Antimicrobial Activity Of Silver Nanoparticles Research Articles

Enhancing the antimicrobial activity of silver nanoparticles against pathogenic bacteria by using Pelargonium sidoides DC extract in microwave assisted green synthesis.

This study presents an optimized microwave-assisted method for the green synthesis of silver nanoparticles (AgNPs) using a root extract obtained from Pelargonium sidoides DC. The influence of temperature, reagent concentration, and irradiation time was systematically investigated to enhance synthesis yield. Characterization techniques including XRD, UV-vis, FTIR, XPS, and zetametry were employed to confirm the successful formation of nanoparticles with a metallic silver core (∼17 nm) functionalized with organic molecules derived from the plant extract. The cytotoxicity of AgNPs was assessed using a cell viability assay, while the Minimum Inhibitory Concentration (MIC) of nanoformulation against pathogenic bacteria, including Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and the carbapenem-resistant Klebsiella pneumoniae (KPC), was determined using the Broth microdilution method. The nanoformulation synthesized with P. sidoides extract exhibited a dose-dependent response, demonstrating superior antimicrobial efficacy compared to the pure plant extract in most cases. The MIC values ranged from 0.85 to 17.1 μg mL-1, with particularly strong performance against the drug resistant KPC strain. The enhanced antimicrobial effect is attributed to the synergistic action of the metallic silver core and phytochemicals from P. sidoides on the surface of nanoparticles, which also contribute to notable colloidal stability of AgNPs at physiological pH levels.

In vitro antimicrobial activity of silver nanoparticles against selected Gram-negative and Gram-positive pathogens

Background and aim. Infections caused by pathogenic bacteria increase patient morbidity and mortality and significantly raise treatment costs. The use of silver nanoparticles as an alternative treatment for S aureus, E coli, MRSA, E faecalis, K pneumoniae and P aeruginosa indicates their antibacterial effect and prompts medical research to consider the next generation of antibacterial drugs that could change antibiotic therapy. By combining silver nanoparticles with different classes of antibiotics, the antibacterial effect is evidenced by increased values of the inhibition zone compared to the values obtained for some antibiotics commonly used in the treatment of bacterial infections. This study focuses on comparing the antibacterial activity of antibiotics versus antibiotics combined with silver nanoparticles against various bacteria, by comparing inhibition zones obtained for both. We aim to prove that the size of the inhibition zone for antibiotics combined with silver nanoparticles is greater, thus confirming the improved antibacterial effect. Metods. In this study we tested the antibacterial activity of solutions of silver nanoparticles alone or in combination with different antibiotics. We used standard bacterial strains, ATCC, both Gram positive bacteria Staphylococcus aureus ATCC 29213, Enterococcus faecalis ATCC 29212, as well as Gram negative bacteria Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, but also on clinical isolates: a strain MRSA (Methicillin Resistant Staphylococcus aureus) and a PDR strain (pan drug resistant) of Klebsiella pneumoniae. Bacterial identification was performed using Vitek MS analyzer (bioMerieux). Antibiotic susceptibility determination was performed with VITEK2 COMPACT SYSTEM (bio Merieux, Inc Durham NC) with ready to use VITEK AST cards. The interpretation of the results was done in compliance with EUCAST 2023-2024 standards. Testing was performed for several classes of antibiotics, silver nanoparticle solutions in 2 concentrations (10 μg/mL and 100 μg/mL) and for combinations of antibiotics with silver nanoparticle solutions. The diameter of the inhibition zone (ZOI) for silver nanoparticles, antibiotics and silver nanoparticles combined with antibiotic against each bacterium was expressed in millimeters. The Kirby-Bauer disk-diffusion method, in accordance with current EUCAST standards, was used to analyze the antibacterial effect of antibiotics, silver nanoparticles, and antibiotics combined with silver nanoparticles at biocompatible doses of 10 and 100 μg/mL. The experiments were conducted in triplicate, and the results were almost identical. Results. The results of this study show that the silver nanoparticles displayed antibacterial activity, proven by the appearance of the inhibition zone, in various sizes, for all bacteria studied. The antibiotic classes tested were beta-lactamins, first, second, third and fourth generation cephalosporins, macrolides, fluoroquinolones, lincosamides, aminoglycosides, glycopeptides, tetracyclines, oxazolidinones, sulfonamides, rifamycins, amphenicols. Testing S aureus ATCC 29213, the highest zone of inhibition was demonstrated for cephalosporins (32.6667 ± 0.701 mm), macrolides (31.6667 ± 0.701 mm, and lincosamides (29.6667 ± 0.701 mm). Testing MRSA (internal code GR0333), the highest zone of inhibition for combination of silver nanoparticles and antibiotics was demonstrated for fluoroquinolones (36.3333 ± 0.701 mm), lincosamides (32.3333 ± 0.701 mm), Fusid acid (32.3333 ± 0.701 mm) and aminoglicosides (31.3333 ± 0.701 mm). Testing E coli ATCC 25922 the highest zone of inhibition was for Fosfomycine, 39 mm and for E faecalis ATCC 29212 for aminoglicosides was 19 mm. For K pneumoniae (internal code GQ8575) the inhibition zone for silver nanoparticles 100 μg/mL was 12.3333 ± 0.701 mm and for P aeruginosa ATCC 27253 was 16 ± 1.214 mm. Conclusions. The use of metallic nanoparticles, especially silver ones, as antimicrobial agents with definite bactericidal activity has led medical specialists to consider this new treatment which may change antibacterial therapy. Studies of in vitro combinations between silver nanoparticles and different classes of antibiotics represent a highly efficient and effective new antibacterial treatment against multidrug-resistant bacteria. To avoid the problem of antimicrobial resistance associated with conventional antibiotics, it is necessary to understand the adaptive mechanisms of bacteria under the action of metal nanoparticles, which could be exploited in future studies. Further in vitro and in vivo studies that would assess specify the biocompatibility and toxicity of silver nanoparticles will make these super nanomaterials the medicines of the future.

Optimization of Synthesis Reaction Parameters of AgNPs Derived from Laser trilobum Plant for Foodborne Pathogens

AbstractIn this study, the antimicrobial activity of silver nanoparticles (AgNPs L21, AgNPs L22) produced using aqueous extracts of the Laser trilobum harvested in 2021 and 2022 was optimized. The experimental design and optimization of antimicrobial activity were performed using the response surface method (RSM). Using RSM, independent variables, such as silver concentration, extraction time, and synthesis temperature, were optimized as a result of the inhibition zone diameter against Staphylococcus aureus, Escherichia coli, Salmonella Typhimurium, and Listeria monocytogenes. Based on the optimization results, the extraction time, silver concentration, and temperature for AgNP L21 and L22 synthesis were determined to be 60 min, 5 mM, and 25 °C, respectively. When the XRD and TEM results of the nanoparticles synthesized under optimal conditions were evaluated, it was determined that the AgNPs were spherical in shape and had an average size of 30 ± 12 nm. Our study revealed that the year of harvest is unimportant for nanoparticles synthesized from L. trilobum, using a cheap and simple method that does not require toxic substances. Owing to the antimicrobial activity of nanoparticles produced under optimal conditions, it is possible to biocontrol and prevent contamination by these bacteria in food science and industry.

Ag-NP-Decorated Carbon Nanostructures: Synthesis, Characterization, and Antimicrobial Properties.

As the global urgency for effective antimicrobial agents intensifies, this work harnesses the widely demonstrated antimicrobial activity of silver nanoparticles (Ag-NPs) and proposes alternative synthesis approaches to metal-organic hybrid systems with antimicrobial activity. In this study, the proposed synthesis route involves decorating metallic nanoparticles into organic substrates without previous doping. The synthesis simultaneously uses polyethylene glycol for three crucial purposes: (1) acting as a mild reducing agent to generate Ag-NPs with a spherical shape and diameters ranging from 10 to just over 20 nm, (2) functioning as a dispersing agent for flakes of commercial nanostructured carbon supports, including reduced graphene oxide (rGO, ID-nano), and commercial carbon nanoplatelets from Sigma-Aldrich (GNPs, Sigma-Aldrich), and (3) serving as a promoter for the homogeneous anchoring of Ag-NPs in the carbon lattice without altering the conformation of the carbon lattice. This intricate interaction involves the π-orbitals from the sp2 hybridization honeycomb and the d-orbitals from the Ag-NPs, leading to the constructive rehybridization of rGO and GNPs. In our study, Ag-NPs/rGO are compared with a support lacking oxygenated groups in the lattice, such as commercial GNPs (Sigma-Aldrich), to produce Ag-NPs/GNPs. This comparison maintains constructive sp2 rehybridization, preserving the characteristic properties of rGO (ID-nano) and graphene nanoplatelets, including commercial GNPs (Sigma-Aldrich). Notably, oxygenated groups from rGO exhibit greater availability for exchanging oxo and hydroxy defects for Ag-NPs compared with GNPs (Sigma-Aldrich). The resulting Ag-NPs/rGO and Ag-NPs/GNP systems are thoroughly physicochemically characterized, employing techniques such as Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, and scanning transmission electron microscopy, revealing the successful integration of Ag-NPs with minimal alteration to the carbon lattice. Subsequent antimicrobial evaluation against Escherichia coli (E. coli) demonstrates significant activity, with Ag-NPs/rGO and Ag-NPs/GNPs registering similar minimum inhibitory concentrations of 50 μg mL-1. This study underscores the potential of our metal-organic hybrid systems as antimicrobial agents and provides insights into the constructive rehybridization process, paving the way for diverse applications in the biomedical and environmental fields.

Antimicrobial activity of silver nanoparticles on biofilm – dental implant model

Antimicrobial activity of silver nanoparticles on biofilm – dental implant model

Antimicrobial activity of silver nanoparticles synthesized from Wrightia tinctoria fruit extracts

Nanoparticles are synthesized by using various chemical methods in higher yields but they are not very environmentally friendly and have hazardous effects on living cells. This can be attributed to the overuse of hazardous chemicals involved in the process. The green approach of nanoparticle synthesis is widely gaining attention worldwide as it is considered as nontoxic, harmless and ecofriendly. Apart from this they also have multiple applications in various fields of science and technology. Nanoparticles synthesized by using various phytochemicals are also effective against a variety of microbial populations. The objective of this study is to synthesize silver nanoparticles (AgNPs) from the fruit extracts of Wrightia tinctoria and evaluating its antimicrobial capacities against gram-positive and negative bacterial strains. Silver nanoparticles were synthesized using different solvent extracts of Wrightia tinctoria pods. The formation of silver nanoparticles was noted by detecting the change in color of the solution. The presence of nanoparticles was detected by performing UV visible spectroscopy and monitoring the spectrum from 400 nm to 800 nm. A small peak at 425 nm suggested the presence of silver nanoparticles. In a later part of the study, the inhibitory effect of green synthesized silver nanoparticles on the growth of E. coli and S. aureus was monitored. The appearance of a zone of inhibition further confirmed the antimicrobial effect of the synthesized nanoparticles.

A review on <i>Azadirachta indica</i> (neem) plant mediated biosynthesis, characterisation and antimicrobial activity of silver nanoparticles

A review on <i>Azadirachta indica</i> (neem) plant mediated biosynthesis, characterisation and antimicrobial activity of silver nanoparticles

Atividade saneante de nanopartículas de prata sintetizadas com produtos naturais sobre superfícies da indústria de laticínio

ABSTRACT: Surface contamination by pathogenic and deteriorating microorganisms is a constant concern in the food industry. Therefore, in this study we evaluated the antimicrobial activity of silver nanoparticles (AgNPs), produced using the essential oil of Lippia origanoides Kunth and ethanolic extract of Hymenaea martiana Hayne, against bacteria used in milk processing. For this, AgNPs were synthesized and their antimicrobial activity was evaluated for minimum inhibitory and bactericidal concentrations, time-kill, interference on the biofilm, and application on the surfaces of different materials. AgNPs showed bacteriostatic and bactericidal activity against Staphylococcus aureus (ATCC 25923), Staphylococcus aureus (ATCC 33591), Escherichia coli (ATCC 25922), Salmonella enterica subsp. enterica serovar Choleraesuis (ATCC 10708), Listeria monocytogenes, Escherichia coli, Salmonella spp.,andPseudomonas aeruginosa,and interfered with biofilm formation more than with consolidated biofilms. A 1hour period was sufficient to reduce the bacterial cells, whereas a Minimum Duration for Killing (MDK) of 99% was reached after approximately 30 min. AgNPs were effective against bacteria attached to stainless steel and polyethylene, but ineffective on tile surfaces. Thus, owing to the growing microbial resistance and the need to develop new products based on the concepts of green chemistry, these AgNPs are presented as a new possibility for cleaning processes in the food industry.

Preparation and antimicrobial activity of silver nanoparticles impregnated with halloysite clay

In the present work, nanotubular halloysite clay was ultrasonically treated and impregnated with silver nanoparticles. The citrate surface-stabilized silver nanoparticles dispersion was prepared using an effective method of electrochemical synthesis. The elemental and phase composition, and the structure of the obtained AgNPs-impregnated and pristine halloysite were investigated by various methods such as X-ray fluorescence (XRF), powder X-ray diffraction analyses and Fourier-transform infrared spectroscopy. The Ag-loaded halloysite sample with 0.454 wt.% silver content was confirmed by the XRF analysis. The antimicrobial activity of the pristine and the AgNPs-impregnated halloysite clay was tested against Escherichia coli ATCC 25922 (Gram-negative) and Bacillus subtilis ATCC 6633 (Gram-positive) strains. The results show that pure halloysite does not exhibit antibacterial activity. The AgNPs-impregnated halloysite demonstrates antibacterial activity against Escherichia coli and Bacillus subtilis with only bacteriostatic effect.

Synthesis of Biodegradable and Antimicrobial Nanocomposite Films Reinforced for Coffee and Agri-Food Product Preservation.

The antimicrobial activity of silver nanoparticles is widely known. However, their application to biodegradable polymeric materials is still limited. In this work, we report a strategy involving the green synthesis of nanocomposite films based on a natural biodegradable matrix. Nanometer-sized silver nanoparticles (C-AgNPs) were synthesized with the aid of ultrasound waves between the silver nitrate solution and the nanocurcumin solution. The green synthesized C-AgNPs were found to have particle sizes in the range of 5-25 nm and demonstrated good antimicrobial activity against Clostridium perfringens, Staphylococcus aureus, Bacillus subtilis, Macrophoma theicola, and Aspergillus flavus. Owing to their physical-chemical and mechanical properties and the excellent antimicrobial activities, the obtained AgNPs were used together with chitosan, cassava starch, and poly(vinyl alcohol) (PVA) to make nanocomposite films, which are suitable for the packaging requirements of various key agricultural and food products such as coffee beans, bamboo straws, and fruits. The nanocomposite films lost up to 85% of their weight after being buried in the soil for 120 days. This indicates that the films made with natural biodegradable materials are environmentally friendly.

Antimicrobial protection of two controlled release silver nanoparticles on simulated silk cultural relic

HypothesisSilver nanoparticles coated with organic-inorganic hybrid silica or inorganic silica have antimicrobial ability, and the coating can also effectively improve the dispersion and stability of the particles. The slow release of silver ions (Ag+) can improve the antimicrobial activity of silver nanoparticles. The synthesized nanoparticles are light yellow, which does not affect the look and feel of the silk cultural relics and meets the requirements of the principle of minimum interference. ExperimentsTwo kinds of silver-based nanoparticles were synthesized: silver core-shell nanoparticle (Ag@mSiO2) and silver yolk-shell nanoparticle (Ag@YSiO2). The morphology, surface properties and Ag+ release efficiency of two nanoparticles were characterized. The antimicrobial effects of two nanoparticles on Aspergillus niger (A. niger) and Penicillium citrinum (P. citrinum) were compared. FindingsBoth of Ag@mSiO2 and Ag@YSiO2 had uniform size and good stability. Two nanoparticles had pore structure and silver nanocore, which provided the basis for the dissolution and exchange of Ag+. Because more silver ions were released, Ag@mSiO2 had higher antimicrobial activity than Ag@YSiO2 for A. niger and P. citrinum. For various silk samples, Ag@mSiO2 exhibited excellent antimicrobial properties. Meanwhile, there was little change in the color and tearing strength of Ag@mSiO2 coated silk.

Antimicrobial Activity of Silver Nanoparticles on Pathogenic Bacteria

Nosocomial infection is acquired contamination of hospitals and health care units caused by multidrug resistant bacteria. Currently, bacterial resistance to antimicrobial medication represents a complicated public health problem. Recent studies on the antimicrobial activity of silver nanoparticles (AgNPs) attracted researchers worldwide to focus on the safe synthesis of AgNPs as antimicrobial agents against multidrug resistant bacteria. The antimicrobial efficacy of AgNPs on pathogenic bacteria isolated from clinical cases of acquired hospital infection was targeted in this project. Fifty specimens of stool were collected through private laboratories in Baghdad from patients who suffered diarrheal symptoms. Bacterial isolation, identification, and characterization via culturing on MacConkey agar, Salmonella shigella agar, and IMVic analysis were done besides, using polymerase chain reaction (PCR) through amplifying inf B gene for molecular characterization. The obtained isolates were tested for antimicrobial sensitivity via disk diffusion assay against; Gentamycin, Amoxicillin, Tetracycline, Ceftriaxone and a suspension of silver nanoparticles (1mM AgNo3 reduced by 1% tri-sodium citrate). Results of isolation and IMVic showed the obtained isolates were Klebsiella spp., Enterobacter spp., Citrobacter spp., and PCR assay confirmed their pathogenicity. Disc diffusion assay showed the sensitivity of the isolates (mm); Gentamycin (24.94 ± 0.1), Amoxicillin (2.11 ± 0.13), Tetracycline (12.15 ± 0.1), Ceftriaxone (12.35 ± 0.1). Whereas, all isolates are sensitive to AgNPs (24.12 ± 0.3). This result of the antimicrobial effect of AgNPs on nosocomial infection promises for developing AgNPs solution as a product used in the sterilization of furniture, floors and hospital water cycles

A Microfluidic Approach for Synthesis of Silver Nanoparticles as a Potential Antimicrobial Agent in Alginate-Hyaluronic Acid-Based Wound Dressings.

The recognized antimicrobial activity of silver nanoparticles is a well-studied property, especially when designing and developing biomaterials with medical applications. As biological activity is closely related to the physicochemical characteristics of a material, aspects such as particle morphology and dimension should be considered. Microfluidic systems in continuous flow represent a promising method to control the size, shape, and size distribution of synthesized nanoparticles. Moreover, using microfluidics widens the synthesis options by creating and controlling parameters that are otherwise difficult to maintain in conventional batch procedures. This study used a microfluidic platform with a cross-shape design as an innovative method for synthesizing silver nanoparticles and varied the precursor concentration and the purging speed as experimental parameters. The compositional and microstructural characterization of the obtained samples was carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and dynamic light scattering (DLS). Four formulations of alginate-based hydrogels with the addition of hyaluronic acid and silver nanoparticles were obtained to highlight the antimicrobial activity of silver nanoparticles and the efficiency of such a composite in wound treatment. The porous structure, swelling capacity, and biological properties were evaluated through physicochemical analysis (FT-IR and SEM) and through contact with prokaryotic and eukaryotic cells. The results of the physicochemical and biological investigations revealed desirable characteristics for performant wound dressings (i.e., biocompatibility, appropriate porous structure, swelling rate, and degradation rate, ability to inhibit biofilm formation, and cell growth stimulation capacity), and the obtained materials are thus recommended for treating chronic and infected wounds.

Comparative study of the antimicrobial activity of silver nanoparticles obtained from Tagetes erecta (Cempasúchil) by green synthesis

Nanomaterials’ application can provide solutions to technological and environmental challenges, in the areas of solar energy conversion, catalysis, medicine and water treatment. Silver nanoparticles (Ag-Np's) stand out for their potential and versatility, due to their optical, electrical, mechanical, and structural properties, their photoactivity promotes them as an antimicrobial agent (bactericide-fungicide). The effect caused by Ag ions in microorganisms is already known, however, the mechanism of action is still not entirely clear. In the present study, silver nanoparticles were synthesized using the Cempasúchil flower (Tagetes erecta) extract as a reducer by a simple and ecological route. Aqueous silver ions exposed to the flower extract were reduced, leading to silver nanoparticles’ biological synthesis. The silver nanoparticles were characterized by UVvisible spectroscopy, where it showed a maximum peak from 410 nm to 425 nm. The silver nanoparticles’ synergistic antimicrobial potential was evaluated with the following microorganisms: Escherichia coli and Aspergillus niger, through the Kirby-Bauer method, where inhibition halos of 2 to 2.2 cm were obtained, showing the antimicrobial activity of the Ag-Np' s.

Characterization and study of antimicrobial activity of silver nanoparticles synthesized from Escherichia coli

Characterization and study of antimicrobial activity of silver nanoparticles synthesized from Escherichia coli

Green Synthesis of Silver Nanoparticles Using Safran (Crocus sativus) Purple flower and Their Antimicrobial activity

Objective: In this research, CS-AgNPs were created, described, and their antibacterial activity assessed utilizing an inexpensive, simple, and ecologically friendly extraction approach from the waste saffron flower's purple flower parts. Methods: : In this study, silver nanoparticles (AgNPs) were synthesized quickly, cheaply, and environmentally friendly utilizing purple flower extract from saffron (Crocus sativus (CS)). For the explanation of the structure of silver nanoparticles synthesized with saffron flower extract (CS-AgNPs); UV-visible (UV-vis.) Spectrophotometer, Fourier Scanning Electron Microscope (FE-SEM), Scanning Electron Microscope (SEM), Electron Distributed X-rays (EDX), Fourier Transform Infrared Spectroscopy (FT-IR), X-Ray Characterized using Diffraction Diffractrometer (XRD), Transmission Electron Microscope (TEM), Zeta potential data. It was discovered that the UV-visible spectrum of the biologically produced silver nanoparticles generated at a maximal wavelength of 405.68 nm in the spectrum collected after 15 minutes. Furthermore, it was noted that the synthesized nanoparticles' UV spectrum, taken a month later, revealed the same wavelength and that the resulting nanoparticles were stable. CS-AgNPs' antimicrobial effects against gram-positive, gram-negative, and fungal pathogens were assessed employing the minimum inhibition concentration approach. Results: The generated CS-AgNPs were found to be active against both fungi and bacteria as a consequence. Conclusion: It turned out that even at very low concentrations, the antimicrobial activity of silver nanoparticles enhanced with decreasing size and had high antibacterial and anticandidal implementation.

Antimicrobial Activity of Silver Nanoparticles Encapsulated in Poly-N-Isopropylacrylamide-Based Polymeric Nanoparticles [Retraction

[This retracts the article DOI: 10.2147/IJN.S153485.].

Antimicrobial Activity of Silver Nanoparticles Synthesized by the Green Method Using Rhus coriaria L. Extract Against Oral Pathogenic Microorganisms.

Background: Oral health is part of general health. Dental caries is the most common chronic disease worldwide. Considering the significance of plaque control, complications of chemical agents, and the optimal antimicrobial efficacy of nanoparticles, this study aimed to assess the antimicrobial activity of silver nanoparticles (AgNPs) synthesized by the green method using Rhus coriaria L. extract against oral pathogenic microorganisms. Methods: In this in vitro experimental study, Rhus coriaria fruit was dried at room temperature. It was then ground, and its aqueous extract was obtained by the maceration technique. The effects of AgNPs synthesized by the green method in different concentrations were evaluated against Enterococcus faecalis (E. faecalis), Streptococcus mutans (S. mutans), Streptococcus sobrinus (S. sobrinus), Lactobacillus acidophilus (L. acidophilus), and Streptococcus salivarius (S. salivarius) using the well-plate technique. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values were also calculated. Data were analyzed by the Wilcoxon test, Kruskal-Wallis test, and Mann-Whitney test. Results: The MIC values were 1024 µg/mL for S. mutans and E. faecalis, and 512 µg/mL for S. sobrinus, S. salivarius, and L. acidophilus. The resistance of S. mutans and E. faecalis was higher than that of S. sobrinus, S. salivarius and L. acidophilus. According to the growth inhibition zones and MBC test results, S. salivarius had the highest resistance to AgNPs followed by L. acidophilus, S. sobrinus, S. mutans, and E. faecalis. Conclusion: AgNPs synthesized by the green method using Rhus coriaria extract was effective against oral pathogenic microorganisms. Thus, they may be used in the formulation of mouthwash and toothpaste.

Synergistic Antimicrobial Activity of Silver Nanoparticles with an Emergent Class of Azoimidazoles

The combination of two or more agents capable of acting in synergy has been reported as a valuable tool to fight against pathogens. Silver nanoparticles (AgNPs) present a strong antimicrobial action, although their cytotoxicity for healthy cells at active concentrations is a major concern. Azoimidazole moieties exhibit interesting bioactivities, including antimicrobial activity. In this work, a class of recently described azoimidazoles with strong antifungal activity was conjugated with citrate or polyvinylpyrrolidone-stabilized AgNPs. Proton nuclear magnetic resonance was used to confirm the purity of the compounds before further tests and atomic absorption spectroscopy to verify the concentration of silver in the prepared dispersions. Other analytical techniques elucidate the morphology and stability of AgNPs and corresponding conjugates, namely ultraviolet-visible spectrophotometry, scanning transmission electron microscopy and dynamic light scattering analysis. The synergistic antimicrobial activity of the conjugates was assessed through a checkerboard assay against yeasts (Candida albicans and Candida krusei) and bacteria (Staphylococcus aureus and Escherichia coli). The conjugates showed improved antimicrobial activity against all microorganisms, in particular towards bacteria, with concentrations below their individual minimal inhibitory concentration (MIC). Furthermore, some combinations were found to be non-cytotoxic towards human HaCaT cells.

Biogenic Synthesis, Characterization and Antimicrobial Activity of Silver Nanoparticles Mediated by Oil Extracted from Waste Seeds of Citrus Sinensis

Nanoparticles have gained significant importance due to their small size and effective surface area. Green synthesis of nanoparticles has become a significant tool in material synthesis due to its eco-friendly, economical and less time-consuming aspects. Sweet lime (Citrus sinensis) peel has been used for extract preparation and synthesis of AgNPs. Such nanoparticles have been shown to have excellent anti-microbial and detoxification properties. Though a large number of studies have shown synthesis of AgNP from peel and other parts of C. sinensis, there are no reports of AgNP synthesis from oil extracted from seeds. In this study, oil was extracted from C. sinensis seeds by solvent extraction. The extracted oil was used for the synthesis of AgNPs by bottom-up path approach. The synthesized AgNPs were found to be spherical in shape with size ranging from 30[Formula: see text]nm and above. SEM and TEM showed that they are uniformly dispersed particles with no aggregation. Different concentrations of AgNO3 (1[Formula: see text]mM, 3[Formula: see text]mM and 10[Formula: see text]mM) showed distinct UV spectra with UV showing sharp peaks for 10[Formula: see text]mM. XRD characterization showed distinct peaks for AgNP when compared to oil extracted. The synthesized AgNPs in this study showed distinct antibacterial activity against E. coli and S. aureus. The AgNPs showed antifungal activity against Pencillium and Rhizopus. Thus, the synthesized AgNPs could be effective antimicrobial agents that could have potential application in food storage and water detoxification.