Synthesis of silver nanoparticles using haloarchaeal isolate Halococcus salifodinae BK3

Numerous bacteria, fungi, yeasts and viruses have been exploited for biosynthesis of highly structured metal sulfide and metallic nanoparticles. Haloarchaea (salt-loving archaea) of the third domain of life Archaea, on the other hand have not yet been explored for nanoparticle synthesis. In this study, we report the intracellular synthesis of stable, mostly spherical silver nanoparticles (AgNPs) by the haloarchaeal isolate Halococcus salifodinae BK₃. The culture on adaptation to silver nitrate exhibited growth kinetics similar to that of the control. NADH-dependent nitrate reductase was involved in silver tolerance, reduction, synthesis of AgNPs, and exhibited metal-dependent increase in enzyme activity. The AgNPs preparation was characterized using UV–visible spectroscopy, XRD, TEM and EDAX. The XRD analysis of the nanoparticles showed the characteristic Bragg peaks of face-centered cubic silver with crystallite domain size of 22 and 12 nm for AgNPs synthesized in NTYE and halophilic nitrate broth (HNB), respectively. The average particle size obtained from TEM analysis was 50.3 and 12 nm for AgNPs synthesized in NTYE and HNB, respectively. This is the first report on the synthesis of silver nanoparticles by haloarchaea.     

Green synthesis of silver nanoparticles using Andean blackberry fruit extract

Green synthesis of nanoparticles using various plant materials opens a new scope for the phytochemist and discourages the use of toxic chemicals. In this article, we report an eco-friendly and low-cost method for the synthesis of silver nanoparticles (AgNPs) using Andean blackberry fruit extracts as both a reducing and capping agent. The green synthesized AgNPs were characterized by various analytical instruments like UV–visible, transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The formation of AgNPs was analyzed by UV–vis spectroscopy at λ_max = 435 nm. TEM analysis of AgNPs showed the formation of a crystalline, spherical shape and 12–50 nm size, whereas XRD peaks at 38.04°, 44.06°, 64.34° and 77.17° confirmed the crystalline nature of AgNPs. FTIR analysis was done to identify the functional groups responsible for the synthesis of the AgNPs. Furthermore, it was found that the AgNPs showed good antioxidant efficacy (>78%, 0.1 mM) against 1,1-diphenyl-2-picrylhydrazyl. The process of synthesis is environmentally compatible and the synthesized AgNPs could be a promising candidate for many biomedical applications.     

Streptomyces sp. LK3 mediated synthesis of silver nanoparticles and its biomedical application

In the present study, the marine actinobacteria mediated biosynthesis of silver nanoparticles (AgNps) was achieved using Streptomyces sp LK3. The synthesized AgNps showed the characteristic absorption spectra in UV–vis at 420 nm, which confirmed the presence of nanoparticles. XRD analysis showed intense peaks at 2θ values of 27.51°, 31.87°, 45.57°, 56.56°, 66.26°, and 75.25° corresponding to (210), (113), (124), (240), (226), and (300) Bragg’s reflection based on the fcc structure of AgNps. The FTIR spectra exhibited prominent peaks at 3,417 cm^?1 (OH stretching due to alcoholic group) and 1,578 cm^?1 (C=C ring stretching). TEM micrograph showed that the synthesized AgNps were spherical in shape with an average size of 5 nm. Surface morphology and topographical structure of the synthesized AgNps were dignified by AFM. The synthesized AgNps showed significant acaricidal activity against Rhipicephalus microplus and Haemaphysalis bispinosa with LC₅₀ values of 16.10 and 16.45 mg/L, respectively. Our results clearly indicate that AgNps could provide a safer alternative to conventional acaricidal agents in the form of a topical antiparasitic formulation. The present study aimed to develop a novel, cost-effective, eco-friendly actinobacteria mediated synthesis of AgNps and its antiparasitic activity.     

Biofabrication of platinum nanoparticles using Fumariae herba extract and their catalytic properties

Due to the increasing popularity of using plant extract in the synthesis of nanoparticles, this study presented the synthesis of platinum nanoparticles using Fumariae herba extract. The formation of platinum nanoparticles was confirmed by UV–visible spectroscopy (UV–Vis), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) with EDS profile. Transmission electron micrograph presented the hexagonal and pentagonal shape of the synthesized nanoparticles sized about 30 nm. Moreover, platinum nanoparticles presented good catalytic properties in the reduction of methylene blue and crystal violet.     

Biogenic synthesis of floral-shaped gold nanoparticles using a novel strain,Talaromyces flavus

A biogenic route was adopted towards the synthesis of gold nanoparticles using the extract of a novel strain, Talaromyces flavus. Reduction of chloroauric acid by the fungal extract resulted in the production of gold nanoparticle, which was further confirmed by the concordant results obtained from UV–visible spectroscopy, energy dispersive spectroscopy (EDS), and dynamic light scattering (DLS) analysis. Morphology and the crystal nature of the synthesized nanoparticles were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD) and selected area electron diffraction (SAED). A direct correlation was observed between nanoparticle formation and the concentration of reducing agent present in the fungal extract. The time-dependent kinetic study revealed that the bioreduction process follows an autocatalytic reaction. Crystalline, irregular, and mostly flower-shaped gold nanoparticles with a mean hydrodynamic radius of 38.54?±?10.34 nm were obtained. pH played a significant role on production of mono-dispersed nanoparticle. FTIR analysis partially deciphered the involvement of –NH₂, ?SH, and –CO groups as the probable molecules in the bio-reduction and stabilization process. Compared to the conventional methods, a time-resolved, green, and economically viable method for floral-shaped nanoparticle synthesis was developed.     

Luminescence study of monodispersed ZnS nanoparticles

Monodispersed ZnS nanoparticles have been successfully synthesized by a chemical precipitation method in an air atmosphere using polyvinylpyrrolidone (PVP) and sodium hexametaphosphate (SHMP) as surfactants. The synthesized nanoparticles were characterized by X‐ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectrometer (FT‐IR), UV–Vis optical absorption and photoluminescence (PL) spectra. Prepared surfactants capped ZnS nanoparticles are highly homogeneous and well dispersed. Optical absorption spectra showed a strong blue shift from the uncapped particles due to the quantum confinement effect. The capped ZnS emission intensity is enhanced than more the uncapped particles. The size of the synthesized particles is around 4–6.5 nm range. Copyright © 2012 John Wiley & Sons, Ltd.     

<Emphasis Type="Italic">Caulerpa racemosa</Emphasis>: a marine green alga for eco-friendly synthesis of silver nanoparticles and its catalytic degradation of methylene blue

In this study, a simple and green method has been demonstrated for the synthesis of highly stable silver nanoparticles (AgNPs) using aqueous extract of Caulerpa racemosa (C. racemosa) as a reducing and capping agent. The formation and stability of AgNPs were studied using visual observation and UV–Visible (UV–Vis) spectroscopy. The stable AgNPs were further characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and high resolution transmission electron microscopy (HR-TEM) with energy dispersive spectroscopic (EDS) methods. The biosynthesized AgNPs showed a sharp surface plasmon resonance peak at 441 nm in the visible region and they have extended stability which has been confirmed by the UV–Vis spectroscopic results. XRD result revealed the crystalline nature of synthesized AgNPs and they are mainly oriented in (111) plane. FT-IR studies proved that the phytoconstituents of C. racemosa protect the AgNPs from aggregation and also which are responsible for the high stability. The size of synthesized AgNPs was approximately 25 nm with distorted spherical shape, identified from the HR-TEM images. The synthesized AgNPs showed excellent catalytic activity towards degradation of methylene blue.     

Green synthesis of silver nanoparticles by Rivina humilis leaf extract to tackle growth of Brucella species and other perilous pathogens

Novel approaches are obligatory to treat chronic intracellular bacterial infectious diseases like Brucellosis specifically, are very complicated to deal with. The aim of the study to take upon nanotechnology approach to exploit the efficacy of the synthesized nanoparticles, to overcome barriers for treatment of Brucella species and other pathogens. Present study used Rivina humilis extract as reductant of silver ions for synthesis of silver nanoparticles for the first time. Rh-AgNP’s was characterized by UV–visible spectroscopy, DLS, FT-IR, SEM, EDS, TEM and XRD. Radical scavenging, antibrucellosis, bactericidal activity was evaluated. Clinical application was assessed by Rate of haemolysis, fibrinolytic and Hemagglutination activity. UV–visible spectrum of synthesized Rh-AgNP’s showed maximum peak at 440 nm indicating the formation of nanoparticles. TEM showed that the average particle size of nanoparticles 51 nm with spherical shape, DLS depicted monodisperse state in water; EDS confirmed the presence of silver metal. Rh-AgNP’s exhibited potential antibrucellosis activity against B. abortus, B. melitensis and B. suis effective inhibition at 800 μg/mL. The bio-compatibility of Rh-AgNP’s was established by rate of haemolysis, hemagglutination and fibrinolytic activity. For the first time it has been proved that Rh-AgNP’s have efficacy as antimicrobial agent with potential application in the biological domain.     

Extracellular synthesis of gold bionanoparticles by <Emphasis Type="Italic">Nocardiopsis</Emphasis> sp. and evaluation of its antimicrobial,antioxidant and cytotoxic activities

Advancement of biological process for the synthesis of bionanoparticles is evolving into a key area of research in nanotechnology. The present study deals with the biosynthesis, characterization of gold bionanoparticles by Nocardiopsis sp. MBRC-48 and evaluation of their antimicrobial, antioxidant and cytotoxic activities. The gold bionanoparticles obtained were characterized by UV–visible spectroscopy, X-ray diffraction analysis, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, energy dispersive X-ray analysis and transmission electron microscopy (TEM). The synthesized gold bionanoparticles were spherical in shape with an average of 11.57 ± 1.24 nm as determined by TEM and dynamic light scattering (DLS) particle size analyzer, respectively. The biosynthesized gold nanoparticles exhibited good antimicrobial activity against pathogenic microorganisms. It showed strong antioxidant activity as well as cytotoxicity against HeLa cervical cancer cell line. The present study demonstrated the potential use of the marine actinobacterial strain of Nocardiopsis sp. MBRC-48 as an important source for gold nanoparticles with improved biomedical applications including antimicrobial, antioxidant as well as cytotoxic agent.     

Biosynthesis of silver nanoparticles by using of the marine brown alga Padina pavonia and their characterization

Silver nanoparticles (AgNPs) are gaining considerable importance due to their attractive physicochemical properties for many applications. In the present study, (Ag NPs) were synthesized by the reduction of aqueous solutions of silver nitrate (AgNO₃) with powder and solvent extracts of Padina pavonia (brown algae). The obtained nanoparticles exhibited high stability, rapid formation of the biogenic process (2 min -3 h), small size (49.58–86.37 nm) (the diameter of formed nanoparticles was measured by TEM and DLS) and variable shapes (spherical, triangular, rectangle, polyhedral and hexagonal). Preliminary characterization of nanoparticles was monitored by using UV–visible spectroscopy (UV–vis), Transmission Electron Microscopy (TEM), Dynamic Light Scattering (DLS) and finally by Fourier Transform Infrared spectroscopy (FTIR). The ratios of converted Ag NPs were recorded as 88.5; 86.2 and 90.5% in case of P. pavonia powder. extract and chloroform extract, respectively.     

Evaluation of plant-mediated Silver nanoparticles synthesis and its application in postharvest Physiology of cut Flowers

Today the use of silver nanoparticles is becoming increasingly widespread due to their wide applications as antimicrobial agent. Green synthesis of silver nanoparticles (SNPs) using the petal extract of saffron (Crocus sativus) as a reducing agent from 5 mM AgNO₃ has been investigated in this work. Diverse petal extracts quantities and reaction times were used for the synthesis of SNPs. The resulting SNPs were characterized by means of UV–Vis, XRD and FTIR techniques. SNPs were synthesized rapidly within 30 min of incubation period and synthesized SNPs showed an absorption peak at 380-400 nm in the UV-Vis spectrum. XRD spectrum confirmed the formation of metallic silver, too. Green synthesized SNPs were used as antimicrobial agent against three bacterial genera of Bacillus, Pseudomonas and Acinetobacter which contaminate preservative solution of cut-flowers, too. According to the results biosynthesized SNPs using saffron petals successfully controlled these bacteria and have made them promising candidates as new generation of antimicrobials. This route is rapid, simple without any hazardous chemicals and economical to synthesized SNPs.     

Biosynthesis of extracellular and intracellular gold nanoparticles by Aspergillus fumigatus and A. flavus

Green chemistry is a boon for the development of safe, stable and ecofriendly nanostructures using biological tools. The present study was carried out to explore the potential of selected fungal strains for biosynthesis of intra- and extracellular gold nanostructures. Out of the seven cultures, two fungal strains (SBS-3 and SBS-7) were selected on the basis of development of dark pink colour in cell free supernatant and fungal beads, respectively indicative of extra- and intracellular gold nanoparticles production. Both biomass associated and cell free gold nanoparticles were characterized using X-ray diffractogram (XRD) analysis and transmission electron microscopy (TEM). XRD analysis confirmed crystalline, face-centered cubic lattice of metallic gold nanoparticles along with average crystallite size. A marginal difference in average crystallite size of extracellular (17.76 nm) and intracellular (26 and 22 nm) Au-nanostructures was observed using Scherrer equation. In TEM, a variety of shapes (triangles, spherical, hexagonal) were observed in both extra- and intracellular nanoparticles. 18S rRNA gene sequence analysis by multiple sequence alignment (BLAST) indicated 99 % homology of SBS-3 to Aspergillus fumigatus with 99 % alignment coverage and 98 % homology of SBS-7 to Aspergillus flavus with 98 % alignment coverage respectively. Native-PAGE and activity staining further confirmed enzyme linked synthesis of gold nanoparticles.     

Synthesis,effect of capping agents and optical properties of manganese‐doped zinc sulphide nanoparticles

Mn²⁺‐doped ZnS nanoparticles have been successfully synthesized by a chemical precipitation method, using non‐ionic surfactants such as PMMA and PEG. The particles were prepared in an air atmosphere at 80°C. X‐ray diffraction (XRD), transmission electron microscopy (TEM), UV‐visible and photoluminescence (PL) studies were used to investigate the effect of the capping agent on the size, morphology and optical properties of the ZnS–Mn²⁺ nanoparticles. Enhanced PL was observed from the surfactant‐capped ZnS–Mn²⁺ nanoparticles. The PL spectra showed a broad blue emission band in the range 460–445 nm and a Mn²⁺‐related yellow‐orange emission band in the range 581–583 nm. Copyright © 2012 John Wiley & Sons, Ltd.     

Green synthesized doxorubicin loaded zinc oxide nanoparticles regulates the Bax and Bcl-2 expression in breast and colon carcinoma

The green synthesis of zinc oxide nanoparticles (ZnONPs) using Borassus flabellifer fruit extract was characterized by UV–visible spectroscopy, FT-IR, XRD, TEM, Zeta potential and EDS analysis. The UV–visible spectrum showed an absorption peak at 368 nm that reflects surface Plasmon resonance (SPR) ZnONPs. TEM photograph showed that the green synthesized ZnONPs were porous in nature and rod like structure with an average size of 55 nm. The Zeta potential value of −21.5 mV revealed the surface charge of green synthesized ZnONPs. In this study, we examined the synthesized DOX-ZnONPs exhibited a dose-dependent cytotoxicity against MCF-7 and HT-29. The inhibitory concentration (IC₅₀) was found to be 0.125 μg mL⁻¹ for MCF-7 and HT-29 cells. An induction of apoptosis was evidenced by nuclear stain Hoechst 33258. In vivo toxicity assessment showed that DOX-ZnONPs have low systemic toxicity in murine model system. The results prove that the DOX-ZnONPs has low toxicity and high therapy efficacy, which provides convincing evidence for the green biosynthesized ZnO as a promising candidate for a drug delivery system.     

Biogenic Synthesis of Selenium Nanoparticles and Their Effect on As(III)-Induced Toxicity on Human Lymphocytes

A bioreductive capacity of a plant, Terminalia arjuna leaf extract, was utilized for preparation of selenium nanoparticles. The leaf extract worked as good capping as well as stabilizing agent and facilitated the formation of stable colloidal nanoparticles. Resulting nanoparticles were characterized using UV–Vis spectrophotometer, transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDAX), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction analysis (XRD), respectively. The colloidal solution showed the absorption maximum at 390 nm while TEM and selected area electron diffraction (SAED) indicated the formation of polydispersed, crystalline selenium nanoparticles of size raging from 10 to 80 nm. FT-IR analysis suggested the involvement of O–H, N–H, C=O, and C–O functional group of the leaf extract in particle formation while EDAX analysis indicated the presence of selenium in synthesized nanoparticles. The effect of nanoparticles on human lymphocytes treated with arsenite, As(III), has been studied. Studies on cell viability using MTT assay and DNA damage using comet assay revealed that synthesized selenium nanoparticles showed protective effect against As(III)-induced cell death and DNA damage. Chronic ingestion of arsenic infested groundwater, and prevalence of arsenicosis is a serious public health issue. The synthesized benign nanoselenium can be a promising agent to check the chronic toxicity caused due to arsenic exposure.     

The effect of temperature on antibacterial activity of biosynthesized silver nanoparticles

The purpose of this study was the evaluation of two different temperatures on antibacterial activity of the biosynthesized silver nanoparticles. 38 silver nanoparticles-producing bacteria were isolated from soil and identified. Biosynthesis of silver nanoparticles by these bacteria was verified through visible light spectrophotometry. Two strains were relatively active for production of silver nanoparticles. These strains were subjected for molecular identification and recognized as Bacillus sp. and Acinetobacter schindleri. In the present study, the effect of temperatures was evaluated on structure and antimicrobial properties of the silver nanoparrticles by transmission electron microscopy (TEM), X-ray diffraction (XRD) analysis and antimicrobial Agar well diffusion methods. The silver nanoparticles showed antibacterial activity against all the pathogenic bacteria; however, this property was lost after treatment of the silver nanoparticles by high temperatures (100 and 300 °C). TEM images showed that the average sizes of heated silver nanoparticles were >100 nm. However, these were <100 nm for non-heated silver nanoparticles. Although, XRD patterns showed the crystalline structure of heated silver nanoparticles, their antibacterial activities were less. This was possible because of the sizes and accordingly less penetration of the particles into the bacterial cells. In addition, elimination of the capping agents by heat might be considered another reason.     

Mycosynthesis and characterization of silver nanoparticles and their activity against some human pathogenic bacteria

The aim of this study was to biosynthesis silver nanoparticles from the fungus Nigrospora sphaerica isolated from soil samples and to examine their activity against five human pathogenic strains of bacteria viz. Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa, Salmonella typhi and Staphylococcus aureus using disc diffusion method. The synergistic effect of silver nanoparticles in combination with commonly used antibiotic Gentamycin against the selected bacteria was also examined. The synthesized silver nanoparticles from free-cell filtrate were characterized by using UV–Vis spectrophotometer analysis, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). UV–Vis spectrophotometer analysis showed a peak at 420 nm indicating the synthesis of silver nanoparticles, FTIR analysis verified the detection of protein capping of silver nanoparticles while SEM micrographs revealed that the silver nanoparticles are dispersed and aggregated and mostly having spherical shape within the size range between 20 and 70 nm. The synthesized silver nanoparticles exhibited a varied growth inhibition activity (15–26 mm diam inhibition zones) against the tested pathogenic bacteria. A remarkable increase of bacterial growth inhibition (26–34 mm diam) was detected when a combination of silver nanoparticles and Gentamycin was used. A significant increase in fold area of antibacterial activity was observed when AgNPs in combination with Gentamycin was applied. The synthesized silver nanoparticles produced by the fungus N. sphaerica is a promising to be used as safe drug in medical therapy due to their broad spectrum against pathogenic bacteria.     

Biosynthesis of copper oxide nanoparticles using Enicostemma axillare (Lam.) leaf extract

In the present study copper oxide nanoparticles (CuONPs) were synthesized via simple and eco-friendly green route using leaf extract of Enicostemma axillare (Lam.). Characterization of synthesized nanoparticles (NPs) was undertaken. The characteristic absorption peak of CuONPs was in range 264nm in UV–Vis spectrum. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies revealed the morphological and structural character of green NPs. The mean particle size was calculated to 30nm. Energy dispersive spectroscopy (EDS) showed high intense metallic peak of copper (Cu), oxygen (O) and low intense peaks of carbon (C), sulfur (S), phosphorus (P) elements due to the capping action of biomolecules of plant extract in CuONPs formation. The X-ray diffraction (XRD) pattern showed distinctive peaks corresponding to (200), (211) and (310) planes revealing the high crystalline nature of synthesized CuONPs with a primitive phase. Zeta potential and size distribution of synthesized green NPs was concluded by Dynamic light scattering (DLS) studies.     

Anticancer,antimicrobial, antioxidant,and catalytic activities of green-synthesized silver and gold nanoparticles using Bauhinia purpurea leaf extract

The synthesis of metal nanoparticles by green methods attained enormous attention in recent years due to its easiness, non-toxicity, and eco-friendly nature. In the present study, noble metal nanoparticles such as silver and gold were prepared using an aqueous leaf extract of a medicinal plant, Bauhinia purpurea. The leaf extract performed as both reducing and stabilizing agents for the development of nanoparticles. The formations of silver and gold nanoparticles were confirmed by observing the surface plasmon resonance peaks at 430 nm and 560 nm, respectively, in UV–Vis absorption spectrum. Various properties of nanoparticles were demonstrated using the characterization techniques such as FTIR, XRD, TEM, and EDX. The synthesized silver and gold nanoparticles had a momentous anticancer effect against lung carcinoma cell line A549 in a dose-dependent manner with IC₅₀ values of 27.97 µg/mL and 36.39 µg/mL, respectively. The antimicrobial studies of synthesized nanoparticles were carried out by agar well diffusion method against six microbial strains. Silver and gold nanoparticles were also showed high antioxidant potentials with IC₅₀ values of 42.37 µg/mL and 27.21 µg/mL, respectively; it was measured using DPPH assay. Additionally, the nanoparticles were observed to be good catalysts for the reduction of organic dyes.

     

Mycocrystallization of gold ions by the fungus Cylindrocladium floridanum

The size and morphology determines the thermodynamic, physical and electronic properties of metal nanoparticles. The extracellular synthesis of gold nanoparticles by fungus, Cylindrocladium floridanum, which acts as a source of reducing and stabilizing agent has been described. The synthesized nanoparticles were characterized using techniques such as UV–Vis spectroscopy, X-ray diffraction (XRD), scanning electron microscopy, energy dispersive X-ray analysis (EDAX), and high-resolution transmission electron microscopy (HR-TEM). Based on the evidence of HR-TEM, the synthesized particles were found to be spherical with an average size of 19.05 nm. Powder XRD pattern proved the formation of (111)-oriented face-centered cubic crystals of metallic gold. This microbial approach by fungus for the green synthesis of spherical gold nanoparticles has many advantages such as economic viability, scaling up and environment friendliness.