Papers by Keyword: Silver Nanoparticle

Abstract: Silver Nanoparticles (Ag-NPs) have been known to have inhibitory and bactericidal effects. Resistance to antimicrobial agents by pathogenic bacteria has emerged in recent years and is a major health problem. The ability of some microorganisms such as bacteria and fungi to control the synthesis of metallic Nanoparticles should be employed in the search for new materials. The present work is the study of biosynthesis of silver Nanoparticles synthesized from different Penicillium spp. The Penicillium species were identified by employing microscopic methods and laboratory manuals. The Nanoparticles synthesis was done by extracellular and intracellular methods. The silver Nanoparticles formed were characterized by Uv-vis spectrophotometer followed by TEM analysis. The maximum absorbance 410nm confirmed the formation of silver Nanoparticles and TEM revealed the particle size in the range of 30-40nm, which after confirmation was checked for its antibacterial activity against selected microbial pathogens like Bacillus cereus, Proteus vulgaris, Staphylococcus aureus and Staphylococcus epidermidis. The Nanoparticles synthesized by Penicillium species showed a well anti microbial activity that was further compared with different antibiotics to check the Nanoparticles activity which can be substituted in place of high dose antibiotics.

Abstract: The proposed study was to synthesize silver nanoparticles by using filamentous fungus Penicillium fellutanum. From the ancient period, silver has been used against microorganisms due to its own antibacterial properties. The fungal culture of Penicillium fellutanum was isolated from the soil samples of Sathyabama University, Chennai, Tamil Nadu, India. The fungal isolates were inoculated in culture medium and incubated at room temperature for three days and the culture filtrate was separated and divided into two parts. One part of the culture filtrate was mixed with equal volume of 1mM silver nitrate [AgNO_3,(1 mM)] and agitated at room temperature in dark condition. And the second half was kept as such. In the other hand only 1mM silver nitrate was added into the equal volume of Milli Q water and one half was plain Milli Q water. All the four samples were tested against pathogens like Bacillus cereus, E. coli, Proteus vulgaris, Staphylococcus aureus, Staphylococcus epidermidis and the results were compared. Proteus vulgaris showed the highest zone where E coli showed the least zone of inhibition, in the culture filtrate added with silver nitrate. The cell filtrate on treatment with silver nitrate and prior incubation were observed for change in color and characterized by UV-Vis spectrophotometer which detected AgNPs in the solution. The maximum absorbance 410nm confirmed the formation of silver nanoparticles. Size and morphology of silver nanoparticle were investigated using Atomic Force microscopy (AFM). The silver Nanoparticles after confirmation were checked for its antibacterial activity against selected pathogenic bacteria. The biologically synthesized Nanoparticles from Penicillium fellutanum showed the good inhibitory effect against the selected pathogens, which would be the novel remedy substituent in the place of high dose antibiotics.

Abstract: The effects of silver nanoparticles on fluorescent properties of methyl orange were studied. When silver colloid was added into methyl orange solution, a decrease of intensity of the absorption peak and the position of peak blue-shifted were observed. The intensities of fluorescence caused by S₂-S₀ electronic transition and S₁-S₀ electronic transition were quenched and enhanced respectively, and the effect trend increases with the increasing of concentration of silver colloid. Same trends were observed in the methyl orange solution with different pH values. The largest and smallest fluorescence enhancement ratios were observed at pH 2.1 and 4.8, respectively. The effects of silver colloid on the fluorescent properties of the methyl orange solution were attributed to the local field enhancement and non-radiative energy transfer and the enhancement of conjugated effect.

Abstract: Silver nanoparticles were deposited on glass slides and surgical suture as antibacterial agent. The silver nanoparticles were prepared by chemical reduction with sodium borohydride and using a synthetic polyelectrolyte as capping agent. Poly (4-styrenesulfonic acid-co-maleic acid) sodium salt PSSMA was used to stabilize the silver nanoparticles and provide an anionic surface charge which then allowed the layer-by-layer deposition method with poly (dially dimethyl ammonium chloride) PDADMAC. Various concentration of capping agent were used to prepare the silver nanoparticles which were then deposited on glass slide and surgical suture. The layer-by-layer deposition of the nanoparticles was studied using UV-Vis spectroscopy by monitoring the intensity of the characteristic Plasmon band of the nanoparticles at 400nm. The leaching of the silver nanoparticles in buffered solutions of pH 3,7 and 9 was monitored by recording the decrease in absorbance of silver nanoparticles film as a function of time for each pH solutions and each capping concentrations. Finally, suture material coated with silver nanoparticles were tested for their antibacterial activity against Staphylococcus aureus and results showed that all coated sutures had more than 99% bacterial reduction. So these suture material could be applied to use in medical products for promoted wound healing and decreased bacterial colony leading to relieve inflammation of patient.

Abstract: In this work, a green route for synthesis of Ag nanoparticles is presensted. For the synthesis of Ag nanoparticles, tulasi leaf extract (Ocimum leaf) in combination with microwave irradiation was used which yielded stable spherical Ag nanoparticle in the range of 5-50 nm. Surface morphology of nanoparticle was analyzed by XRD and TEM. UV-Vis analysis was also carried out to characterize the synthesized nanoparticles. The main feature of the process is that it is carried out in a very short span of time in comparison to other conventional physical, chemical and biological methods. Microwave assisted synthesis suppresses the enzymatic action to keep the process easy, fast and eco-friendly.

Abstract: In this work, silver nanoparticles have been successfully prepared with a simple, cost-effective and reproducible aqueous room temperature green synthesis method. Honey was chosen as the eco-friendly reducing and stabilizing agent replacing most reported reducing agents such as hydrazine, sodium borohydride (NaBH₄) and dimethyl formamide (DMF) which are highly reactive chemicals but also pose a biological risk to the society and environment. The size and shape of silver nanoparticles were modulated by varying the honey concentration and pH of the aqueous solution that contain silver nitrate as the silver precursor, sodium hydroxide as the pH regulator and ethylene glycol as the solvent. The silver nanoparticles obtained are characterized by field-emission scanning electron microscope (FESEM), ultraviolet-visible spectra (UV-Vis) and Fourier transform infrared spectroscopy (FTIR). From SEM analysis, it was found that by increasing the concentration of honey, the size of silver nanoparticles produced decreased, from the range of 18.98 nm - 26.05 nm for 10 g of honey to 15.63 nm - 17.86 nm for 40 g of honey. Similarly, the particle size decreased as the pH of the aqueous solution increased. UV-Vis spectra revealed large anisotropic and polydispersed Ag nanoparticle were produced.

Abstract: This work reports a simple chemical reduction route for the preparation of uniformed Ag nanoparticles whereby a fine control over the sizes of the Ag nanoparticles was studied by varying the concentrations of the reducing agents used. In characterization, UV-Vis spectroscopy showed the changes in optical properties of the Ag nanoparticles with regards to their sizes, where as the XRD patterns of the synthesized Ag nanoparticles confirmed the distinct peaks approximately at 2θ = 38.1°, 44.3°, 64.4°, 77.4°, and 81.5 representing Bragg’s reflections from (111), (200), (220), (311), and (222) planes of the face centred cubic lattice phase. This route of synthesis is feasible to produce Ag nanoparticles with diameters in the range of 30-45 nm.

Abstract: The aim of the present study is to synthesize silver nanoparticles, using an aqueous floral extract of common Lotus, i.e Nelumbo nucifera. The synthesized nanoparticles were characterized using UV, TEM, EDX, AFM & XRD. The synthesized AgNPs were confirmed due to the colour change from colourless to reddish brown just after the addition of the aqueous floral extract of Nelumbo nucifera. The UV results of AgNPs showed the excitation of surface Plasmon resonance band at 427 nm. TEM results showed that the synthesized AgNPs were uniformed; monodispersed,spherical in shape and the particle size were found to be 77.81 ± 3.54 nm. EDX spectrum of AgNPs confirms strong signals from Ag (64%) and other elements such as C, O and Cl. The morphology of the synthesized AgNPs by AFM analysis resembled the TEM micrograph. The crystalline nature of the AgNPs was confirmed by XRD. The present study concludes that the aqueous floral extract of Nelumbo nucifera could be used as an effective reducing agent for the synthesis of AgNP. The green synthesis ofsilver nanoparticles is non-toxic and cost-effective and thus remains to be an alternative method to other physical and chemical reduction methods.

Abstract: We have synthesized silver nanoparticles using the leaf extract of Henna (Lawsonia inermis). The synthesized silver nanoparticles were characterized using UV – visible spectroscopy, Atomic Force Microscopy and FTIR. Effect of leaf extract concentration, pH and reaction temperature on the formation of silver nanoparticles has been analysed by studying the variations in absorbance and wavelength of SPR of silver nanoparticles. The silver nanoparticle increases photoabsorption due to Localized Surface Plasmon Resonance. In this current study, we have fabricated Photo Enhanced Dye Sensitized Solar Cell (PE – DSSC) using the Henna dye reduced silver nanoparticles as sensitizer to improve photocurrent. We have obtained photocurrent output of Henna reduced silver nanoparticle dye sensitized solar cell.

Abstract: Silver nanoparticles are known to have antimicrobial activity. The green synthesis method of nanoparticle synthesis is one of the most cost effective and eco friendly method. The present study is based on the synthesis of silver nanoparticles by the self reduction of silver nitrate by the leaf extracts of Vitex negundo which is one of the novel methods used in developing nanoparticles. The characterization of the particle was done by UV-Vis spectrophotometer, Fourier Transform Infra Red Spectroscopy, X-ray Diffraction analysis and the size of the synthesized nanoparticle was analyzed in the Scanning Electron Microscopy. The size of the particle was found to be 56 nm. The obtained silver nanoparticles showed anti-microbial activity against E.coli and Klebsiella pneumonia.