Antimicrobial Activity Of AgNPs Research Articles

Biological nanosilver particles for the protection of archaeological stones against microbial colonization

The inhabitation of microorganisms and their subsequent interaction with mineral matrix of the stone substrate under varied environmental conditions encourages deterioration of stones leading to the loss of strength, durability and aesthetic. This study highlighted the synthesis of nanosilver particles (AgNPs) using the biogenic volatiles of the bacterial strain Nesterenkonia halobia. The antimicrobial activities of AgNPs were evaluated against the gram positive bacterial strain Streptomyces parvullus and fungal strain Apergillus niger. Furthermore, the silver particles were mixed with two types of consolidation polymers and were used to coat the external surfaces of sandstone and limestone blocks. The stones treated with silicon polymer loaded with AgNPs showed an elevated antimicrobial potentiality against A. niger and S. parvullus. Scan electron microscope (SEM) and electron dispersive X-ray spectroscopy (EDX) analysis of treated stones demonstrated the existence of nano-composite structures containing the elemental silver. Polymers functionalized with AgNPs can be used not only as potent biocides but also for the consolidation of the historic monuments and artifacts.

Green Synthesis and Characterization of Silver Nanoparticles for Antimicrobial Activity Against Burn Wounds Contaminating Bacteria

Silver nanoparticles ( AgNPs ) were prepared from the plant extract of N. arbor-tristis under atmospheric conditions through green synthesis and characterized by various physicochemical techniques like UV-Visible spectroscopy, IR Spectra, energy dispersive X-ray spectrometry (EDS), X-ray diffraction and transmission electron microscopy (TEM) and the results confirmed the synthesis of homogeneous and stable AgNPs by the plant extracts. The antimicrobial activity of AgNPs was investigated against most common bacteria found in burn wound Staphylococcus epidermidis and Pseudomonas aeruginosa. In these tests, Mueller Hinton agar plates were used with AgNPs of various concentrations, supplemented in liquid systems. P. aeruginosa was inhibited at the low concentration of AgNPs , whereas the growth-inhibitory effect on S. epidermidis was mild. These results suggest that AgNPs can be used as effective growth inhibitors of various microorganisms, making them applicable to diverse medical devices and antimicrobial control systems.

Síntese, caracterização e aplicação de nanopartículas de prata como agentes antimicrobianos

The synthesis of silver nanoparticles (Ag NPs) has attracted the interest of many researchers in recent years, both from scientific and technological point of view. These NPs present unique physical, chemical and biological properties when compared to metal at a macroscopic scale, and have been used in applications such as catalysis, optoelectronic devices and medical area. In this context, the aim of this work was to synthesize and characterize Ag NPs and evaluate its antimicrobial efficiency against Gram-positive and Gram-negative bacteria. Ag NPs were initially prepared by chemical reduction of silver ions with sodium borohydride in the presence of sodium citrate tribasic dihydrate. Then, they were characterized by molecular absorption spectroscopy in the ultraviolet and visible (UV-Vis) region and transmission electron microscopy (TEM). The evaluation of antimicrobial activity of Ag NPs was performed with basis on the qualitative antibiogram method against Escherichia coli and Staphylococcus aureus . In general, the UV-Vis spectra of colloidal solutions of Ag NPs (18 ppm and 1000 ppm, respectively) were very similar to each other, indicating the presence of a single band centered at approximately 400 nm, which is indicative of NPs with spherical shape. This result was corroborated by TEM analysis which showed Ag NPs with average sizes of 7.3 ± 4.3 nm (colloidal solution of 18 ppm) and 15.2 ± 7.4 nm (colloidal solution 1000 ppm). The antibiograms, in turn, revealed that only the colloidal solution of 1000 ppm showed antimicrobial activity against the two bacterial strains tested. Key words: Nanotecnology, silver nanoparticles, antimicrobial agents.

Biogenic nano-scale silver particles by Tephrosia purpurea leaf extract and their inborn antimicrobial activity

In this paper we report the green synthesis of silver nanoparticles (Ag NPs) using Tephrosia purpurea leaf extract. The biomolecules present in the leaf extract are responsible for the formation of Ag NPs and they found to play dual role of both reducing as well as capping agents. The high crystallinity of Ag NPs is evident from bright circular spot array of SAED pattern and diffraction peaks in XRD profile. The synthesized Ag NPs are found to be nearly spherical ones with size approximately ∼20nm. FTIR spectrum evidences the presence of different functional groups of biomolecules participated in encapsulating Ag NPs and the possible mechanism of Ag NPs formation was also suggested. Appearance of yellow color and surface plasmon resonance (SPR) peak at 425nm confirms the Ag NPs formation. PL spectra showed decrement in luminescence intensity at higher excitation wavelengths. Antimicrobial activity of Ag NPs showed better inhibitory activity towards Pseudomonas spp. and Penicillium spp. compared to other test pathogens using standard Kirby–Bauer disc diffusion assay.

Anti-biofilm activity of silver nanoparticles against different microorganisms

Biofilms confer protection from adverse environmental conditions and can be reservoirs for pathogenic organisms and sources of disease outbreaks, especially in medical devices. The goal of this research was to evaluate the anti-biofilm activities of silver nanoparticles (AgNPs) against several microorganisms of clinical interest. The antimicrobial activity of AgNPs was tested within biofilms generated under static conditions and also under high fluid shears conditions using a bioreactor. A 4-log reduction in the number of colony-forming units of Pseudomonas aeruginosa was recorded under turbulent fluid conditions in the CDC reactor on exposure to 100 mg ml−1 of AgNPs. The antibacterial activity of AgNPs on various microbial strains grown on polycarbonate membranes is reported. In conclusion, AgNPs effectively prevent the formation of biofilms and kill bacteria in established biofilms, which suggests that AgNPs could be used for prevention and treatment of biofilm-related infections. Further research and development are necessary to translate this technology into therapeutic and preventive strategies.

Ecofriendly synthesis of silver nanoparticles from commercially available plant powders and their antibacterial properties

Use of various plant materials for the biosynthesis of nanoparticles is considered a green technology, as it does not involve any harmful chemicals. The present study reports that silver nanoparticles (Ag NPs) were synthesized from a silver nitrate solution by commercially available plant powders, such as Solanum tricobatum, Syzygium cumini, Centella asiatica and Citrus sinensis. Ag NPs were characterized by UV–vis spectrophotometer, X-Ray Diffractometer (XRD), Atomic Force Microscopy (AFM) and fourier transform infrared (FTIR) spectroscopy. The formation and stability of the reduced silver nanoparticles in the colloidal solution were monitored by UV–vis spectrophotometer analysis. The mean particle diameter of silver nanoparticles was calculated from the XRD pattern, according to the line width of the plane, and the refraction peak, using Scherrer’s equation. AFM showed the irregular shapes of Ag NPs, and the formation of silver nanoparticles was found to be 53, 41, 52 and 42 nm, corresponding to Syzygium cumini, Citrus sinensis, Solanum tricobatum and Centella asiatica, respectively. FTIR spectroscopy confirmed the presence of protein as the stabilizing agent surrounding the Ag NPs. Antimicrobial activity of the silver bio-nanoparticles was performed by a well diffusion method. The highest antimicrobial activity of Ag NPs synthesized by C. sinensis and C. asiatica was found against Pseudomonas aeruginosa (16 mm). The Ag NPs synthesized in this process were found to have efficient antimicrobial activity against pathogenic bacteria.

Interaction of Silver Nanoparticles and Chitin Powder with Different Sizes and Surface Structures: The Correlation with Antimicrobial Activities

Silver nanoparticles (Ag NPs) were 5.17 ± 1.9 nm in diameter, and four <5% deacetylated chitins (A, B, C, and D) differing in size of powder and surface structure properties were used in the study. Chitin/Ag NP composites were synthesized by mixing Ag NP suspensions with each chitin powder at room temperature for 30 min. The Ag NPs were homogenously dispersed and stably adsorbed onto the chitins A and B powders. The resulting chitin/Ag NP composites were brown; darker composites were obtained when larger amounts of Ag NPs were reacted with chitin. Approximately, 26 and 22 μg of Ag NPs maximally adsorbed to 1 mg of chitins A and B, respectively, whereas only 2.5 and 1.5 μg of Ag NPs maximally adsorbed to chitins C and D, respectively. As the bactericidal and antifungal activities of the chitin/Ag NP composites increased with increasing amounts of Ag NPs adsorbed to the chitin, the antimicrobial activity of chitins A and B/Ag NP composites was much higher than that of chitins C and D/Ag NP composites. These results suggest that the particle size and surface structure of the chitin powder critically influence both the adsorption and antimicrobial activity of Ag NPs.

Silver nanoparticles: Antibacterial activity against wound isolates &invitro cytotoxic activity on Human Caucasian colon adenocarcinoma

ObjectiveTo synthesize the silver nanoparticles (AgNPs) using the extracts of Hypnea sp. and to investigate the antibacterial activity against Eshcherichia coli, Staphylococcus aureus and invitro cytotoxic activity on HT-29. MethodsIn the present study, AgNPs were synthesized using the aqueous extract of marine macro-algae, and were characterized using UV-visible spectroscopy, Fourrier Transform Infra red (FT-IR) spectroscopy, X-ray diffraction (XRD) analysis and Transmission Electron Microscopy (TEM) analysis. Further these synthesized AgNPs were evaluated for their antibacterial activity with the clinical isolates from wound specimens. The isolates were characterized by different tests viz., microscopical observation, colony morphology, biochemical & sugar fermentation tests. The synthesized AgNPs were tested for its antibacterial activity against the isolates by agar well diffussion method. The AgNPs were assessesd for its cytotoxic activity on Human Caucasian colon adenocarcinoma (HT-29) cell lines. ResultsIn this study, it is clear that the synthesized AgNPs were spherical measuring 10–20nm and was found to be more bactericidal against Gram-negative bacteria (E. coli) than Gram-positive bacteria (Staphylococcus aureus) isolated from wound specimen. The invitro screening of the AgNPs showed potential cytotoxic activity against the colon cancer cell lines. ConclusionsProteins can bind to nanoparticles either through the electrostatic attraction of negatively charged carboxylate groups in Hypnea sp. and stabilization of the AgNPs by protein occurs. The antimicrobial activities of AgNPs are influenced by the dimensions of the particles the smaller the particles, the greater antimicrobial effect. The cytotoxic activity may be due to the presence of alkaloids present in the Hypnea sp.

Electrochemical Synthesis of Silver Nanoparticles and their Potential Use as Antimicrobial Agent: a Case Study on Escherichia Coli

Silver nanoparticles (AgNP) were synthesized by electrochemical method using high purity metallic silver in the presence of the surfactant Pluronic® f127. The synthesized nanoparticles were characterized using UV-Vis spectroscopy, Dynamic Light Scattering (DLS), X-Ray Dispersion Spectroscopy (XDS) and Scanning Electron Microscopy (SEM). The antimicrobial activity of AgNP was evaluated against Escherichia Coli. In presence of surfactant, the prepared nanoparticles led to a monomodal distribution with an average size less than 100 nm. The minimal inhibitory concentration (MIC) of the resulting suspension was evaluated using micro dilution method and the MIC results are satisfactory .

Synthesis of Plant-Mediated Silver Nanoparticles UsingDioscorea batatasRhizome Extract and Evaluation of Their Antimicrobial Activities

The eco-friendly synthesis of nanoparticles through various biological means helps to explore various plants for their ability to synthesize silver nanoparticles (AgNPs). Here we have synthesized AgNPs by using rhizome extract ofDioscorea batatasat as well as room temperature (). AgNPs were characterized under UV-vis spectrophotometer, SEM, FTIR, XRD, and EDX. The antimicrobial activity of AgNPs was evaluated on gram positive (B. substilisandS. aureus), gram negative (E. coli), and fungi (S. cerivisaeandC. albicans). At room temperature,S. cerivisaeandC. albicanswere found to be more susceptible to AgNPs than at .