAG laser ablation in water

The pulsed laser ablation in liquid (PLAL) technique was used to successfully synthesise silver nanoparticles (Ag NPs). With the goal of controlling their size, a laser wavelength of 1064 nm was focused on the Ag bulk target immersed in distilled water in a glass vessel with different laser fluences. The effect of laser fluence, and thus Ag NPs concentration on the bacterial pathogenic was investigated. While the Fourier-transform infrared spectroscopy (FTIR) and x-ray diffraction (XRD) patterns confirm the presence of Ag NPs, UV–vis spectrophotometry revealed a significant absorption peak at around 405 nm, which is attributed to the obtained Ag NPs’ characteristic surface plasmon resonance (SPR) peak. The SPR peak shifted towards a shorter wavelength as the laser fluence was increased, indicating that the Ag NPs have reduced in size. The transmission electron microscopy and size distribution images of Ag NPs clearly showed the effects of laser fluence on size reduction of Ag NPs. Bacteria activity was effectively inhibited by the Ag NPs which are found to be more effective against Gram-negative (Escherichia coli) than Gram-positive strains (Streptococcus aureus). PLAL has proven to be an effective method for controlling the size of NPs, which can be used in a variety of applications.

Antibacterial Activity of Silver Nanoparticles Derived from Extracellular Extract of Enterococcus aerogenes Against Dental Disease Bacteria Isolated

Antibacterial Activity of Silver Nanoparticles Derived from Extracellular Extract of Enterococcus aerogenes Against Dental Disease Bacteria Isolated

Nano-silver-modified polyphosphazene nanoparticles with different morphologies: Design, synthesis, and evaluation of antibacterial activity

Drug-resistant bacteria present a severe threat to public health, emphasizing the importance of developing broad-spectrum antibacterial agents that are free from drug resistance. Among silver-based antibacterial agents, nano-silver has been found to exhibit the most promising and comprehensive performance. The exploration of the antibacterial capacity and morphological changes of silver nanoparticles (AgNPs) could offer a starting point for the development of safe and efficient antibacterial agents. In this study, three types of nano-silver-modified polyphosphazene (PRV) nanoparticles with different morphologies were synthesized using precipitation polymerization. These nanoparticles were characterized using various techniques, including Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). The antibacterial activity of these nanoparticles against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was assessed using minimum inhibitory concentration (MIC)/minimum bactericidal concentration (MBC) tests and inverted fluorescence microscopy. Our results revealed that the antibacterial activity of silver nanoparticles can vary significantly depending on their immobilized form. Ag@PRV Strawberry-like nanoparticles (NPs) exhibited higher antibacterial activity compared to Ag@PRV Yolk-Shell NPs and Ag@PRV Cable-like nanofibers (NFs). Notably, all three types of synthesized nanoparticles demonstrated a stronger bactericidal effect on Gram-positive bacteria than Gram-negative bacteria. Live/dead bacterial staining and scanning electron microscopy demonstrated that silver can kill bacteria by altering the permeability of their cell membranes. These findings offer valuable insights for designing and practically applying new silver-based antibacterial agents in the future.

Effect of Size, Shape and Surface Functionalization on the Antibacterial Activity of Silver Nanoparticles.

Silver nanoparticles (AgNPs) are the most investigated antibacterial agents against multidrug resistant (MDR) pathogens. They can lead to cellular death by means of different mechanisms, damaging several cell compartments, from the external membrane, to enzymes, DNA and proteins; this simultaneous attack amplifies the toxic effect on bacteria with respect to traditional antibiotics. The effectiveness of AgNPs against MDR bacteria is strongly correlated with their chemical and morphological properties, which influence the pathways involved in cellular damage. In this review, AgNPs' size, shape and modification by functional groups or other materials are reported, both to investigate the different synthetic pathways correlated with nanoparticles' modifications and to evaluate the related effect on their antibacterial activity. Indeed, understanding the synthetic conditions for obtaining performing antibacterial AgNPs could help to tailor new and improved silver-based agents to combat multidrug resistance.

Green Biofabrication of Silver Nanoparticles of Potential Synergistic Activity with Antibacterial and Antifungal Agents against Some Nosocomial Pathogens.

Nosocomial bacterial and fungal infections are one of the main causes of high morbidity and mortality worldwide, owing to the high prevalence of multidrug-resistant microbial strains. Hence, the study aims to synthesize, characterize, and investigate the antifungal and antibacterial activity of silver nanoparticles (AgNPs) fabricated using Camellia sinensis leaves against nosocomial pathogens. The biogenic AgNPs revealed a small particle diameter of 35.761 ± 3.18 nm based on transmission electron microscope (TEM) graphs and a negative surface charge of -14.1 mV, revealing the repulsive forces between nanoparticles, which in turn indicated their colloidal stability. The disk diffusion assay confirmed that Escherichia coli was the most susceptible bacterial strain to the biogenic AgNPs (200 g/disk), while the lowest sensitive strain was found to be the Acinetobacter baumannii strain with relative inhibition zones of 36.14 ± 0.67 and 21.04 ± 0.19 mm, respectively. On the other hand, the biogenic AgNPs (200 µg/disk) exposed antifungal efficacy against Candida albicans strain with a relative inhibition zone of 18.16 ± 0.14 mm in diameter. The biogenic AgNPs exposed synergistic activity with both tigecycline and clotrimazole against A. baumannii and C. albicans, respectively. In conclusion, the biogenic AgNPs demonstrated distinct physicochemical properties and potential synergistic bioactivity with tigecycline, linezolid, and clotrimazole against gram-negative, gram-positive, and fungal strains, respectively. This is paving the way for the development of effective antimicrobial combinations for the effective management of nosocomial pathogens in intensive care units (ICUs) and health care settings.

Cytotoxic effect of silver and oxide graphene nanoparticles on aberrant forms of Escherichia coli

The acquisition of aberrant morphological variations by microorganisms can serve as a phenotypic manifestation of antibiotic resistance, which results from ad-aptation to growth in a potentially toxic environment. Therefore, morphogenesis should be considered as an adaptive process that makes a great contribution to the ubiquity and universality of prokaryotes. The aim of the research was to evaluate the antibacterial activity of silver and oxidized graphene nanoparticles on pheno-typically aberrant forms of Escherichia coli. As a result of research, it was found that the antibacterial activity of silver nanoparticles is significantly higher compared to that of oxidized graphene nanoparticles on pleomorphic varieties of Escherichia coli, as the minimum inhibitory concentration of silver nanoparticles is lower (13.1 µg/ml) than that of oxidized graphene nanoparticles (75.3-94.9 µg/ml). The mor-phological variance of E. coli correlated with the acquisition of antibiotic resistance by the bacterium, but was not accompanied by a simultaneous increase in resistance to the nanoparticles. According to the results of atomic force microscopy, the toxic effect of oxidized graphene nanoparticles at supratoxic concentrations on aberrant forms of E. coli did not differ from that on canonical forms of the bacterium and was expressed in the destruction of the bacterial population and filling the intercel-lular space with biomass of degraded bacterial cells.

Investigation of antibacterial activity of silver nanoparticles against staphylococcus aureus strain

Investigation of antibacterial activity of silver nanoparticles against staphylococcus aureus strain