Green Synthesis of Silver Nanoparticles Using Neem Leaf (Azadirachta indica) Extract
Silver nanoparticles were successfully synthesized using crude neem leaf (Azadirachta indica) extract at room temperature. The formation and crystallinity of synthesized silver nanoparticles was confirmed by X-Ray diffraction (XRD) pattern. The average size of these silver nanoparticles is about 20–50 nm as observed by Transmission electron microscopy (TEM) images. Optical absorption measurements were performed to determine band-edge energy gap of these silver nanoparticles. Photoluminescence (PL) studies were performed to emphasize its emission properties. The synthesized silver nanoparticles could have major applications in the area of nanoscale optoelectronics devices and biomedical engineering. Our synthesis method has advantage over other conventional chemical routes because it is cost effective & environmental compatibility.
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- "As the different extract of onion, garlic, papaya and apple were added to aqueous silver nitrate solution, the colour of the solution changed from faint light to yellowish brown to reddish brown and finally to colloidal brown indicating AgNP formation. Similar changes in colour have also been observed in previous studies (Shukla et al., 2010) and hence confirmed the completion of reaction between all extracts and silver nitrate solution. The UV-VIS spectra of CH-AgNPs were observed plasmon peak at 398 nm with absorption of 0.06 are shown in Figure 2. A surface plasmon peak of Bio-AgNPs were observed at 399 nm with absorption of 1.11, 400 nm with absorption of 0.23, 420 nm with absorption of 2.66 and 410 nm with absorption of 0.90 indicates the presence of nanoparticles in garlic, onion, papaya and apple respectively are shown in Figure 3& 4. "
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ABSTRACT: Biomolecule present in onion, garlic, apple and papaya extracts can be used to reduce metal ions to nanoparticles in a single step green synthesis process. This biogenic reduction of metal ions to base metal is quite rapid, rapidly conducted at room temperature and pressure, and easily scaled up. Chemically synthesized silver nanoparticles (CH-AgNPs) and biologically synthesized silver nanoparticles (Bio-AgNPs) was proved under UV–vis absorption spectroscopy and observed plasmon peak maximum at 399 nm, 400 nm, 420 nm and 410 nm for Bio-AgNPs synthesized from garlic, onion, papaya and apple respectively and 398 nm for CH-AgNPs. The findings of Fourier Transformation Infrared Spectroscopy (FTIR) indicate that it is not just the size and shape of proteins, but the conformation of protein molecules that plays an important role for the formation of nanoparticles. The Scanning Electron Microscope (SEM) micrograph observed the size in the range 50-100-nm with spherical shape highly dense silver nanoparticles and Transmission Electron Microscope (TEM) results observed the particles spherical in shape and uniformly distributed without significant agglomeration. We analyzed only Bio-AgNPs from apple and papaya for FTIR, SEM and TEM. Toxicity of both CH-AgNPs and Bio-AgNPs were tested by using toxtrak test and calculate the toxic effect value in form of percentage inhibition (PI) against B. subtilis and E. coli. The PI of CH-AgNPs was much greater than the Bio-AgNPs synthesized from apple onion, garlic and followed by papaya. The observed PI value indicated that the gut microbial community probiotic B. subtilis and E. coli was killed in higher percentage of CH-AgNPs as compare to Bio-AgNPs synthesized from apple, onion garlic and papaya. Hence, Bio-AgNPs is the most suitable metallic coating material coat to drugs instead of CH-AgNPs in pharmaceutical industries.
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ABSTRACT: Present "green" synthesis is an efficient, easy-going, fast, renewable, inexpensive, eco-friendly and non-toxic approach for nanosilver formation, which offers numerous benefits over physiochemical approaches. The X-ray diffraction (XRD) pattern suggests the formation and crystallinity of nanosilver. The average particle size of silver nanoparticles was 8.25±1.37 nm as confirmed by transmission electron microscopy (TEM). The UV-vis absorption spectrum shows a characteristic absorption peak of silver nanoparticles at 410 nm. FTIR confirms Azadirachtin as reducing and stabilizing agent for nanosilver formation. In addition, the nanosilver modified electrode (Ag/GC) exhibited an excellent electro-catalytic activity toward the reduction of hydrogen peroxide (H(2)O(2)). The produced nanosilver is stable and comparable in size. These silver nanoparticles show potential applications in the field of sensors, catalysis, fuel cells and nanodevices.
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ABSTRACT: Green synthesis technology is one of the rapid, reliable and best routes for the synthesis of silver nanoparticles (AgNPs). There are bioactive compounds with enormous potential in Azadirachta indica (Neem). The extraordinary mosquitoes warrant nanotechnology to integrate with novel molecules. This will be sustainable technology for future. Here, we synthesized AgNPs using aqueous extracts of leaves and bark of Az. indica (Neem). We tested AgNPs as larvicides, pupicides and adulticides against the malaria vector Anopheles stephensi and filariasis vector Culex quinquefasciatus. The results were obtained using UV-visible spectrophotometer and the images were recorded with a transmission electron microscope (TEM). The efficacy tests were then performed at different concentrations varying many hours by probit analysis. The synthesized AgNPs were spherical in shape and with varied sizes (10.47-nm leaf and 19.22-nm bark). The larvae, pupae and adults of filariasis vector C. quinquefasciatus were found to be more susceptible to our AgNPs than the malaria vector An. stephensi. The first and the second instar larvae of C. quinquefasciatus show a mortality rate of 100 % after 30 min of exposure. The results against the pupa of C. quinquefasciatus were recorded as LC50 4 ppm, LC90 11 ppm and LC99 13 ppm after 3 h of exposure. In the case of adult mosquitoes, LC50 1.06 μL/cm(2), LC90 2.13 μL/cm(2) and LC99 2.4 μL/cm(2) were obtained after 4 h of exposure. These results suggest that our AgNPs are environment-friendly for controlling malarial and filarial vectors.
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