Showed Surface Plasmon Resonance Research Articles

The investigation of thickness-dependent mono-fractal, optical and optoelectronics properties of sputtered silver thin film for silicon solar cell

Here we report, the room temperature deposition of silver (Ag) thin films on silicon, glass and silicon solar cell substrates by magnetron sputtering. The effect of thickness on the deposited thin films and their morphological, fractal, optical and solar cell parameters have been extensively investigated. AFM results show that the Ag thin films are composed of different-size of nano-grains and the grain size increases with increasing thickness. Mono-fractal parameters, namely fractal dimension (Df) and Hurst exponent (H), were determined from the power spectral density function. X-ray photoelectron spectroscopy studies indicate that the deposited samples exhibit the presence of oxidation state of Ag (0) in thin films, confirming the stable structure. The optical analysis shows that the transmittance of the deposited thin films decreases with increasing thickness, on the other hand, the silver thin film with thickness of 20 nm shows surface Plasmon resonance (SPR) at 436 nm. Current-voltage (I–V) curves were measured in dark and under illumination mode at standard testing conditions, i.e., 300K, 1000 W/m2 and 1.5 AM global using a solar simulator. These measurement studies indicate that thicknesses are effectively impacts on photovoltaic performance. The calculated values of change in solar efficiency (Δη) are 0.26, −0.20, −0.76 and −6.88 % for thin films with nominal thickness 0.5, 1, 2 and 20 nm respectively.

GREEN SYNTHESIS AND CHARACTERIZATION OF CERIUM OXIDE NANOPARTICLES USING Piper Betle Leaves.

Cerium Oxide Nanoparticles were synthesized by using piper betle leaf extract. The UV absorption spectrophotometer analysis of piper betle leaf extract and metal compounds showed absorbance spectra in the range of 300-350 nm. The UV-Vis spectroscopy shows surface Plasmon resonance of CeO2 nanoparticles at 310 nm indicating the particles are poly dispersed. The FT-IR measurements were carried out to identify the formation of Cerium oxide nanoparticles and possible molecules such as OH, C=C, C=O, and aromatic compounds. The FT-IR analysis played a vital role in displaying the nanoparticles which showed strong absorbance in the range 671.05cm-1 for Cerium oxide nanoparticles. The diffraction peaks and planes of ions are indexed. From the ‘X’ ray diffraction studies, the size of the Cerium oxide nanoparticles is 27 nm as calculated by using Debye Scherrer’s equation. The size, shape, and structure of nanoparticles were also analyzed by scanning electron microscope which shows an almost spherical shape of nanoparticles aggregation. This Eco-Friendly synthesis method has many advantages over chemical methods because it reduces the use of toxic metals in the synthetic process.

Green Synthesis, Characterization and Antibacterial Activity of Copper Nanoparticles from the Roots Extract of Piliostigma Reticulata Fabaceae

Nanotechnology is a fast-growing area in science which is an interdisciplinary field of both science and technology. In this study, the Roots extracts of Piliostigma reticulata were used for the green synthesis of Copper (Cu) nanoparticles (NPs) from copper Sulphate solution. Green synthesized metallic nanoparticles were characterized by UV– visible spectrophotometer, X-ray diffraction (XRD), Fourier Transform Infra-Red spectrophotometer (FTIR) and Scanning Electron Microscope (SEM). Using the Debye Scherrer formula, the average crystalline size of CuNPs was calculated as 51.0nm respectively. The UV–Vis spectroscopy results showed Surface Plasmon Resonance peaks at 500nm respectively. Fourier transform infrared spectroscopy was measured to identify the possible functional group of the biomolecules in the extract that act as reducing and capping agents of the nanoparticles. SEM analysis describes surface morphology of the synthesized nanoparticles which were roughly spherical in shape. The synthesized Nanoparticles showed antibacterial activity against pathogenic bacteria (Escherichia coli and Staphylococcus aureus) and the highest antibacterial activity was found in Cu-NPS compared plant root extract.

Unveiling enhanced dark photocatalysis: Electron storage-enabled hydrogen production in polymeric carbon nitride

Researchers have successfully replicated light-driven reactions of natural photosynthesis on semiconductors. However, an important problem limiting practical applications of these reactions is their dependence on light. Catalytic activity of the semiconductors is lost once light ceases, as the generation of charge carriers (i.e., electron-hole pairs) stops. In light of this problem, photosynthetic reactions in the dark are worthy of extra attention. Despite several reports on dark photocatalysis, the energy conversion efficiency remains low, and the mechanism is unclear. In this study, we developed an artificial photocatalytic system capable of decoupling the light and dark hydrogen production reactions. The system is composed of polymeric carbon nitride (PCN), in which electron storage sites are deliberately created. By tuning the number of the electron storage sites in the system, a record hydrogen production rate of 1480 μmol g−1 h−1 was achieved after termination of the visible-light (λ > 420 nm) illumination. In-situ spectroscopic techniques reveal that these electron reservoirs are composed of cyanamide groups capable of storing electrons. Moreover, these electron reservoirs can be excited and show surface plasmon resonance (SPR) effects, leading to the enhanced optical absorption. Importantly, the oxidation side of the dark photocatalytic reaction is found to stem from a cascade reaction involving hole-derived radicals rather than electron-generated oxygenic species reported in literature. We established a complete and stepwise dark photocatalytic reaction process as well as distinguished a rate-determining step.

Dual S-scheme CuSe-Cu3Se2/Ag-PANI heterostructures for the impressive degradation of dye pollutants

A dual S-scheme structure for the photocatalytic activity of copper selenide (CuxSey)/Ag-polyaniline (CuxSey/Ag-PANI) nanocomposites to degrade dye pollutants under visible light illumination conditions has been proposed. In the first step, PANI composites have been decorated by Ag nanoparticles (NPs) with different concentrations of Ag NPs. Then, a cost-effective and straightforward co-precipitation method has synthesized the CuxSey/Ag-PANI nanocomposites with different Ag NPs concentrations. Additions of the CuxSey/Ag-PANI nanocomposites, pristine CuxSey nanostructures, and CuxSey/PANI nanocomposites have also been synthesized with the same conditions. X-ray diffraction patterns (XRD) and high-resolution transmission electron microscopy (HRTEM) images indicated the CuxSey nanostructures in the nanocomposites included two phases that were CuSe nanodisks with a few nanometers in thickness and Cu3Se2 NPs with average diameters of 10±2 nm. In contrast, the pristine CuxSey nanostructures have included several extra phases. These microscopy images showed the Cu3Se2 NPs have decorated the CuSe nanodisks. According to the UV–vis results, the Ag NPs in the CuSe-Cu3Se2/Ag-PANI nanocomposites showed surface plasmon resonance (SPR) effects, and this factor became one of the most critical factors for the better photocatalytic performance of the CuSe-Cu3Se2/Ag-PANI nanocomposites. By comparing the Fermi level (Ef) of the structures that make up the CuSe-Cu3Se2/Ag-PANI heterostructures, these structures had the conditions for forming the dual S-scheme structure. Based on this structure and also the synergistic effect of the plasmonic properties of the Ag NPs, the reason for the better photocatalytic performance of the CuxSey/Ag-PANI nanocomposites compared to the pristine CuxSey nanostructures and CuxSey/PANI nanocomposites has been explained.

Biosynthesis and Characterization of Copper Nanoparticles Using a Bioflocculant Produced by a Yeast Pichia kudriavzevii Isolated from Kombucha Tea SCOBY

Over recent years, the ‘green’ chemistry approach to synthesizing nanoparticles has made significant developments. Because of their unique features, nanoparticles have received a lot of attention. The use of a bioflocculant to promote the environmentally friendly synthesis of copper nanoparticles is described in this paper. Copper nanoparticles were biosynthesized using bioflocculant which was produced from a yeast, Pichia kudriavzevii. The chemical reduction approach was used to synthesize copper nanoparticles (CuNPs) using a bioflocculant as a capping agent. Characterization of the as-synthesized copper nanoparticles was conducted using Fourier transform infrared (FT-IR) spectroscopy, UV-visible spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX). The FT-IR spectra revealed characteristic peaks at 3267, 2956, 1656, 1059, and 511 cm−1 for the bioflocculant, while for the bioflocculant passivated CuNPs, the characteristic peaks were at 3482 (-OH), 3261, 1640, 1059, 580, and 519 cm−1 (Cu-O). These peaks revealed that functional groups such as hydroxyls, amines, and copper oxide bonds were present. The UV-Vis analysis showed surface plasmon resonance (SPR) at an absorbance range of 500–600 nm, with peak maxima at 555 and 575 nm for the as-synthesized CuNPs. The XRD pattern revealed planes such as (200) and (220) at 2θ = 43 and 52°, and the particle size (30 nm) was determined by the Debye–Scherrer equation. The transmission electron microscopy analysis revealed a spherical-shaped particle with an average size of 20 nm. The EDX analysis of the as-synthesized CuNPs revealed the presence of the element Cu, which was not present in the EDX image of the bioflocculant used in the synthesis of the CuNPs; this indicated the success of biosynthesis.

Bioproduction and Application of Orange and Yellow Pigments Obtained from Chryseomicrobium palamuruense and Micrococcus luteus

Colour is a fundamental and most likely one of the primary attributes to be observed by the human senses, making it an essential part of human life and culture. This study investigates the bioproduction and potential application of bacterial pigments obtained from abattoir wastewater. Bacteria isolates recovered from abattoir wastewater were screened for pigment production and identified using the 16S rRNA gene sequence. Optimal physicochemical conditions of parameters were investigated and harnessed for bulk pigment production. Pigments produced were characterised using UV-Visible Spectrophotometer and Fourier Transform Infra-Red (FTIR) Analysis. The antibacterial and dyeing ability of the extracted pigments were evaluated. Two bacteria namely, Chryseomicrobium palamuruense strain PUI and Micrococcus luteus strain 1k produced orange and yellow pigments respectively. The UV-visible spectrum of the orange pigment produced by Chryseomicrobium palamuruense showed surface plasmon resonance peaks at 262, 426, and 453 nm while that of the yellow pigment produced by Micrococcus luteus showed a single peak at 260 nm. The FTIR analysis of the extracted pigments indicated the presence of some functional groups namely hydroxyl (OH), C-H, primary and secondary C-O, and skeletal C-C vibrations. Chryseomicrobium palamuruense and Micrococcus luteus showed no antibacterial activity against the selected typed bacterial isolates assessed in this study. The orange pigment extracted from Chryseomicrobium palamuruense was retained on cotton and polyester producing different shades of colour on the two fabrics when used as a dyeing agent. The pigment-producing potentials of these organisms suggest their relevance as promising dyes in textile industry.

GREEN SYNTHESIS OF COPPER OXIDE NANOPARTICLE FROM PLANT EXTRACT AND ITS ANTIBACTERIAL ACTIVITY

Objective: The present study focused on the synthesis of copper oxide nanoparticles (CuO NPs) using cinchona bark extract, its characterization, and studies on antibacterial activities.
 Methods: The CuO NPs were synthesized using 1 mM CuSO4.5H2O with 2% (m/v) aqueous bark extract of cinchona under optimum conditions (pH = 11).
 Result: The formation of CuO NPs has been confirmed first by the color change from colorless to light yellow and then to Brownish. Using a UV-Visible spectrophotometer the kinetics of the reaction was studied that showed surface plasmon resonance at 382nm. Zeta potential and particle size were calculated to be -15.2mV and, 197 nm respectively. The antibacterial activity of CuO NPs was tested against gram-positive and gram-negative culture, which shows desirable activity.
 Conclusion: The outcome of the study demonstrates that cinchona bark extract serves as a reducing and stabilizing agent, transforming Cu2+ metallic ions into CuO nanoparticles The green synthesis of the copper oxide nanoparticles (CuO NPs) using cinchona bark extract, characterization, and their antibacterial activity was successfully carried out and gram-positive (S. aureus) shows more activity compared to gram-negative (E.coli) bacteria.
 

Green Synthesis, Characterization, Antioxidant and Photocatalytic Dye Degradation Effects of Copper (Cu) Nanoparticles from the Aqueous Extract of Persea americana

Nanoparticles have played a very important role in modern research. This technology involves the synthesis of nanoparticles with controllable size, shape, and material dispersion at nanometer-scale lengths. In the current work, copper nanoparticles have been synthesized by simple green technology using Persea americana leaf extract. The formation of Cu NPs was monitored by recording UV-Vis absorption spectra showing surface plasmon resonance at 320 nm. The green synthetic copper nanoparticles will be further characterized by FT-IR, FESEM, EDS and XRD. FT-IR identified the presence of active groups and phenolic groups. The crystal morphology and size of the nanoparticles will be determined by FESEM and X-ray diffraction studies. It was found that the average particle size of the copper nanoparticles was in the range of 71 nm. These biosynthetic copper nanoparticles were tested for the photocatalytic dye degradation of commercially important textile dyes such as methylene blue The antioxidant activity of green synthesized nanoparticles from the fruit extract was analysed by DPPH-free radical scavenging assay method. The results show that green synthetic nanoparticles have strong dye degradation potential.

Catalytic reduction of 4‐nitrophenol using synthesized and characterized CoS@MorphcdtH/CoS@4‐MPipzcdtH nanoparticles

[email protected] NPs and [email protected] NPs were synthesized by precipitation method involving three mechanisms: inclusion, occlusion, and adsorption. The synthesized NPs were characterized with the help of UV-Vis spectroscopy, FESEM-EDAX, powder x-ray diffraction, TEM, ESIMS, TG/DSC analysis. The morphology of the [email protected] NPs and [email protected] NPs were hexagonal and rectangular, and the particles were in the range 7–12 nm. UV–visible spectral measurements showed surface plasmon resonance at 320 nm–340 nm with band gap of 3.65 eV–3.86 eV. The catalytically active CoSNPs called were investigated for the reduction of 4-nitrophenol (4-NP) via hydrogenation using sodium borohydride (NaBH4) as a reducing agent. Both the CoS NPs successfully reduced 4-NP to 4- aminophenol (4-AP) in a short time, catalytic performances are almost unchanged for the first five cycles. Herein, we report the preparation and characterizations of efficient active CoS NPs consisting carbodithioic acid framework as a support/capping material, along with catalytic property.

Characterization and Biofabrication of Silver Nanoparticles Utilizing Isochrysis Extract along with its in vitro Antibacterial and Antioxidant Applications

Abstract: Background: At present, bio-green methods are more expedient than physical and chemical approaches due to their prompt, simple, lucrative, scalable and conservational synthesis of nanoparticles. Aim: This study investigates the extracellular biogenic synthesis of silver nanoparticles (AgNPs) using the ethanolic-hexane extract of Isochrysis sp. (EHEI). Materials and Methods: Biosynthesized AgNPs were nano-characterized by UV-Vis spectroscopy, Field Emission Scanning Electron Microscope (FESEM), Dynamic light scattering (DLS), X-ray diffraction (XRD), Energy Dispersive X-ray (EDX), Fourier Transform Infrared Spectra (FTIR), and Gas Chromatography Mass Spectrometry (GCMS) and finally examined for antibacterial and antioxidant activity. Results: The biosynthesis of AgNPs was evidenced with UV-Vis spectra showing surface plasmon resonance (SPR) at 421 nm; fabrication of highly stable, well dispersed, spherical AgNPs with an average size of 64.47 nm which were evidenced by FESEM. The crystalline nature of AgNPs was apparent from the diffraction peaks of XRD. The Zeta potential value of-22.3 mV demonstrated the colloidal stability of AgNPs. FTIR spectra showed that functional groups existing in fatty acids, lipids, proteins, xanthophylls, polyphenols and amines are accountable for the formation and stabilization of AgNPs. GCMS confirmed that biomolecules like fatty acid ethyl esters (FAEE) are involved in capping, biochemical reduction of Ag+ ions and stabilization of AgNPs. Also, the synthesized NPs displayed high antimicrobial activity against pathogenic G+ve and G-ve bacteria. In vitro antioxidant properties were ascertained by 1,1-diphenyl-2-picryl-hydrazyl (DPPH), hydrogen peroxide and reducing power assays which established that AgNPs have an incomparable scavenging potential than the extracts. Conclusion: Use of such a microalgal system postulates an alternative template for biofabrication of multifunctional nanomaterials in extensive prototype that might be extensively applicable in biomedical sectors. Keywords: Isochrysis, AgNPs, FESEM, GCMS, Antibacterial, Antioxidant.

Evaluation of the Antioxidant, Antidiabetic, and Anticholinesterase Potential of Biogenic Silver Nanoparticles from Khaya grandifoliola.

In recent years, plant-mediated synthesis of silver nanoparticles has evolved as a promising alternative to traditional synthesis methods. In addition to producing silver nanoparticles with diverse biomedical potential, the biosynthesis approach is known to be inexpensive, rapid, and environmentally friendly. This study was aimed at synthesizing silver nanoparticles using ethanolic stem and root bark extracts of Khaya grandifoliola and highlighting the biomedical potential of the nanoparticles by evaluating their antioxidant, antidiabetic and anticholinesterase effects in vitro. Silver nanoparticles were prepared using ethanolic stem and root bark extracts of K. grandifoliola as precursors. The biogenic silver nanoparticles were characterized using UV-visible spectroscopy, fourier transform infrared spectroscopy, scanning electron microscopy and energydispersive X-ray analysis. Furthermore, 2,2-Diphenyl-1-picrylhydrazyl radical scavenging, ferric ion reducing antioxidant power, and nitric oxide scavenging assays were used to determine the antioxidant property of the nanoparticles. The antidiabetic potential of the nanoparticles was determined by evaluating their inhibitory effect on the activity of α-amylase and α-glucosidase. The anticholinesterase potential of the nanoparticles was determined by assessing their inhibitory effect on the activity of acetylcholinesterase and butyrylcholinesterase. UV-visible spectroscopy showed surface plasmon resonance bands between 425 and 450 nm. Scanning electron microscopy revealed almost round nanoparticles with a maximum size of 91 nm. Fourier transform infrared spectroscopy affirmed the role of the phytoconstituents present in K. grandifoliola as reducing and stabilizing agents. The biogenic silver nanoparticles showed remarkable antioxidant, antidiabetic, and anticholinesterase effects. Biogenic silver nanoparticles could be useful in biomedical and pharmacological applications.

Prunella vulgaris leaf extract assisted green synthesis of silver nanoparticles: Antimicrobial activity

In the present study, we have developed a simple, cost-effective and eco-friendly method for synthesis of silver nanoparticles (AgNPs) by bio-reduction of silver nitrate (AgNO 3 ) in presence Prunella vulgaris leaf extract as a reducing and stabilizing agent for the first time. Synthesis of silver nanoparticles (AgNPs) was observed by change in color (from slight reddish to dark brown) and UV-Visible spectra of AgNPs showed surface plasmon resonance at around 430nm. The Green-synthesized AgNPs were successfully characterized on the basis of UV–Vis spectrophotometer, Fourier transform infrared (FT-IR) spectroscopy, X-ray difraction analysis (XRD), and transmission electron microscopy (TEM). The results revealed the spherical shape of prepared nanoparticles with an average size 2–20 nm. EDS analysis confirmed the elemental composition of AgNPs. The antimicrobial activities of synthesised AgNPs have been studied against selected microbial pathogens.

Valorisation of fruit peel bioactive into green synthesized silver nanoparticles to modify cellulose wrapper for shelf-life extension of packaged bread

Fruit peels are rich source of bioactive compounds such as polyphenols, flavonoids, and antioxidants but are often discarded as waste due to limited pharmaceutical and nutraceutical applications. This study aimed to valorise pomegranate and citrus fruit peel into green synthesised silver nanoparticles (AgNPs) in order to modify cellulose-based wrapping material for prospective food packaging applications and propose an alternate and sustainable approach to replace polyethene based food packaging material. Four different concentrations of AgNO3 (0.5 mM, 1 mM, 2 mM, and 3 mM) were used for green synthesis of AgNPs from fruit peel bioactive, which were characterised followed by phytochemical analysis. Ultraviolet–Visible spectroscopy showed surface plasmon resonance at 420 nm, XRD analysis showed 2θ peak at 27.8°, 32.16°, 38.5°, 44.31°, 46.09°, 54.76°, 57.47°, 64.61° and 77.50° corresponding to (210), (122), (111), (200), (231), (142), (241), (220) and (311) plane of face centred cubic crystal structure of AgNPs. Fourier-transform infrared spectroscopy analysis of AgNPs green synthesised from pomegranate and kinnow peel extract showed a major peak at 3277, 1640 and 1250–1020 1/cm while a small peak at 2786 1/cm was observed in case of pomegranate peel extract which was negligible in AgNPs synthesized from kinnow peel extract. Particle sizes of AgNPs showed no statistically significant variance with p > 0.10 and thus, 2 mM was chosen for further experimentation and modification of cellulose based packaging material as it showed smallest average particle size. Zeta potential was observed to be nearly neutral with a partial negative strength due to presence of various phenolic compounds such as presence of gallic acid which was confirmed by ultrahigh performance liquid chromatography-photodiode array(UHPLC-PDA) detector. Thermal stability analysis of green synthesised AgNPs qualified the sterilisation conditions up to 100 °C. AgNPs green synthesized from both the peel extracts had higher polyphenolic content, antioxidant and radical scavenging activity as compared to peel extracts without treatment (p < 0.05). The cellulose based food grade packaging material was enrobed by green synthesised AgNPs. The characterisation of modified cellulose wrappers showed no significant difference in thickness of modified cellulose wrappers as compared with untreated cellulose wrapper (p > 0.42) while weight and grammage increased significantly in modified cellulose wrapper (p < 0.05). The colour values on CIE scale (L*, a* and b*) showed statistically significant increase in yellow and green colour (p < 0.05) for modified cellulose wrappers as compared to control wrapper. The oxygen permeability coefficient, water vapour permeability coefficient, water absorption capacity and water behaviour characteristics (water content, swelling degree and solubility) showed significant decrease (p < 0.05) for modified cellulose wrapper as compared to control wrapper. A uniform distribution and density of green synthesised AgNPs across cellulose wrapper matrix was observed through scanning electron microscopy (SEM) images with no significant aggregation, confirming successful enrobing and stable immobilisation of nanoparticles from cellulose matrix. A seven-day storage study of bread wrapped in modified and control cellulose wrappers showed delayed occurrence of microbial, yeast and mould count in bread packaged in modified cellulose wrappers and thus, resulting in shelf life extension of bread. The results are encouraging for the potential applications of modified cellulose wrappers to replace polyethene based food packaging.

Biosynthesis of silver nanoparticles using actinomycetes, phytotoxicity on rice seeds, and potential application in the biocontrol of phytopathogens.

To find effective silver nanoparticles (AgNPs) for control of phytopathogens, in this study, two strains of actinomycetes isolated from the soil of the Brazilian biome Caatinga (Caat5-35) and from mangrove sediment (Canv1-58) were utilized. The strains were identified by using the 16S rRNA gene sequencing as Streptomyces sp., related to Streptomyces mimosus species. The obtained AgNPs were coded as AgNPs 35 and AgNPs58 and characterized by size and morphology using dynamic light scattering, zeta potential, transmission electron microscopy, and Fourier transformed infrared (FTIR). The antifungal activity of the AgNPs35 and AgNPs58 was evaluated in vitro by the minimal inhibitory concentration (MIC) assay on the phytopathogens, Alternaria solani, Alternaria alternata, and Colletotrichum gloeosporioides. The phytotoxic effect was evaluated by the germination rate and seedling growth of rice (Oryza sativa). AgNPs35 and AgNPs58 showed surface plasmon resonance and average sizes of 30 and 60 nm, respectively. Both AgNPs presented spherical shape and the FTIR analysis confirmed the presence of functional groups such as free amines and hydroxyls of biomolecules bounded to the external layer of the nanoparticles. Both AgNPs inhibited the growth of the three phytopathogens tested, and A. alternate was the most sensible (MIC ≤ 4 µM). Moreover, the AgNPs35 and AgNPs58 did not induce phytotoxic effects on the germination and development of rice seedlings. In conclusion, these AgNPs are promising candidates to biocontrol of these phytopathogens without endangering rice plants.

Green Synthesis and characterization of Lead Oxide Nanoparticles using Piper Betle leaf

Lead oxide nanoparticles were synthesized by using cost effective and eco friendly green method assisted by piper betle leaf extract. The UV absorption spectrophotometer analysis of leaf extract and metal compounds showed absorbance spectra in the range 300-400 nm. The UV-Vis spectroscopy shows Surface Plasmon resonance of PbO nanoparticles at 320 nm indicating that the particles are poly dispersed. The FT-IR measurements were carried out to identify the formation of lead oxide nanoparticles and possible molecules such as OH, C=C, C=O and aromatic compounds. The FT-IR analysis played a pivoted role in displaying the nanoparticles which showed strong absorbance in the range 518-600 cm-1 for lead oxide nanoparticles. The diffraction peaks and planes of ions are indexed. From the ‘X’ ray diffraction analysis, the size of the lead oxide nanoparticles is 70 nm as calculated by Debye scherrer’s equation. The size, shape and structure of nanoparticles were also analyzed by Scanning electron microscope showing tetragonal shape of nanoparticles aggregation. This green synthesis method has many advantages over the chemical method because it reduces the use of toxic metals in the synthesis process.

Influences of Plasma Plume Length on Structural, Optical and Dye Degradation Properties of Citrate-Stabilized Silver Nanoparticles Synthesized by Plasma-Assisted Reduction.

Citrate-capped silver nanoparticles (Ag@Cit NPs) were synthesized by a simple plasma-assisted reduction method. Homogenous colloidal Ag@Cit NPs solutions were produced by treating a -trisodium citrate-deionized water with an atmospheric-pressure argon plasma jet. The plasma-synthesized Ag@Cit NPs exhibited quasi-spherical shape with an average particle diameter of about 5.9−7.5 nm, and their absorption spectra showed surface plasmon resonance peaks at approximately 406 nm. The amount of Ag@Cit NPs increased in a plasma exposure duration-dependent manner. Plasma synthesis of Ag@Cit NPs was more effective in the 8.5 cm plume jet than in the shorter and longer plume jets. A larger amount of Ag@Cit NPs were produced from the 8.5 cm plume jet with a higher pH and a larger number of aqua electrons, indicating that the synergetic effect between plasma electrons and citrate plays an important role in the plasma synthesis of Ag@Cit NPs. Plasma-assisted citrate reduction facilitates the synthesis of Ag@Cit NPs, and citrate-capped nanoparticles are stabilized in an aqueous solution due to their repulsive force. Next, we demonstrated that plasma-synthesized Ag@Cit NPs exhibited a significant degradation of methylene blue dye.

Chitosan and cetyltrimethylammonium bromide capped Iridium-silver bimetallic nanoparticles: A comparative study

Cetyltrimethylammonium bromide (CTAB) and chitosan capped iridium-silver nanoparticles (Ir-AgNPs) were synthesized by using seedless co-reduction of metal salts precursors with sodium borohydride. CTAB and chitosan capped Ir-Ag shows surface Plasmon resonance (SPR) band at 420 nm and 430 nm, respectively. Chitosan + Ag+ + Ir3+ reaction mixture reduced much faster than that of CTAB + Ag+ + Ir3+ with NaBH4. Average Brunauer-Emmett-Teller (BET) surface area, particle size, cumulative pore size, cumulative pore volume were found to be 49.07 m2/g, 2.77 nm, 8.10 nm, 0.19 cc/g and 41.84 m2/g, 3.25 nm, 7.85 nm, 0.16 cc/g, respectively, for CTAB and chitosan capped Ir-AgNPs. The CTAB-Ir-AgNPs exhibit better stability in the wide range of pH and temperature for ca. several months. SEM, TEM, EDX, XRD, XPS, and FTIR were used to analyze the surface morphology, size, elemental composition, crystalline nature, oxidation states of metals and functional groups capping action of as-prepared Ir-AgNPs.

Comparative study of antifungal activity of two preparations of green silver nanoparticles from Portulaca oleracea extract

The green silver nanoparticles (green AgNPs) exhibit an exceptional antimicrobial property against different microbes, including bacteria and fungi. The current study aimed to compare the antifungal activities of both the crude aqueous extract of Portulaca oleracea or different preparations of green AgNPs biosynthesized by mixing that aqueous extract with silver nitrate (AgNO3). Two preparations of the green AgNPs were synthesized either by mixing the aqueous extract of P. oleraceawith silver nitrate (AgNO3) (normal AgNPs) or either irradiation of the AgNPs, previously prepared, under 60Co γ-ray using chitosan (gamma-irradiated AgNPs). Characterization of different AgNPs were tested by Zeta potential analyzer, Ultraviolet (UV) Visible Spectroscopy, and Fourier-Transform Infrared (FTIR) spectrometry. Three different plant pathogenic fungi were tested, Curvularia spicifera, Macrophomina phaseolina, and Bipolaris sp. The antifungal activities were evaluated by Transmission Electron Microscope (TEM) for either the crude aqueous extract of P. oleracea at three doses (25%, 50%, and 100%) or the newly biosynthesized AgNPs, normal or gamma-irradiated. With a few exceptions, the comparative analysis revealed that the irradiated green AgNPs at all three concentrations showed a relatively stronger antifungal effect than the normal AgNPs against all the three selected fungal strains. UV–visible spectroscopy of both preparations showed surface plasmon resonance at 421 nm. TEM results showed that both AgNPs were aggregated and characterized by a unique spherical shape, however, the gamma-irradiated AgNPs were smaller than the non-irradiated AgNPs (0.007–0.026 µM vs. 0.009–0.086 µM). TEM photographs of the fungal strains treated with the two AgNPs preparations showed flaccid structures, condensed hyphae, and shrunken surface compared with control cells. The data suggested that the biosynthesized P. oleracea AgNPs have antifungal properties against C. spicifera, M. phaseolina, and Bipolaris sp. These AgNPs may be considered a fungicide to protect different plants against phytopathogenic fungi.

Synthesis of Silver Nanoparticles Using Dichloromethane Extract of Chrysanthemum cinerariaefolium and Its Bioactivity

Common methods of synthesizing metallic nanoparticles are chemical and physical. However, they are expensive and use toxic chemicals. Green synthesis is less costly and safer hence a potential alternative. Silver nanoparticles (Ag NPs) were synthesized using dichloromethane extract of Chrysanthemum cinerariaefolium and colour change from pale green to dark brown was observed. Scanning Electron Microscopy (SEM) images were faceted and others formed clusters. Transmission Electron Microscopy (TEM) images were spherical with an average size of 22.8± 17.5 nm. EDX analysis showed the nanoparticles had percentage abundance of 67.26%. Fourier-transform Infrared Spectroscopy (FTIR) analysis showed absorption bands at 3489.59 cm-1, 3217.80 cm-1, 2384.74 cm-1 , 1633.05 cm-1, 1405.08 cm-1, 1109.32 cm-1 and 505.93 cm-1. The UV-Vis analysis showed Surface Plasmon Resonance (SPR) peak at 434 nm. The nanoparticles were more active on P. aeruginosa with an MIC of 15 µg/ml while the cytotoxicity assay showed Ag NPs had an MIC of 33.33 µg/ml hence were noncytotoxic against Vero cells.