Presence Of Surface Plasmon Resonance Research Articles

BIOGENIC NANOSCALE SILVER PARTICLES: A STUDY ON THEIR ANTIMICROBIAL POTENTIAL

A sustainable method for producing silver nanoparticles (AgNPs) using Vitis vinifera seed extract has been proposed. The formation of AgNPs was confirmed through spectroscopy, X-ray Diffraction (XRD), and electron microscopy. The UV-visible spectrophotometer revealed distinct absorbance peaks at 398.80 nm and 416.24 nm, signifying the presence of Surface Plasmon Resonance (SPR). XRD, quasi-elastic light scattering, and surface topography results exposed that the AgNPs were crystalline and had rod-like shapes. FTIR identified seed extract functional groups that reduced silver ions to AgNPs and acted as capping agents. The nanoparticles showed inhibition against gram-positive microorganisms like Staphylococcus pneumonia and Mycobacterium tuberculosis, surpassing their effectiveness against gram-negative microorganisms such as Pseudomonas fluorescens. This environmentally responsible approach not only offers a green synthesis method but also holds promise for combating specific pathogenic bacteria.

Polychaeta-mediated synthesis of gold nanoparticles: A potential antibacterial agent against Acute Hepatopancreatic Necrosis Disease (AHPND)–causing bacteria, Vibrio parahaemolyticus.

Gold nanoparticles (AuNPs) have emerged as a promising application in aquaculture. Their nano-sized dimensions, comparable to pathogens offer potential solutions for combating antibiotic resistance. In this study, AuNPs were synthesized by using polychaetes, Marphysa moribidii as the bio-reducing agent. Modifications were made to reduce agglomeration in green-synthesized AuNPs through ultrasonication. The antibacterial activities of AuNPs against V. parahaemolyticus were evaluated. The physicochemical characteristics of the green synthesized AuNPs were comprehensively investigated. The successful formation of AuNPs was confirmed by the appearance of a red ruby colour and the presence of surface Plasmon resonance (SPR) absorption peaks at 530 nm as observed from UV–vis spectroscopy. Scanning electron microscopy (SEM) revealed spherical-shaped AuNPs with some agglomerations. Transmission electron microscopy (TEM) showed particle size of AuNPs ranging from 10 nm to 60 nm, meanwhile dynamic light scattering (DLS) analysis indicated an average particle size of 24.36 nm. X-ray diffraction (XRD) analysis confirmed the high crystallinity of AuNPs, and no AuNPs were detected in the polychaetes extracts prior to synthesis. A brief ultrasonication significantly reduced the tendencies for AuNPs to coalesce. The green-synthesized AuNPs demonstrated a remarkable antibacterial efficacy against V. parahaemolyticus. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) tests revealed that a concentration of 0.3 g/ml of AuNPs effectively inhibited V. parahaemolyticus. These findings highlighted the potential of green-synthesized AuNPs as antibacterial agents for the prevention and management of AHPND in aquaculture.

Facile one-step synthesis of gold nanoparticles using Viscum album and evaluation of their antibacterial potential.

Nanostructure gold nanoparticles (Au NPs) are well-known biological active materials, synthesised under different environment-friendly approaches that has gained significant interest in the field of biomedicine. This study investigated a novel, fast, easy, cost-effective and the eco-friendly method to synthesise Au NPs from mediated Viscum album Linn plant extract, where the plant metabolites act as stabilising and reducing agents. The synthesised Au NPs were analysed by UV/Vis spectroscopy that gave strong signals and a sharp absorption peak at 545nm due to the presence of surface plasmon resonance (SPR) bands. In addition, energy dispersive X-ray spectroscopy (EDX) showed that strong signals of Au NPs appeared at 9.7 and 2.3keV, as the rays of light passed. X-ray diffraction recognised the crystalline material and provided information on the cell unit that the synthesised Au NPs are face-centreed cubic in structure. The diffraction of X-ray spectra showed intense peaks at 38.44°, 44.7°, 44.9° and 77.8°. The mediated V. album plant extracts and synthesised Au NPs were screened against gram-positive and gram-negative (Enterobacter, Salmonella typhi, Escheria coli and Bacillus subtilis) bacterial strains, confirming their antibacterial potential. Au NPs showed strong antibacterial activity due to its unique steric configuration. Au NPs damaged bacterial cell membrane leading to the leakage of the cytoplasm and death of the cell.

Properties of SiC and Si3N4 Thin Films Containing Self-Assembled Gold Nanoparticles

The properties of semiconductor materials can be strongly affected by the addition of metallic nanoparticles. Here we investigate the properties of SiC + Au and Si3N4 + Au thin films prepared by magnetron sputtering deposition followed by thermal annealing. The influence of gold addition on the optical and electrical properties is explored. We show the formation of self-assembled Au nanoparticles in SiC and Si3N4, with the size and arrangement properties determined by the deposition and annealing conditions. Both SiC- and Si3N4-based films show an increase in the overall absorption with increasing Au content, and its decrease with increasing annealing temperature. All films show the presence of surface plasmon resonance, whose peaks shift toward larger wavelengths with increasing Au nanoparticle size. The resistivity significantly drops with the Au content increase for both types of matrices, although the resistivity of Si3N4-based films is much higher. The incorporated quantity of Au in the host matrix was chosen in such a way to demonstrate that a huge range of optical and electrical characteristics is achievable. The materials are very interesting for application in opto-electronic devices.

Synthesis of Ag nanoparticles capped by thiol molecules

The controlled size, Form and organisation of metal nanocrystals is significant because of strong relationship between these components with electrical photocatalytic and optical properties. Among the metal nanocrystals nobles’ metal is that the most generally utilized in the technology trade during a types of application like medical drug, antiviral antifungal, anticancer and catalytical biosensing. Herein we report the an environmental-friendly and facile approach was developed to synthesize Ag nanoparticles (Ag NPs) by chemical precipitation route using thioglycolic acid (TGA) as capping molecules with NaBH4 as reducing agent. The particles size is manipulated by attention of the precursor and capping molecules. The optical absorption and photoluminescence measurement shows the clear presence of surface plasmon resonance (SPR) with small size Ag nanoparticles. The X-ray powder diffraction (XRD) measurements shows the face centred cubic (fcc) phase. The calculated particle size is 18.00 nm in size. The estimated size from TEM measurement is 20.0 nm. The present method of synthesis of silver nanoparticles is low cost and useful in biological imaging and biosensing applications.

Microwave assisted biosynthesis of Borassus flabellifer fruit mediated silver and gold nanoparticles for dye reduction, antibacterial and anticancer activity

Biosynthesis of silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) employing Borassus flabellifer fruit (BFF) extract as reducing and stabilizing agent under microwave irradiation is demonstrated in the present work for the reduction of organic dyes and biological applications. Formation, structure, size, morphology and binding state of the as-synthesized nanoparticles were characterized by UV–vis spectrophotometer, X-ray diffraction (XRD), Fourier transform infrared (FTIR), Dynamic light scattering (DLS), Transmission electron microscopy (TEM) techniques, and X-ray photoelectron spectroscopy (XPS). The presence of surface plasmon resonance (SPR) absorption band at 410 nm and 534 nm in UV-Visible spectra revealed the formation of AgNPs and AuNPs which was supported by XRD results. The average particle sizes of AgNPs and AuNPs with spherical morphology were in the range of ~ 7–9 nm and ~ 5–7 nm, respectively. The reduction of methylene blue (MB) and congo red (CR) dye was observed at faster rate over AgNPs and AuNPs with high selectivity and sensitivity. The biosynthesized NPs demonstrated potential antibacterial and anticancer properties on tested microorganisms and Human breast cancer (MCF-7) cells. The mechanism of the reduction of MB and CR dyes and biological activity over biosynthesized NPs are discussed. The facile and environmentally benign NPs could be a new alternative catalysts for toxic dye reduction and the proposed biological applications.

Fabrication of stable high-performance urchin-like CeO2/ZnO@Au hierarchical heterojunction photocatalyst for water remediation

In this paper, the urchin-like CeO2/ZnO@Au photocatalyst was rationally designed and prepared through hydrothermal method, chemical precipitation and photo reduction deposition. The optimal photocatalyst (CZA8) degraded Rhodamine B (RhB), 4-nitrophenol (4-NP) and Naproxen (NPX) about 100% within 20 min, 91.4% within 60 min and 88.9% within 30 min under Xe lamp illumination, respectively. Besides, the CZA8 possesses outstanding photo corrosion resistance capacity which has been verified with the cycle degradation experiments. The photocatalyst displays excellent light response and efficient separation of photo-induced carriers due to the fabrication of type-II heterojunction, the presence of surface plasmon resonance (SPR) effect and as well as the oxygen vacancy. The oxygen vacancy was systematically characterized by XPS, PL and Raman. Moreover, the photocatalytic degradation pathways are proposed based on the LC-MS results. Finally, a novel photocatalytic mechanism for photocatalytic oxidation of RhB, 4-NP and NPX is discussed and schematically illuminated.

Investigation of Electrical Conductivity of Gold Nanoparticles Scattered in Polyvinylidene Fluoride/Polyvinyl Chloride via Laser Ablation for Electrical Applications

The electrical characterization of polyvinylidene fluoride (PVDF)/polyvinyl chloride (PVC) composites after scattering by gold nanoparticles (AuNPs) has been studied by a one-way laser ablation process. AuNPs@PVDF/PVC nanocomposites were synthesized in films formed via traditional casting technique. The electrical conductivity of AuNPs@PVDF/PVC films was also studied. FT-IR indicated that adding AuNPs to PVDF/PVC confirmed the interaction and complexation between a PVDF/PVC composite and AuNPs. UV–Vis results confirmed the presence of surface plasmon resonance of AuNPs at 519 nm. The indirect optical bandgap was decreased by increasing the scattered AuNPs in the PVDF/PVC from 2.26 eV for pure PVDF/PVC to 1.61 eV for AuNPs@PVDF/PVC at 20 min ablation time. The addition of AuNPs to a PVDF/PVC composite enhances the conductivity due to the increase in the number of ions resulting from increasing ablation time.

MICROWAVE ASSISTED GREEN SYNTHESIS OF SILVER NANOPARTICLES USING COLEUS AMBOINICUS LEAF EXTRACT

Objective: Current study is aimed at the formulation of silver nanoparticles loaded with the extract of Coleus amboinicus leaf extract by microwave irradiation. A facile and green synthesis of silver nanoparticles by using a biological agent such as plant extracts with the aid of microwave irradiation is proposed as an economical and environmentally friendly approach alternative to chemical and physical methods.
 Methods: In order to fabricate silver nanoparticles by microwave irradiation, aqueous extract of leaves Coleus amboinicus (CA) were treated with aqueous silver nitrate solution and mixture was placed in the microwave oven for exposure to microwave. Optimizations of the process were carried out by varying the quantity of extract, silver nitrate concentration and duration of microwave irradiation. Formations of nanoparticles were confirmed by UV-visible spectroscopy observing for the presence of surface plasmon resonance (SPR) peak. Nanoparticles were characterized by scanning electron microscopy, transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectroscopy.
 Results: Silver nanoparticle showed the SPR optical absorption band peak at 434 nm by UV-Visible spectrophotometer. Reaction mixture containing 2 mmol silver nitrate and 9 ml of extract subjected to microwave irradiation of 60 sec at a temperature of 60 °C was found to be optimised condition, which produced nanoparticles that were spherical in shape and had an average diameter of 15.685 nm.
 Conclusion: This research study opens an innovative design to progress our understanding of how silver nanoparticles behave can be optimized to improve their surface morphology, which is beneficial to improve its therapeutic effect.

Biosynthesis of gold nanoparticles (AuNPs) by marine baitworm Marphysa moribidii idris, hutchings and arshad 2014 (annelida: polychaeta) and its antibacterial activity

Gold nanoparticles (AuNPs) have unique and outstanding optical properties that can be applied in various applications. The current productions of AuNPs are cumbersome owing to the use of reducing agents which are highly reactive and toxic in nature. Hence, a biogenic synthesis of AuNPs by exploiting local marine baitworm (Polychaeta), Marphysa moribidii as potential reducing agents was conducted. AuNPs were biosynthesised by using different masses of polychaete extracts (5, 10, 15, and 20 g) and observed up to 3 months. The formation of AuNPs was confirmed by the appearance of red-ruby colour and the presence of surface plasmon resonance (SPR) absorption peaks (548–563 nm) from UV-Vis spectroscopy. The AuNPs were in spherical-like shapes with large aggregations based on scanning electron microscope (SEM). The average particle size and morphology of AuNPs were confirmed using transmission electron microscopy (TEM) (30–150 nm) and dynamic light scattering (DLS) (20–100 nm). Fourier transformed infrared (FTIR) analysis and X-ray diffraction (XRD) were carried out on polychaete extracts to explore the functional groups existing and also to prove the absence of AuNPs in them. Lastly, the antibacterial assessment of AuNPs was examined using Kirby-Bauer disc diffusion method and revealed the exhibition of antibacterial activity on both Gram-positive and Gram-negative bacteria.

Synthesis and photoluminescence of silver and europium codoped germinate tellurite oxyfluoride glasses

Germinate tellurite oxyfluoride glasses of composition TeO2-GeO2-WO3-Li2O3-EuF3-AgCl (TGEUAC) were synthesized by melt quenching and heat-treated for the growth of silver nanoparticles (AgNPs). The presence of surface Plasmon resonance (SPR) absorption band of silver species with Eu3+ ions absorptions peaks for differently heat-treated glass samples were measured by the absorption spectrum. The green, red and deep- red photoluminescence intensity variation of Eu3+ ions under the influence of AgNPs has been observed. Maximum three-fold enhancement of TGEUAC-6 sample for green, red and mainly deep- red emission of Eu3+ caused by SPR of silver nanoparticles has also been observed. On the other hand, emission quenching of after long heat-treated of other samples was attributed to back energy transfer from Eu3+ ions to silver species or local field saturation. The emission intensities characterized through the CIE diagram and energy transfer mechanism of the Ag NPs to Eu3+ ions in glasses are discussed for potential application of optical devices.

Tuning Surface Plasmon Resonance Peak of Glass Containing Metallic Nanoparticles

Recent development in various host glasses has a beneficial feature for its application in optical devices. This present work is done by incorporating TiO2 metallic nanoparticles (NPs) in glass matrix due to their surface roughness and plasmonic properties as well as to overcome the limitation of rare earth ions in stimulating emission. A series of tellurite glass is prepared with composition of (70-x-y)TeO2-2ÜZnO-9Na2O-1Er2O3-(x)TiO2, where x= 0, 0.1, 0.2 and 0.3 mol% via melt-quenching method. In addition, glass batch without erbium content is prepared in order to identify the presence of surface plasmon resonance (SPR) peak of metallic nanoparticles. Glass samples are characterized by using X-ray diffraction (XRD), Ultraviolet-Visible spectroscopy (UV-Vis) and Transmission electron microscopy (TEM). XRD pattern confirms the amorphous structure of glass. UV-VIS spectra of glass with erbium content shows the appearance of seven absorbance peaks represent the transitions of erbium ion from ground state to excited state. Glass sample without erbium content shows the appearance of plasmon peak in range of 554 nm to 555 nm due to contribution of titanium nanoparticles. TEM image confirmed the presence of titanium NPs with Gaussian distribution having mean aspect ratio of 1.5.

On the Role of Plasmonic Nanoparticles on the Photocatalytic of TiO2 Nanoparticles for Visible-Light Photoreduction of Bicarbonate

The potential application of anatase titanium dioxide (TiO2) nanoparticles for solar fuel generation has been recently attracting many attentions due to its excellent chemical stability. Nevertheless, the fast charge recombination during photoexcitation process may often reduce the photocatalytic activity. This work presents the role of plasmonic Au nanoparticles on enhancing the photocatalytic activity of TiO2 nanoparticles for a visible-light-driven conversion of bicarbonate to formate. Here, two types of nano-sized Au and TiO2 heterostructures, i.e., Au-TiO2 Janus nanostructures and core-shell Au@TiO2 nanostructures were successfully prepared and characterized using UV-Vis and HR-TEM. Results demonstrated that Au-TiO2 Janus nanostructures had a superior photocatalytic activity compared to TiO2 nanoparticles and core-shell Au@TiO2 nanostructures. This photocatalytic enhancement is believed due to the presence of surface plasmon resonance (SPR) phenomenon in Au nanoparticles that provides a Fermi energy level, which could prevent the charge recombination process during photoexcitation.

Exposing TiO2 (001) crystal facet in nano Au-TiO2 heterostructures for enhanced photodegradation of methylene blue

Abstract This article reports an investigation on the effect of crystal facet of TiO2 in nano Au-TiO2 heterostructures for enhanced photocatalytic degradation of organic dyes. Here, nano Au-TiO2 heterostructures with two distinct TiO2 morphologies, i.e. nanospindles and nanocubes, were successfully prepared and utilized for photodegradation of methylene blue (MB). Based on the photocatalytic experiments, it is found that TiO2 nanospindles exhibited superior photocatalytic performance than TiO2 nanocubes which primarily due to the exposure of (001) crystal facet. It is observed that the exposure of (001) crystal facet was able to increase the photocatalytic reaction rate by four folds. Additionally, integration with Au nanoparticles was also found to have a synergistic effect in photodegradation activity due to the presence of surface plasmon resonance (SPR) effect. According to the result, Au-TiO2 nanospindles was found to be most efficient catalyst for photocatalytic degradation of MB with pseudo-first order reaction rate of 0.1570 min−1.

Impact on optical, electrical and antibacterial response of microwave irradiated silver nanoparticles

Silve spectroscopy, Fourier transform infrared spectroscopy (FTIR), photoluminescence, Raman spectroscopy, X-ray powder diffraction (XRD), scanning and transmission electron microscopy (SEM–TEM), zeta potential and dynamic light scattering (DLS). The presence of surface plasmon resonance (SPR) band (416 nm) confirmed fabrication of AgNPs. The effect of microwave irradiation time showed that the size, shape and stability of AgNPs depend on increasing of peak intensity with increasing reaction time. FTIR spectrum confirmed the possible functional group in the product indicating presence of PVP. The enlargement in the size and agglomeration of nanoparticles were prevented by r nanoparticles (AgNPs) have been formulated using microwave irradiation from non-aqueous solution of silver nitrate (AgNO3) and poly (N-vinyl-2-pyrrolidone) (PVP) as a stabilizer. Ethanol has also been reacted like a reducer for microwave irradiation process which is quite rapid, homogeneous and efficient. The as synthesized AgNPs was further characterized by ultraviolet–Visible (UV–Vis)encapsulation of PVP during the reaction. XRD spectra illustrated that AgNPs are higher crystalline having face-centered cubic surface. The morphological analysis found that the AgNPs are homogeneous and spherical with the size of 18 ± 5 nm. The zeta potential measurement affirms the higher stability of AgNPs due to its negatively charged surface. The prepared AgNPs also exhibited electrical properties obeying the ohm’s law and significantly antimicrobial activities against Escherichia coli due to the small size.

Enhancement of Edge Emission of ZnO Nanorods in a Magnetic Field

Enhancement of UV luminescence and random lasing of disordered arrays of ZnO nanorods with Ag coating has been found to take place in a magnetic field of about 1 T at ambient temperature. A possible interpretation of the effect is suggested based on the assumption of the formation of magnetoexcitons in ZnO under action of a magnetic field in the presence of surface plasmon resonance.

Unconventional generation of optical vortex beam using axicon pair and a birefringent lens: Validation of plasmonic excitation

We generate a nondiffracted Bessel beam using an axicon. A simple setup is presented to generate a zero order Bessel beam. Moreover, we introduce certain modifications in this optical setup for unconventional generation of an optical vortex beam using an axicon pair and a birefringent lens. An optical vortex beam with a topological charge of 1 is generated, and the corresponding spiral pattern has been demonstrated, which confirms the presence of orbital angular momentum in the optical vortex beam. Further, plasmonic excitation is validated using both zero order and first order Bessel beams. Our approach to confirm the presence of surface plasmon resonance relies on the use of a Wollaston prism. We are able to separately identify the coupling of surface plasmons with the p-polarized components via the absence of the corresponding annular beam.

Atom beam sputtered Ag-TiO2 plasmonic nanocomposite thin films for photocatalytic applications

The development of nanocomposite coatings with highly enhanced photocatalytic activity is important for photocatalytic purification of water and air. We report on the synthesis of Ag-TiO2 nanocomposite thin films with highly enhanced photocatalytic activity by atom beam co-sputtering technique. The effects of Ag concentration on the structural, morphological, optical, plasmonic and photocatalytic properties of the nanocomposite thin films were investigated. UV–visible DRS studies revealed the presence of surface plasmon resonance (SPR) peak characteristic of Ag nanoparticles together with the excitonic absorption peak originating from TiO2 nanoparticles in the nanocomposites. XRD studies showed that the nanocomposite thin films consist of Ag nanoparticles and rutile TiO2 nanoparticles. The synthesized Ag-TiO2 nanocomposite thin films with 5at% Ag were found to exhibit highly enhanced photocatalytic activity for sun light driven photocatalytic degradation of methylene blue in water, indicating their potential application in water purification.

Quantum particle interacting with a metallic particle: Spectra from quantum Langevin theory

The effect of a nearby metallic particle on the quantum optical properties of a quantum particle in the four-level double Raman configuration is studied using the quantum Langevin approach. We obtain analytical expressions for the correlated quantum fields of Stokes and anti-Stokes photons emitted from the system and perform analysis on how the interparticle distance, the direction of observation or detection, the strengths of controllable laser fields, the presence of surface plasmon resonance, and the number density of the quantum particle affect the quantum spectra of the Stokes and anti-Stokes fields. We explore the physics behind the quantum-particle\char21{}metallic-nanoparticle interaction within the dipole approximation, that is, when the interparticle distance is much larger than the sizes of the particles. Our results show the dependence of the spectra on the interparticle distance in the form of oscillatory behavior with damping as the interparticle distance increases. At weaker laser fields the enhancement of quantum fields which manifests itself in the form of a Fano dip in the central peak of the spectra becomes significant. Also, the quantum-particle\char21{}metallic-nanoparticle coupling, which is affected by the size of the metallic nanoparticle and the number density of the quantum particle, changes the angular dependence of the spectra by breaking the angular rotational symmetry. In the presence of surface plasmon resonance the oscillatory dependence of the spectra on the interparticle distance and angles of observation becomes even stronger due to the plasmonic enhancement effect.

Rapid green synthesis of silver nanoparticles and nanorods using Piper nigrum extract

We report sun light driven rapid green synthesis of stable aqueous dispersions of silver nanoparticles and nanorods at room temperature using photoreduction of silver ions with Piper nigrum extract. Silver nanoparticles were formed within 3min of sun light irradiation following addition of Piper nigrum extract to the AgNO3 solution. The effects of AgNO3 concentration and irradiation time on the formation and plasmonic properties of biosynthesized silver nanoparticles were studied using UV–visible absorption spectroscopy. The morphology and structure of silver nanoparticles were well characterized by atomic force microscopy (AFM) and X-ray diffraction (XRD). The size of Ag nanoparticles increased with increase in irradiation time, leading to the formation of anisotropic nanostructures. Increasing the AgNO3 concentration resulted in the formation of Ag nanorods. UV–visible absorption studies revealed the presence of surface plasmon resonance (SPR) peaks which red shift and broaden with increasing AgNO3 concentration. We have demonstrated a facile, energy efficient and rapid green synthetic route to synthesize stable aqueous dispersions of silver nanoparticles and nanorods.