Silver Surface Plasmon Research Articles

Green synthesis of magnetic silver nanocomposite: the photocatalytic performance of nanocomposite to decolorize organic dyes

ABSTRACT The magnetite-silver nanocomposites (Fe3O4-Ag NCs) were synthesized via a facile and green process by Citrus sinensis peel extract. The deposition of silver nanoparticles (NPs) was confirmed by observing an absorption peak at the maximum wavelength at 422 nm in the suspension solution of samples, which is related to silver surface plasmon resonance (SPR). The characteristic diffraction patterns of Fe3O4 and Ag phases were characterized utilizing the XRD patterns and the average size of the crystals was 21 nm. The photocatalytic behavior of Fe3O4-Ag NCs was studied for the destruction of three organic dyes methyl green (MG), methyl orange (MO), and methylene blue (MB) below UV radiation. The effect of the amount of photocatalyst and volume of hydrogen peroxide as an oxidant in the process of dye degradation was also investigated. The complete degradation time of dyes MB, MG, and MO under UV irradiation in the presence of 0.002 g Fe3O4-Ag NCs were 57, 33, and 49 min, respectively. The time of degradation reactions showed the high photocatalytic performance of Fe3O4-Ag NCs. These results proved that the synergistic effect of magnetite in the role of supporting the silver NPs was a significant contribution to the excellent decolorization behavior of Fe3O4-Ag NCs.

Phytomediated synthesis of silver nanoparticles using Lepidium Sativum L. and their antifungal and cytotoxic potential

Bio-inspired synthesis of nanoparticles has received immense attention recently due to their vast applications in the biomedical field. Herein, a facile process using aqueous extracts of Lepidium sativum was used for the synthesis of nanosilver. The phytosynthesized silver nanoparticles showed characteristic silver surface plasmon absorption peaks at 420 and 440 nm for nanoparticles synthesized by Lepidium sativum seeds and leaves, respectively. Moreover, the spherical, non-aggregated nanoparticles exhibited a particle size of 150 nm and a zetapotential of -15.2 mv countering 111 nm and a zeta potential of -20 mv for those phytosynthesized by Lepidium sativum seeds and leave aqueous extract correspondingly. Both phytofabricated silver nanoparticles exhibited a potential antifungal effect against Candida albicans with a minimum inhibitory concentration of 1.75 and 2.08 ppm and a promising cytotoxic effect against MCF-7 breast cancer cell line with an IC­50 of 20.1 and 9.3 ppm for nanosilver phytosynthesized by seeds and leaves extracts respectively. The current work provided a simple, environmentally friendly approach for the green synthesis of silver nanoparticles with a potential anticandidal and cytotoxic action against the MCF-7 breast cancer cell line. However, more investigation is required to clarify their safety and precise mode of action.

Nanoarchitectonics of Ag-modified g-C3N4@halloysite nanotubes by a green method for enhanced photocatalytic efficiency

In this study, a facile and cost effective green synthesis has been utilized for the synthesis of silver nanoparticles (Ag-NPs)–modified graphitic carbon nitride (Ag-g-C3N4) and halloysite nanotubes (HNTs) using Centella Asiatica (L.) extract, urea and mineral source of natural halloysite (HNTs), respectively. Here, silver ions (Ag+) were reduced to Ag-NPs using an aqueous Centella Asiatica (L.) as reducing and capping agent. The synthesized Ag-g-C3N4@HNTs were characterized by various physiochemical methods such as XRD, FT-IR, BET, SEM, TEM, EDS–mapping, UV–vis-DRS, PL, XPS and EPR methods. In the photocatalytic experiment, Ag-g-C3N4@HNTs nanocomposite with silver surface plasmon resonance of Ag-NPs and multi-layer hollow nanotubes was outperformed by the individual components. With an in-depth study on the photocatalytic mechanisms, we can conclude that the enhanced performance of the nanocomposite is due to the effective separation of photogenerated electrons and superoxide radicals (•O2–) in water molecules. The photocatalyst preserved excellent photostability for up to four cycles (with a minor activity reduction from 95% to 91%). These results demonstrated the development of novel semiconductors from inexpensive resources with effective photoactivity to mitigate environmental problems.

Green Biosynthesis of Silver Nanoparticles from Moringa oleifera Leaves and Its Antimicrobial and Cytotoxicity Activities.

The plant occupied the largest area in the biosynthesis of silver nanoparticles, especially the medicinal plants, and it has shown great potential in biotechnology applications. In this study, green synthesis of silver nanoparticles from Moringa oleifera leaves extract and its antifungal and antitumor activities were investigated. The formation of silver nanoparticles was observed after 1 hour of preparation color changing. The ultraviolet and visible spectrum, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy techniques were used to characterize synthesis particles. Ultraviolet and visible spectroscopy showed a silver surface plasmon resonance band at 434 nm. Fourier transform infrared analysis shows the possible interactions between silver and bioactive molecules in Moringa oleifera leaves extracts, which may be responsible for the synthesis and stabilization of silver nanoparticles. X-ray diffraction showed that the particles were a semicubic crystal structure and with a size of 38.495 nm. Scanning electron microscopy imaging shows that the atoms are spherical in shape and the average size is 17 nm. The transmission electron microscopy image demonstrated that AgNPs were spherical and semispherical particles with an average of (50–60) nm. The nanoparticles also showed potent antimicrobial activity against pathogenic bacteria and fungi using the well diffusion method. Candida glabrata found that the concentration of 1000 μg/mL exhibited the highest inhibition. As for bacteria, the concentration of 1000 μg/mL appeared to be the inhibition against Staphylococcus aureus. Moringa oleifera AgNPs inhibited human melanoma cells A375 line significant concentration-dependent cytotoxic effects. The powerful bioactivity of the green synthesized silver nanoparticles from medical plants recommends their biomedical use as antimicrobial as well as cytotoxic agents.

Performance Optimization of Surface Plasmon Resonance Imaging Sensor Network Based on the Multi-Objective Optimization Algorithm.

In this work, we report performance optimization of a wireless sensor network (WSN) based on the plain silver surface plasmon resonance imaging (SPRi) sensor. At the sensor node level, we established the refractive index-thickness models for both gold and silver in the sensor and calculated the depth-width ratio (DWR) and penetration depth (PD) values of the sensor of different gold and silver thicknesses by the Jones transfer matrix and Kriging interpolation. We optimized the DWR and PD simultaneously by using the multi-objective optimization genetic algorithm (MOGA). In the following performance optimization of WSN, we simultaneously optimized the transmission success rate and information dimension with the number of nodes and transmission failure rate of the sensor node as variables by the same algorithm. By calculating the information dimension and the transmission success rate of each Pareto optimal solution, we obtained the number of nodes and transmission failure probability of the node available for practical deployment of WSN. The above results indicate that the Pareto optimal solution set obtained from MOGA can help to provide the best solution for the optimization of some certain performance parameters and also assist us in making the trade-off decision in the structure design and network deployment if optimal values of all the performance parameters can be obtained simultaneously.

Analysis of Adhesion Strength between Silver Film and Substrate in Plain Silver Surface Plasmon Resonance Imaging Sensor

Analysis of Adhesion Strength between Silver Film and Substrate in Plain Silver Surface Plasmon Resonance Imaging Sensor

Sensitivity Optimization of Plain Silver Surface Plasmon Resonance Imaging Sensor

Plain silver surface plasmon resonance imaging (SPRi) sensor has been studied extensively due to its high sensitivity and desirable stability in liquid environments. To further enhance sensitivity performance of the sensor, angular sensitivity, angular slope and depth-width ratio (DWR) of SPR curve, and imaging sensitivity are evaluated at different thickness combinations of the gold and silver films respectively. In this work, the angular slope of SPR curve is found to be the critical factor to the optimized imaging sensitivity of plain silver SPRi sensor. In the comparative study, the above parameters of the plain silver SPR sensor, single gold film and bimetallic SPRi sensors are compared. Plain silver SPRi sensor is proved to be of the highest imaging sensitivity, which is 4.08 and 1.18 times imaging sensitivity of the single gold film and bimetallic SPRi sensors separately.

Effect of Different Process Parameters on the formation of Silver Nanoparticles using Crude and Modified Neem (Azadirachta indica) Leaf Extracts

In recent times, the biosynthesis of nanoparticles, which has led to significant growth in the field of nanotechnology. The use of plant extracts has become an impetus in this field as it is a simple and eco-friendly method. This study was an attempt to study different parameters in biosynthesis of silver nanoparticles using Azadirachta indica (Neem) leaf extracts. Four different process parameters such as concentrations of neem leaf extract, types of neem leaf extract, mixing ratios and the reaction time period were investigated on the formation of silver nanoparticles. Initially, the formation of silver nanoparticles was detected by the visual observation. Then, the synthesized silver nanoparticles were characterized using UV-Visible spectroscopy and scanning electron microscopy (SEM). The change of color from yellow to reddish brown color confirmed the formation of silver nanoparticles. The silver surface plasmon resonance (SPR) band obtained in the expected visible range of UV-Visible spectroscopy confirmed the synthesis of the nanoparticles. SEM images showed that silver nanoparticles are roughly spherical and of uniform particle size, and the average particle size is 100 nm. Further, the maximum absorbance of SPR band was considerably varied with different process parameters used in the present study. The UV-Visible spectra of 2.5 g/100 mL of crude neem leaf extract without any dilution showed maximum absorbance in the expected range with the mixing ratio of (Neem and AgNO3) 1:8. However, the maximum absorbance of modified neem leaf extracts (pH 10) resulted lower in value than the crude extracts in the 20 times diluted sample with the mixing ratio of 1:9. Moreover, modified extract with UV radiation exposure increased the absorbance in the expected visible range. It concludes that fine tuning of the bioprocess parameters would enhance nanoparticle synthesis.

Photocatalytic Conversion of Organic Pollutants in Air: Quantum Yields Using a Silver/Nitrogen/TiO2 Mesoporous Semiconductor under Visible Light

This research studies the photocatalytic conversion of methanol (25–90 µmol/L range) as a volatile organic compound (VOC) surrogate into CO2, using a N/Ag/TiO2 photocatalyst under visible light irradiation in a Photo-CREC Air unit. The N/Ag/TiO2 mesh supported photocatalyst is prepared via the solvothermal method. While the bare-TiO2 is inactive under visible light, the N/Ag/TiO2 2 wt.% loaded stainless-steel woven mesh displays 35% quantum yields, with 80% absorbed photons and 60% methanol conversion in a 110 min irradiation period. Results obtained are assigned to silver surface plasmon resonance, silver and nitrogen species synergistic impacts on band gap, and their influence on particle agglomerate size and semiconductor acidity. The determined quantum yields under visible light in a Photo-CREC Air unit, are the highest reported in the technical literature, that these authors are aware of, with this opening unique opportunity for the use of visible light for the purification of air from VOC contaminants.

Improving the electroluminescence of Si nanocrystal via black silicon and silver surface plasmons

In this paper, black silicon (Si) and silver (Ag) surface plasmons were used to improve the electroluminescence (EL) intensity of silicon nanocrystals (Si-nc), and the mechanism of black Si and Ag nanoparticles enhancing the EL of Si-nc LED is analyzed. The Ag nanoparticles are introduced into Si-nc LED to generate surface plasmons. The surface plasmons radiate the local electromagnetic field, which can increase the excitation probability of Si-nc and increase the EL intensity of Si-nc LED. In addition, black silicon can improve the charge injection efficiency and light emission efficiency. The atomic force microscope (AFM) and reflectivity spectra of black silicon at different etching time, as well as the AFM and absorption spectra of Ag nanoparticles at different postannealing temperatures, were measured. Three different device structures were designed. The EL intensity of Si-nc increased by 3.2 times at the etching time of 5 minutes and increased by 4.9 times at the postannealing temperature of 200 °C, respectively. A maximal 8.5-fold EL enhancement of Si-nc was readily achieved after using the black Si as substrate and incorporating Ag surface plasmons.

Anticrossing Behavior in Nanolayered Heterostructures Caused by Coupling between a Planar Waveguide Mode in an Anthracene Single Crystal and a Silver Surface Plasmon Polariton Mode: Implications for Attenuated Total Reflection Spectroscopy

Coupling between a planar waveguide (PWG) mode in an organic single crystal and a surface plasmon polariton (SPP) mode is investigated in this paper. Anticrossing behavior appearing under the stron...

The Silver Surface Plasmon Enhancement for Er3+ Ion Upconversion of 978 and 1 539 nm Laser in Bismuth Glass

The Silver Surface Plasmon Enhancement for Er3+ Ion Upconversion of 978 and 1 539 nm Laser in Bismuth Glass

Circular dichroism of spatially complementary chiral nanostructures

Circular dichroism (CD) is widely used in biology, medicine, and physics. Three-dimensional (3D) chiral structures have been extensively studied because of their ability to produce significant CD effects. Previously reported 3D chiral structures are limited due to the complexity of fabrication processes and CD mechanisms. Here, spatially complementary chiral nanostructure (SCCN) arrays, which comprise bottom silver films with zigzag-shaped nanoslit and top complementary silver zigzag-shaped nanowires, are theoretically and experimentally shown to provide the CD effect. SCCN arrays are prepared experimentally by combining electron beam lithography (EBL) with normal electron beam deposition (NEBD) method and by utilizing EBL and NEBD only once. Numerical results demonstrate that localized surface plasmon excited on top complementary silver zigzag-shaped nanowires and surface plasmon polariton excited on bottom silver films with zigzag-shaped nanoslit result in the CD effect of SCCN arrays. In addition, the CD effect can be tuned by changing the width of the top complementary silver zigzag-shaped nanowires. Such type of chiral nanostructures has easy tunability, simple fabrication, and a better understanding of chiral optical response, which provides a new design for spatially chiral optoelectronic devices.

Instrumental Characterization and Antibacterial Investigation of Silver Nanoparticles Synthesized From Garcinia Kola Leaf

The need to devise another method of synthesizing nanoparticles from sources that are eco-friendly, non-hazardous and cost effectiveness is of great importance in preventing environmental and health problems. The aim of this study was to evaluate the efficiency of Garcinia kola leaves as reducing and stabilizing agent for silver nanoparticles synthesis. The leaves of Garcinia kola obtained were authenticated, air dried, pulverized and extracted. The extract was mixed with aqueous solution of silver nitrate solution to form silver nanoparticles and were characterized using Ultra violet (UV) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The antibacterial investigation of the synthesized silver nanoparticle was carried out following the disk diffusion method. UV analysis revealed the silver surface plasmon band at 425.18 nm, The FTIR indicated -OH, -C=C- and alkane as the functional groups responsible for the stabilization of the silver nanoparticle formed. The morphological assessment from SEM and TEM analysis confirmed that the silver nanoparticle formed are spherical in shape with an average particle size of 28.80nm.The EDX analysis ascertained that the silver surface plasmon resonance at 2.8–3.2 keV was confirmed the reduction of silver ion (Ag+ to Ag0). The XRD study revealed the crystalline nature of the nanoparticles synthesized. The antibacterial investigation showed high inhibition against the growth of tested bacteria. This study ascertained that the green synthesis of silver nanoparticle without the use of harmful solvent that are offensive to the environment is achievable. 
 Keywords: Silver nanoparticles, Biosynthesis, Characterization, Antibacterial activity and Garcinia kola.

Green synthesis of Ag/TiO2 Nanocomposite Assisted by Gambier Leaf (Uncaria gambir Roxb) Extract

Studies of green synthesis of nanoparticles mediated by plants extract is extensively explored and studied in recent time due to eco-friendliness, cost-effectiveness, and use a minimum amount of toxic chemicals in the process of inorganic material synthesis. In this study, the immobilization of silver nanoparticles on the surface of titanium dioxide (TiO2) was carried out using Uncaria gambier Roxb. leaf extract as a silver ion (Ag+) reducing agent. The synthesized Ag/TiO2 nanocomposite was characterized by UV-Vis spectroscopy, X-ray diffraction (XRD), and Diffuse Reflectance Spectroscopy (DRS). The formation of silver nanoparticles was confirmed through UV-Vis spectroscopic analysis, which showed a silver surface plasmon resonance (SPR) band at 426 nm. The X-ray diffraction pattern shows that Ag can inhibit the transition of the anatase into rutile phase. The presence of Ag particles in TiO2 can increase the absorption ability from an initial wavelength of 407 nm to 438 nm. Based on the results of Rhodamin B degradation, it can be seen that Ag/TiO2 has a higher photocatalytic activity than bare TiO2 with 99% percent degradation at 120 minutes of irradiation time.

Design and analysis of thin film GaAs solar cells using silver nanoparticle plasmons

In this paper, we present a design and analysis of thin film GaAs solar cells using silver nanoparticle array. In the front surface design of GaAs solar cells, we assembled silver nanoparticle array on the top of quarter wavelength antireflection layers. For rear surface design, a reflection layer structure is designed using surface plasmon effects induced by the silver nanoparticle array. The transmittance of light for front and rear surfaces is monitored by using finite difference time domain (FDTD) method in the wavelength range of 400–900 nm. The simulation results confirm that the utilization of light within solar cells may be increased by optimizing the structural parameters associated with silver nanoparticle array. This analysis also revealed that grating characteristics of silver nanoparticle array and surface plasmon effects induced by silver nanoparticles play important roles for effective design of GaAs solar cells.

Extracellular biosynthesis of silver nanoparticles from Penicillium italicum and its antioxidant, antimicrobial and cytotoxicity activities.

The synthesis of silver nanoparticles and its antioxidant, antimicrobial and cytotoxic activities was investigated and extracellularly biosynthesized using Penicillium italicum isolated from Iraqi lemon fruits. The formation of synthesized nanoparticles was observed after 72h of incubation. Color changing, ultraviolet and visible spectrum, X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and energy dispersive analysis X- ray confirmed the biosynthesis and characterization of silver nanoparticles. Ultravioletandvisible spectroscopy showed silver surface plasmon resonance band at 415nm. X- ray diffraction showed that the particles were crystalline with face-centered cubic lattice phase and a size of 39.5nm. Fourier transform infrared analysis shows the possible interactions between silver and bioactive molecules, which may be responsible for synthesis and stabilization of silver nanoparticles. Scanning electron microscopy imaging revealed different morphologies of the AgNPs, some of nanoparticles were close to spherical in shape, while others had platelet like structure, in size range between 32 and 100nm. The transmission electron microscopy image demonstrated that AgNPs were spherical with a size < 50nm. The biosynthesized silver nanoparticles were proved to be potential antioxidants by showing effective radical scavenging activity against 2, 2-diphenyl-1-picrylhydrazyl, hydroxyl radical and resazurin. The nanoparticles also showed potent antimicrobial activity against various pathogens, including bacteria and fungi as well as significant concentration-dependent cytotoxic effects against human breast cancer cells. The powerful bioactivity of the synthesized silver nanoparticles recommends their biomedical use as antioxidant, antimicrobial as well as cytotoxic agents.

Graphene Oxide Effect on Improvement of Silver Surface Plasmon Resonance D-Shaped Optical Fiber Sensor

Abstract This research focuses on the side-polished Single-Mode Optical Fibers (SMOF) as refractive index (RI) sensor utilizing properties of Surface Plasmon Resonance. The SMOF with cladding stripped off shows a D-shaped optical fiber with high sensitivity functionalization. Here we show silver protected by graphene oxide (GO) as viable candidates. A few layers of GO on top of silver thin layer were applied as a material to overcome silver coating degradation process. This silver/GO sensor was characterized using various RIs of analyte likely deionized water and alcohol solutions. Sensor with GO has shown fast response and high sensitivity in respect of RI, where sensitivity increases in range from 1.30 to 1.34 RIU (refractive index unit). This device shows highest sensitivity of up to 833.33 nm/ RIU. The polishing process using SMOF stops at few microns above the core of the fiber with the drop of output power fixed to be 1 dB as an indication to standardize the amount of cladding been removed. The thickness of 30 nm Ag was deposited using electron beam evaporation method on D-shaped optical fiber with subsequent protected layer of GO in solutions form. The use of COMSOL Multiphysics has also been carried out to observe numerical findings. The response of the GO has shown a sensitivity improvement which proves new promising approaches for the newly developed sensors.

Green synthesis and characterization of silver nanoparticles using leaves extracts of neem (&lt;i&gt;Azadirachta indica&lt;/i&gt;) and bitter leaf (&lt;i&gt;Vernonia amygdalina&lt;/i&gt;)

Silver nanoparticles (AgNPs) were synthesized using Azadirachta indica and Vernonia amygdalina leaves extracts. Current nanotechnology research uses a lot of chemicals which are quite often toxic and flammable. In this research article, a simple and eco-friendly synthetic method for silver nanoparticles preparation was reported using the leaves extracts of Azadirachta indica (commonly called neem) and Vernonia amygdalina (commonly called bitter leaf) as reducing agents. The synthesis of AgNPs was monitored and confirmed with the use of UV-Visible spectrophotometer, Fourier Transform Infrared (FTIR) spectroscopy and Powder X-ray Diffraction (PXRD). The reduction process of Ag+ to Ag0 was observed by the change of color from yellow to brown for both leaves. The UV-Vis Spectra of AgNPs in aqueous solution showed absorbance peaks around 455 nm for Azadirachta indica and 460 nm for Vernonia amygdalina due to silver surface plasmon resonance. Crystallinity of the AgNPs was confirmed with PXRD. In addition, FTIR spectra showed that the AgNPs were capped with phytochemicals from the leaves extracts.Keywords: AgNPs, UV-Vis, FTIR, Azadirachta indica, Vernonia amygdalina

Facile Photochemical Syntheses of Conjoined Nanotwin Gold-Silver Particles within a Biologically-Benign Chitosan Polymer.

A simple photochemical method for making conjoined bi-metallic gold-silver (Au/Ag) nanotwins, a new breed of nanoparticles (NPs), is developed. To the best of our knowledge, the photochemical method resulted in distinct, conjoined, bimetallic nanotwins that are different from any well-established alloyed or core-shell nanostructures in the literature. The conjoined Au-Ag NPs possessed surface plasmon resonance (SPR) properties of both metals. The bimetallic nanostructures possessing distinctive optical properties of both metals were obtained using Au NPs as seeds in the first step, followed by the addition of a silver precursor as feed in the second step during a photochemical irradiation process. In the first step, small, isotropic or large, anisotropic Au NPs are generated by photoinduced reduction within a biocompatible chitosan (CS) polymer. In the second step, a silver precursor (AgNO3) is added as the feed to the AuNPs seed, followed by irradiation of the solution in the ice-bath. The entire photochemical irradiation process resulting in the formation of bimetallic Au-AgNPs did not involve any other reducing agents or stabilizing agents other than the CS polymer stabilizer. The small, conjoined Au-Ag bi-metallic NPs exhibited SPR with peak maxima centering at ~400 nm and ~550 nm, whereas the large conjoined nanoparticles exhibited SPR with peak maxima centering at ~400 nm, 550 nm, and 680 nm, characteristic of both gold and silver surface plasmons in solution. The tunability in the SPR and size of the bimetallic NPs were obtained by varying the reaction time and other reaction parameters, resulting in average sizes between 30 and 100 nm. The SPR, size, distribution, and elemental composition of the bi-metallic NPs were characterized using UV-Vis absorption, electron microscopy, and energy dispersive X-ray spectroscopy (EDS) studies.