Plasmon Resonance Of Silver Nanoparticles Research Articles

Plasmon-enhanced dye-sensitized solar cells through porphyrin-silver nanoparticle hybrid structures: Experimental and computational studies

Surface plasmon resonance of silver nanoparticles (Ag NPs) was used to improve light absorption of porphyrins in plasmon-enhanced porphyrin-sensitized solar cells (PSSCs). Porphyrins with different substituents consisting –H, -Me, -MeO, –F, -Cl, -Br, –CO2H, –SO3H, –NO2, and –NH2 were used to study the effect of the interactions between photoactive dye molecules and plasmonic Ag NPs on the performance of PSSCs. The obtained results revealed that zinc tetra(4-carboxyphenyl)porphyrin and zinc tetra(4-aminophenyl)porphyrin have made the biggest impact on the performance of plasmon-enhanced PSSCs. Computational studies were done to study the electronic properties of porphyrin molecules with electron-withdrawing and electron-donating substituents interacted with Ag NPs. The theoretical studies confirmed that the electronic nature of substituents of porphyrins has a considerable effect on the electronic properties of porphyrin-AgNPs systems. In continue, [email protected] core-shell NPs were prepared to overcome the challenge of corrosion of Ag plasmonic nanoparticles. The results showed that using [email protected] systems, in many cases, the performance of PSSCs is increased relative to corresponding porphyrins but is decreased relative to porphyrin-AgNPs systems.

Ultrasensitive prostate specific antigen monitoring based on electrochemiluminescent immunesystem with synergistic signal amplification effect of resonance energy transfer coupling with K2S2O8-H2O2 dual coreactants

• The synergistic effect of coupling dual coreactants with the surface plasmon resonance of AgNPs enhancement was used as an effective signal amplification strategy. • OH • arising in the process was able to induce the decomposition of S 2 O 8 2− into SO 4 • − resulting in a vigorous ECL enhancement. • The amplified ECL immunosensor was fabricated for highly-sensitive detection of PSA. • The sensing system provides an alternative charming method for other biomolecules assays. In this work, an effective signal amplification strategy was used for the fabrication of the ultrasensitive sandwich-typed electrochemiluminescence (ECL) immunosensing platform. The combining of K 2 S 2 O 8 -H 2 O 2 dual coreactants with the localized surface plasmon resonance of silver nanoparticles (AgNPs) resulted in the remarkable increase of ECL response. Noticeably, because of the perfect overlap between the plasmon spectra of AgNPs and the ECL emission spectra of graphitic carbon nitride quantum dots (g-CNQDs), a plasmon-enhanced ECL phenomenon was proved in g-CNQDs/AgNPs system result from high efficient energy transfer. Besides, the ECL signal of the ECL immunosensor was greatly improved in the presence of K 2 S 2 O 8 -H 2 O 2 dual coreactants. Consequently, this synergistic amplified ECL sensing platform was applied for the specific prostate specific antigen (PSA) analysis. Under the optimum conditions, the immunoassay strategy demonstrated excellent sensing performance with a wide linear concentration of PSA from 1.0 × 10 − 5 ng mL −1 to 500 ng mL −1 and a detection limit of 0.0046 pg mL −1 (S/N = 3). Considering the favorable analytical feedback in actual serum samples assay, the developed strategy indicated an enormous potential for biomarkers analysis.

Photogated Coordination Switching of Silver Nanoparticles for Reversible Coloration/Discoloration of Hydrogel

AbstractHydrogels remain challenging for the reversible high‐resolution coloration/discoloration in response to external stimuli. Herein, a photogated coordination‐switching mechanism is proposed to alter the localized surface plasmon resonance of silver nanoparticles (AgNPs) inside a hydrogel network, which enables the reversible color change. The hydrogel is synthesized by free‐radical crosslinking of N,N'‐bisacrylylcystamine (BACA), sodium p‐styrenesulfonate (NASS), and acrylamide (Am) in the presence of AgNPs. Upon light irradiation at λ = 400 nm (300 mW cm−2), the AgNPs selectively coordinate with the disulfide bond of BACA to result in a reddish‐brown hydrogel in 30 s. In dark condition, this coordinating effect is replaced by the sulfonate of NASS and AgNPs, which brings the hydrogel into gray white. Such a photogated coordination‐switching mechanism is a physical process that enables the coloration/discoloration cycles without apparent reduction in the resolution. By means of a high‐precision mask, it allows writing, storing, and erasing of complicated information at the hydrogel surface, showing a great potential in informatics, cryptology, and security areas.

Measuring of metanephrine by UV-Vis peak of surface absorption Plasmon resonance of silver nanoparticles by response surface methodology

A simple and low-cost spectrophotometry method was proposed based on resonance Plasmon peak of silver nanoparticles for measurement of metanephrine(MN) drug. This method was based on reducing property of metanephrine and it was founded that this compound reduces silver ions in presence of polyvidone (PVP) as stabilizer compound. In this condition the formed silver nanoparticles show a localized surface plasmon resonance (LSPR) peak of about 423 nm. The resulted nano-particles were analyzed by transmission electron microscope (TEM) technique and nanoparticles size was estimated to be maximum of 200nm. Furthermore, realized that the absorption of solution depends on concentration of metanephrine and the maximum of absorption was found at 〖AgNO〗_3 concentration of 1.53 mM, NaOH concentration of 4.10 mM, 〖NH〗_3 concentration of 2.51 mM and 1.15 ml of PVP. Also, the proposed method showed a good linear relationship than MN concentration in the range of 2.5-20 µM and limit of detection was obtained as 0.6 µM for metanephrine. Finally, this method was used for measuring epinephrine in real samples and the acceptable results were obtained.

Utilization of Localized Surface Plasmon Resonance of Silver Nanoparticles for the Spectrofluorimetric Estimation of Oxymetazoline in Dosage Forms: Application to Aqueous Humor.

A simple, novel, cost-effective and highly sensitive spectrofluorimetric method was developed for estimation of the nasal decongestant oxymetazoline (OMZ) whether per se or in its pharmaceutical preparations using colloidal silver nanoparticles (AgNPs). The method is based on the high catalytic potential activity of AgNPs on the fluorescence intensity of OMZ leading to 12-fold increase in its fluorescence intensity. The response was linear over the range of 20.0 to 700.0ng/mL with lower detection limit of 5.0ng/mL and limit of quantification of 14.0ng/mL. The proposed method was applied to the assay of commercial nasal drops, nasal spray and synthetic aqueous humor. Interference likely to be encountered from co-administered drugs was studied. The developed method was optimized and validated as per International Council of Harmonization (ICH). An explanation for the drug-AgNPs interaction was proposed.

Highly sensitive determination of methionine by solvent-based de-emulsification dispersive liquid-liquid microextraction using bio-stabilized silver nanoparticles.

In this study, a solvent-based de-emulsification dispersive liquid-liquid microextraction method coupled with surface plasmon resonance of silver nanoparticles was developed for determination of trace levels of methionine. The stable and dispersed silver nanoparticles were synthesized by applying ascorbic acid as reducer and Stenotrophomonas sp. bacterial suspension as bio-stabilizer and then preconcentrated in organic phase according to a facile dispersive liquid-liquid microextraction procedure based on 1-octanol as extraction solvent, methyltrioctylammonium chloride (aliquat 336) as disperser and acetone as de-emulsifier. The presence of methionine influenced the intensity of plasmon resonance absorbance of silver nanoparticles, which was employed as a colorimetric probe for the determination of this amino acid. Under the optimal conditions, the linear analytical range of 5.6 to 234.5nmol/L and a detection limit of 3.4nmol/L were achieved for methionine. The relative standard deviation for seven replicate measurements of 33.5 and 107.2nmol/L of methionine was 4.3 and 2.1%, respectively. The suggested method was successfully applied for the determination of methionine in biological samples.

The relationship between tunable optical absorption and SERS activity of Ag/ZnO nanocomposites

The optical characteristics of Ag/ZnO composite nanostructures have long been of particular interest and, thus, the subject of broad experimental and theoretical studies. This work is focused on the synthesis and properties of Ag/ZnO nanocomposites and demonstrates the possibility of their application as active substrates for surface-enhanced Raman spectroscopy (SERS) in detection of pesticides. The samples were synthesized by pulsed laser deposition (PLD) of ZnO thin films, followed by Ag+-ion implantation in the ZnO matrix and by laser annealing of the heterostructures produced. The morphology and properties of the samples were studied with respect to the processing parameters. The optical absorption studies revealed the existence of tunable surface plasmon resonance of silver nanoparticles in the ZnO matrix. Theoretical calculations of the optical properties, as extinction, absorption and scattering efficiencies, were performed based on a generalized multi-particle Mie (GMM) approach. The simulated system assumed in this comparative study consists of a surface-embedded ensemble of silver nanoparticles in a ZnO surrounding media and in air. The simulated structures were reproduced from the corresponding SEM images after laser annealing at 355 nm and 532 nm.

Improved optical absorption by local surface plasmon resonance of silver nanoparticles in nanocolumnar CdTe thin films

Cadmium telluride (CdTe) thin films with a nanocolumnar morphology were grown on glass substrates using the Sublimated Vapor Effusion Deposition technique and a rotational source in counter-rotation with respect to the substrate. Afterward, it was proceeded to coat with silver nanoparticles whose average size was of ~ 100 ± 40 nm. X-ray diffraction analysis showed that all samples presented the zinc-blend structure with a preferred orientation of (111), with a crystallite size of ~ 52 nm, and that they were under tensile stress. The bandgap value was EG = 1.53 eV and the Urbach energy E0 ~ 13.2 meV. The porosity value was estimated at ~ 0.0562 (5.6%). A Localized Surface Plasmon Resonances effect was presented for the Ag nanoparticles near the wavelengths close to 548 nm and 660 nm, and this resulted in improved light absorption in the CdTe nanocolumnar layer compared to samples grown only with a CdTe nanocolumnar structure.

Simulation of Localized Surface Plasmon Resonance of Silver Nanoparticles with Graphene Coating Utilizing Maxwell-Garnett Theory

Simulation of Localized Surface Plasmon Resonance of Silver Nanoparticles with Graphene Coating Utilizing Maxwell-Garnett Theory

Green synthesis of silver nanoparticles using canthaxanthin fromDietzia marisAURCCBT01 and their cytotoxic properties against human keratinocyte cell line

Nano-biotechnologically synthesizing silver nanoparticles via canthaxanthin pigment extracted from Dietzia maris AURCCBT01 and assessing their cytotoxic therapeutic potential against human keratinocyte cell line (HaCaT) were the key objectives of this study. The pigment extracted from D. maris AURCCBT01 was identified as canthaxanthin using UV-VIS spectroscopy, FTIR, NMR (1 H NMR and 13 C NMR) and MS. Canthaxanthin, treated with silver nitrate solution, produced canthaxanthin-mediated silver nanoparticles and they were characterized by UV-VIS spectroscopy, FTIR, XRD, FESEM-EDX and TEM-SAED techniques. UV-VIS spectroscopy pointed out an absorption band at 420nm, relating to the surface plasmon resonance of silver nanoparticles. FTIR findings suggested that the diverse functional groups of canthaxanthin bio-molecules played a significant task in capping the silver nanoparticles. XRD analysis exhibited 40·20nm for the crystal size of nanoparticles. FESEM and TEM exhibited that the biosynthesized silver nanoparticles were spherical in shape with crystalline nature and the particle size was 40-50nm. Moreover, the cytotoxicity assessment of the synthesized nanoparticles in HaCaT revealed significant cytotoxicity in the cultured cells with an IC50 value of 43µgml-1 . Stable silver nanoparticles synthesized using canthaxanthin from D. maris AURCCBT01 were found effective for application in wound healing activity. Biosynthesized silver nanoparticles via canthaxanthin bacterial pigment exhibited their cytotoxicity effect in HaCaT and testified their eventual therapeutic potential in the wound healing activity with no side effects in a cost effective and eco-friendly process.

Biosynthesis and Characterization of Silver Nanoparticles from Marine Macroscopic Brown Seaweed Colpomenia sinuosa (Mertens ex Roth) Derbes and Solier

In the present study energy efficient, economically scalable colloidal silver (Ag) nanoparticles were biosynthesized from marine brown seaweed Colpomenia sinuosa by green synthesis method. The marine macroscopic brown seaweed Colpomenia sinuosa was used in the experimental study for the biosynthesis of silver nanoparticle since they are rich in phytochemicals, bioactive compounds and secondary metabolites which has reducing agents that may be environmentally acceptable and eco-friendly. The biosynthesized silver nanoparticles from marine macroscopic brown seaweed were characterized by UV-vis spectroscopy which confirmed the surface plasmon resonance of silver nanoparticles, Fourier transform infrared (FT-IR) spectroscopy to identify the presence of various functional groups in biomolecules responsible for the bio reduction of Ag+ and capping/stabilization of silver nanoparticles. X-ray diffraction (XRD) to observe face center cubic (fcc) and crystalline nature of silver nanoparticles, thermogravimetric analysis (TGA) which revealed the thermal stability and purity of the silver nanoparticles. Particle size distribution and morphology were investigated by scanning electron microscope (SEM) which showed silver nanoparticles in the size range of 54-85 nm. The particle distribution under different nanometers was analyzed using transmission electron microscopy (TEM).

Green synthesis and spectral characterization of silver nanoparticles from Psidium guajava leaf extract

Cost-effective, eco-friendly green synthesis of silver nanoparticles was prepared using Psidium guajava plant leaf extract. In this study the reducing potential of Psidium guajava leaf extract was investigated for the synthesis of silver nanoparticles without any external addition of reducing agents. The brown color formation was evident for the synthesis of silver nanoparticles. The synthesized silver nanoparticles were characterized by UV–Visible spectroscopy, Fourier transform-infrared spectroscopy (FTIR), particle size analyzer, X-ray diffraction (XRD) and scanning electron microscope (SEM). UV–Vis spectroscopy explained that the main peak was formed at around 419 nm, which corresponds to surface plasmon resonance of silver nanoparticles. FTIR spectroscopy elucidated the involvement of various functional groups during the synthesis of silver nanoparticles. The particle size analysis demonstrated the sizes of nanoparticles are 62 nm. The morphology of silver nanoparticles was analyzed using scanning electron microscope. Antibacterial assay of silver nanoparticles showed potent antibacterial properties.

Phthalocyanine-silver nanoparticle structures for plasmon-enhanced dye-sensitized solar cells

The localized surface plasmon resonance of silver nanoparticles (Ag NPs) was examined to improve the performance of phthalocyanine (MTXPc) in the plasmon-enhanced phthalocyanine-sensitized solar cells. When MTXPc dyes directly conjugated to Ag NPs (MTXPc-AgNPs) were used to sensitize solar cells, both of short-circuit current density (JSC) and open-circuit voltage (VOC) of phthalocyanine-sensitized solar cells were significantly increased. In the case of MTXPc conjugated to Ag@ZIF-8 (MTXPc-Ag@ZIF-8), slightly increasing in the JSC compared to alone MTXPc are observable but their VOC are significantly greater than alone MTXPc. Increasing in the JSC and VOC of the MTXPc-AgNPs and MTXPc-Ag@ZIF-8 lead to improve the performance of phthalocyanine in plasmon-enhanced phthalocyanine-sensitized solar cells compared to alone MTXPc. Also, the examination of the effect of the carboxyl- and sulfonyl-anchored dye (ZnTCPc-AgNPs and ZnTSPc-AgNPs, respectively) in conjunction with plasmonic NPs on the performance of DSSCs showed that ZnTCPc-AgNPs and ZnTSPc-AgNPs perform significantly better than their unsubstituted analogues. The studying the effect of the metal in the central cavity of phthalocyanine using zinc, manganese, iron, cobalt, and nickel showed that the metal in the central cavity of phthalocyanine has the critical role toward the photovoltaic performance of the plasmon-enhanced phthalocyanine-sensitized solar cells.

Influence of surfactant, particle size and dispersion medium on surface plasmon resonance of silver nanoparticles

Clear influence of particle size, surfactants and dispersion medium on surface plasmon resonance (SPR) features of Ag nanoparticles (NPs), synthesized in thermal decomposition method, in the broad range of ultraviolet (UV) radiation, critical for many potential applications such as a photocatalyst, UV-sensor and detector, has been demonstrated here. It involves adsorbate coverage, interparticle distance or agglomeration, surface charge density and solvent refractive index (µ). NP agglomeration and surface charge density in solvents of varying µ have been studied systematically through zeta-potential (ζ) and hydrodynamic diameter (HD) using dynamic light scattering (DLS). The main SPR feature found at 316 nm in 31.5 nm NPs shifts to 320 nm in 15.1 nm NPs. The peak at 320 nm in air shifts to 259, 261 and 277 nm in polar solvent methanol, deionized water and ethanol, respectively and to 255, 275 and 282 nm in non-polar solvent n-hexane, benzene and toluene, respectively. In general, the decrease in particle size and increase in µ of solvents show red-shift. Curiously, a number of peaks up to seven in these solvents that are attributed to charge-transfer mechanism and change in inter-particle interaction of the NPs turning from a single peak of SPR in air has been observed for the first time. A model for re-adjustment of Fermi level (EF) of Ag NP and the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) to explain them has also been used. Moreover, the Drude model for shift in the position of SPR in these NPs is only applicable in non-polar solvents, not in polar solvents. Such novel features will be potential candidates for various applications.

Fabrication and ultraviolet-visible-near infrared absorption properties of silver nano arrays based on aluminum

In this paper, the highly ordered periodic silver nanosphere arrays are fabricated by vacuum evaporation based on anodic aluminum oxide (AAO) template. The diameter and spacing of silver nanosphere in the arrays are adjusted just by controlling the thickness of evaporation. Furthermore, this can effectively modulate the absorption peaks and bandwidths in ultraviolet-visible-near-infrared regions. The measurement results of absorption spectra show that the nano-arrays have obvious electromagnetic wave absorption characteristics in the ultraviolet, visible and near-infrared bands. The finite-difference time-domain theoretical simulation combined with experiments is used to analyze the physical mechanism of light absorption characteristics in different wavebands. The ultraviolet strong absorption is due to the Fano resonance induced by asymmetric dielectric environment of silver and aluminum; the visible absorption originates from local surface plasmon resonance of silver nanoparticles; the near-infrared strong absorption is attributed to the surface lattice resonance of silver nanosphere arrays.

XPS and thermal studies of silver doped SiO2 matrices for plasmonic applications

Silver nanocrystals doped SiO2 matrices were synthesized through sol–gel route using acid catalyst. The prepared silica matrices with different concentrations of silver were annealed at different temperatures and characterized using, XRD, FTIR, Absorption spectroscopy, XPS, thermogravimetric and differential thermal analysis. The XRD data confirm the amorphous nature of silica and crystalline nature of silver nanocrystals. Using the Fourier-transform infrared red spectrum the formation of silica glass was confirmed. The characteristic Surface Plasmon Resonance of silver nanoparticles obtained around 400 nm from the absorption spectrum. The observed blue shift and skewness in SPR with increasing silver concentrations were studied. The 3d doublet state of silver at a binding energy of 368.4 eV with the splitting of 6 eV obtained in XPS confirm the state Ag0 along with the presence of a minor quantity of silver (II) oxide. The thermal stability and nature were analyzed using TGA-DTG and DTA and showed good thermal stability from 400 °C to higher temperatures.

Charge transfer and properties of localized plasmon resonance in Ag-TiO2 nanostructures

In the paper the results of the synthesis of Ag – TiO2 nanostructures are presented. Nanostructures consist of a silver core and a TiO2 semiconductor shell. The size of nanostructures (NSs), determined by the method of dynamic light scattering, was 20 nm and 50 nm in different medias. The effect of the semiconductor shell of TiO2 on the properties of the localized plasmon resonance of silver nanoparticles is investigated. The quantitative index of localized plasmon resonance in NSs (electron density) was deteriorated, while the qualitative indicator of localized plasmon resonance (attenuation coefficient of plasma oscillations) can improve in the case of a thin TiO2 shell. After the synthesis of the TiO2 shell an additional luminescence band of the Ag – TiO2 NS is observed. The observed luminescence is associated with charge transfer from TiO2 on Ag. The dependence of the maximum recombination luminescence band on the value of the charge on silver nanoparticles is observed.

The influence of copper and silver in various oxidation states on the photoluminescence of Ho3+/Yb3+ doped zinc-silicate glasses

Transition metals, such as silver or copper, can be used to enhance the photoluminescence of rare-earth ions. In this work, a novel zinc-silicate glass containing holmium and ytterbium was prepared and subsequently doped with silver or copper by means of ion exchange. The concentration of transition metals was evaluated by electron microprobe analysis (EMPA), and the oxidation state was analysed by absorption spectroscopy and transmission electron microscopy (TEM). The waveguiding properties of the prepared samples were evaluated by m-line spectroscopy. Most importantly, the effect of transition metals on the photoluminescence of Ho3+ ions was evaluated by photoluminescence spectroscopy. The results show that copper has no positive effect on the photoluminescence of Ho3+ ions. On the other hand, silver shows significant promise because the photoluminescence of the glass increased by as much as 20%. It has been determined that the main mechanism behind this increase is energy transfer from small clusters rather than the surface plasmon resonance of silver nanoparticles.

Biosynthesis of silver nanoparticles using baker’s yeast, Saccharomyces cerevisiae and its antibacterial activities

The biosynthesis of silver nanoparticles extracellularly using baker’s yeast, Saccharomyces cerevisiae and its antibacterial activity was investigated in this study. Biosynthesised silver nanoparticles were chaterized by using UV-Visible spectroscopy, which showed a distinct observed absorption peak at 429.00 nm that is attributed to the plasmon resonance of silver nanoparticles; X-ray diffraction, which determined the average size of the silver nanoparticles to be approximately 16.07 nm; presence of oval shaped silver nanoparticles determined by scanning electron microscopy; and Fourier-transform infrared, which revealed notable peaks at 3332.2, 2903.6 and 1636.3 cm−1 corresponding to the binding of the silver nanoparticles to active biomolecules, alcohols and phenols, carboxylic acids and aromatic amines respectively. The silver nanoparticles were also found to be stable for ninety days. Antibacterial activity of the silver nanoparticles was also studied. The silver nanoparticles was significantly active (P>0.05) against the test organisms at an extract concentration of 75 µg ml−1. Concentrations less than or equal to 50 µg ml−1 were not as effective as the colony forming units at this concentration, 1.61×106 for methicillin-resistant Staphylococcus aureus and 1.45×106 for Pseudomonas aeruginosa respectively were about the same range a small the colony forming units of the controls. The silver nanoparticles inhibited methicillin-resistant S. aureusmore than they inhibited P. aeruginosa. The LD50 of the synthesized silver nanoparticles after oral administration was seen to be greater than 5000 mg kg−1 body weight and is therefore thought to be safe. This study supports the use of silver nanoparticles as therapeutic agents.

Biosynthesis of silver nanoparticles from leaf extract of Litchi chinensis and its dynamic biological impact on microbial cells and human cancer cell lines

Green synthesis of metallic nanoparticles has attracted a great deal of attention from scientific community due to its biocompatibility and environment friendly nature. In the present study, silver nanoparticles were biologically synthesized using leave extracts of Litchi chinensis. Biosynthesized silver nanoparticles were characterized and their applications were observed by different methodologies. Bio-reduction reaction was confirmed by the surface plasmon resonance of silver nanoparticles at 417 nm through UV-VIS spectrophotometer. FTIR analysis revealed that the amine groups present in the leaf extracts were responsible for the reduction of silver ions to silver nanoparticles. X-ray diffraction analysis was used to determine the crystalline nature of silver nanoparticles and their diameter was noted in the range of 41-55 nm by scanning electron microscopy. Antibacterial activity was observed against gram positive and gram negative strains of bacteria. Furthermore, human epithelial type 2 cancer cells (HEp-2) and Human breast adenocarcinoma cells lines (MCF-7) were treated with the biosynthesized silver nanoparticles using MTT assay. The resulting cell death rate was noted up to 40.91+1.99%. This study concludes that plant mediated biosynthesis of nanoparticles is the superior alternative compared to chemical and physical approaches, to utilize them as drug delivery tool and need to conjugate apoptosis inducing biological agents with silver nanoparticles to suppress the uncontrolled division of cancer cells.