Antimicrobial Activity Of AgNPs Research Articles

Green Synthesis of Silver Nanoparticles Using Calabash (Crescentia cujete) Fruit Extract and Their Antimicrobial Properties

Conventional methods in synthesizing silver nanoparticles (AgNPs) make use of toxic chemicals and are expensive; thus, green chemistry has become the current trend in metal nanoparticle synthesis. In this study, ethanolic calabash (Crescentia cujete) fruit extract was used for the synthesis of AgNPs. The total phenolic content and free radical scavenging activity of the extract were 0.017 mg gallic acid equivalent/mg extract and 1.963 mg/mL, respectively. The presence of surface plasmon resonance peak within the range of 416–426 nm confirmed the formation of AgNPs. An optimization study was conducted to determine the conditions that would lead to the formation of smaller-sized nanoparticles. The optimum conditions were 60 °C for 24 h. Based on the transmission electron microscopy analysis, the AgNPs were spherical in shape with a size ranging from 4–7 nm. The antimicrobial activity of AgNPs was determined using the resazurin microtiter assay. The minimum inhibitory concentration (MIC) of the AgNPs against Staphylococcus aureus and Escherichia coli was 6.25 μg/mL. It is also noted that AgNPs had a greater inhibitory effect than chloramphenicol. The findings of this study provide a facile and eco-friendly approach for the large-scale production of AgNPs using calabash fruit extract. This also suggests the potential of AgNPs for the treatment of antibiotic-resistant bacteria.

Bio-inspired synthesis of silver nanoparticles assisted Murraya koneigii leaf extract and its antimicrobial activity

Bio-inspired synthesis of silver nanoparticles (Ag NPs) using Murraya Koneigii leaf extract is reported in this study. The rapid reduction of silver (Ag+) ions was monitored by using UV–Vis spectrophotometer and showed the formation of Ag NPs within 30 min. Further, XRD pattern confirmed the crystalline phase of silver with FCC crystal structure. FT-IR analysis was carried out to identify the phytochemicals responsible in bio-reduction of silver ions. SEM and TEM showed the formation of Ag NPs with an average particle size of 35–80 nm. In an addition, antimicrobial activity of Ag NPs was checked at different concentrations.

Valorization of Food Waste to Produce Eco‐Friendly Means of Corrosion Protection and “Green” Synthesis of Nanoparticles

Agrifood by‐products are a key element within Europe’s sustainable strategies. Valorization and reuse of zero‐waste technologies are becoming more popular, and they are commonly named as “second‐generation food waste management.” The present study is directed to the valuable extracts of “green” organic compounds from the by‐products of fruit and berry/vegetable crops, which can be revalorized in sustainable chemical technology and engineering, namely, in the production of “green” synthesis of nanoparticles and for the inhibition of corrosion and scaling of metals in corrosive media. Numerous types of agrifood by‐products (rapeseed pomace, sugar beet pulp, fodder radish cake, grape pomace, and pomegranate peels) were investigated. The waste extracts for corrosion and scale inhibitors of mild steel in tap water were prepared by the conventional extraction method that uses 2‐propanol and characterized by gas chromatography‐mass spectroscopy (GC‐MS). Inhibition of scaling and corrosion was investigated in thermal scaling conditions on the surface of the electrode manufactured from mild steel. The LPR technique was applied to measure the corrosion rate, and the scaling rate was determined gravimetrically. The extracts were found to inhibit the corrosion rate 2‐3 times, while only radish cake extract inhibited both the corrosion and scaling rates. The waste extracts to produce nanoparticles were prepared by the ultrasound‐assisted water extraction with subsequent oxidation by oxygen purge and characterized by liquid chromatography‐mass spectroscopy (LC‐MS). The aqueous grape pomace and pomegranate peel extracts were screened for total phenolic content (TPC) and total flavonoid content (TFC). The reduction capacity of the extracts was assessed using ferric reducing power (FRAP) and phosphomolybdenum (PM) assays. AgNPs were characterized by UV‐Vis spectroscopy, dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FT‐IR), scanning electron microscope (SEM), and energy‐dispersive X‐ray spectroscopy (EDX) analysis. The particle size of AgNPs ranged between 40 and 50 nm. The antimicrobial activity of AgNPs was tested against Escherichia coli using the agar diffusion method and optical density.

A Review on silver nanoparticles-The powerful nanoweapon against oral pathogens

In the human oral cavity, complex microbe-host relationships occurs. Dental disease is prevalent in about 89% of the Indian population, of which 72% are residing in the rural areas whose economic values are low to afford the treatment. Indian greeneries are the chief and economical source of medicinal plants and plant products. In recent years, green synthesis of silver nanoparticles (AgNPs) has gained much interest from researchers. As a wide range of metabolites are present in the plant products/extracts, nanoparticles produced by plants are more stable, and the rate of synthesis is faster in comparison to microorganisms. Silver in the form of various compounds have been used in Ayurveda to treat several bacterial infections since time immemorial. The present review explores the huge plant diversity to be utilized for the synthesis of AgNPs and describes the antimicrobial activities of AgNPs against the oral and nonoral microflora.

Tissue reaction and anti-biofilm action of new biomaterial composed of latex from Hancornia speciosa Gomes and silver nanoparticles.

In this work, the natural latex extracted from Harconia speciosa was incorporated with silver nanoparticles (AgNP) to compose a functional biomaterial associating the intrinsic angiogenic activity of the latex and the antimicrobial activity of AgNP. Tissue reaction after subcutaneous implantation in dorsum of rats of membranes without AgNP and with 0.05%, 0.4% AgNP was compared at 3, 7 and 25 days. No statistically significant difference in the tissue response of the different biomaterials was observed, indicating that AgNP did not interfere with the inflammatory reaction (p > 0.05) or with the angiogenic activity of latex. Biomembranes were also tested against bacterial biofilm formation by Staphylococcus aureus and the antimicrobial activity of the new biomaterial can be found with bacteria crenation (0.05% AgNP) and no biofilm deposition (0.4% AgNP). Therefore, this biomaterial has interesting properties for the tissue repair process and may be feasible for future applications as dressing.

A comparative study on the antimicrobial activity of irreversible hydrocolloid mixed with silver nanoparticles and chlorhexidine

Impressions taken from patients have the potential of cross-transmission of infection among dentistry personnel. The present study aimed to compare the antimicrobial activity of chlorhexidine (CHX) and silver nanoparticles (AgNPs) combined with irreversible hydrocolloid. This experimental study examined the in vitro antimicrobial effects of irreversible hydrocolloid mixed with silver nanoparticles and chlorhexidine using four groups, namely CHX (0.2%) solution and mouthwash mixed with irreversible hydrocolloid Groups 1 and 2), AgNPs (0.1 and 0.2%) (Groups 3 and 4), and specimens mixed with distilled water as a control group (Group 5) on bacterial strains, namely, Staphylococcu saureu s,Enterococcu sfaecali s,Pseudomona saeruginos a,Escherichi acoli, andStaphylococcu sepidermidi s through disc diffusion method. There were three replications per bacterial species. As data were not normally distributed, Kruskal-Wallis test was used at a significance level of 0.05. No antimicrobial activity was observed in the control groups. In S. aureus, CHX mouthwash had the highest antimicrobial activity, and AgNPs 0.1% and 0.2% groups had lower antimicrobial activity, and there was a significant difference between the two concentrations of AgNPs (P < 0.05). InE.faecali s, the effects of CHX compounds and AgNPs 0.2% were similar to each other and were higher than the effect of AgNPs 0.1% (P < 0.05). In E. coli, CHX compounds exhibited the highest efficacy relative to other materials (P < 0.05), and the AgNPs had no effect. In P. aeruginosa, AgNPs showed the highest growth inhibition zone, which had a significant difference compared to other materials (P ≤ 0.01), whereas the CHX compounds were not effective. InS.epidermidi s, the effect of CHX compounds was similar to one another and was higher than the effect of AgNPs (P ≤ 0.01). According to our observations, the antimicrobial activity of AgNPs at 0.1 and 0.2% against five tested bacterial strains was similar to those of pure CHX 0.2% solution and CHX 0.2% mouthwash.

Hawthorn berries extract for the green synthesis of copper and silver nanoparticles

Silver and copper nanoparticles (AgNPs and CuNPs) have attracted worldwide attention due to their unique antimicrobial properties. Ethanol and water extracts of hawthorn fruit were chosen to prepare AgNPs and CuNPs. The effects of the pH, contact time, temperature of the solution, type of precursor of metal ions and type of hawthorn extract on the size distribution of particles were studied. The monodispersed and stable AgNPs and CuNPs were prepared with an average size of 60 nm and 200 nm, respectively. Total phenolic content and the anthocyanin content of extracts were determined. The antimicrobial activities of AgNPs and CuNPs were carried out with a series of microbial assays.

Characterization of silver nanoparticle produced by Pseudopediastrum boryanum (Turpin) E. Hegewald and its antimicrobial effects on some pathogens

The aim of this research was to investigate the antimicrobial activity of silver nanoparticles (AgNPs) biosynthesized by Pseudopediastrum boryanum (Turpin) E. on several human pathogen microorganisms. AgNPs were isolated from P. boryanum. The biosynthesis of AgNPs was carried out using a UV–visible spectrophotometer and FTIR spectroscopy analysis. The antimicrobial activity of AgNPs was evaluated against various pathogen microorganisms using the well diffusion method, and MIC was estimated by qualitative experimentation by microbroth dilution method. The antimicrobial activities of AgNPs at three different concentrations (1 mM, 2 mM and 3 mM) were measured using the diameter of the inhibition zone (DIZ) of the pathogen microorganisms. AgNPs demonstrated various antimicrobial effects on pathogen microorganisms at different concentrations. The highest antimicrobial activity was determined in Proteus vulgaris [DIZ = 30 ± 0.2 mm (2 and 3 mM)], followed by Candida parapsilosis (M006) [DIZ = 25 ± 0.1 mm (3 mM)], followed by Pseudomonas aeruginosa [DIZ = 20 mm (2 and 3 mM)] and Candida parapsilosis (M006) [DIZ = 20 mm (1 and 2 mM)]. The lowest antibacterial effects of AgNPs were observed on Aeromonas hydrophila [DIZ = 5 ± 0.1 mm (3 mM)], Staphylococcus epidermidis [DIZ = 5 ± 0.1 mm (1 mM)], Candida parapsilosis [DIZ = 5 ± 0.1 mm (2 mM)] and Candida albicans [DIZ = 5 ± 0.1 mm (3 mM)]. Gram-negative bacteria Proteus mirabilis, Enterobacter aerogenes, Salmonella typhimurium, Shigella dysenteriae, Escherichia coli and Serratia marcescens and Gram-positive bacteria Listeria monocytogenes and Enterococcus faecalis exhibited no zone of inhibition. Our results confirm that AgNPs biosynthesized from P. boryanum may be used as an effective antimicrobial agent against human pathogens.

Fruit peels waste for the green synthesis of silver nanoparticles with antimicrobial activity against foodborne pathogens

In this work we report an eco-friendly and low cost method for reducing and capping silver nanoparticles with a lyophilized extract from grape and orange wastes. The synthesis of silver nanoparticles (AgNPs) was monitored by UV–Vis spectroscopy and their characterization was carried out using Transmission Electron Microscopy (TEM), Diffuse Reflectance Infrared Spectroscopy (DRIFT) and X Ray Diffraction (XRD). The AgNPs were crystalline and spherical, with diameters from 3 to 14 nm and 5–50 nm for the nanoparticles obtained from the grape and orange extract, respectively. DRIFT spectroscopy suggested the involvement of various functional groups from extract secondary metabolites during nanoparticle synthesis and capping nanoparticles. The antimicrobial activity of AgNPs was tested against Escherichia coli O157:H7 and Listeria monocytogenes using the agar diffusion method and optical density (OD600). Non-significant difference of L. monocytogenes growth inhibition was observed between AgNPs obtained from both extracts, demonstrating a 13.5 mm diameter growth inhibition at 100 μg/ml. For E. coli O157:H7, only the AgNPs obtained from the grape extract exhibited a dose-dependent antimicrobial activity showing a final OD of 0.42 at 100 μL.

Antioxidant activity and potential of Caesalpinia sappan aqueous extract on synthesis of silver nanoparticles.

The aim of this study was to investigate the antioxidant activity of Caesalpinia sappan aqueous extract (CE) and its potential on synthesis of silver nanoparticles (AgNPs). The antioxidant activity of CE was investigated using ferric reducing antioxidant power (FRAP) assay and two radical scavenging methods using 2,20-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) as free radicals. Silver nitrate (AgNO3) was used as precursor for the synthesis of AgNPs. Effects of AgNO3 concentration, reaction temperature, and duration of reaction were investigated. The obtained AgNPs was characterized using UV-Vis and photon correlation spectrophotometers. The antimicrobial activity of AgNPs was studied by means of diffusion method. The results from FRAP demonstrated that CE had high reducing property of 78.7 ± 2.4 mM Fe2+/mg. The trolox equivalent antioxidant capacity of CE determined by ABTS was 64.8 ± 4.2 µM/mg. The concentration of CE that can inhibit 50% of DPPH radicals (IC50) was 51.2 ± 3.2 µM. These results indicated that CE possesses strong antioxidant and reducing activities. The present study also showed that CE can act as reducing agent to produce AgNPs. The concentration of AgNO3, reaction temperature, and reaction time play an important role on the particles size and zeta potential of the obtained AgNPs. The antimicrobial activity of the AgNPs against Escherichia coli, Candida albicans, and Streptococcus mutants was stronger than against Staphylococcus aureus.

Chitosan-Stabilized Ag Nanoparticles with Superior Biocompatibility and Their Synergistic Antibacterial Effect in Mixtures with Essential Oils

Silver nanoparticles (AgNPs) are considered a promising alternative to the use of antibiotics in fighting multidrug-resistant pathogens. However, their use in medical application is hindered by the public concern regarding the toxicity of metallic nanoparticles. In this study, rationally designed AgNP were produced, in order to balance the antibacterial activity and toxicity. A facile, environmentally friendly synthesis was used for the electrochemical fabrication of AgNPs. Chitosan was employed as the capping agent, both for the stabilization and to improve the biocompatibility. Size, morphology, composition, capping layer, and stability of the synthesized nanoparticles were characterized. The in vitro biocompatibility and antimicrobial activities of AgNPs against common Gram-negative and Gram-positive bacteria were evaluated. The results revealed that chitosan-stabilized AgNPs were nontoxic to normal fibroblasts, even at high concentrations, compared to bare nanoparticles, while significant antibacterial activity was recorded. The silver colloidal dispersion was further mixed with essential oils (EO) to increase the biological activity. Synergistic effects at some AgNP–EO ratios were observed, as demonstrated by the fractionary inhibitory concentration values. Our results reveal that the synergistic action of both polymer-stabilized AgNPs and essential oils could provide a significant efficiency against a large variety of microorganisms, with minimal side effects.

Catalytic reduction of p-nitrophenol and methylene blue by microbiologically synthesized silver nanoparticles

Catalytic Reduction of p-nitrophenol and Methylene blue by Microbiologically Synthesized Silver Nanoparticles was studied in the present investigation. Catalytic reduction of 4-Nitophenol/p-nitrophenol (PNP) and methylene blue (MB) was assessed using both intra and extracellular silver nanoparticles (AgNP) with and without immobilization. Both intracellular and extracellular AgNP were synthesized from actinomycetes. Antimicrobial activity of AgNP was also assessed and it was found that, intracellular AgNP have significant antibacterial activity against E. coli, S. typhi and B. subtilis. Synthesized biogenic silver nanoparticles were characterized by UV–visible spectrophotometry, FTIR, XRD, and TEM-EDS.It was found that, extracellular AgNP are efficient as compared to intracellular AgNP in terms of PNP reduction.

Extracellular directed ag NPs formation and investigation of their antimicrobial and cytotoxic properties

The use of microbial cell culture a valuable tool for the biosynthesis of nanoparticles is considered a green technology as it is eco-friendly, inexpensive and simple. Here, the synthesis of nanosilver particle (AgNP) from the yeast, Saccharomyces cerevisiae, gram (+), Bacillus subtilis and gram (−), Escherichia coli was shown. In this field we are the first to study their the antimicrobial effects of the microorganisms mentioned above against pathogens and anticancer activity on MCF-7 cell line. Silver nanoparticles in the size range of 126–323 nm were synthesized extracellularly by the microorganisms, which have different cell structures. Optical absorption, scanning electron microscopy, and zetasizer analysis confirmed the silver nanoparticles formation. Antimicrobial activity of AgNPs was evaluated the minimum inhibition concentration and disc diffusion methods. AgNPs inhibited nearly 90% the growth of Gram-positive Listeria monocytogenes, Streptococcus pneumoniae and Gram-negative Haemophilus influenzae, Klebsiella pneumoniae, Neisseria meningitidis bacterial pathogens. Anticancer potentials of AgNPs were investigated by MTT method. The synthesized AgNPs exhibited excellent high toxicity on MCF-7 cells and had a dose-dependent effect on cell viability. Especially AgNP 2 eliminated 67% of the MCF-7 cells at the concentration of 3.125 μg/mL. We found that extracellular synthesis of nanoparticles from microbial culture may be ‘green’ alternative to physical and chemical methods from the point of view of synthesis in large amounts and easy process.

Synthesis of Metallic Silver Nanoparticles by Fluconazole Drug and Gamma Rays to Inhibit the Growth of Multidrug-Resistant Microbes

Here we tailored a methodology, including green synthesis of silver nanoparticles (AgNPs) in aqueous solution using Fluconazole (Fluc.), a broad-spectrum antifungal agent under the influence of gamma rays. AgNPs were characterized by UV–Vis., FTIR, XRD, DLS, and TEM image. Antimicrobial activities of AgNPs, Fluc., and Ag+ were investigated against multidrug-resistant (MDR) bacteria and unicellular fungi. From our results, AgNPs production was found to be dependent on the concentration of Ag+, Fluc. and gamma doses. DLS with TEM image explained the size and shape of AgNPs and were found to be spherical with diameter of 11.65 nm. FTIR analysis indicates that, the hydroxyl, nitrogen and fluoride moiety in Fluc. were responsible for the reduction and binding process. AgNPs possesses antimicrobial activity against all tested microbes more than Ag+. It produced high efficacy against Acinetobacter baumannii (20.0 mm ZOI). AgNPs are synergistically active towards Candida albicans (17.0 mm ZOI). Investigated action mechanisms for AgNPs activity had been discussed. Thereby, owing to its unique features as cost-effective with continued-term stabilization, it can discover potential targets in biomedical applications and infectious diseases control.

Comparative catalytic and bacteriostatic properties of silver nanoparticles biosynthesized using three kinds of polysaccharide

Silver nanoparticles (Ag NPs) were biosynthesized using konjac glucomannan (KGM), κ-carrageenan (CRG) and inulin as reducing and capping agent through one-spot method. The structure and morphology of Ag NPs were investigated using UV-visible spectroscopy, transmission electron microscopy, Fourier transform infrared and X-ray powder diffraction. The catalysis and antibacterial properties were also evaluated. Results showed that Ag NPs fabrication was influenced by the incubation temperature and polysaccharide category. CRG displayed a stronger reduction of Ag+ than KGM, and the lowest was inulin. A High incubation temperature promoted the reduction of Ag NPs. As for Ag100 NPs, the kapp of Ag NPs based on CRG, inulin, and KGM were 5.80×10-2 s-1, 2.14×10-2 s-1, and 2.16×10-2 s-1 respectively. Bacteriostatic test showed excellent antimicrobial activity of Ag NPs for Escherichia coli and Staphylococcus aureus. Thus, natural polysaccharide could be effective reducing and stabilizing agents for Ag NPs biosynthesis. The excellent antibacterial and catalytic properties may facilitate their use in medical, food, and biological applications.

Antimicrobial Activity of a Colloidal AgNP Suspension Demonstrated In Vitro against Monoculture Biofilms: Toward a Novel Tooth Disinfectant for Treating Dental Caries.

A novel silver nanoparticle (AgNP) formulation was developed as a targeted application for the disinfection of carious dentine. Silver nitrate (AgNO3) was chemically reduced using sodium borohydrate (NaBH4) in the presence of sodium dodecyl sulfate (SDS) to form micelle aggregate structures containing monodisperse 6.7- to 9.2-nm stabilized AgNPs. AgNPs were characterized by measurement of electrical conductivity and dynamic light scattering, scanning electron microscopy, transmission electron microscopy, and inductively coupled plasma mass spectrometry. Antimicrobial activity of AgNPs was tested against planktonic cultures of representative gram-positive and gram-negative oral bacteria using well diffusion assays on tryptic soy broth media and monoculture biofilms grown with brain heart infusion ± sucrose anaerobically at 37°C on microtiter plates. Biofilm mass was measured by crystal violet assay. Effects were compared to silver diamine fluoride and chlorhexidine (negative controls) and 70% isopropanol (positive control) exposed cultures. In the presence of AgNPs, triplicate testing against Streptococcus gordonii DL1, C219, G102, and ATCC10558 strains; Streptococcus mutans UA159; Streptococcus mitis I18; and Enterococcus faecalis JH22 for planktonic bacteria, the minimum inhibitory concentrations were as low as 7.6 µg mL-1 and the minimum bacteriocidal concentrations as low as 19.2 µg mL-1 silver concentration. Microplate readings detecting crystal violet light absorption at 590 nm showed statistically significant differences between AgNP-exposed biofilms and where no antimicrobial agents were used. The presence of sucrose did not influence the sensitivity of any of the bacteria. By preventing in vitro biofilm formation for several Streptococcus spp. and E. faecalis, this AgNP formulation demonstrates potential for clinical application inhibiting biofilms.

Synthesis, characterization and evaluation of antimicrobial and cytotoxic activities of biogenic silver nanoparticles synthesized from Streptomyces xinghaiensis OF1 strain

We report synthesis of silver nanoparticles (AgNPs) from Streptomyces xinghaiensis OF1 strain, which were characterised by UV–Vis and Fourier transform infrared spectroscopy, Zeta sizer, Nano tracking analyser, and Transmission electron microscopy. The antimicrobial activity of AgNPs alone, and in combination with antibiotics was evaluated against bacteria, namely Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus subtilis, and yeasts viz., Candida albicans and Malassezia furfur by using micro-dilution method. The minimum inhibitory concentration (MIC) and minimum biocidal concentration of AgNPs against bacterial and yeast strains were determined. Synergistic effect of AgNPs in combination with antibacterial and antifungal antibiotics was determined by FIC index. In addition, MTT assay was performed to study cytotoxicity of AgNPs alone and in combination with antibiotics against mouse fibroblasts and HeLa cell line. Biogenic AgNPs were stable, spherical, small, polydispersed and capped with organic compounds. The variable antimicrobial activity of AgNPs was observed against tested bacteria and yeasts. The lowest MIC (16 µg ml−1) of AgNPs was found against P. aeruginosa, followed by C. albicans and M. furfur (both 32 µg ml−1), B. subtilis and E. coli (both 64 µg ml−1), and then S. aureus and Klebsiella pneumoniae (256 µg ml−1). The high synergistic effect of antibiotics in combination with AgNPs against tested strains was found. The in vitro cytotoxicity of AgNPs against mouse fibroblasts and cancer HeLa cell lines revealed a dose dependent potential. The IC50 value of AgNPs was found in concentrations of 4 and 3.8 µg ml−1, respectively. Combination of AgNPs and antibiotics significantly decreased concentrations of both antimicrobials used and retained their high antibacterial and antifungal activity. The synthesis of AgNPs using S. xinghaiensis OF1 strain is an eco-friendly, cheap and nontoxic method. The antimicrobial activity of AgNPs could result from their small size. Remarkable synergistic effect of antibiotics and AgNPs offer their valuable potential in nanomedicine for clinical application as a combined therapy in the future.

Investigation of Green Synthesized Silver Nanoparticles Using Aqueous Leaf Extract of Artemisia Argyi for Antioxidant and Antimicrobial Potentials

The current study employs green synthesis to acquire silver nanoparticles (AgNPs) using Artemisia argyi and appraise their antioxidant and antimicrobial potentials. AgNPs were synthesized using aqueous leaf extract of Artemisia argyi by sunlight irradiation. They were characterized using UV-visible spectrophotometer, FESEM, FTIR and XRD. The antioxidant capacity of AgNPs were evaluated using ABTS, DPPH, iron chelation, FRAP and NO radical scavenging methods. Antimicrobial activities of AgNPs were tested against Esherichia coli and Staphylococcus aureus using disc diffusion method. Descriptive statistical analysis was used to identify significant relationship between antioxidant activities of AgNPs. The synthesized AgNPs exhibited brown color light scattering and absorbed maximum wavelength of light at 450 nm. The synthesis of AgNPs was optimum at 0.01 M AgNO3. The green synthesized AgNPs were spherical in shape with size ranging from 16 nm to 32 nm. The FTIR analysis revealed the presence of proteins, phenolic and polar nitrile compounds in the AgNPs. The purified AgNPs possessed a face centered cubic structure with coexistence of silver chloride crystals. The total phenolic and flavonoid of AgNPs were found to be 77.45 mg GAE/g AgNPs and 205.29 mg GAE/g AgNPs respectively. The radical scavenging activity (EC50) showed highest activity for NO (31.33 μg/ml) followed by ABTS (128.82 μg/ml), DPPH (263.03 μg/ml) and Fe2+ (1445.44 μg/ml) with a FRAP value of 1.22 mmol Fe2+ /mg dry weight. AgNPs possessed inhibitory effect against both strains of bacteria in concentration dependent manner. This study discovered that green synthesized AgNPs using Artemisia argyi are promising sources of effective antioxidants and antimicrobial agents with a high surface area catalytic activity.

Silver nanoparticles: Antimicrobial activity, cytotoxicity, and synergism with N-acetyl cysteine.

The fast progression of nanotechnology has led to novel therapeutic interventions. Antimicrobial activities of silver nanoparticles (Ag NPs) were tested against standard ATCC strains of Staphylococcus aureus (ATCC 9144), Escherichia coli (O157:H7), Pseudomonas aeruginosa (ATCC 27853), and Candida albicans (ATCC 90028) in addition to 60 clinical isolates collected from cancer patients. Antimicrobial activity was tested by disk diffusion method and MIC values for Ag NPs alone and in combination with N-acetylcysteine (NAC) against tested pathogens were determined by broth microdilution method. Ag NPs showed a robust antimicrobial activity against all tested pathogens and NAC substantially enhanced the antimicrobial activity of Ag NPs against all tested pathogens. Synergism between Ag NPs and NAC has been confirmed by checkerboard assay. The effect of Ag NPs on tested pathogens was further scrutinized by Transmission Electron Microscope (TEM) which showed disruption of cell wall in both bacteria and fungi. Ag NPs abrogated the activity of respiratory chain dehydrogenase of all tested pathogens and released muramic acid content from S. aureus in culture. The cytotoxic effect of Ag NPs alone and in combination with NAC was examined using human HepG2 cells and this revealed no cytotoxicity at MIC values of Ag NPs and interestingly, NAC reduced the cytotoxic effect of Ag NPs at concentrations higher than their MIC values. Taken together, Ag NPs have robust antimicrobial activity and NAC substantially enhances their antimicrobial activities against MDR pathogens which would provide a novel safe, effective, and inexpensive therapeutic approach to control the prevalence of MDR pathogens.

Advanced multi-targeted composite biomaterial dressing for pain and infection control in chronic leg ulcers

This study aimed to develop advanced biomaterial polysaccharide based dressings to manage pain associated with infected chronic leg ulcers in older adults. Composite carrageenan (CARR) and hyaluronic acid (HA) dressings loaded with lidocaine (LID) and AgNPs were formulated as freeze-dried wafers and functionally characterized for porous microstructure (morphology), mechanical strength, moisture handling properties, swelling, adhesion and LID release. Antimicrobial activity of AgNPs was evaluated (turbidity assay) against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus whilst cell viability studies (MTT) was performed on normal adult human primary epidermal keratinocyte cells. The wafers were soft, flexible and elegant in appearance. HA affected the wafer structure by increasing the resistance to compression but still possessed a balance between toughness and flexibility to withstand normal stresses and prevent damage to newly formed skin tissue respectively. Water uptake was influenced by HA, whilst equilibrium water content and LID release were similar for all the formulations, showing controlled release up to 6h. AgNPs loaded CARR/HA wafers were effective in inhibiting the growth of both Gram positive and Gram negative bacteria. MTT assay showed evidence that the AgNPs/LID loaded wafers did not interfere with cell viability and growth. CARR/HA wafers seem to be a promising system to simultaneously deliver LID and AgNPs, directly to infected chronic leg ulcers.