Plasmon Resonance Of Silver Nanoparticles Research Articles

Enhanced thermoluminescence, radioluminescence, and optically stimulated luminescence from lithium fluoride and silver nanoparticles composites

Plasmonic properties of metals can increase the sensitivity of ionizing radiation dosimeters. In this work, we study the plasmon resonance of silver nanoparticles (AgNp) to increase the optically stimulated luminescence (OSL) intensity of lithium fluoride (LiF) polycrystals. We produced LiF/Ag nanocomposites with different volumes of a silver nanoparticle dispersion and investigated their OSL response. We also investigated their thermoluminescence (TL) and radioluminescence/scintillation (RL) responses. X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV–vis spectroscopy characterized the synthesized materials. XRD results clearly show the characteristic peaks of LiF and AgNps. TEM images revealed silver nanoparticles with diameters between 80 and 120 nm and LiF crystals with sizes between 1 and 5 μm. Reflectance spectroscopy showed a band around 420 nm, attributed to the plasmon resonance of silver nanoparticles. The responses of the OSL curves to X-ray irradiation were analyzed, showing higher OSL sensitivity with 14 mL AgNp, attributed to the AgNp plasmon resonance. A significant increase in TL and RL intensity could be observed for the LiF/Ag nanocomposites. TL, RL, and OSL results support that addition of AgNps do not lead to the creation of more and new traps or luminescent centers. The increase of TL and RL intensities is therefore related to the coupling of the luminescent centers with the AgNPs plasmons, in an energy-transfer mechanism (plasmon-coupled emission), whereas the enhanced OSL intensity directly correlates with the increased photoionization cross-section of the electronic traps under plasmon resonance conditions (plasmon-coupled excitation). Therefore, these results indicate that AgNp are potential candidates to increase the OSL, TL, and RL intensity from LiF dosimeters.

Efficiency Enhancement of Biophotovoltaic Solid‐State Solar Cells

Biophotovoltaic solid‐state solar cells are new environmentally friendly solar cells inspired by photosynthesis phenomena. Photosystem I, a complex protein located in the chloroplast of the plant leaves that has a principal role in light absorption, is the most common light absorber used in biophotovoltaic solid‐state solar cells. Low efficiency and low current density are the main challenges in this kind of solar cell. Herein, to vacillate the motion of electrons and holes, carbon nanotubes and tyrosine are used as transfer layers and to increase light absorbance, a solution of Photosystem I with silver nanoparticles as an absorber layer is used. It is shown that the short circuit current density and the efficiency can be enhanced to 6.61 mA cm−2 and 0.83%, respectively which are the highest values for current density and efficiency reported for this kind of solar cell. These enhancements are due to the high electrical conductivity of carbon nanotubes, proper porosity of tyrosine, and the localized surface plasmon resonance of silver nanoparticles induced under light irradiation. The results can illuminate hopes and dreams for biophotovoltaic solid‐state solar cells with higher current density and higher efficiency.

Application of the localized surface plasmon resonance of silver nanoparticles for the determination of ethion in water samples

Application of the localized surface plasmon resonance of silver nanoparticles for the determination of ethion in water samples

Efficient generation of singlet oxygen due to localized surface plasmon resonance of silver nanoparticles in rose bengal–silver nanoparticle composite films

The effect of silver nanoparticles (AgNP) on the generation of singlet oxygen (1O2*) using rose bengal (RB) as a photosensitizer for photodynamic therapy (PDT) was examined by measuring the phosphorescence spectra of 1O2* from RB-AgNP composite film and RB film on glass plates in CCl4. 1O2* was successfully detected by direct observation of the characteristic 1O2* phosphorescence around 1275 nm in two films. The excitation spectra of 1O2* in the two films were in agreement with the that of RB in film or in solution. The results indicate that the generation of 1O2* is ascribed to a PDT type Ⅱ reaction. The phosphorescence intensity of 1O2* in RB-AgNP composite film was larger than that in RB film. The enhancement of the phosphorescence intensity of 1O2* is most likely attributable to the strong electric fields due to the localized surface plasmon resonance of AgNP aggregates.

Colorimetric Sensor for Determination of Pregabalin Based on Localized Surface Plasmon Resonance of Silver Nanoparticles

Colorimetric Sensor for Determination of Pregabalin Based on Localized Surface Plasmon Resonance of Silver Nanoparticles

Effect of media on plasmon resonance of silver nanoparticles

Effect of media on plasmon resonance of silver nanoparticles

Synthesis and synergistic effect of antibacterial composites based on concentrated hydrosols of silver nanoparticles combined with cephalosporins antibiotics

Silver nanoparticles may be used as potential antimicrobial agents. Concentrated silver nanoparticles (AgNPs) were synthesised by the Carey Lee method. Then, antibiotics, such as disodium ceftriaxone, sodium cefotaxime, sodium cefazolin and sodium cefoperazone, were added to the AgNPs at the ratio of AgNPs:antibiotic = 5:1. The concentrated hydrosols were examined using UV–Vis, FTIR-spectroscopy, dynamic light scattering and transmission electron microscopy. The spectra plasmon resonance of silver nanoparticles and their combination with antibiotics had a single strong peak at 412–415 nm. The transmission electron microscopy micrographs showed different forms. The average size of AgNPs-antibiotic particles was smaller than that of AgNPs. The antibacterial activities of AgNPs, antibiotics and AgNPs-antibiotics were determined by the disk diffusion method against Staphylococcus aureus and Escherichia coli. The most significant enhancement of the antibacterial effect over the antibiotic was demonstrated by AgNPs-disodium ceftriaxone against E.coli. Also, the minimal inhibitory concentration (MIC) of the AgNPs-antibiotics was defined. All the AgNPs-antibiotic exhibited a synergistic enhancement by AgNPs and the antibiotic of antibacterial activity. A possible explanation of this phenomenon was proposed. Our results suggest that the synthesis of the concentrated hydrosol of the AgNPs-antibiotics is essential for studying similar nanosystems.

Performance of graphene/P-InP Schottky diode enhanced by silver nanoparticles

In this paper, a Schottky junction near-infrared photodetector is formed by the combination of two-dimensional(2D) material graphene and P-InP. By using the surface plasmon resonance of silver nanoparticles(Ag NPs), a layer of Ag NPs was spin-coated on the single-layer graphene(SLG)/P-InP structure to improve the response rate. As a result, the response rate and detection rate were improved, and the response rate was increased from 1.227 mA/W to 7.876 mA/W, the detection rate was also increased from 5.052 × 109 cmHz1/2W−1 to 1.178 × 1010 cmHz1/2W−1. Since the defects and dangling bonds on the semiconductor surface can be reduced by depositing a thin oxide layer between graphene and semiconductor as a passivation layer, a 2 nm Al2O3 layer was inserted between graphene and P-InP to form Ag NPs/SLG/Al2O3/P-InP structure. The Schottky barrier height was increased from 0.675 eV to 0.815 eV, the response rate was further greatly improved, up to 40.195 mA/W, and the detection rate was also increased to 6.08 × 1010 cmHz1/2W−1.

Fitting Procedure to Reconstruct the Size Distribution and the Concentration of Silver Colloidal Nanoparticles from UV-Vis Spectra.

In this work, a complete fitting procedure of UV-Vis spectra of silver nanoparticles in colloidal solutions is reported. The fitting function, based on the Beer–Lambert law, Mie theory, and log-normal probability distribution of nanoparticles’ sizes, is developed and confirmed by 33 different independent measurements. In order to validate the accuracy of the function’s behavior on different spectra, freely accessible measurements were used, proving that the fitting function works independently of the method of their production—laser or chemical synthesis of nanoparticles. The developed fitting function is, to the best of our knowledge, novel and not based on any conventional spectral analysis approaches like the Mie–Gans procedure. Furthermore, since fitted parameters are all physical, it allows determination of the mode diameter of nanoparticles as well as the standard deviation of the log-normal distribution of sizes. It enables the reconstruction of size distribution of nanoparticles in colloidal solution. Step-by-step derivation of the fitting function is provided with a physical explanation of all parameters. The importance of Lorentzian dependence emerging at the core of Beer–Lambert law is physically discussed and linked to harmonic oscillator behavior of localized surface plasmon resonance of silver nanoparticles in a colloidal solution. Size distribution reconstruction from fitted parameters according to a log-normal distribution function is provided and a concentration calculation is presented.

Effect of Plasmon Resonance of Silver Nanoparticles on the Fluorescent Properties of Doxycycline

Effect of Plasmon Resonance of Silver Nanoparticles on the Fluorescent Properties of Doxycycline

Phytosynthesis, antimicrobial and catalytic activities of silver nanoparticles derived using leaf and stem extracts of Indigofera macrophylla

Background: The phytosynthesis of metal nanoparticles is a promising green alternative to traditional chemical approaches.Objective: The aim of this study was to synthesize silver nanoparticles (AgNPs) with antimicrobial and biocatalytic activities using aqueous leaf and stem extracts of Indigofera macrophylla.Methods: Critical reaction variables for the biosynthesis of AgNPs were optimized using UV-vis spectroscopy before the biosynthesised AgNPs were characterized using various spectroscopic and microscopic techniques. The biological activities of the biogenic nanoparticles were then investigated with particular focus on their antimicrobial activity and biocatalytic efficiency in the degradation of methylene blue.Results: The surface plasmon resonance of silver nanoparticles biosynthesized using aqueous extracts of leaf (LE-AgNPs) and stem (SE-AgNPs) of I. macrophylla occurred at 430 and 426 nm respectively. Scanning electron microscopy images of the nanoparticles showed highly aggregated polymorphs with mostly spherical shape. The particle sizes of LE-AgNPs and SE-AgNPs as determined by Transmission electron microscopy were 48.61±8.60 and 18.09±4.13 nm respectively with Energy dispersive X-ray analysis confirming characteristic absorption band at 3 KeV. In susceptibility assays, LE-AgNPs showed dose-dependent zones of inhibition against Escherichia coli (18 mm), Staphylococcus aureus (18 mm), Pseudomonas aeruginosa (20 mm) while SE-AgNP was only active against Staphylococcus aureus (10 mm). Both LE-AgNPs and SE-AgNPs showed good biocatalytic efficiency in the degradation of methylene blue with rate constants of 0.0204 and 0.0182 min-1 respectively.Conclusion: Silver nanoparticles with antimicrobial and catalytic activities have been biosynthesized using the aqueous extract of Indigofera macrophylla.

Studies of surface plasmon resonance of silver nanoparticles reduced by aqueous extract of shortleaf spikesedge and their catalytic activity

This study describes the synthesis of silver nanoparticles (AgNPs) using shortleaf spikesedge extract (SSE) to reduce AgNO3. Visual observation, in addition to analyses of UV-vis, EDX, XRD, FTIR, and TEM was employed to monitor the formation of AgNPs. The effects of SSE concentration, AgNO3 concentration, reaction time, pH, and temperature on the synthesis of AgNPs were studied based on the surface plasmon resonance (SPR) band. From the TEM image, highly-scattered AgNPs of quasi-spherical shape with an average particle size of 17.64 nm, were observed. For the catalytic study, the reduction of methylene blue (MB) was evaluated using two systems. A detailed batch study of the removal efficiency (%RE) and kinetics was done at an ambient temperature, various MB initial concentrations, and varying reaction time. Employing the electron relay effect in System 2, the batch study clearly highlighted the significant role of AgNPs in boosting the catalytic activity for MB removal. At 30–100 mg/L initial concentrations, MB was reduced by 100% in a very short reaction time between 1.5 and 5.0 mins. The kinetic data best fitted the pseudo-first-order model with a maximum reaction rate of 2.5715 min−1. These findings suggest the promising application of AgNPs in dye wastewater treatment. The SSE-driven AgNPs were prepared using unwanted dried biomass of shortleaf spikesedge extract (SSE) as a reducing as well as stabilizing agent. Employing the electron relay effect, the batch study clearly highlighted the significant role of SSE-driven AgNPs in boosting the catalytic activity for MB removal. At 30–100 mg/L initial concentrations, MB was reduced by 100% in a very short reaction time between 1.5 and 5.0 mins. In this sense, SSE-driven AgNPs acted as an electron relay point that behaves alternatively as acceptor and donor of electrons. The findings revealed the good catalytic performance of SSE-driven AgNPS, proving their viability for dye wastewater treatment.

Green Synthesis, Characterization and Antimicrobial Potency of Silver Nanoparticles from <i>Psidium</i><i> </i><i>guajava</i> Leaf Extract

In this Research work, Silver Nanoparticles were green synthesized from Psidium guajava leaves and different Characterization techniques including UV-Visible, FT-IR, SEM and XRD were all employed to ascertain the absorption peaks, functional group, surface morphology and crystalline size of the nanoparticles respectively. These nanoparticles green synthesized were applied against four different pathogens namely, S. aureus (gram- positive bacteria), E. coli (gram- negative bacteria), C. albicans (gram- positive fungus) and Aspergillus niger and the investigation showed that the Silver nanoparticles synthesized were potent against the selected pathogens. From the UV-Vis spectral analysis, it was observed that highest absorption peaks appeared at 400nm and 500nm reflecting the surface plasmon resonance of silver Nanoparticles from guava leaves which is characteristic of Silver Nanoparticles. From the FT-IR spectrum of the sample under studied, the peaks 3416.85 cm-1, 2923.51 cm-1, 1618.95 cm-1, 1384.49 cm-1 and 1033.63 cm-1 were observed where the absorption band at 3416.85 cm-1 corresponds to the stretching due to N-H, while the band at 2923.51 cm-1 is associated with C-H stretch of alkane and O-H stretching. The peak at 1618.95 cm-1 shows C=C stretching, 1384.49 cm-1 reveals the existence of C-H bending and 1033.63 cm-1 depicted C-O stretching. The SEM analysis revealed the shape of the nanoparticles as being spherical while XRD result admits that the average size of the green synthesized Ag NPs was 45.5 nm using the Scherer’s formula. Augmentin was used as control at concentration of 300μg/L throughout antimicrobial studies. Different concentrations of 100, 200, 300, 400 and 500μg/L of Silver Nanoparticles were tested against each pathogen. It was discovered that with increase in concentrations of Silver Nanoparticles of all the pathogens, there generally appeared to be increase in inhibition zone. At higher concentration of 500μg/L, the zones of inhibition were in the following order; 22.50 mm, 17.00mm, 15.44mm, and 13.23mm for E. Coli, S. aureus, C. albicans and Aspergillus niger respectively. For each concentration investigated, E. coli, demonstrated higher zone of inhibition as opposed to all other pathogens investigated in this research.

Compensative Electrochromic Device Utilizing Electro-deposited Plasmonic Silver Nanoparticles and Manganese Oxide to Achieve Retention of Chromatic Color

Silver deposition-based electrochromic (EC) device enabled various optical states by using either the electrodeposition of silver thin films or silver nanoparticles on an indium tin oxide electrode. These optical states, including chromatic colors such as cyan, magenta, yellow, and green, are based on absorption by the localized surface plasmon resonance of silver nanoparticles. However, an ideal counter-reaction material that does not affect the color representation by silver nanoparticles and does not dissolve the deposited silver has not been reported. To achieve both color retention and chromatic color representation, MnO2 was utilized as the counter electrode material. The EC properties of the novel device with the MnO2 counter electrode were investigated in terms of charge density and its ability to change color. The novel EC device achieved both representations of chromatic color and retained its color without power supply.

Antibacterial Activity of Green Synthesised Silver Nanoparticles on Saccharomyces cerevisiae

Green synthesis of nanoparticles is a widely researched and popular direction in the development of nanotechnology. It is a simple, cheap and effective method for obtaining nanoparticles with interesting biological properties. In light of the development of antibiotic resistance to important clinical strains of bacteria, this method was used in the present study to obtain silver nanoparticles with antibacterial activity. The aim of this study was to synthesise silver nanoparticles with antibacterial action by yeast in a process known as “green synthesis”. We are also considering the prospect of using silver nanoparticles as an antibacterial substance for drug development. The production of nanoparticles was confirmed by UV spectroscopy. Staphylococcus aureus ATCC 25923 and Escherichia coli ATCC 25922 test strains and Staphylococcus aureus 1536 and Klebsiella pneumoniae 520 clinical isolates were used to study the antibacterial effect. The effect of synthesised nanoparticles on the metabolic activity of bacterial cells and their ability to adhere, as well as the minimum inhibitory concentrations (MICs) of synthesised nanoparticles for each of the strains, were determined. Following UV spectroscopy, the nanoparticles obtained were found to have a pronounced peak in optical absorption at 400 nm, corresponding to the plasmon resonance of silver nanoparticles, and demonstrated a high antibacterial effect against all the strains studied.

Fabrication, characterization, anti-inflammatory, and anti-diabetic activity of silver nanoparticles synthesized from Azadirachta indica kernel aqueous extract

The Azadirachta indica is an excellent and pharmaceutically valuable phytochemicals enriched traditional medicinal plant. The purpose of the research was to assess the ability of A. indica aqueous kernel extract to synthesize silver nanoparticles as well as their anti-inflammatory and anti-diabetic activity in vitro. The obtained results state that the aqueous kernel extract of A. indica can fabricate the silver nanoparticles and be confirmed by standard analytical techniques. Under UV–visible spectrophotometer analysis, the absorbance peak was found at 430 nm was related to the surface plasmon resonance of silver nanoparticles. The FTIR (Fourier-transform infrared spectroscopy) analysis revealed that numbers of functional groups belong to the pharmaceutically valuable phytochemicals, which act as reducing, capping, and stabilizing agent on silver nanoparticles synthesis. The size and shape of the silver nanoparticles were examined as 19.27–22.15 nm and spherical in shape. Interestingly, this kernel fabricated silver nanoparticles possess a reasonable anti-inflammatory (69.77%) and anti-diabetic (73.5%) activity at 100 μg mL−1 and these were partially comparable with standards (anti-inflammatory: 81.15%; anti-diabetic: 87.9%). Thus, the aqueous kernel extract fabricated silver nanoparticles can be considered for further in-vivo study to assess the practical possibility to promote as a pharmaceutical agent.

Metal-enhanced fluorescence of dyes with quadrupole surface plasmon resonance of silver nanoparticles.

Silver colloidal films (SCFs) composed of homogeneous 60–220 nm silver nanoparticles were synthesized for optimal fluorescence enhancement of chromophores with the dipole and quadrupole surface plasmons. The fluorescence enhancements with the SCFs of three chromophores, 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran, 4-dimethylamino-4′-nitrobiphenyl, and coumarin 343 whose emission spectra are centered distinctively in the 470–560 nm wavelength range were compared. Fluorescence enhancements and lifetime changes were investigated via time-resolved fluorescence spectroscopy. The spectral overlap between the chromophore's emission and the dipole or quadrupole surface plasmon resonance (SPR) bands determined the fluorescence enhancements with the SCFs. The dipole and quadrupole SPR bands both appeared to provide effective fluorescence enhancements of chromophores. This knowledge allows researchers to develop sensitive fluorescence sensors by combining nanoparticles with optimal dipole or quadrupole SPR bands in order to achieve fluorescence enhancement of a specific chromophore. The emission dynamics measurements with the SCFs were combined with the finite-difference time-domain simulation results for the local electric fields around the silver nanoparticles to enable discussion of metal-enhanced fluorescence mechanisms, including excitation and emission enhancements.

Biosynthesis of Silver Nanoparticles by Conyza canadensis and Their Antifungal Activity against Bipolaris maydis

Silver nanoparticles were biosynthesized from Conyzacanadensis leaf extract with the help of a microwave oven. The UV-vis spectrum showed the maximum absorption at 441 nm, corresponding to the surface plasmon resonance of silver nanoparticles. Transmission electron microscope and scanning electron microscope images showed that the synthesized silver nanoparticles were spherical or near-spherical with an average diameter of 43.9 nm. X-ray diffraction demonstrated nanoparticles with a single-phase cubic structure. As-synthesized silver nanoparticles displayed prominent antifungal activity against Bipolaris maydis. The colony inhibition rate reached 88.6% when the concentration of nanosilver colloid was 100 μL·mL−1 (v/v). At such a concentration, no colony formation was observed on the solid plate. The diameter of the inhibition zone was 13.20 ± 1.12 mm. These results lay the foundation for the comprehensive control of plant pathogens using an environmentally friendly approach.

Modeling of plasmon resonance of silver nanoparticles on a silicon surface

Silver nanoparticles have unique optical properties due to resonance effects that arise due to the presence of conduction electrons in them. When these electrons interacte with photons, they can create localization of electric fields at the interfaces with the environment. Silver nanoparticles deposited on a transparent substrate are often used for research, while Ag nanostructures on Si are studied in this work. They have great potential for practical applications. The interaction of light with nanostructures can be described using various models (pseudo-dielectric functions, effective medium, thin-layer structures, etc.) and optical methods for the experimental determination of their parameters (refractometry, spectrophotometry). Bulk plasmon resonance is considered in this work, which is excited when plasmons are excited at their resonant frequency by an external electromagnetic wave. Calculations were performed for different diameters of silver nanoparticles on a silicon substrate with different structure periods. The calculated spectra are in good agreement with the experimental data of the obtained samples. As a result of the plasmon resonance modeling, the position of the plasmon resonance depends on the density of the arrangement of silver nanoparticles, with an increase in the displacement resonance towards the long-wavelength region.

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.