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This paper describes a simple approach for creating silver (Ag) nanocubes using pulsed laser ablation in a liquid medium. The development of nanocubical formations of Ag obtained by laser ablation using Nd: YAG laser was conducted for 5, 10, 15, and 20 min. The surface morphological analysis was performed using field-emission scanning electron microscopy (FESEM) to show the formation of silver nanocubes with edge lengths ranging from 150 nm to 250 nm. The UV-visible spectroscopy demonstrates that the concentration of Ag nanostructures, evidenced by the characteristic localized surface plasmon resonance band near 400 nm in the colloidal solution containing Ag nanoparticles, increased with the increasing laser ablation duration from 5 min to 20 min. The growth mechanism for Ag nanocubes can be easily understood with the change in laser ablation time from 5 to 10, 15, and then 20 min. The Ag sheets with no specific shape start to develop after 5 min of laser ablation, and after 10 min, larger particles form. Then, after 15 min, a small number of cube-like nanostructures with rough and uneven edges was obtained. At the end of 20 min, a complete cubic formed with fine and distinct edges and a very large amount of nanocubes. The elemental silver signal was present in Ag nanocubes, as revealed by the energy-dispersive X-ray spectroscopy (EDS) spectra. The produced Ag nanocubes may be used to construct two-dimensional nanocomposites with practical applications in the electrical, optoelectronic, electrochemical, and biological areas. [ABSTRACT FROM AUTHOR]

The study aims at synthesizing a simple, cost-effective, selective, and sensitive colorimetric sensor based on chlorophyll-coated silver nanoparticles (Chl-AgNPs) using microwave-assisted method for the determination of Cr(VI) ions in an aqueous medium. The characterization reveals that synthesized nanoparticles are 20–30 nm in size and spherical in shape. The presence of methyl, carboxyl, aldehyde, and ketone groups on the surface of Chl-AgNPs results in the formation of size controlled, well dispersed, and stable silver nanoparticles. The prepared nano-colloidal solution has been used for selective and sensitive determination of Cr(VI) in water samples. The addition of single drop of Chl-AgNPs solution immediately changes the color of water samples containing Cr(VI) to red displaying good sensitivity from 10 to 100 µM and high selectivity even in the presence of other metal ions. The ultraviolet–visible spectra show that in the presence of Cr(VI), the localized surface plasmon resonance (LSPR) band of Chl-AgNPs at 410 nm shifts to 470 nm with a new peak at 357 nm. Furthermore, the absorbance of the LSPR band decreases and the absorbance at 357 nm increases linearly with the concentration of Cr(VI). The functional groups on the surface of nanoparticles bind Cr(VI) on the surface leading to agglomeration and alterations in interparticle distance that are observed as changes in the color and LSPR profile. The limits of detection and quantification for Cr(VI) ions were determined to be 0.62 µM and 1.88 µM, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] Plasmon-mediated chemical reaction (PMCR) is a highly attractive field of research. Here we report in situ surface-enhanced Raman spectroscopic (SERS) monitoring of plasmonic-mediated S S bond-forming reaction. The reaction is thought to be a self-coupling reaction proceeding by photoinduced aromatic S C bond arylation. Surprisingly, the S C arylation and S S coupling are found to be occurred on both partially oxidized silver and silver nanoparticles. The results demonstrated that silver oxide or hydroxide and small molecule donor sacrifice agent played a crucial role in the reaction. This work facilitates the in-situ manipulation and characterization of the active silver electrode interface in conjunction with electrochemistry, and also establishes a promising new guideline for surface plasmon resonance photocatalytic reactions on metal nanostructures with high efficiency. [ABSTRACT FROM AUTHOR]

Gold and silver nanoparticles have witnessed increased scientific interest due to their colourful colloidal solutions and exceptional applications. Comparing the localized surface plasmon resonance (LSPR) of gold and silver nanoparticles is crucial for understanding and optimizing their optical properties. This comparison informs the design of highly sensitive plasmonic sensors, aids in selecting the most suitable nanoparticles for applications like surface-enhanced infrared spectroscopy (SEIRA) and biomedical imaging, and guides the choice between gold and silver nanoparticles based on their catalytic and photothermal properties. Ultimately, the study of LSPR facilitates the tailored use of these nanoparticles in diverse scientific and technological applications. Two SEIRA methods combined with partial least squares regression (PLSR) chemometric tools were developed. This development is based on the synthesis of homogeneous, high-dense deposited metal nanoparticle islands over the surface of glass substrates to be used as lab-on-chip SEIRA sensors for the determination of bisacodyl (BIS) and its active metabolite in plasma. SEM micrographs revealed the formation of metallic islands of colloidal citrate-capped gold and silver nanoparticles of average sizes of 29.7 and 15 nm, respectively. BIS and its active metabolite were placed on the nanoparticles' coated substrates to be directly measured, then PLSR chemometric modelling was used for the quantitative determinations. Plasmonic citrate-capped gold nanoparticle substrates showed better performance than those prepared using citrate-capped silver nanoparticles in terms of preparation time, enhancement factor, PLSR model prediction, and quantitative results. This study offers a way to determine BIS and its active metabolite in the concentration range 15–240 ng/mL in human plasma using inexpensive disposable glass-coated substrates that can be prepared in 1 h to get results in seconds with good recovery between 98.77 and 100.64%. The sensors provided fast, simple, selective, molecular-specific and inexpensive procedures to determine molecules in their pure form and biological fluid. [ABSTRACT FROM AUTHOR]

The synthesis of Cyanobacteria‐mediated nanoparticles has attracted great attention due to its ecofriendly, cost‐effective and biocompatible properties. Silver nanoparticles (AgNPs) are used in different areas such as medicine, household products, disinfectants or food storage. The present study aimed the biosynthesis of AgNPs from Cyanobacterial Chroococcus sp. and their antimicrobial activities on some important pathogen bacterial species. According to the obtained data, optimal conditions for synthesis of AgNPs were extract rate 3 : 1 v/v (cell extract/AgNO3), silver salt concentration 10 mM, pH 7, temperature 60 °C and time 30 minutes. The surface plasmon resonance peak of AgNPs was observed at 420–430 nm, and AgNPs were well‐dispersed spherical with an average size of 11–13 nm in diameter by TEM. SEM‐EDX analysis revealed a strong signal of silver. With FTIR analyzes, shift in the absorption bands after the AgNPs formation was confirmed. X‐ray diffraction analysis exhibited that the AgNPs were cubic crystalline shape. Zeta potential of AgNPs showed ‐ 20 mV. The AgNPs strong showed antibacterial activity on an opportunistic bacterial pathogens of Micococcus luteus, Bacillus subtilis and Pseudomonas aeroginosa. The effective and rapid synthesis of Chroococcus‐mediated AgNPs and their strong antimicrobial effects can create an important potential for their use in biomedical and environmental applications. [ABSTRACT FROM AUTHOR]

Localized Surface Plasmons (LSPs) can be excited on metallic nanoparticles, which can induce a strong enhancement of electromagnetic field in the near-field region (resonance amplification) leading to its extensive applications in Surface-Enhanced Raman Scattering (SERS), fluorescence enhancement, refractive index (RI) measurement, biomolecular interaction detection, and so on. In this work, we utilize the phenomenon of LSPR and study the optical properties of silver nano particles (Ag NPs) - a Box-Behnken design with three variables: AgNO3 (x1), H2O2 (x2), and NaBH4 (x3) were used. We have controlled some of the variables such as metal precursor, stabilizer, oxidizing, and reducing agents present in the solution (reaction medium) to synthesize different sizes of Ag NPs. In this work, the effect of the interaction between the components Ag+, H2O2, Tri-Sodium citrate (TSC), and NaBH4 on the formation of colloidal Ag NPs was also characterized by the chemical route method. [ABSTRACT FROM AUTHOR]

Femtosecond time-resolved pump–probe absorption kinetic spectroscopy was used to show that the presence of plasmonic silver nanoparticles in Ag–CuPc hybrid thin-fi lm nanocomposites leads to a significant reduction in the relaxation time of induced absorption from an excited singlet state of copper phthalocyanine fi lm as compared to the pure fi lm. The observed effect is associated with intersystem crossing acceleration in CuPc molecules located in a nonuniform field near the surface of plasmonic silver nanoparticles in the hybrid nanocomposite. The detected effects were demonstrated to depend on the thickness of the copper phthalocyanine layers in the hybrid (Ag–CuPc)nAg nanocomposites. [ABSTRACT FROM AUTHOR]

Nanotechnology has emerged as a promising field for the development of novel antibacterial agents with reduced environmental impact. In this study, we present a novel green synthesis approach for the production of silver nanoparticles (AgNPs) using a plant-based extract. These AgNPs were subsequently characterized using various analytical techniques, including UV-Vis spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FTIR). UV-Vis spectroscopy confirmed the formation of AgNPs by exhibiting a characteristic surface plasmon resonance peak at around 401 and 420 nm. XRD analysis revealed the crystalline nature of the AgNPs, with distinct diffraction peaks corresponding to the face-centered cubic structure of silver. TEM analysis demonstrated that the synthesized AgNPs were predominantly spherical in shape and exhibited an average size within the nanoscale range. FTIR analysis was employed to elucidate the potential bioactive compounds present in the plant extract responsible for the reduction and stabilization of AgNPs. Furthermore, we evaluated the antibacterial activity of these synthesized AgNPs against a panel of bacterial isolates. All the bacterial isolates were sensitive to the silver nanoparticles. Staphylococcus aureus as found to be most resistant, while E. coli as found to be the most sensitive. [ABSTRACT FROM AUTHOR]

This paper presents a simple, fast, and inexpensive method for the large-scale fabrication of polymer-based humidity sensors on glass substrates. The nanoparticles were synthesized using laser ablation, this is an environmentally friendly method for fabricating metal nanoparticles and provides a unique tool for nanofabrication. In this work, humidity sensing material, poly(3,4 ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) along with different kinds of nanoparticles, Au and Ag, are employed to enhance the stability and sensitivity to humidity sensing. Based on the experimental results, the TEM images show the crystallinity of the nanoparticles, indicating alloying of the nanoparticles. Based on XRD, this result indicates that the amorphous structure of PEDOT:PSS is only slightly affected by mixing with nanoparticles. According to FE-SEM analysis, the formation of interconnected crystallites facilitates the charge transport mechanism in the polymer chains due to improved conduction paths. Has been Characterization of humidity sensors Using (LCR), study the effect of humidity on capacitance at different frequencies (100 Hz, 1 kHz, 10 kHz, and 100 kHz), and the response and recovery time characteristics. The results show excellent linear and active behavior of the capacitive humidity response. Ag, PEDOT, and Au NPs have a synergistic effect, exhibiting a more extended sensing range and better stability. This work shows a high-sensitivity and low-cost sensing material for different humidity sensor applications. [ABSTRACT FROM AUTHOR]

Adsorption of silver nanoparticles on polymers may affect the processes in which they participate, adjusting the analytical characteristics of methods for the quantitation of various substances. In the present study, a composite material based on silver triangular nanoplates (AgTNPs) and polyurethane foam was proposed for chemical analysis. The prospects of its application for the solid-phase/colorimetric determination of organic thiols were substantiated. It was found that aggregation of AgTNPs upon the action of thiols is manifested by a decrease in the AgTNPs' localized surface plasmon resonance band and its significant broadening. Spectral changes accompanying the process can be registered using household color-recording devices and even visually. Four thiols differing in their functional groups were tested. It was found that their limits of detection increase in the series cysteamine < 2-mercaptoethanol < cysteine = 3-mercaptopropionic acid and come to 50, 160, 500, and 500 nM, respectively. The applicability of the developed approach was demonstrated during the analysis of pharmaceuticals and food products. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (nano‐Ag0) fixed on supports or in colloidal solution exhibit surface plasmon resonance, but there have been few attempts at surface plasmon resonance‐based liquid chromatographic separation. Here, for the first time, a capped Ag(I) green tea colloidal solution was used as a precursor to anchor nano‐Ag0 on silica. Nano‐Ag0 supported on silica was confirmed by spectroscopy and microscopy, and nano‐Ag0 particles (average diameter 20 nm) were scattered on the silica surface. This ecologically friendly approach for doping nanoparticles on solid supports was as efficient as chemical methods and could be used to separate polycyclic aromatic sulfur heterocycles from a heavy aromatic fraction. Using a nano‐Ag‐silica ligand exchanger, parts‐per‐million concentrations of sulfur heterocycles were probed by surface plasmon resonance nano‐Ag0 on a solid substrate. Using this approach, mass detection shielding can be eliminated to isolate polycyclic aromatic sulfur heterocycles from aromatic fractions. This study presents an innovative approach to producing dispersed silver nanoparticles on a solid substrate. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nanocomposites of ZIF-8, carbon nanodots and silver nanoparticles are prepared. • A novel fluorescent sensing strategy is developed for the detection of H 2 O 2 and glucose based on AgNP-CD-ZIF-8. • Excellent analytical performances are achieved, which might inspire future studies on MOF assembly. In this study, a novel fluorescent biosensor is developed for the detection of H 2 O 2 and glucose based on Zeolitic Imidazolate Framework-8 (ZIF-8) nanocomposites. ZIF-8 encapsulating carbon nanodot (CD) exhibits bright fluorescence emission. After further loading of AgNP, the fluorescence is quenched, which is mainly based on the excited electron transfer from CD to AgNP. Besides, the excitation wavelength of CD falls within the adsorption range of AgNP, which leads to efficient inhibition of the excitation energy. The as-prepared AgNP-CD-ZIF-8 nanocomposites can be utilized as a highly sensitive platform for the analysis of H 2 O 2 and glucose. In the presence of glucose, H 2 O 2 can be generated by the catalysis of glucose oxidase (GOD), which induces the etching of AgNP and subsequent recovery of CD-ZIF-8 fluorescence. This "turn on" biosensor can be applied for facile and convenient quantification of H 2 O 2. It can also be further extended to detect glucose in real samples after combining specific catalytic effect of GOD. The analytical performances are excellent, which demonstrates great potential for practical utility. [ABSTRACT FROM AUTHOR]

The effect of the dielectric and chemical properties of the surrounding medium on the extinction spectra of silver island films is determined. The shift of the plasmon resonance maximum towards low energies with an increase in the permittivity of the medium (for SiO2 and Al2O3) corresponds to the calculated value, essentially depending on the shape of nanoparticles. Simultaneously with the shift, an increase in the optical density at the plasmon resonance frequency is observed. For nanoparticles immersed in an anisotropic medium, liquid crystal in particular, the shift of the plasmon resonance maximum depends on the local permittivity in the immediate vicinity of nanoparticles, i.e., on how exactly the surrounding molecule interacts with the substrate and the nanoparticle. In this case, the displacement can either be completely absent or be significantly greater than the displacement in isotropic media, depending on the shape of nanoparticles. The increase in optical density also depends on the local permittivity. The partial oxidation of nanoparticles leads to an insignificant but noticeable shift towards higher energies. In this case, the plasmon lifetime in the nanoparticle increases. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to provide an in-depth review of plasmonic metal nanoparticles made from rhodium, platinum, gold, or silver. We describe fundamental concepts, synthesis methods, and optical sensing applications of these nanoparticles. Plasmonic metal nanoparticles have received a lot of interest due to various applications, such as optical sensors, single-molecule detection, single-cell detection, pathogen detection, environmental contaminant monitoring, cancer diagnostics, biomedicine, and food and health safety monitoring. They provide a promising platform for highly sensitive detection of various analytes. Due to strongly localized optical fields in the hot-spot region near metal nanoparticles, they have the potential for plasmon-enhanced optical sensing applications, including metal-enhanced fluorescence (MEF), surface-enhanced Raman scattering (SERS), and biomedical imaging. We explain the plasmonic enhancement through electromagnetic theory and confirm it with finite-difference time-domain numerical simulations. Moreover, we examine how the localized surface plasmon resonance effects of gold and silver nanoparticles have been utilized for the detection and biosensing of various analytes. Specifically, we discuss the syntheses and applications of rhodium and platinum nanoparticles for the UV plasmonics such as UV-MEF and UV-SERS. Finally, we provide an overview of chemical, physical, and green methods for synthesizing these nanoparticles. We hope that this paper will promote further interest in the optical sensing applications of plasmonic metal nanoparticles in the UV and visible ranges. [ABSTRACT FROM AUTHOR]

This paper reports the effects of the silver nanoparticle (Ag-NP) deposition on the optical properties of silicon nanowire (SiNW) layer. Vertically, SiNW arrays were prepared in HF/AgNO3 aqueous solution using metal-assisted chemical etching of p-type silicon. The insertion of Ag particles in SiNWs was performed by electroless deposition method by varying the concentration of the silver nitrate solution. Scanning electron microscopy (SEM) micrographs show arrays of parallel nanowires as well as the presence of Ag-NPs on SiNWs layer. Fourier transform infrared (FTIR) and Raman spectroscopies reveal the existence of new vibration bands that are related to silver particles and their interactions with SiNW surface. By Raman spectroscopy, we also observed the manifestation of SERS effect for SiNWs/Ag composites. The optical properties of the elaborated samples were investigated by photoluminescence spectroscopy (PL). The integrated PL intensity of SiNWs was increased fourteen times by the deposition of silver nanoparticles on their surfaces for a silver nitrate concentration of 0.05 M which is essentially due to localized surface plasmon resonance. The PL spectrum of SiNWs/Ag exhibits intense emission band at 2.36–2.39 eV which is related to the interband and intraband transitions between the electronic states of Ag nanoparticles. Energy band diagram showing the emission mechanism in Ag/SiNWs composites was proposed. [ABSTRACT FROM AUTHOR]

The broad array of potential applications of silver and gold nano-particles in diverse fields is well-known. The utilization of lethal reagents is included in the contemporary procedures of synthesizing nanoparticles. In present times, there is necessity to augment novel mechanisms that lead to the synthesis of gold and silver nano-particles with the help of environmentally safe reagents. The reliable green synthesis of silver and gold nano-particles with the help of Colocasia esculenta root extract popularly called as Arvi, has been investigated here. The experimental procedure employed here to scrutinize and observe the synthesis of silver and gold nano-particles based on quantity is UV-Vis absorption spectroscopy. Surface Plasmon Resonance (SPR) was exhibited by UV/Vis spectrum for silver and gold nano-particles at 420 and 540 nanometers, respectively. The mean diameter of gold and silver nanoparticles synthesized in the solution was found to be 85 nm and 105 nm, respectively. The particles that were synthesized had a spherical shape. [ABSTRACT FROM AUTHOR]

Background: Increasing prevalence of microbial resistance and side effects of currently available drugs compels the researchers to look for alternate therapies and formulations to overcome this problem. Plant based formulations have been proved to be most reliable agents in recent times. Objective: In the current study, bio fabricated herbal silver nanoparticles (HSNPs) were prepared by reducing silver nitrate (AgNO3) solution with ethyl acetate fractions (EAF) of Blumea lacera extracts. These bios conjugated HSNPs were then assessed for potential anti-inflammatory and antibacterial activities along with in vitro antioxidant effect. Methods and results: The synthesis was confirmed by absorbance peak at 441 nm due to surface plasmon resonance in UV-visible spectrophotometer. FTIR spectra of HSNPs indicated the phytochemicals having C-O bond responsible for reducing of Ag+ to Ago. Average size of HSNPs was found to be 59.21 nm which was in good agreement with TEM and SEM results. EDS analysis showed the existence of Silver, Nitrogen and Carbon in HSNPs. The antibacterial activity of HSNPs in terms of zone of inhibition (ZOI) via disc diffusion assay and against Staphylococcus aureus and Escherichia coli was found to be 25.0±1.19 mm and 18.3±2.08 mm, respectively. The minimum inhibitory concentration (MIC) of HSNPs was found to be 50 µg/ml and 60 µg/ml against S. aureus and E. coli, respectively. The antioxidant capacity of the HSNPs was insignificant as compared to EAF but the results of anti-inflammatory activity was significant (p<0.05). Conclusion: The overall result demonstrated better in-vitro pharmacological potential of HSNPs compared to neat extract/EAF. [ABSTRACT FROM AUTHOR]

The results of the testing of silver nanoparticles (AgNPs) antibacterial activity obtained in aqua solutions of high molecular chitosan and oligochitosans at near‐physiological pH values are demonstrated. Aggregative stable AgNPs were synthesized in solutions of chitosans of average molecular weight of 6, 12 and 311 kDa. Nanodispersions were characterized by UV‐Vis and FTIR, SEM and TEM. AgNPs formation was confirmed by the presence of the surface plasmon resonance peak at nearly 425 nm in the extinction spectrum and TEM. The average size of approximately 40–90 nm was determined by DLS, electron microscopy and UV‐Vis. Minimal inhibitory concentrations were determined by microdilution in the Mueller‐Hinton broth method. The AgNPs dispersions exhibit a significant antibacterial effect toward both Gram‐positive and Gram‐negative bacteria strain (MIC values are of 1–8 μg/ml). The effect is little dependent on polymer molecular weight. A two‐stage Staphylococcus aureus growth suppression effect was found for the first time. [ABSTRACT FROM AUTHOR]

The silver nanoparticles (Ag-Nps) synthesized by green reduction process using the leaf extract of Acacia leucophloea exhibited the surface plasmon resonance (SPR) at 435 nm. There were several techniques like UV–visible spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and selected area electron diffraction patterns (SAED) used to examine the growth kinetics, surface morphology, and crystallinity aspects of Ag-Nps in the absence and the presence of cationic surfactant, cetyltrimethylammonium bromide (CTAB). Fourier transform infrared spectrometry (FTIR) was used to confirm the reducing utility of leaf extract. The size of synthesized Ag-Nps varied from 10 to > 100 nm in the absence of CTAB and from 10 to 50 nm in its presence. While irregular or polytope-outlined Ag-NPs were detected in the absence of CTAB, spherical or oval shape prevailed in its prevalence. Williamson-Hall models were employed to deduce the crystallinity aspects of the procured Ag-Nps. Furthermore, the Ag-Nps effected in the presence of CTAB exhibited more antibacterial efficacy. [ABSTRACT FROM AUTHOR]

[Display omitted] • Caralluma adscendens R.Brown var. bicolor was used for the phytosynthesis of nanomaterials. • Both nanoparticles exhibited greater pharmacological activities. • Prepared nanomaterials were characterized using FTIR, HR-TEM, EDX, and UV–Vis analysis. • Both nanoparticles showed higher wound-healing activity than CABL extract based on the MTT assay and fluorescence analysis. Nanomaterials employed in nanomedicine have the potential to function as both diagnostic and therapeutic tools for individuals. Over the past few decades, significant efforts have been made to synthesize a range of metal nanoparticles through the utilization of different plant extracts. Caralluma adscendens R. Brown var. bicolor leaves (CABL) extract was employed in this study as a reducing/capping agent for the synthesis of gold/silver nanoparticles (CABL@AgNPs/CABL@AuNPs) and explore their pharmacological properties. The successful synthesis of CABL@AgNPs and CABL@AuNPs was confirmed through the observation of surface plasmon resonance (SPR) at 439 and 522 nm using ultraviolet–visible spectrophotometer (UV–Vis). High resolution-transmission electron microscopy (HR-TEM) and energy dispersive X-ray (EDX) techniques were employed to evaluate the shape, size, and chemical composition of the as-synthesized CABL@AgNPs and CABL@AuNPs. Fourier-transform infrared spectroscopy (FTIR) was used to determine the biomolecules responsible for the reduction of metal ions and the stability of metal nanoparticles generated using plant extract. An evaluation was performed to assess the antibacterial and antifungal efficacy of the prepared aqueous CABL extract, CABL@AgNPs, and CABL@AuNPs through the implementation of the disc diffusion technique. The results demonstrated that CABL@AgNPs exhibited greater efficiency when compared to both CABL extract and CABL@AuNPs. The dose-dependent nature of antimicrobial activities was clearly demonstrated through the results of antioxidant and anti-inflammatory experiments. The wound healing activity of the prepared nanomaterials was evaluated using a variety of techniques, including MTT assay, fluorescence staining test, and in vitro scratch assay. The wound-healing capacity of prepared nanomaterials was evaluated using an in vitro scratch assay with Fibroblast L929 cells. The impact of nanoparticles at the IC 50 concentration range was analysed through a fluorescence staining experiment and MTT assay to determine toxicity levels. The environmentally friendly approach of current study shown that both nanoparticles have the potential to be effective therapeutic agents for treating different illnesses. [ABSTRACT FROM AUTHOR]

In this study, a novel approach for fabricating silver nanohole arrays (AgNAs) on silicon/hyperbolic metamaterial (Si/HMM) substrates is described. This approach involves the use of fixed-size plastic nanoparticles combined with reactive-ion etching, followed by decoration with silver nanoparticles (AgNPs) around the edges of the Ag nanoholes. The HMM structure is composed of six pairs of alternating layers of silver and silicon dioxide (Ag/SiO 2). Herein, the interaction of the localized surface plasmon resonance (LSPR) is investigated by the analysis of photoluminescence (PL) responses of 4-(dicyanomethylene)-2- t -butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) molecules over the AgNAs on the Si/HMM substrates. Both configurations, i.e., with and without ring-shaped AgNPs, are investigated extensively by a combination of experimental measurements and numerical simulations. The substantially enhanced PL for the proposed substrates can be attributed to increased light absorption, leading to the fine-tuning of surface-enhanced electromagnetic fields. Notably, the PL intensity of DCJTB is significantly enhanced (16.4 times) in comparison with that of the reference substrate. Concurrently, the PL lifetime is reduced by 49.45% (0.91 ns–0.46 ns). These results underscore the transformative potential of these enhanced substrates in reshaping the landscape of sensing platforms. The enhanced PL response coupled with the precisely tunable LSPR effects demonstrates promise for innovative applications in optical and photonic technologies. [Display omitted] • Ag nanohole arrays with ring-shaped AgNPs were prepared on a Si (40 nm)/HMM substrate. • The PL intensity of DCJTB was enhanced by 16.5-fold for this proposed substrate. • The PL lifetime of DCJTB was reduced by 49.45% for this proposed substrate. • The proposed substrate can improve the optoelectronic device performance owing to the LSPR effect. [ABSTRACT FROM AUTHOR]

Central composite design (CCD) as one of response surface designs was employed to optimize the biosynthesis process of silver nanoparticles (AgNPs). In this design, fungal cell-free filtrate of Talaromyces stipitatus was applied as a biosource for the biosynthesis of AgNPs. Different variables with five levels were used to optimize AgNPs biosynthesis. Independent variables were concentration of silver nitrate (AgNO3; mmole), temperature (°C), time, pH and ratio of AgNO3 to cell free extract. While dependent variable was peak intensity of surface plasmon resonance (SPR) at wavelength 420 nm. The predicted optimal setup parameters were AgNO3 concentration of 7 mmol, temperature of 25 °C, time of 91.2 hr, pH of 8 and ratio of AgNO3 solution to cell-free extract of 2:1. The characteristics of biosynthesized AgNPs were revealed using Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), zeta potential, energy dispersive x-ray analysis (EDX), and transmission electron microscopy (TEM). Biosynthesized AgNPs appeared to be spherical, with mean size of 13.95 nm and zeta potential of 9.85 mV. Biosynthesized AgNPs were also examined for their antimicrobial properties against selected bacterial and fungal pathogens including Staphylococcus aureus, Bacillus cereus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Aspergillus flavus, A. niger, Fusarium oxysporum and Alternaria alternata. [ABSTRACT FROM AUTHOR]

A complex nanostructure composed of silver nanocrystals randomly immobilized carbon nanoparticles randomly immobilized carbon nanoparticles was in situ synthesized by one-step solvothermal method using Toluene as carbon sources. [Display omitted] Silver nanoparticles (Ag NPs) have attracted extensive research interest in bioimaging and biosensing due to their unique surface plasmon resonance. However, the potential aggregation and security anxiety of Ag NPs hinder their further application in biomedical field due to their high surface energy and the possible ionization. Here, binary heterogeneous nanocomplexes constructed from silver nanoparticles and carbon nanomaterials (termed as C-Ag NPs) were reported. The C-Ag NPs with multiple yolk structure were synthesized via a one-step solvothermal route using toluene as carbon precursor and dispersant. The hydrophilic functional groups on the carbon layer endowed the C-Ag NPs excellent chemical stability and water-dispersity. Results showed that C-Ag NPs demonstrated excellent safety profile and excellent biocompatibility, which could be used as an intracellular imaging agent. Moreover, the C-Ag NPs responded specifically to hydroxyl radicals and were expected to serve as a flexible sensor to efficiently detect diseases related to the expression of hydroxyl radicals in the future. [ABSTRACT FROM AUTHOR]

We report on biosynthesis of silver nanoparticles using aqueous leaf extract of Euphorbia sanguinea and its photocatalytic degradation of Congo red dye and melanogenesis inhibition activity of mushroom tyrosine enzyme. Surface Plasmon resonance bands obtained from UV-Vis spectra were within the range 430–436 nm. FT-IR studies reveal the presence of functional groups of the plant metabolites used as stabilizing agents of nanoparticles. The shape of silver nanoparticles is spherical with size ranges about 20–28.8 nm as confirmed by SEM. XRD patterns displayed well-defined crystalline peaks corresponding to the face-centred cubic structures of metallic silver nanoparticles. The results of photocatalysis showed high photocatalytic efficiency of 86% and 90% within 5 min and 60 min, respectively at a rate of solar radiation of in the degradation of Congo red dye. The AgNPs gave dose dependent melanogenesis inhibition activity with IC50 of 71.96 µg/ml, showing non competitive mode of inhibition. Rapid formation of silver nanoparticles using 0.5 mL extract of Euphorbia sanguinea. AgNPs are spherical, monodispersed and with sizes in the range of 20–29 nm. High photocatalytic efficiency of 86% was obtained within 5 min of solar radiation of AgNPs in the degradation experiment of Congo red dye. First order kinetics with a correlation coefficient of 0.9472 and a rate of 0.0063 min−1 was established for the photocatalytic process. AgNPs showed dose dependent melanogenesis inhibition activity of IC50 71.96 µg/ml. [ABSTRACT FROM AUTHOR]

In this report, Ag nanoparticles were fabricated using the single-step glancing angle deposition (SS-GLAD) technique upon In2O3/TiO2 thin film. Afterward, a detailed analysis was done for the two samples such as In2O3/TiO2 thin film and In2O3/TiO2 thin film/Ag nanoparticles, to inspect the field emission scanning electron microscopy (FESEM), energy-dispersive X-ray analysis (EDAX), X-ray diffraction (XRD), ultraviolet (UV) spectroscopy, and electrical properties. The reduction in bandgap energy for the samples of In2O3/TiO2 thin film/Ag nanoparticles (~4.16 eV) in comparison with the In2O3/TiO2 thin film (~4.28 eV) was due to trapped e–h recombination at the oxygen vacancies and electron transmission of Ag to the conduction band of the In2O3/TiO2 thin films. Moreover, under irradiation of photons Ag nanoparticles generated inorganic Ag–O compound attributable to the localized surface plasmon resonance (LSPR). Also, a ~90% high transmittance, ~60% and ~25% low reflectance in UV and visible region, fill factor (FF) of 53%, as well as power conversion efficiency (PCE) of 15.12% was observed for In2O3/TiO2 thin film/Ag nanoparticles than the In2O3/TiO2 thin film. Therefore, the use of Ag nanoparticles textured In2O3/TiO2 thin film–based device is a promising approach for the forthcoming photovoltaic applications. [ABSTRACT FROM AUTHOR]

Plasmonic nanofluids have emerged as strong candidates for future working fluids in direct absorption solar collectors (DASC). However, in novel DASC systems, a significant temperature gradient exists over working fluid depth increasing emissive losses and hence, results in low thermal conversion efficiency. Considering these issues, a laboratory scale prototype of reverse-irradiated DASC system (RR–DASC) has been tested under controlled laboratory conditions and compared with a direct irradiated DASC system (DR–DASC) using silver nanofluids at three different mass concentrations i.e., 0.1 mg/L, 0.2 mg/L, and 0.4 mg/L. Ag nanoparticles were having monodisperse spherical shape with surface plasmon resonance (SPR) peak occurring around 395–400 nm. The experimental results showed that RR–DASC maintains uniform temperature over the fluid depth, while about 3–4°C temperature gradient was noticed in direct irradiated DASC system under similar operating conditions. A maximum photo-thermal conversion efficiency of about 80% was observed using 0.4 mg/L Ag nanofluids in RR–DASC system. The presented work can pave the ways for future development of highly efficient DASC systems for low to high temperature solar applications. [ABSTRACT FROM AUTHOR]

Silver nanoparticles/nanocomposites are gaining popularity for their unique features and wide-range of applications including bactericidal behaviour, sensing, and photocatalysis. In this report, a novel, single-step, sustainable, and low-cost fabrication of silver carbon quantum dot (Ag/CQD) nanocomposites by using coal-derived carbon quantum dots (CQDs) as a reductant and stabilizer having great potential for simple and quick synthesis of silver nanocomposites has been documented for the first time in this paper. The HRTEM image of the Ag/CQD nanocomposite depicts the crystalline nature with two distinct d-spacings of 0.22 and 0.24 nm attributed to the (100) and (110) in-plane of the graphitic core or aromatic carbon and d-spacings of 0.24 and 0.27 nm were also observed which are attributed to the (111) and (122) lattice planes of Ag. The size distribution histogram derived from the TEM image indicates the particles to be within 2–12 nm in diameter, complying with the Gaussian distribution. SAED patterns of the Ag/CQD nanocomposite showed concentric diffraction rings with the (111), (200), (220), and (311) lattice planes of the fcc-structured silver metal, which indicates the composition of silver nanoparticles. From the XPS deconvoluted Ag 3d spectrum of the nanocomposites, the binding energies of Ag 3d5/2 and Ag 3d3/2 at 367 and 373 eV can be observed, which indicates that the silver is present in the metallic zero valent [Ag(0)] oxidation state in the nanocomposite. Moreover, UV-vis spectra show a major absorption peak at 422.47 nm that contributes to surface plasmon resonance of the Ag/CQD nanocomposite. The nanocomposite shows a zeta potential of −9.91 mV, signifying their high stability. The effect of base and concentrations of the CQDs in the synthesis of Ag/CQD nanocomposites has also been studied. Oxygen possessing functional groups present on the CQD surface were observed to play a significant role in the reduction of Ag/CQD nanocomposites. In addition, the nanocomposite has promising bactericidal behaviour for both Gram-positive and -negative bacterial strains for application as an antibacterial material. The Ag/CQD nanocomposite shows a maximum inhibition against bacterial strain Rhodococcus soli with an inhibition zone diameter of 17 mm as compared to the other strains. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ferroelectric LiNbO3 and Plasmonic Ag@LiNbO3 photocatalyst was successfully synthesized and fully characterized. • The photocatalysis pharmaceutical degradation ability of Ag@LiNbO3 was investigated using sulfadiazine as a pollutant target. • The Ag@LiNbO3 catalyst exhibited enhanced photocatalytic activity and stability. • photodegradation mechanism of Sulfadiazine as pharmaceutical pollutant during the photocatalytic process was proposed. Semiconductors are highly sought after as photocatalysts owing to their High-performance ability to decompose organic pollutants. In this current work, LiNbO 3 assembled silver nanoparticles were synthesized using the hydrothermal technique, in order to combine the surface plasmon resonance (SPR) effect and spontaneous polarisation of Lithium niobate to improve the photocatalytic activity. The prepared catalysts were examined by diverse analytical methods such as X-ray diffraction (PXRD), scanning electron microscope (SEM) coupled with EDS analysis spectroscopy, TEM microscope, Raman spectroscopy, The ferroelectric P-E loop, and Diffuse Reflectance Spectroscopy (DRS). X-ray diffraction patterns reflected the successful preparation of pure LiNbO 3 using the hydrothermally synthesized method and the formation of silver-loaded LiNbO 3. The scanning electron microscopy and EDS analysis demonstrated the loaded Ag nanoparticles' distribution and the silver presence in the LiNbO 3 powder. The photocatalytic degradation performance of the Ag-assembled LiNbO 3 nanocomposite was evaluated under Visible light irradiation by following the photodegradation of sulfadiazine (pharmaceutical pollutant). The photocatalytic performance of the Ag-loaded LiNbO 3 was better than that of pristine LiNbO 3 with a ∼89.4 % removal of SDZ over 60 min of visible irradiation and displays good reusability and stability even after the four regenerated cycles. It has been indicated that the Ag nanoparticles improve photocatalytic activity. Based on the optical properties of Ag@LiNbO 3 nanocomposite, a possible mechanism for sulfadiazine degradation is proposed. The Our findings demonstrate that the synthesized Ag@LiNbO 3 will be appropriate for pollutant remediation. [ABSTRACT FROM AUTHOR]

Highly selective and sensitive detection of toxic mercury ions (Hg2+) has become a critical issue in recent decades, due to increasing environmental and health requirements. Herein, carbon dots reduced and decorated Ag (CDs/Ag) nanoparticles based fiber probes were fabricated, providing a "turn-off" surface-enhanced Raman spectroscopy (SERS) for low-concentration Hg2+ ions detection. The CDs/Ag nanoparticles fiber probe exhibits better SERS performance than that of Ag nanoparticles fiber, attributed to the stronger electromagnetic intensities induced by localized surface plasmon resonance (LSPR) and larger hot-spot areas resulting from the interaction between silver nanoparticles and carbon dots, under 532 nm beam excitation. As low as 10−11 M Hg2+ ions can be detected through the decrease in Raman scattering intensities of CV molecules, due to the SERS inactive Hg metal layer wrapping the surface of silver nanoparticles, through the reduction of Hg2+ ions by carbon dots. The dropping of silver nanoparticles' LSPR induced absorption peak, EDS elemental mapping, and XPS analysis all confirm that the wrapping decreases the LSPR effect and corresponding Raman intensity. Furthermore, the detection shows high selectivity and can only be applied for detecting Hg2+ ions, owing to the reduction capability of carbon dots. The close analysis results obtained using SERS fiber probes and commercial inductively coupled plasma-mass spectrometry (ICP-MS) for detecting Hg2+ ions in real water sample confirm the reliability of this detection method. This research indicates the CDs/Ag fiber probe has a great potential application for environmental Hg2+ ions detection. [Display omitted] • Carbon dots directly reduced Ag+ ions and the formation of CDs/Ag composite nanoparticles fiber probes; • Better SERS performance from CDs/Ag nanoparticles fiber probes due to stronger LSPR effect and larger hot-spot areas; • Highly selective trace mercury ions detection from the decrease of CV molecules SERS intensities; • CDs reduced Hg2+ into metallic layer wrapping on CDs/Ag nanoparticles. [ABSTRACT FROM AUTHOR]

This study describes a simple one-pot photochemical method to synthesize triangular silver nanoprisms (T-AgNPs), for which a mixture of silver nitrate (AgNO 3) and citrate was irradiated with an ultraviolet-C (UVC) lamp reactor. We successfully synthesized T-AgNPs with edge lengths ranging from 50 to 150 nm, showing a significant localized surface plasmon resonance (LSPR) band over a wavelength of 1200 nm. This photochemical reaction appears to be unrestricted by plasmon resonance conditions, allowing for the formation of colloidal T-AgNPs with an LSPR band in the near-IR region. In addition, this new method does not require any highly reactive reducing agents or initially prepared silver seed solution. The reduction of Ag+ ions by citrate is induced by UVC light, and the nascent Ag first undergoes nucleation to form spherical or quasi-spherical silver nanoparticles (S-AgNPs). Subsequently, continuous irradiation with UVC light facilitates the transformation of these S-AgNPs into T-AgNPs. The growth kinetics of the nanoparticles with different reaction conditions were examined using ultraviolet–visible–near-infrared spectroscopy and transmission electron microscopy. This new method offers a simple, efficient, and cost-effective means to synthesize T-AgNPs with near-IR LSPR, contributing to wider applications in the fields of optoelectronics, spectroscopics, photovoltaics, etc. [Display omitted] • Triangular silver nanoprisms (T-AgNPs) with 50-150 nm edges were synthesized via seed-free UVC-assisted citrate reduction. • The photoreaction formed T-AgNPs with near-IR LSPR bands, unconstrained by plasmon resonance conditions. • The shape evolution of silver nanoparticles was monitored by recording time-dependent UV–Vis spectra and TEM images. [ABSTRACT FROM AUTHOR]

One of the hallmarks of Alzheimer's disease (AD) pathogenesis is the production, aggregation, and deposition of amyloid-β (Aβ) peptide. Surface-enhanced Raman spectroscopy (SERS) is a promising analytical technique capable of providing valuable information on chemical composition and molecule conformations in biological samples. However, one of the main challenges for introducing the SERS technique into the practice is preparation of scalable and at the same time stable nanostructured sensors with uniform spatial distribution of nanoparticles. Herein, we propose SERS platforms for reproducible, sensitive, label-free quantification of amyloid-β aggregates for short-wavelength – 532 and 633 nm – lasers. A SERS sensor – based on silver nanoparticles immobilized into a chitosan film (AgNP/CS) – provided a uniform distribution of AgNPs from a colloidal suspension across the SERS sensor, resulting in nanomolar limits of detection (LODs) for Aβ42 aggregates with a portable 532 nm laser. The laser-induced deposition was used to obtain denser periodic plasmonic sensors (AgNP/LID) with a uniform nanoparticle distribution. The AgNP/LID SERS sensor allowed for 15 pM LOD for Aβ42 aggregates with 633 nm laser. Notably, both nanostructured substrates allowed to distinguish amyloid aggregates from monomers. Therefore, our approach demonstrated applicability of SERS for detection of macromolecular volumetric objects as amyloid-β aggregates for fundamental biological studies as well as for "point-of-care" diagnostics and screening for early stages of neurodegenerative diseases. [Display omitted] • AgNP/CS composite sensor for detection of amyloid-β aggregates with 532 nm laser. • Sensors demonstrate high uniformity and batch-to-batch reproducibility. • AgNP/LID sensor can be used for detection of amyloid-β aggregates with 633 nm laser. • SERS screening of amyloid-β aggregates can be performed in blood samples. [ABSTRACT FROM AUTHOR]

Hydrogels 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. [ABSTRACT FROM AUTHOR]

Surface plasmon resonance could increase the efficiency of solar cells, when light is trapped by the noble metallic nanoparticles arrangement at and into the silicon solar cell (SSC) surface. Pure noble metal (silver and gold) nanoparticles (NPs) have been synthesized as colloids in de-ionized water (DW) by pulsed laser ablation (PLA) process at optimum laser fluence. Silicon solar cell with low efficiency was converted to plasmonic silicon solar cell by overcasting deposition method of silver nanoparticles on the front side of the SSC. The performance of plasmonic solar cell (PSC) was increased due to light trapping. Two mechanisms were involved : inserting silver nanoparticles (Ag NPs) inside the silicon layer by the heating effect of pulsed laser and depositing gold nanoparticles (Au NPs) on the surface of the SSC by overcasting method. The optical properties of silver and gold colloidal solutions were studied with UV- Visible spectrophotometer with a range from 190 nm to 1100 nm. The absorption spectra showed single absorption peak located at about the characteristic value for silver and gold nanoparticles due to the surface plasmon resonance. Atomic Force Microscope (AFM) images were studied, the ablated noble NPs by pulsed laser have an average diameter less than 100 nm. AFM images showed the morphology of SSC surface without and with nanoparticles before and after overcasting and heating by laser methods. Electrical measurements for SSC namely current – voltage ( I-V )characteristics and responsivity (Rλ) displayed higher efficiency after these procedures. The efficiency rise to(5.2%) due to the localized surface plasmons excitation of (Ag NPs) that were embedded into the silicon layer by the heating effect of pulsed laser. The deposition of AuNPs on the silicon surface of the plasmonic SC additionally increased the efficiency to (7.28%), due to light trapping by scattering from Au NPs towards the plasmonic solar cell depth. [ABSTRACT FROM AUTHOR]

In this study, silver (Ag) nanoparticle thin films were deposited on microscope slide glass and Si wafer substrates using the pulsed-laser deposition (PLD) technique in Ar ambient gas pressures of 1 × 10−3 and 7.5 × 10−1 mbar. AFM analysis has shown that the number of Ag nanoparticles reaching the substrate decreased with increasing Ar gas pressure. As a result of Ar ambient gas being allowed into the vacuum chamber, it was observed that the size and height of Ag nanoparticles decreased and the interparticle distances decreased. According to the absorption spectra taken by a UV–vis spectrometer, the wavelength where the localised surface plasmon resonance (LSPR) peak appeared was shifted towards the longer wavelength region in the solar spectrum as Ar background gas pressure was decreased. This experiment shows that LSPR wavelength can be tuned by adjusting the size of metal nanoparticles, which can be controlled by changing Ar gas pressure. The obtained extinction cross section spectra for Ag nanoparticle thin film was theoretically analysed and determined by using the metal nanoparticle–boundary element method (MNPBEM) toolbox simulation program. In this study, experimental spectrum and simulation data for metal nanoparticles were acquired, compared, and determined to be in agreement. [ABSTRACT FROM AUTHOR]

The fabrication of strain sensors with high sensitivity, large sensing range and excellent stability is highly desirable because of their promising applications in human motion detection, human-machine interface and electric skin, etc. Herein, by introducing a highly conductive silver nanowire (AgNW) layer between two serried silver nanoparticle (AgNP) layers, forming a sandwich structure, a strain sensor with high sensitivity (a large gauge factor of 2.8 × 105), large sensing range (up to 80% strain) and excellent stability (over 1000 cycles) can be achieved. A combination of experimental and mechanism studies shows that the high performance of the obtained strain sensor is ascribed to the synergy of the highly conductive AgNW layer, astatic AgNP layers and the presence of large cracks in stretching. As a proof-of-concept application, the obtained strain sensor can be used for highly effective human motion detection ranging from large scale motions, i.e. kneel bending and wrist flexion, to subtle scale motions, i.e. pulse and swallowing. [ABSTRACT FROM AUTHOR]

The measurement of total antioxidant capacity (TAC) indicating the cooperative action of all antioxidants in a complex sample is an important analytical challenge. A novel green silver nanoparticle-based antioxidant capacity (GSNP-AC) method using carob extract was designed for TAC measurement. Green synthesis of nanoparticles has various advantages such as environmentally friendliness, reliability, sustainability and fast production. In the presence of silver seeds formed with carob extract, Ag+ is reduced to spherical silver nanoparticles (SNPs) with antioxidants, resulting in enlarged particles with a symmetric surface plasmon resonance (SPR) absorption band at 434 nm. The SPR of SNPs allowed quantification of antioxidants (i.e., increase in SPR absorbance being correlated to antioxidant concentration), and the GSNP-AC method gave a linear response over a wide concentration range of antioxidants. The molar absorptivity and LOD for trolox were 11700 L mol−1 cm−1 and 0.31 µM, respectively. The proposed method was validated in terms of concentration-dependent linear response, additivity of absorbances, precision and accuracy. The results obtained with the proposed method for standard antioxidants, synthetic mixtures and real sample extracts were correlated with those of the traditional CUPRAC method. This green synthesized silver nanoparticle-based TAC method showed simple, rapid, cost-effective, and eco-friendly superiorities over similar other nanoparticle-based assays. [ABSTRACT FROM AUTHOR]

The present work reported synthesis, characterization, and biocompatibility of starch encapsulated silver nanoparticles (St-PF-AgNPs) and their antibacterial activity. The synthesis of St-PF-AgNPs involved in two steps: (i) synthesis of the biogenic silver nanoparticles using the fungal extracts (PF-AgNPs); and, (ii) encapsulation of starch in PF-AgNPs (St-PF-AgNPs). The surface plasmon resonance was found at 420 nm for the PF-AgNPs while it was at 260 and 420 nm for the St-PF-AgNPs. FTIR spectrum demonstrated the capping and encapsulation of the fungal extracts and starch in PF-AgNPs and St-PF-AgNPs. The XRD and TEM-EDS confirmed the crystalline nature, spherical-shaped , and polydispersed- PF-AgNPs and St-PF-AgNPs with strong signals of Ag. The St-PF-AgNPs showed a Z -average size of 115.2 d.nm and zeta potential of −17.8 (mV) as indicated by DLS and zeta potentials. The cytotoxicity results demonstrated higher toxicity of PF-AgNPs than St-PF-AgNPs in HEK293 cells. The antibacterial activity of St-PF-AgNPs were higher than PF-AgNPs in S. aureus. Overall, this work concluded that the starch encapsulation significantly increased the antibacterial activity of PF-AgNPs and this opens a new avenue for the treatment of bacterial infections through the sustained release of PF-AgNPs to target pathogenic bacterial cells. [Display omitted] • Starch capped silver nanoparticles (St-PF-AgNPs) prepared and characterized. • Encapsulation of starch reduced the cytotoxicity of silver nanoparticles (PF-AgNPs). • Starch encapsulation improved the stability and antibacterial activity of St-PF-AgNPs. • St-PF-AgNPs exhibited the antibacterial activity through bacterial cell damage. [ABSTRACT FROM AUTHOR]

Colloidal silver nanoparticles were synthesized using chitosan as a stabilizing agent and a reducing agent, assisted by microwave irradiation. It is a new strategy on synthesis via gel phase using sodium hydroxide (NaOH) as an accelerator with silver nitrate (AgNO3) as a salt precursor. UV-Vis spectrophotometer was used to investigate silver nanoparticles formation indicating the appearance of the Localized Surface Plasmon Resonance (LSPR) phenomenon. The size and shape of silver nanoparticles were characterized by Transmission electron microscopy (TEM). Silver nanoparticle stability was investigated based on the LSPR phenomenon and colloidal viscosity during storage for 16 weeks at ambient and low temperatures. The absorption peak at about 400 nm of UV-Vis spectra proved that the silver nanoparticles had been formed. The amount of accelerator NaOH, time of microwave irradiation, and AgNO3 concentration affected the intensity of peak absorption. Based on the TEM image, the size of silver nanoparticles is about 3 - 7 nm with spherical shape. The colloidal of silver nanoparticles were stable for 16 weeks after preparation with neglected aggregation. Storage on low temperature for 16 weeks showed better stability of colloidal silver nanoparticles than that at ambient temperature based on LSPR phenomenon. [ABSTRACT FROM AUTHOR]

This study aimed at using a green, rapid, and efficient method for silver nanoparticles synthesis using different types of agri-waste. Ag was reduced to Ag-NPs using the banana, apple and walnut waste extracts that served as both capping and reducing agent. Silver nitrate solution (1mM) was mixed with the vegetal extract (1:9 ratio) and sonicated in a cleaning bath, at 60C. The successful bio-reduction of silver nitrate into silver nanoparticles was confirmed by UV-Vis spectroscopy, a characteristic surface plasmon resonance (SPR) band being recorded for all the samples. Concluding, agri-waste may be harnessed to phyto-fabricate eco-friendly silver nanoparticles, with multiple applications in the agri-food sector. [ABSTRACT FROM AUTHOR]

The emergence of multidrug-resistant microbes and newly outbreaking diseases are one of the major threats before mankind. This paves the way for researchers to explore new antimicrobial agents that possess common day-to-day applications. In this concern, we have fabricated the antimicrobial Ag-kaolin functional nanostructures by simple and sustainable protocol employing Murraya koenigii fruit extract. UV-visible spectra (UV-Vis) of the Ag-kaolin exhibit absorption peak at 430 nm which corresponds to the characteristic surface plasmon resonance of Ag nanoparticles. X-ray diffraction pattern (XRD) shows the diffraction peak at 37.6° confirms their face-centred cubic nature with (111) plane. Furthermore, the formation of Ag-kaolin functional nanostructures was confirmed through a scanning electron microscope (SEM) and energy-dispersive X-ray spectrum (EDX) analysis. The transmission electron microscopic (TEM) studies reveal the effective formation of quasi-spherical monodispersed Ag nanoparticles having 20–30-nm diameters on the kaolin clay. The bio-synthesized Ag-kaolin nanostructures showed excellent antimicrobial activity against pathogenic gram-positive (Staphylococcus aureus, Bacillus subtilis) and gram-negative (Escherichia coli) bacteria respectively with the inhibition zones of 26 mm, 25 mm and 30 mm. [ABSTRACT FROM AUTHOR]

LiNbO3 ceramic was fabricated using solid‐state reaction route. Silver nanoparticles (NPs) were loaded on LiNbO3 at room temperature using silver nitrate and polyethylene glycol reagents, without the use of external heat and light energy. The X‐ray diffraction showed only LiNbO3 phase in Ag‐loaded LiNbO3 sample with no peak related to Ag metal due to small fraction of Ag loading. X‐ray energy diffraction spectroscopy elemental color mapping confirmed the uniform loading of Ag metal on LiNbO3 particles. Ag metal was loaded in the form of NPs as visualized under transmission electron microscope. Ag NPs‐loaded LiNbO3 showed enhanced absorption of visible light owing to the phenomenon of surface plasmon resonance (SPR). The loading of Ag NPs had no effect on the band gap energy of LiNbO3 ceramic. X‐ray photoelectron spectroscopy technique confirmed the metallic chemical state of Ag in Ag NPs‐loaded LiNbO3. Ag NPs‐loaded LiNbO3 degraded ∼97% rhodamine‐B model dye from the solution when irradiated for 240 minutes under visible light. The dye degradation follows pseudo‐first‐order kinetic having k‐value (kinetic rate constant) of as 0.013 min−1. The •OH (hydroxyl) and O2‐• (superoxide) radicals were the main active species behind the photocatalytic activity of Ag NPs‐loaded LiNbO3. Thus, Ag NPs‐loaded LiNbO3 could be a potential material for degrading organic dyes from water. [ABSTRACT FROM AUTHOR]

A simple, rapid, and sensitive colorimetric assay for ascorbic acid (AA) was developed based on poly(methacrylic acid)‐stabilized silver nanoclusters (PMAA‐AgNCs). The AgNCs were prepared via a single‐step synthesis exploiting PMAA as both a reducing agent and a stabilizer. The sensing capability of this method is based on the color change associated with the growth in size of AgNCs, which turn into nanoparticles, resulting from the reduction of free Ag+ present in AgNCs solution to Ag0 by AA. In the presence of AA, an apparent surface plasmon resonance absorption peak of the silver nanoparticles was observed at 430 nm, and its intensity increased linearly with AA concentration, so that a solution color change could be observed with the naked eye. The proposed method exhibited a linear working concentration range of 0.25–100 μM and a detection limit of 95 nM. The sensor was employed to determine AA concentration in fruit juice and vitamin C tablet samples, affording results of high accuracy. [ABSTRACT FROM AUTHOR]

Hollow metal nanostructures are fascinating because of their unique and surrounding environment-sensitive localized surface plasmon resonances (LSPRs). Herein, we have investigated the hollow silver nanoshell (HSN) sensitivity of different inner core radii and shell thicknesses with respect to change in surrounding medium refractive index. Also, we have shown that the extinction peak of HSNs can be fine-tuned in the visible region as well as biological windows by manipulating the size parameters. Moreover, an enhancement in refractive index sensitivity of 133 to 283 nm/RIU can be achieved in the biological windows by thick hollow silver nanoshells in comparison to thin ones. To achieve a comprehensive study, the sensitivity of homogeneous LSPR extinction inflection points with change in refractive index is also investigated. A consistent improvement in bulk refractive index sensitivity of 36% and 15% is predicted with thick and thin shell layers, respectively. Finally, thick HSNs showed higher refractive index sensitivity when compared with thin ones. Moreover, we envision the idea of more than one molecule detection by tracking the curvature changes. Therefore, we provide a deeper insight into the refractive index sensitivity of homogeneous LSPR inflection points for their use in LSPR-based sensors. [ABSTRACT FROM AUTHOR]

The AgNPs@NCN composite was prepared by loading silver nanoparticles (AgNPs) onto the surface of carbon nitride (g-C 3 N 4) with nitrogen-vacancy and cyanide defect and used for the synergistic degradation of methylene blue (MB) by the structural defect of g-C 3 N 4 , the surface plasmon resonance of AgNPs and Schottky barrier formed between them. The morphology, structure, chemical composition and photoelectrochemical properties were characterized by SEM, TEM, FTIR, XRD, XPS, BET and UV–Vis. The effects of different loads of AgNPs on photocatalytic performance were investigated and the results showed 10%AgNPs@NCN exhibited good photodegradation performance. The maximum degradation efficiency of MB by 10%AgNPs@NCN reached 100% with the rate constant of 0.05443 min−1, which was 9.15 and 6.89 times higher than those of g-C 3 N 4 (0.00595 min−1) and NCN (0.0079 min−1), respectively. The mineralization degree of organic pollutants was evaluated by total organic carbon (TOC) and the results showed that the TOC removals of 10%AgNPs@NCN photocatalytic reaction were 77% and 93% for MB and wastewater, respectively. After four cycles of photocatalytic degradation experiments, the degradation rate of MB was still more than 98.2% and there was no significant change in the characteristic stretching of the catalyst, indicating that the prepared photocatalyst had good stability and reusability. Synergistic degradation of MB based on AgNPs@NCN. Due to the synergistic effect of the nitrogen-vacancy and cyanogen defect of NCN, the surface plasmon resonance of AgNPs and Schottky barrier formed between them, the effective degradation of methylene blue (MB) by AgNPs@NCN composite under visible light irradiation is realized. Under simulated sunlight irradiation, AgNPs@NCN photocatalyst could degrade 100% MB in the solution in 60 min, and the degradation rate was 15.3 and 11.5 times that of g-C 3 N 4 and NCN. [Display omitted] • AgNPs@NCN was prepared by depositing AgNPs on g-C 3 N 4 with structural defect. • The synergistic degradation of MB is realized by structural defect, AgNPs and Schottky barrier. • Under simulated sunlight irradiation, AgNPs@NCN could degrade 100% MB in 60 min. • The proposed method based on the AgNPs@NCN for degrading MB showed high stability. [ABSTRACT FROM AUTHOR]

[Display omitted] • Plasmonic based Gastric cancer biosensor with high sensitivity was made by simple method. • Sensing characterization was simulated accurately by combination of discrete dipole approximation (DDA) and molecular polarizability methods. • Formation of zig-zag chain structures of silver nanoparticles confirmed by experimental and theoretical results. • The presented method have high potential for deep investigating other plasmonic based cancer biosensors. In this research, a highly sensitive gastric cancer biosensor based on the (LSPR) properties of silver nanoparticles has been produced to identify the microRNA-21. This biosensor has been analyzed by UV–Visible spectrophotometer (UV) and Field Emission Scanning Electron Microscopy (FESEM). The obtained results show that our optimized synthesis process leads to the creation of approximately zig-zag chain structures consisting of 4 or 5 nanoparticles which can sense the cancer agent by a maximum shift in the plasmonic peak position. In addition, the mentioned results were confirmed by a comprehensive simulation of the biosensors using discrete dipole approximation (DDA) modified by the molecular polarizability method. The simulation process has been made by considering the effects of the actual molecular structures for both the receptor and target microRNAs on the surface of nanoparticles. The mentioned approach led to approximately accurate results that were matched with experimental achievements. This comparison indicates that the presented method is a suitable way for deep analysis of (LSPR)-based cancer biosensors. [ABSTRACT FROM AUTHOR]

[Display omitted] • This communication involves a green synthesis of silver nanoparticles(AgNPs) using a monosacchharide viz., galactose. • The comparative preparatory studies have also been performed with few monoscasccharides, a discccharide and a polysaccharide. • The truncated hexagonal bipyramidal geometries were seen in the HR-TEM images of as prepared AgNPs. • The as prepared AgNPs exhibited excellent colorimetric response (greenish yellow to brown) upon their interaction with H 2 S. • These AgNPs exhibited very nice SERS characteristics also against H 2 S. We report hereby, a simple and easy to perform experimental protocol for highly selective and real time dual mode (Colorimetric and SERS) detection of hydrogen sulfide (H 2 S) in aqueous medium through galactose activated silver nanoresonators. The truncated hexagonal bipyramids were clearly seen in TEM images of as prepared silver nanoparticles. The interaction of H 2 S with these AgNPs induced their etching followed by agglomeration and led optical (greenish yellow to brown) as well as SERS changes. The optical changes were further exploited to determine the H 2 S from its two spiked samples of human saliva and blood serum each with their percent recovery rates of 91, 82 and 67, 72 respectively. These determinations were totally free from any visual interference from any biothiols like cysteine, homocysteine and glutathione. The optimized silver nanosensor exhibited an excellent linear response in the concentration range of 50–130 nM along with its limit of detection (LOD) as 2.83 nM. Moreover, consecutive additions of different aliquots of H 2 S to a fixed volume of these silver colloids exhibited stepwise decrease in intensity of their absorption bands in the Raman silent (10–500 cm−1) and Raman finger print regions (500–1800 cm−1) upon their excitation at 532 nm. Our findings are well supported by spectroscopic (FTIR, UV–Vis and Raman) and microscopic (SEM, TEM, DLS and zeta potential). [ABSTRACT FROM AUTHOR]

[Display omitted] • Size controlled Solanum torvum (Solanaceae) mediated Ag nanoparticle were synthesised. • AgNPs show remarkable stability at room temperature. • The Synthesised silver nanoparticles are spherical in shape with a size range of 10–20 nm. • HRTEM were used for morphological analysis of the AgNPs. • Prepared AgNPs exhibits good nonlinear optical behaviour and used for Optical limiting applications. Synthesis of metal nanoparticles using plant extract is one of the effective methods which will reduce the use of toxic chemicals as reducing agents. It is known to be an eco-friendly method as well. In this present study, highly biocompatible silver nanoparticles have been successfully synthesized. The crystalline structure of the synthesized AgNPs were analysed using Powder X-ray diffraction (XRD) and Surface Plasmon Resonance (SPR) band were investigated by UV–Visible spectrum. Fourier transform infrared spectroscopy is used to identify the molecules such as phenolic groups and cysteine residues in the proteins that are responsible for reduction and stabilization of nanoparticles. The size and the atomic arrangement of particles are determined by High Resolution Transmission Electron Microscopic (HRTEM) analysis and it is concluded as average size is 20 nm. The Energy Dispersive X-ray (EDX) analyser was used to calculate the percentage of elements in the sample. Nonlinear optical properties of the silver nanoparticles were studied using the Z-scan technique and found that which exhibits third order negative nonlinearity. The negative nonlinearity of AgNPs can be used for optical limiting application. [ABSTRACT FROM AUTHOR]

We report a simple and fast microwave-assisted method to grow silver nanoparticle films with tunable plasmon resonance band. Microwaving time controls nucleation and growth as well as particle agglomeration, cluster formation, particle morphology, and the plasmonic properties. Films produced with times shorter than 30 s presented a single well-defined plasmon resonance band (~ 400 nm), whereas films produced with times longer than 40 s presented higher wavelength resonances modes (> 500 nm). Plasmon band position and intensity can be easily tuned by controlling microwaving time and power. SEM and AFM images suggested the growth of asymmetrical silver nanoparticles. Simulated extinction spectra considering particles as spheres, hemispheres, and spherical caps were performed. The films were employed to enhance the sensitivity of ionizing radiation detectors assessed by optically stimulated luminescence (OSL) via plasmon-enhanced luminescence. By tuning the plasmon resonance band to overlap with the OSL stimulation (530 nm), luminescence enhancements of greater than 100-fold were obtained, demonstrating the importance of tuning the plasmon resonance band to maximize the OSL intensity and detector sensitivity. This versatile method to produce silver nanoparticle films with tunable plasmonic properties is a promising platform for developing small-sized radiation detectors and advanced sensing technologies. [ABSTRACT FROM AUTHOR]

In this examination, we researched the advantages of DNA fragmentation and metallic nanoparticles well‐appointed with biomolecules. A novel interpretation of DNA damage by Silver Nano‐Clusters (AgNCs) which were developed by the utilization of green synthesis method was demonstrated. The green synthesis of AgNCs was accomplished by utilizing the leaf extract of Salacia mulbarica (SM). The preparation of SM‐AgNCs was developed by estimating surface plasmon resonance peak around 449 nm by using a UV–Visible spectrophotometer. The effect of phytochemicals in SM leaf extract on the development of stable SM‐AgNCs was confirmed by FTIR spectroscopy. The size of the fabricated SM‐AgNCs was estimated by dynamic light scattering and zeta‐sizer analysis and the morphology of the SM‐AgNCs was examined by transmission electron microscopy. The presence of clusters of Ag particles in the prepared SM‐AgNCs was recognized by energy dispersion X‐ray analysis. The results show that saponins, phytosterols, and phenolic compounds present in plant extract may play a great part in developing the SM‐AgNCs in their specialized particles. The succeeded SM‐AgNCs shows incredible anti‐bacterial action towards Escherichia coli and Bacillus subtilis. In‐light of the antibacterial study, these SM‐AgNCs were analyzed with calf thymus‐DNA and found significant damage to the strand of thymus‐DNA. [ABSTRACT FROM AUTHOR]

This article presents a localized surface plasmon resonance (LSPR) phenomenon based optical fiber sensor (OFS) for the detection of dopamine (DA). DA functions as a hormone and a neurotransmitter in the human body and plays a crucial role in the peripheral system. To develop the OFS for DA detection, taper fiber probe was fabricated and immobilized with silver nanoparticles (AgNPs) and functionalized with Polyethylene glycol (PEG). The developed sensor shows the great selectivity in the presence of ascorbic acid (AA) oxidation due to PEG coating. The morphology of the AgNPs and uniformity of coating over the surface of sensing probe were confirmed with UV-visible spectrophotometer, transmission electron microscope (TEM), energy-dispersive X-ray spectroscopy (EDS), and scanning electron microscope (SEM). The calibration curve is found to be linear over the range of 10 nM−1 μM with the lowest detection limit of 0.058 μM. Also provides a wide dynamic range of detection (10 nm–100 μM). The parameters responsible for the performance of OFS, such as sensitivity, detection limit, and selectivity are greatly improved in the proposed sensor. The applicability of the proposed sensor has been validated and have the potential to use for routine diagnosis. [ABSTRACT FROM AUTHOR]