Showed Surface Plasmon Resonance Research Articles

Green Synthesis of Ag/Ag₂O Nanoparticles Using Aqueous Leaf Extract of Eupatorium odoratum and Its Antimicrobial and Mosquito Larvicidal Activities.

The health challenges associated with pathogens and ectoparasites highlight the need for effective control approaches. Metal nanoparticles have been proposed as highly effective tools towards combatting different microbial organisms and parasites. The present work reports the antimicrobial and larvicidal potential of biosynthesized Ag/Ag2O nanoparticles using aqueous leaf extract of Eupatorium odoratum (EO). The constituents of the leaf extract act as both reducing and stabilizing agents. The UV-VIS spectra of the nanoparticles showed surface plasmon resonance. The particle size and shape of the nanoparticles was analysed by transmission electron microscopy (TEM). The larvicidal study was carried out using third and fourth instar Culex quinquefasciatus larvae. The mosquito larvae were exposed to varying concentrations of plant extract (EO) and the synthesized nanoparticles, and their percentage of mortality was accounted for at different time intervals of 12 h and 24 h periods of exposure. The nanoparticles were more lethal against third and fourth instars of Culex quinquefasciatus larvae at the 24 h period of exposure with lower lethal concentration values (LC50 = 95.9 ppm; LC90 = 337.5 ppm) and (LC50 = 166.4 ppm; LC90 = 438.7 ppm) compared to the plant extract (LC50 = 396.8 ppm; LC90 = 716.8 ppm and LC50 = 448.3 ppm; LC90 = 803.9 ppm, respectively). The antimicrobial properties of the nanoparticles were established against different clinically-isolated microbial strains and compared to that of the plant extract (EO) and standard antimicrobial drugs. The nanoparticles were generally more active than the plant extract against the selected microbial organisms. The Gram-negative bacterial strains Escheerichua coli and Salmonella typhi were more susceptible towards the nanoparticles compared to the Gram-positive strains and the fungal organism.

Potential of biosynthesized silver nanoparticles using Stenotrophomonas sp. BHU-S7 (MTCC 5978) for management of soil-borne and foliar phytopathogens

Stenotrophomonas sp. is emerging as a popular microbe of global concern with various potential ecological roles. Biosynthesis of gold and silver nanoparticles (AgNPs) using this bacterial strain has shown promising applications in life sciences. However, there is no report on efficient agricultural applications of biosynthesized AgNPs using Stenotrophomonas sp. In this regard, successful biosynthesis of AgNPs using Stenotrophomonas sp. BHU-S7 (MTCC 5978) was monitored by Uv-visible spectrum showing surface plasmon resonance (SPR) peak at 440 nm. The biosynthesized AgNPs were spherical with an average mean size of ~12 nm. The antifungal efficacy of biosynthesized AgNPs against foliar and soil-borne phytopathogens was observed. The inhibitory impact of AgNPs (2, 4, 10 μg/ml) on conidial germination was recorded under in vitro conditions. Interestingly, sclerotia of Sclerotium rolfsii exposed to AgNPs failed to germinate on PDA medium and in soil system. Moreover, AgNPs treatment successfully managed collar rot of chickpea caused by S. rolfsii under greenhouse conditions. The reduced sclerotia germination, phenolic acids induction, altered lignification and H2O2 production was observed to be the probable mechanisms providing protection to chickpea against S. rolfsii. Our data revealed that AgNPs treated plants are better equipped to cope with pathogen challenge pointing towards their robust applications in plant disease management.

Dependence of the structural optical and thermo-physical properties of gold nano-particles synthesized by laser ablation method on the nature of laser

This current project is dedicated to a fast, easy and one step method for the synthesis of gold nano-particles. Gold (Au) nano-particles have been fabricated by laser ablation method in de-ionized water. The purpose was to explore the dependence of the various properties of the gold nano particles on the nature of laser. In order to prepare colloidal solutions, a low power continuous wave (CW) diode laser and a nanosecond pulsed Nd:YAG laser have been used to ablate the gold target. The structural, physical, optical and thermal characteristics of prepared nano-particles have been investigated by X-ray diffraction (XRD), atomic force microscopy (AFM), UV–vis spectroscopy and thermal conductivity of liquids and gases unit (TCLGU), respectively. The XRD analyses revealed the formation of polycrystalline gold nano-particles with (111), (200) and (220) plans in case of both the lasers. AFM micrographs showed that prepared nano-particles are spherical in dimensions. The size of nanoparticles synthesized by CW laser ranges from 5 to 20nm whereas the size ranges from 12 to 49nm in case of pulsed laser. UV–vis spectroscopy showed surface plasmon resonance (SPR) peak at 512nm for CW laser prepared nanoparticles as compared to pulsed laser at 525nm which is also indicative of the smaller size in case of CW laser. The thermal conductivity of colloidal solution prepared by CW laser is 33% whereas in case of pulsed laser is 48% more as compared to the deionized water (base liquid).

Antimicrobial efficacy of biosynthesized silver nanoparticles from different solvent extracts of Waltheria americana root

The extensive application of silver compounds especially in nanomedicine, has increased the need to develop environmental friendly and cost effective route to synthesizing silver nanoparticles (AgNPs). Water, diethyl ether, and ethanol were used in the extraction of Waltheria americana root. Silver nanoparticles (AgNPs) were synthesized by reacting 0.001 M AgNO3 solution with the different crude extracts of W. americana root in the ratio of 10:1. The synthesized AgNPs were analyzed using UV–visible spectrophotometer, X–ray diffraction (XRD), scanning electron microscope (SEM), and FTIR techniques. The different crude extracts and their synthesized colloidal AgNPs were tested against Proteus species, Streptococcus species, Klebsiella species, Staphylococcus aureus, and ciprofloxacin (control). UV–vis results showed surface plasmon resonance (SPR) at 415, 435, and 425 nm for synthesized colloidal AgNPs from water, diethyl ether, and ethanol extracts, respectively. When screened against all test organisms, the synthesized colloidal AgNPs from diethyl ether extract of W. americana root (WARDEEP) showed more improved antimicrobial efficacy than other crude extracts and their synthesized AgNPs. The strongest antimicrobial activity of WARDEEP against all test organisms were at 400, 100, and 200 mg/mL concentrations for Proteus species and Staphylococcus aureus, Klebsiella species, and Streptococcus species, respectively. From minimum inhibitory concentration (MIC) results, it was observed that WARDEEP exhibited a strong antibiotic activity against Proteus and Streptococcus species at a least value of 12.5 mg/mL concentration. Minimum bactericidal concentration (MBC) results showed that WARDEEP exhibited a minimum antibiotic activity at 25 mg/mL concentration against Proteus and Streptococcus species. Therefore, silver nanoparticles were sucessfully synthesized from all the crude extracts. The synthesized silver nanoparticles could comparatively provide better alternative treatment to both gram–positive and gram–negative bacteria than the crude plant extracts.

Localized surface plasmon resonance frequency tuning in highly doped InAsSb/GaSb one-dimensional nanostructures

We report a detailed analysis of the influence of the doping level and nanoribbon width on the localized surface plasmon resonance (LSPR) by means of reflectance measurements. The plasmonic system, based on one-dimensional periodic gratings of highly Si-doped InAsSb/GaSb semiconductor nanostructures, is fabricated by a simple, accurate and large-area technique fabrication. Increasing the doping level blueshifts the resonance peak while increasing the ribbon width results in a redshift, as confirmed by numerical simulations. This provides an efficient means of fine-tuning the LSPR properties to a target purpose of between 8–20 μm (1250−500 cm−1). Finally, we show surface plasmon resonance sensing to absorbing polymer layers. We address values of the quality factor, sensitivity and figure of merit of 16 700 nm RIU–1 and 2.5, respectively. These results demonstrate Si-doped InAsSb/GaSb to be a low-loss/high sensitive material making it very promising for the development of biosensing devices in the mid-infrared.

One-pot green synthesis of gold nanoparticles and studies of their anticoagulative and photocatalytic activities

A green approach for synthesis of gold nanoparticles (Au NPs) using dried biomass of Momordica cochinchinensis(Lour.) Spreng. leaf is reported. The as-synthesized nanoparticles were characterized by time-dependent UV–visible, Fourier transform infrared (FT-IR), powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX) analyses. The UV–visible spectra of synthesized Au NPs showed surface plasmon resonance (SPR) at 552nm after 12h. The TEM image showed the Au NPs are mostly spherical, oval and triangular with sizes 10–80nm. As-synthesized Au NPs shows pronounced photocatalytic effect on degradation of dyes under solar light illumination. Ability of Au NPs to inhibit coagulation of human blood plasma was also investigated.

Biosynthesis of gold nanoparticles using Capsicum annuum var. grossum pulp extract and its catalytic activity

Biological synthesis approach has been regarded as a green, eco-friendly and cost effective method for nanoparticles preparation without any toxic solvents and hazardous bi-products during the process. This present study reported a facile and rapid biosynthesis method for gold nanoparticles (GNPs) from Capsicum annuum var. grossum pulp extract in a single-pot process. The aqueous pulp extract was used as biotic reducing agent for gold nanoparticle growing. Various shapes (triangle, hexagonal, and quasi-spherical shapes) were observed within range of 6–37nm. The UV–Vis spectra showed surface plasmon resonance (SPR) peak for the formed GNPs at 560nm after 10min incubation at room temperature. The possible influences of extract amount, gold ion concentration, incubation time, reaction temperature and solution pH were evaluated to obtain the optimized synthesis conditions. The effects of the experimental factors on NPs synthesis process were also discussed. The produced gold nanoparticles were characterized by transform electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray (EDS) and Fourier Transform infrared spectroscopy (FTIR). The results demonstrated that the as-obtained GNPs were well dispersed and stable with good catalytic activity. Biomolecules in the aqueous extract were responsible for the capping and stabilization of GNPs.

Biosynthesis and Biomedical Applications of Gold Nanoparticles Using Eclipta prostrata Leaf Extract

This study reports the biological synthesis of gold nanoparticles (AuNPs) by the reduction of HAuCl4 by using of Eclipta prostrata leaf extract as the reducing and stabilizing agent. AuNPs were characterized using Ultraviolet–visible (UV-vis) spectroscopy, X-ray diffraction (XRD), Fourier Transform-Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), High Resolution-Transmission Electron Microscopy (HRTEM), and Energy Dispersive X-ray analysis (EDAX). The UV-visible spectrum of the synthesized AuNPs showed surface plasmon resonance (SPR) around 534 nm. The face-centered cubic (FCC) structure of the AuNPs was confirmed by XRD peaks at 38.10°, 44.13°, 64.43°, and 77.32°, which correspond to (111), (200), (220), and (311) miller indices, respectively, with clear circular spots in the selected area electron diffraction (SAED). FTIR measurements showed the AuNPs having a coating of phenolic compounds, indicating a possible role of biomolecules responsible for capping and efficient stabilization of the AuNPs. The HRTEM images determined the particles are spherical, hexagonal, and triangular in shape, with an average size of 31 ± 1.6 nm. The synthesized AuNPs show good antibacterial, antioxidant, and cytotoxic activity. The outcomes of this study indicate that these nanoparticles could be effectively utilized in pharmaceutical, biotechnological, and biomedical applications.

Surface plasmon resonance based selective and sensitive colorimetric determination of azithromycin using unmodified silver nanoparticles in pharmaceuticals and human plasma

In this article we report a novel method for colorimetric sensing and selective determination of a non-chromophoric drug-azithromycin, which lacks native absorbance in the UV–Visible region using unmodified silver nanoparticles (AgNPs). The citrate-capped AgNps dispersed in water afforded a bright yellow colour owing to the electrostatic repulsion between the particles due to the presence of negatively charged surface and showed surface plasmon resonance (SPR) band at 394nm. Addition of positively charged azithromycin at a concentration as low as 0.2μM induced rapid aggregation of AgNPs by neutralizing the negative charge on the particle surface. This phenomenon resulted in the colour change from bright yellow to purple which could be easily observed by the naked eye. This provided a simple platform for rapid determination of azithromycin based on colorimetric measurements. The factors affecting the colorimetric response like pH, volume of AgNPs suspension and incubation time were suitably optimized. The validated method was found to work efficiently in the established concentration range of 0.2–100.0μM using two different calibration models. The selectivity of the method was also evaluated by analysis of nanoparticles-aggregation response upon addition of several anions, cations and some commonly prescribed antibiotics. The method was successfully applied for the analysis of azithromycin in pharmaceuticals and spiked human plasma samples with good accuracy and precision. The simplicity, efficiency and cost-effectiveness of the method hold tremendous potential for the analysis of such non-chromophoric pharmaceuticals.

Phyto-mediated biosynthesis of silver nanoparticles using the rind extract of watermelon (Citrullus lanatus) under photo-catalyzed condition and investigation of its antibacterial, anticandidal and antioxidant efficacy

The biological synthesis of nanoparticles has gained tremendous interest, and plants and plant extracts are preferred over other biological sources for this process because of their rich content of bioactive metabolites. In this study, silver nanoparticles (AgNPs) were produced utilizing the aqueous extract of watermelon rind (WRA), an agricultural waste material under photo exposed condition at room temperature, and tested for their antibacterial, anticandidal and antioxidant activities. The synthesized AgNPs showed surface plasmon resonance at 425nm with an average size of 109.97nm. The morphology and elemental composition was confirmed by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric and differential thermogravimetric analysis (TG/DTG) confirmed that the bioactive compounds from the WRA extract were involved in the synthesis and capping of AgNPs. X-ray diffraction (XRD) revealed the crystallite nature of the AgNPs. The AgNPs exhibited strong broad spectrum antibacterial activity against five different foodborne bacteria with zones of inhibition 9.12–14.54mm in diameter. When AgNPs were mixed with kanamycin and rifampicin the mixture exhibited strong antibacterial synergistic activity. The AgNPs also exerted strong synergistic anticandidal activity when they were combined with amphotericin b. The AgNPs had high antioxidant activity and reducing power. Overall, the results confirmed the bio-potentials of the synthesized AgNPs using WRA, which could have applications in the biomedical, cosmetic, pharmaceutical, food preservation and packaging industries.

Colloidal europium nanoparticles via a solvated metal atom dispersion approach and their surface enhanced Raman scattering studies

Chemistry of lanthanide metals in their zerovalent state at the nanoscale remains unexplored due to the high chemical reactivity and difficulty in synthesizing nanoparticles by conventional reduction methods. In the present study, europium(0) nanoparticles, the most reactive of all the rare earth metals have been synthesized by solvated metal atom dispersion (SMAD) method using hexadecyl amine as the capping agent. The as-prepared europium nanoparticles show surface Plasmon resonance (SPR) band in the visible region of the electromagnetic spectrum. This lead to the investigation of its surface enhanced Raman scattering (SERS) using visible light excitation source. The SERS activity of europium nanoparticles has been followed using 4-aminothiophenol and biologically important molecules such as hemoglobin and Cyt-c as the analytes. This is the first example of lanthanide metal nanoparticles as SERS substrate which can possibly be extended to other rare-earth metals. Since hemoglobin absorbs in the visible region, the use of visible light excitation source leads to surface enhanced resonance Raman spectroscopy (SERRS). The interaction of biomolecules with Eu(0) has been followed using FT-IR and UV–visible spectroscopy techniques. The results indicate that there is no major irreversible change in the structure of biomolecules upon interaction with europium nanoparticles.

Biosynthesis of AgNPs using Carica Papaya peel extract and evaluation of its antioxidant and antimicrobial activities

Waste fruit peel mediated synthesis of silver nanoparticles (AgNPs) is a green chemistry approach that links nanotechnology and biotechnology. Using biological medium such as peel extract for the biosynthesis of nanoparticles is an ecofriendly and emerging scientific trend. With this back drop the present study focused on the biosynthesis of AgNPs using Carica Papaya peel extract (CPPE) and evaluation of its antimicrobial potentials of the nanoparticles against different human pathogens and to investigate the free radical scavenging activity. Water soluble antioxidant constituents present in Carica Papaya peel extract were mainly responsible for the reduction of silver ions to nanosized Ag particles. UV–vis spectral analysis shows surface plasmon resonance band at 430nm. The presence of active proteins and phenolic groups present in the biomass before and after reduction was identified by Fourier transform infrared spectroscopy. X-ray diffraction study shows the average size of the silver nanoparticles is in the range of 28nm, as well as revealed their face centered cubic structure. Atomic force microscope image gives the 3D topological characteristic of silver nanoparticles and the particle size ranges from 10 to 30nm. The average particle size distribution of silver nanoparticles is 161nm (Dynamic light scattering) and the corresponding average zeta potential value is −20.5mV, suggesting higher stability of silver nanoparticles. Biologically synthesized nanoparticles efficiently inhibited pathogenic organisms both gram-positive and gram-negative bacteria. The biosynthesized nanoparticles might serve as a potent antioxidant as revealed by DPPH and ABTS+assay.

Biogenic synthesis of antioxidant, shape selective gold nanomaterials mediated by high altitude lichens

Biogenic synthesis of gold nanoparticles have been accomplished using dried biomass of two high altitude lichen species, collected from the alpine region of Eastern Himalaya in Arunachal Pradesh state of North East India, without addition of any external reducing or stabilizing chemicals. The nanoparticles were characterised by UV–visible, FT-IR spectroscopy, powder X-ray diffraction (XRD), and transmission electron microscopy (TEM). The as-obtained gold nanoparticles showed surface plasmon resonance (SPR) band at ~535nm. The XRD study furnished evidence for the formation of face-centered cubic structure of gold nanomaterials. The nanoparticles produced with Acroscyphus sp. consisted of multiply twinned quasi-spherical and prismatic shapes while those accessed with Sticta sp. are exclusively multiply twinned. The biomatrix loaded gold nanomaterial exhibited pronounced antioxidant activity.

Ionic Liquid Mediated Biosynthesis of Gold Nanoparticles Using Elaeis Guineensis (Oil Palm) Leaves Extract

This study reports that ionic liquid mediated Elaeis. guineensis (oil palm) leaves extract can be used for reduction of gold precursor to obtain stable gold nanoparticles (AuNPs). E. guineensis leaf extract was prepared by using a mixture of distilled water and 2% aq. ionic liquid (1-Ethyl-3-methylimidazolium chloride) as solvents. UV-vis spectra of reaction medium showed surface plasmon resonance (SPR) peak (λmax) at 539-557nm confirm formation of gold nanoparticles. λmax was blue shifted toward 539nm with increase in volume extract up to 0.60ml while further addition of extract in the reaction medium resulted in red shifting of SPR band. Emim chloride functioned as a capping agent and results in synthesis of small size gold nanoparticles. TEM image analysis confirmed that average particles size of gold nanoparticles was 20.09±12.36nm synthesized with an aqueous solution containing 2% Emim chloride as compared to average particle size of 39.60±13.63nm when only distilled water was used as solvent for extraction of oil palm leaves. FTIR spectra analysis of the extracts identified presence of phenolic, carboxylic and amide groups that play important roles in reduction of gold precursor.

Biosynthesis of silver nanoparticles using Lantana camara flower extract and its application

Search of new pigment for the green synthesis of nanoparticles has emerged new scope for the chemist. In this report, we describe the synthesis of silver nanoparticles (AgNPs) using notorious weed, Lantana camara L. flower extract. The AgNPs were characterized by visual, UV–visible spectrophotometer, transmission electron microscopy (TEM), dynamic light scattering and X-ray diffraction (XRD). UV–visible spectroscopy showed surface plasmon resonance at 470 nm clearly reveals the formation of AgNPs. TEM analysis confirmed that the AgNPs are spherical and 33 ± 5 nm average sized. XRD analysis reveals the formation of pure silver metal with face-centered cubic symmetry and confirms crystalline nature. The AgNPs showed significant antioxidant efficacy at different time intervals against 1,1-diphenyl-2-picrylhydrazyl and photocatalytic activities by the degradation of the methylene blue. From the results obtained, it is suggested that surface-modified AgNPs could be used effectively in future biotechnology concerns.

Photocatalytic and antibacterial activities of gold and silver nanoparticles synthesized using biomass of Parkia roxburghii leaf

The present study reports a green approach for synthesis of gold (Au) and silver (Ag) nanoparticles (NPs) using dried biomass of Parkia roxburghii leaf. The biomass of the leaf acts as both reductant as well as stabilizer. The as-synthesized nanoparticles were characterized by time-dependent UV–visible, Fourier transform infrared (FT-IR), powder X-ray diffraction (XRD), and transmission electron microscopy (TEM) analyses. The UV–visible spectra of synthesized Au and Ag NPs showed surface plasmon resonance (SPR) at 555 and 440nm after 12h. Powder XRD studies revealed formation of face-centered cubic structure for both Au and Ag NPs with average crystallite size of 8.4 and 14.74nm, respectively. The TEM image showed the Au NPs to be monodispersed, spherical in shape with sizes in the range of 5–25nm. On the other hand, Ag NPs were polydispersed, quasi-spherical in shape with sizes in the range of 5–25nm. Investigation of photocatalytic activities of Au and Ag NPs under solar light illumination reveals that both these particles have pronounced effect on degradation of dyes viz., methylene blue (MB) and rhodamine b (RhB). Antibacterial activity of the synthesized NPs was studied on Gram positive bacteria Staphylococcus aureus and Gram negative bacteria Escherichia coli. Both Au and Ag NPs showed slightly higher activity on S. aureus than on E. coli.

Eco-friendly microwave-assisted green and rapid synthesis of well-stabilized gold and core–shell silver–gold nanoparticles

Herein, we present a new approach for the synthesis of gold nanoparticles (AuNPs) individually and as bimetallic core–shell nanoparticles (AgNPs–AuNPs). The novelty of the approach is further maximized by using curdlan (CRD) biopolymer to perform the dual role of reducing and capping agents and microwave-aided technology for affecting the said nanoparticles with varying concentrations in addition to those affected by precursor concentrations. Thus, for preparation of AuNPs, curdlan was solubilized in alkali solution followed by an addition of tetrachloroauric acid (HAuCl4). The curdlan solution containing HAuCl4 was then subjected to microwave radiation for up to 10min. The optimum conditions obtained with the synthesis of AuNPs were employed for preparation of core–shell silver–gold nanoparticles by replacing definite portion of HAuCl4 with an equivalent portion of silver nitrate (AgNO3). The portion of AgNO3 was added initially and allowed to be reduced by virtue of the dual role of curdlan under microwave radiation. The corresponding portion of HAuCl4 was then added and allowed to complete the reaction. Characterization of AuNPs and AgNPs–AuNPs core–shell were made using UV–vis spectra, TEM, FTIR, XRD, zeta potential, and AFM analysis. Accordingly, strong peaks of the colloidal particles show surface plasmon resonance (SPR) at maximum wavelength of 540nm, proving the formation of well-stabilized gold nanoparticles. TEM investigations reveal that the major size of AuNPs formed at different Au+3concentration lie below 20nm with narrow size distribution. Whilst, the SPR bands of AgNPs–AuNPs core–shell differ than those obtained from original AgNPs (420nm) and AuNPs (540nm). Such shifting due to SPR of Au nanoshell deposited onto AgNPs core was significantly affected by the variation of bimetallic ratios applied. TEM micrographs show variation in contrast between dark silver core and the lighter gold shell. Increasing the ratio of silver ions leads to significant decrease in zeta potential of the formed bimetallic core–shell. FT-IR discloses the interaction between CRD and metal nanoparticles, which could be the question of reducing and stabilizing metal and bimetallic nanoparticles. XRD patterns assume insufficient difference for the AuNPs and AgNPs–AuNPs core–shell samples due to close lattice constants of Ag and Au. Based on AFM, AuNPs and AgNPs–AuNPs core–shell exhibited good monodispersity with spherical particles possessing different sizes in the studied samples. The average sizes of both metal and bimetallic core–shell were found to be 52 and 45nm, respectively.

Green synthesis of copper nanoparticles for the efficient removal (degradation) of dye from aqueous phase.

The present work reports the utilization of a common household waste material (fish scales of Labeo rohita) for the synthesis of copper nanoparticles. The method so developed was found to be green, environment-friendly, and economic. The fish scale extracts were acting as a stabilizing and reducing agents. This method avoids the use of external reducing and stabilizing agents, templates, and solvents. The compositional abundance of gelatin may be envisaged for the effective reductive as well as stabilizing potency. The mechanisms for the formation of nanoparticles have also been presented. The synthesized copper nanoparticles formed were predominantly spherical in nature with an average size of nanoparticles in the range of 25-37 nm. The copper nanoparticles showed characteristic Bragg's reflection planes of fcc which was supported by both selected area electron diffraction and X-ray diffraction pattern and showed surface plasmon resonance at 580 nm. Moreover, the energy dispersive spectroscopy pattern also revealed the presence of only elemental copper in the copper nanoparticles. The prepared nanoparticles were used for the remediation of a carcinogenic and noxious textile dye, Methylene blue, from aqueous solution. Approximately, 96 % degradation of Methylene blue dye was observed within 135 min using copper nanoparticles. The probable mechanism for the degradation of the dye has been presented, and the degraded intermediates have been identified using the liquid chromatography-mass spectroscopy technique. The high efficiency of nanoparticles as photocatalysts has opened a promising application for the removal of hazardous dye from industrial effluents contributing indirectly to environmental cleanup process.

Surface Plasmon Properties of Silver Nanostructures Fabricated Using Extremely Non-Equilibrium, Hot and Dense Plasma

We present fabrication of silver nanostructures on glass substrates using highly energetic and high fluence material ions generated by one shot of hot, dense and extremely non-equilibrium plasma such as found in modified dense plasma focus (DPF) device. The substrates were first placed at 4.0 cm and 6.0 cm from the top of anode. Nanodots and nanocapsules are observed in the scanning electron microscopy (SEM) images of silver ions deposited with DPF shot on glass. The interparticle distance is found to decrease whereas mean size of nanodots is found to increase slightly when the distance of glass substrate is increased from 4.0 cm to 6.0 cm. The X-ray diffraction (XRD) pattern of the fabricated nanostructures has peaks at 2θ equals 37.90o, 44.24o and 64.20o which correspond to (111), (200) and (220) planes of silver having face-centered cubic structure. The nanostructures obtained on glass placed at 4.0 cm show surface plasmon resonance (SPR) peak at 420 nm whereas nanostructures obtained on glass placed at 6.0 cm has a SPR peak at 428 nm. Redshift of the SPR peak is attributed to increased interaction as a result of decrease in interparticle distance of the nanostructures as well as increase in mean size of nanodots.

Nanosized silver–palm pollen nanocomposite, green synthesis, characterization and antimicrobial activity

Palm pollen (PP) has been widely used in nutrition, pharmaceutical and cosmetic industries. In the present study, we explored the potential of PP in the synthesis of a silver nanoparticle (Ag NP). PP was used as both reducing and stabilizing agent. The Ag/PP nanocomposite was examined by field emission electron microscopy, X-ray diffraction, Fourier transform infrared (FT-IR) spectroscopy, ultraviolet spectroscopy and zeta potential measurement. The biosynthesized NPs showed surface plasmon resonance centered at 425 nm with an average particle size measured to be 23 nm and a zeta potential of −30.9 mV. Prominent FT-IR signals were obtained and ascribed to phenolic and carbohydrate compounds involved in the formation of the Ag NPs, and proteins which participated in stabilization of the Ag NPs. The biologically synthesized Ag NPs were found to be extremely effective against E. coli (13.8 ± 0.25 mm) with a minimum inhibitory concentration of 20 µg/mL. Thus, such biosynthesized Ag NPs can be used in medicinal applications.