Surface Plasmon Band Research Articles

Green synthesis of silver nanoparticles from the essential oil of Curcuma amada and their antihyperglycemic effect in STZ induced diabetic rats

A surfactant-free environmentally friendly approach for synthesising silver nanoparticles using Curcuma amada rhizome essential oil has been demonstrated. The composition and structure of silver nanoparticles are analysed using transmission electron microscopy, UV–visible spectroscopy, and Fourier transform infrared spectroscopy. The identification of a surface plasmon band at 428 nm by UV–visible spectroscopy provides preliminary evidence for the formation of silver nanoparticles. The transmission electron microscope verifies that the silver nanoparticles have an average particle size of 12.4 nm confirming a spherical shape. Self-stabilization of silver nanoparticles is discussed and correlated with the in-situ grafting of oil functional groups on surface nanoparticles. In-vitro and in-vivo antidiabetic studies are done for silver nanoparticles considering their antidiabetic potential, low toxicity, and the presence of curcumin functionalities on their surface. Specifically, the in-vitro study is done with α-amylase assay and in-vivo antidiabetic studies are done with streptozotocin-induceddiabetic rats. The percentage inhibition of α-amylase assay by silver nanoparticles is found concentration (20 μl–100 μl) dependent. The best result is seen at 100 μl concentration of silver nanoparticles (72 % inhibition) which is near to the standard taken (acarbose, 78 % inhibition). In-vivo study, the toxicity of two doses of Curcuma amada rhizome essential oil (200 mg/kg and 400 mg/kg) and synthesized silver nanoparticles (5 and 10 mg/kg) is checked and it is found safe. During the invivo study, silver nanoparticles with a dose of 5 mg/kg are capable of lowering the blood glucose level of all the streptozotocin-induced diabetic rats within 21 days (range ∼340–120 mg/dL). The histopathological analysis also supported the fact that there is an improvement in the pancreatic β-cells of all the diabetic groups compared to control group.

Hot electron transfer induced by surface Plasmon in Ag/TiO2 system

Metal-semiconductor nanostructures are promising materials in plasmonic photocatalysis because the structures exhibit a pronounced surface plasmon absorption. The surface plasmon can induce charge transfer in metal-semiconductor system. Herein, we assembled Ag/TiO2 systems and measured ultrafast dynamics by femtosecond transient absorption spectroscopy. A bleach signal of Ag/TiO2 nanocomposites was observed, and the strong coupling of Ag/TiO2 nanocomposites resulted in the broadening of the surface plasmon band. In order to further elucidate the microphysical mechanism of charge transfer in Ag/TiO2 system, the ultrafast dynamics of the composite system were analyzed. The results show that hot electron injection is completed in 150 fs, and the charge recombination time constant is 3.2 ps. Hot electron transfer is beneficial to improve photocatalytic performance.

Green synthesis of Ag nanoparticles from Verbascum insulare Boiss. and Heldr.: Evaluation of antimicrobial, anticancer, antioxidant properties and photocatalytic degradation of MB

In recent years, due to the environmental friendliness of nanoparticle production, biosynthesis methods using plant extracts and possible physical, chemical, thermal and biological properties of the synthesized nanoparticles are frequently the subject of research. In the present study, hydrothermally assisted synthesis of Ag nanoparticles using twig-leaf extract of Verbascum insulare Boiss. and Heldr., (VIE-AgNPs) a plant endemic to Turkey, was successfully carried out for the first time in this study. The presence of 24 of the 53 phytochemicals investigated in the content of the extract of Verbascum insulare Boiss. and Heldr. (VIE) determined by the LC-MS/MS system was detected. In addition, the amount of phenolic substance involved in reduction was found to be 60.42 ± 9.11 µg Gallic acid equivalent/mg-extract. The synthesized AgNPs were characterized by UV–visible spectra (UV–vis), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transforms infrared spectroscopy (FTIR), and X-ray diffraction (XRD). In particular, the surface plasmon band observed at 422 nm, the characteristic peaks observed in XRD, and the bond energy values seen in XPS strongly confirmed the formation of AgNPs. XRD and TEM data showed that AgNPs had an average size range of 25–30 nm. FTIR data indicated the presence of some herbal agents on the surface of AgNPs. The properties of the VIE-AgNPs were compared in vitro with chemically produced AgNPs (C-AgNPs). The OSI level of C-AgNPs was 87.78 ± 1.75 AU, while that of VIE- AgNPs was 110.42 ± 7.54 AU. It was observed that the nanoparticle and VIE used in the study had antimicrobial activity. It was determined that its antibacterial activity was stronger than its antifungal activity. When the analyzed inflammatory parameter levels (TNF-α, IL1β, TGF-β, and DEF-β2) were examined, the effect of VIE on inflammation in A549 cells could not be detected. However, it was determined that VIE-AgNPs, one of the nanoparticles used in the study, increased anti-inflammatory levels more than C-AgNPs. When the received data are evaluated together, it can be said that biosynthesized AgNPs suppress proliferation and stimulate apoptosis in cancer cells by increasing oxidative stress and inflammation levels compared to chemical AgNPs, thus showing an anticarcinogenic effect. It was found that VIE-AgNPs could effectively degrade the water pollutant methylene blue (MB) dye. VIE-AgNP mediated 78 % photocatalytic degradation of MB in 180 min. All superior biological properties are thought to be due to the low particle size and the interaction of active components with AgNPs during the biosynthesis process. Because it has been observed that VIE-AgNPs, which have a smaller particle size, have higher biological (cytotoxic, anticarcinogenic, inflammatory, etc.) activities than C-AgNPs. It can be said that AgNPs produced by biosynthesis may have potential use in the production of environmentally friendly, antibacterial/anticarcinogenic materials.

Biosynthesis of Silver, Copper, and Their Bi-metallic Combination of Nanocomposites by Staphylococcus aureus: Their Antimicrobial, Anticancer Activity, and Cytotoxicity Effect

AbstractThe present study outlines an easy, cheap, and environmentally friendly way to make Staphylococcus aureus-mediated bimetallic silver-copper nanocomposites (Ag/Cu) that can fight cancer and germs. The gram-positive S. aureus synthesized Ag, Cu, and their bi-metallic nanocomposites extracellularly. We aimed to prepare the bimetallic nanocomposite in two different ways, and we compared them in terms of characterization and biological applications. The first one is a bimetallic nanocomposite (Ag/Cub) that was made by mixing Ag and Cu metal ions in equal amounts (50:50). Then, the whole mixture was reduced. The second is the after-reduction bimetallic nanocomposite (Ag/Cua), in which each metal ion was reduced separately, and then the nanocomposites were mixed (50:50%) during biological applications. Nanocomposites were characterized using UV–visible spectrophotometry, Fourier-transform infrared spectroscopy, dynamic light scattering, and transmission electron microscopy. The results demonstrated that surface plasmon bands were at 320 nm for Ag NPs and 525 nm for Cu NPs, and a shift from these peaks was observed at 290 nm in the Ag/Cub bimetallic nanocomposite. The synthesized nanocomposites were confirmed to be in the nanoscale with 20, 40, and 80 nm spherical crystals, respectively. Nanocomposites were assayed for their antimicrobial activity against the gram-negative Pseudomonas aeruginosa, the acid-fast Mycobacterium smegmatis, the gram-positive Bacillus cereus, and S. aureus, in addition to three fungal species, which were Aspergillus flavus, A. fumigatus, and Candida albicans. The minimum inhibitory concentration and minimum bactericidal concentration were determined. The Ag/Cua/Cuaetallic nanocomposite was the most potent antimicrobial compound. The anticancer activity of the tested compounds was assayed against the hepatocellular carcinoma cell line (HepG-2). Low cytotoxic activity was recorded in most assayed nanocomposites against the baby hamster kidney cell line (BHK).

Role of silver nanoparticles and silver nanoclusters for the detection and removal of Hg(ii).

Silver metal, being a 3d transition metal in group 11 in the periodic table, is widely used in material science for its distinguished plasmonic properties. Nanoparticles (NPs) and nanoclusters (NCs) are widely used in sensing applications having a surface plasmon band and emissive properties, respectively. Mercury is one of the detrimental toxins and threats to various ecosystems. The distinction between nanoparticles and nanoclusters, the utility and toxicity of heavy metal mercury, fluorometric and colorimetric approaches to the recognition of mercury ions with NPs and NCs, the mechanism of detection, spot detection, and natural water sample analyses were illustrated in detail in this review article. Moreover, the sensing platform and analyte (Hg2+) fate were described for substantiating the mechanism. It was observed that NCs are mostly utilized for fluorometric approaches, while NPs are mostly employed for colorimetric approaches. Fluorometric detection is mainly quenching-based. However, sensing with enhancement was found in a few reports. Adulteration of other metals with silver particles often modifies the sensing platform.

Nanorod-associated plasmonic circular dichroism monitors the handedness and composition of α-synuclein fibrils from Parkinson's disease models and post-mortem brain.

Human full-length (fl) αSyn fibrils, key neuropathological hallmarks of Parkinson's disease (PD), generate intense optical activity corresponding to the surface plasmon resonance of interacting gold nanorods. Herein, we analysed fibril-enriched protein extracts from mouse and human brain samples as well as from SK-N-SH cell lines with or without human fl and C-terminally truncated (Ctt) αSyn overexpression and exposed them to αSyn monomers, recombinant fl αSyn fibrils or Ctt αSyn fibrils. In vitro-generated human recombinant fl and Ctt αSyn fibrils and fibrils purified from SK-N-SH cells with fl or Ctt αSyn overexpression were also analysed using transmission electron microscopy (TEM) to gain insights into the nanorod-fibril complexes. We found that under the same experimental conditions, bisignate circular dichroism (CD) spectra of Ctt αSyn fibrils exhibited a blue-wavelength shift compared to that of fl αSyn fibrils. TEM results supported that this could be attributed to the different properties of nanorods. In our experimental conditions, fibril-enriched PD brain extract broadened the longitudinal surface plasmonic band with a bisignate CD couplet centred corresponding to the absorption band maximum. Plasmonic CD (PCD) couplets of in vivo- and in vitro-generated fibrils displayed sign reversal, suggesting their opposite handedness. Moreover, the incubation of in vitro-generated human recombinant fl αSyn fibrils in mouse brain extracts from αSyn null mice resulted in PCD couplet inversion, indicating that the biological environment may shape the handedness of αSyn fibrils. These findings support that nanorod-based PCD can provide useful information on the composition and features of αSyn fibrils from biological materials.

Interactions of Turmeric- and Curcumin-Functionalized Gold Nanoparticles with Human Serum Albumin: Exploration of Protein Corona Formation, Binding, Thermodynamics, and Antifibrillation Studies.

In order to better understand the bioavailability and biocompatibility of polyphenol-assisted surface-modified bioengineered nanoparticles in nanomedicine applications, here, we address a series of photophysical experiments to quantify the binding affinity of serum albumin toward polyphenol-capped gold nanoparticles. For this, two different gold nanoparticles (AuNPs) were synthesized via the green synthesis approach, where curcumin and turmeric extract act as reducing as well as capping agents. The size, surface charge, and surface plasmon bands of the AuNPs were highly affected by the adsorption of human serum albumin (HSA) during protein corona formation, which was investigated using dynamic light scattering (DLS), ξ-potential, ultraviolet-visible (UV-vis) spectroscopy, and transmission electron microscopy (TEM) measurements. Fluorescence-based methods, absorbance, and SERS experiments were carried out to evaluate the binding aspects of AuNPs with HSA. We found that the AuNPs show moderate binding affinity toward HSA (Kb ∼ 104 M-1), irrespective of the capping agents on the surface. Hydrophobic association, along with some contribution of electrostatic interaction, played a key role in the binding process. The binding interaction was more toward the subdomain IIA region of HSA, as indicated by the competitive displacement studies using site-specific binders (warfarin and flufenamic acid). Because of the large surface curvature of small-sized AuNPs, the secondary structural conformations of HSA were slightly altered, as revealed by circular dichroism (CD), Fourier transform infrared (FT-IR) spectroscopy, and surface-enhanced Raman scattering (SERS) measurements. Additionally, the findings of the binding interactions were re-evaluated using molecular dynamics (MD) simulation studies by determining the root-mean-square deviation (RMSD), root-mean-square fluctuation (RMSF), radius of gyration (Rg), and changes in the binding energy of HSA upon complexation with AuNPs. To determine the tentative evidence for pharmacokinetic administration, these biocompatible AuNPs were applied to inhibit the amyloid fibril formation of HSA and monitored by using the thioflavin T (ThT) assay, ANS fluorescence assay, fluorescence microscopic imaging, and FESEM. AuNPs were found to show better resistance toward fibrillation of the adsorbed protein.

Optimization with 2K factorial design in green synthesis of silver nanoparticles (AgNPs) using Porophyllum ruderale extract

In recent years, metal nanoparticles (MNPs) have garnered interest in scientific development due to their novel properties, among which are optical, electrical, and magnetic properties, along with absorption capacity and high surface. There are currently several synthesis methods for MNPs, but many are costly and generate toxic agents as byproducts into the environment. Therefore, in this work, a green, ecological, and affordable synthesis of silver nanoparticles (AgNPs) was carried out using Porophyllum Ruderale (P. Ruderale). The AgNPs obtained were characterized by Fourier transform infrared spectroscopy (FTIR) to observe the functional groups that intervene in the synthesis. UV-Vis spectroscopy was used to study the surface plasmon band, confirming the peak absorbance wavelength at 385 nm. The morphological analysis by scanning electron morphology (SEM) showed AgNPs measuring 70–500 nm and spherical shapes. The synthesis process was optimized using two factors: temperature, reducing agent and precursor agent ratio (extract:RA) (AgNO3–PA), and an output variable, which is the particle size evaluated by SEM. The optimal temperature for AgNP formation was found to be 90 ºC; it was a key parameter to form AgNPs. The work proved AgNPs can be obtained and potentially used as biosensors, antimicrobial agents, and herbicides, among others.

The Optical and Structural Properties of the Fe@Au Core–Shell Nanoparticles Prepared by PLAL

In this research, metal targets dipped in 3 mL of distilled water (DW) were subjected to pulsed laser ablation. Colloidal dispersions of Fe and Au, and bimetallic Fe@Au core/shell nanoparticles are created. The core/shell structure of these particles was subsequently studied using X-ray diffraction. UV–Vis and HRTEM measurements are used to determine surface Plasmon resonance (SPR) and particle sizes. We also carried out an investigation to gauge the stability in terms of the surface charge of the produced nanoparticles (Zeta-potential). The findings show that maximum absorption value of Fe Nps was 0.45 in the range (200–350) nm, while Au exhibits a surface Plasmon resonance (SPR) peaked at a wavelength of 545 nm in the range (290–1100) nm. Another peak was noticed at (555) nm for the surface Plasmon band of the particles Fe@Au in the range (290–1100) nm, HRTEM measurement was used to check the shape and particle size, and the results showed that the average particle size was less than 50 nm.

Silver nanoparticles coated by Schiff base as an adsorbent of lead from polluted water.

Synthesis of silver nanoparticles coated with Schiff base was achieved . Silver nanoparticles are reduced and coated using Schiff base. Schiff base serves as a capping to stop silver oxide from overgrowing. Schiff base produces silver nanoparticles with a novel form and a distinctive appearance. The presence of Schiff base as a reducing and capping agent can give a new shape for prepared silver nanoparticles. The structure of Schiff base was analyzed based on spectral data (1 H nuclear magnetic resonance (H1NMR), Mass spectroscopy, and Fourier-transform infrared spectroscopy (FTIR). The formation of silver nanoparticles within a surface plasmon band at 461 nm was observed using UV-Vis Spectroscopy. Silver nanoparticles with a spherical shape and a particle size between 50 and 100 nm are visible in a scanning electron microscope image. For the first time, silver nanoparticles coated with Schiff base were used to adsorb lead from a sample of polluted water. The rate of adsorption was 69%.

Toward microfluidic SERS and EC-SERS applications via tunable gold films over nanospheres

Many promising applications of surface-enhanced Raman scattering (SERS), such as microfluidic SERS and electrochemical (EC)-SERS, require immersion of plasmonic nanostructured films in aqueous media. Correlational investigations of the optical response and SERS efficiency of solid SERS substrates immersed in water are absent in the literature. This work presents an approach for tuning the efficiency of gold films over nanospheres (AuFoN) as SERS substrates for applications in aqueous environment. AuFoN are fabricated by convective self-assembly of colloidal polystyrene nanospheres of various diameters (300–800 nm), followed by magnetron sputtering of gold films. The optical reflectance of the AuFoN and Finite-Difference Time-Domain simulations in both water and air reveal the dependence of the surface plasmon band on nanospheres’ diameter and environment. SERS enhancement of a common Raman reporter on AuFoN immersed in water is analyzed under 785 nm laser excitation, but also using the 633 nm line for the films in air. The provided correlations between the SERS efficiency and optical response in both air and water indicate the best structural parameters for high SERS efficiency and highlight a route for predicting and optimizing the SERS response of AuFoN in water based on the behavior in air, which is more practical. Finally, the AuFoN are successfully tested as electrodes for EC-SERS detection of the thiabendazole pesticide and as SERS substrates integrated in a flow-through microchannel format. The obtained results represent an important step toward the development of microfluidic EC-SERS devices for sensing applications.

Enhanced Plasmonic Photocatalysis of Au-Decorated ZnO Nanocomposites

The rapid development of technological processes in various industrial fields has led to surface water pollution with different organic pollutants, such as dyes, pesticides, and antibiotics. In this context, it is necessary to find modern, environmentally friendly solutions to avoid the hazardous effects on the aquatic environment. The aim of this paper is to improve the photocatalytic performance of zinc oxide (ZnO) nanoparticles by using the plasmonic resonance induced by covering them with gold (Au) nanoparticles. Therefore, we evaluate the charge carriers’ behavior in terms of optical properties and reactive oxygen species (ROS) generation. The ZnO-Au nanocomposites were synthesized through a simple chemical protocol in multiple steps. ZnO nanoparticles (NPs) approximately 20 nm in diameter were prepared by chemical precipitation. ZnO-Au nanocomposites were obtained by decorating the ZnO NPs with Au at different molar ratios through a reduction process. X-ray diffraction (XRD) analysis and transmission electron microscopy (TEM) confirmed the simultaneous presence of hexagonal ZnO and cubic Au phases. The optical investigations evidenced the existence of a band-gap absorption peak of ZnO at 372 nm, as well as a surface plasmonic band of Au nanoparticles at 573 nm. The photocatalytic tests indicated increased photocatalytic degradation of the Rhodamine B (RhB) and oxytetracycline (OTC) pollutants under visible light irradiation in the presence of ZnO-Au nanocomposites (60–85%) compared to ZnO NPs (43%). This behavior can be assigned to the plasmonic resonance and the synergetic effects of the individual constituents in the composite nanostructures. The spin-trapping experiments showed the production of ROS while the nanostructures were in contact with the pollutants. This study introduces new strategies to adjust the efficiency of photocatalytic devices by the combination of two types of nanostructures with synergistic functionalities into one single entity. ZnO-Au nanocomposites can be used as stable photocatalysts with excellent reusability and possible industrial applications.

Microwave-assisted green synthesis of silver nanoparticles using extract of mint leaves

Silver nanoparticles are widely used in areas such as biosensing, hydrogen production, electronics, photovoltaics, antimicrobials, and biomedical engineering applications. Biological synthesis is regarded as a safe and non-toxic process, but its main disadvantage is the slow processing time. The mint leaf extract can act as both a reducing and stabilizing agent for the biological synthesis of silver nanoparticles. In this work, a rapid and green method for the microwave-assisted biological synthesis of silver nanoparticles was investigated using an aqueous leaf extract of mint as a biosource of cost-effective, non-hazardous reducing and stabilizing agents. The optimum conditions for microwave extraction of mint leaves were 220 s at 800 W and a 5 g/L mint-to-water ratio. Meanwhile, the optimal conditions for the biological synthesis of silver nanoparticles were as follows: concentration of silver nitrate solution = 2 mM, microwave reaction time = 100 s at 800 W, and pH = 8. The silver nanoparticles obtained by the microwave heating process showed a surface plasmon band centered at 420 nm with a higher peak height than those prepared by the conventional heating process. Dynamic light scattering analysis has shown the synthesized silver nanoparticles to have an average diameter of 54 nm.

Magnetic Field Assisted Spark Discharge-Generated Gold Nanostructures: XPS Study of Nitrogen Gas Fate and Chemical Composition of Gold Thin Films

The sparking discharge process utilises high voltage to melt and evaporate tips of electrodes to create particles that can be deposited on substrate. In our research, we examine the influence of a magnetic field and nitrogen flow on gold thin-film formation onto quartz substrate. A positive effect of nitrogen flow and a 0.3 T external magnetic field was observed, in enhancement of surface plasmon band in UV visible and dispersal of nanoparticles without agglomeration. We also detected and described nitrification occurrences of gold measured by XPS at 407 eV and nitridification of quartz substrate on which gold particles are collected. These nitrogen-based chemical reactions occurred during sparking of gold wire inside of ambient air and in the magnetic field, as well during pure nitrogen flow. We measured the valence band electronic structure of gold nanoparticles deposited onto quartz substrate and found that gold thin film prepared in the magnetic field under nitrogen flow has the lowest value of 1.5 eV. Preparation of gold thin films in the magnetic field under nitrogen flow offers a highly dispersed and convenient method for productions of thin films.

To decipher the phytochemical agent and mechanism for Urginea indica mediated green synthesis of Ag nanoparticles and investigation of its antibacterial activity against Methicillin-resistant Staphylococcus aureus

Globally, Methicillin-Resistant Staphylococcus aureus bacteraemia is one of the commonest bloodstream infections associated with clinical complications and high mortality. Thence, devising effective and targeted biogenic silver based strategies are in great demand. However, limited insights regarding the biosynthesis methodologies impedes the possible scale up and commercial potentials. We, hereby demonstrate the biosynthesis of Ag nanoparticles using the phytochemical agent extracted and purified from bulb extract of Urginea indica. The chemical structure of the phytochemical agent is investigated by various chromatographic and spectroscopic techniques and was found closely relatable to N-ethylacetamide. Ag nanoparticles synthesis by this agent was found to have a strong Surface Plasmon band at 402 nm. X-ray diffraction and transmission electron microscopy further validated the formation of Ag nanoparticles with face-centred cubic structure with a size range of 20–30 nm. The biogenic metal nanoparticles have shown potential antibacterial activity against S. aureus and MRSA (within a range of 10–50 μg/mL). The nanoparticles have also shown promising anti-biofim activity against the above mentioned strains. The nanoparticles were expected to induce ROS mediated bactericidal mechamism. Cell viability and in-vitro infection studies advocate noticeable biocompatibility and future clinical potential of the developed nanoparticles against Staphylococcus infections.

One-Step Formation of Plasmonic Cu Nanodomains in p-Type Cu2O Matrix Films for Enhanced Photoconversion of n-ZnO/p-Cu2O Heterojunctions

Plasmonic Cu nanoparticles were in-situ grown into a Cu$_2$O semiconductor matrix by using reactive magnetron sputtering and adjusting the amount of oxygen available during the synthesis in order to prevent the oxidation of part of copper atoms landed on the film surface. Varying only the oxygen flowrate (OFR) and using a single Cu target it was possible to observe the evolution in the simultaneous formation of metallic Cu and Cu$_2$O phases for oxygen-poor conditions. Suchformation is accompanied by the development of the surface plasmon band (SPB) corresponding to Cu, as evidenced by UV-Vis spectrophotometry and spectroscopic ellipsometry. The bandgap values of the elaborated composites containing embedded Cu plasmonic nanodomains were lower than the bandgap of single-phased Cu$_2$O films, likely due to the higher defect density associated to the nanocrystalline nature of films, promoted by the presence of metallic Cu. The resistivity of the thin films increased with more oxidative deposition conditions and was associated to an increase in Cu$_2$O/Cu ratio and smaller and more isolated Cu particles, as evidenced by high resolution transmission electron microscopy and X-ray diffraction. Photoconversion devices based on the studied nanocomposites were characterized by I-V and spectral photocurrent measurements, showing an increase in the photocurrent density under light illumination as consequence of the plasmonic particles excitation leading to hot carrier's injection in the nearby ZnO and Cu$_2$O semiconductors.

Fighting multidrug-resistant Enterococcus faecalis via interfering with virulence factors using green synthesized nanoparticles

This study aims to synthesize silver nanoparticles by the green method and test it against specific virulence factors in multi-drug resistant Enterococcus faecalis bacteria. virulence factors of E. faecalis clinical isolates were determined and the most potent isolate was selected for further investigations. The prepared Ag-NPs were characterized using UV spectroscopy, FTIR spectroscopy, dynamic light scattering, and transmission electron microscopy (TEM). The result revealed the concentration of 0.0625 mg/ml Ag-NPs was significantly reducing virulence factors in multidrug-resistant E. faecalis without affecting planktonic cell growth. UV–Visible spectroscopy characterization revealed a characteristic surface Plasmon band [SPR] at a wavelength ranging from 256 to 345 and 510 nm in the prepared Ag-NPs. dynamic light scattering indicated it tended to an electrostatic attraction between nanoparticles in the prepared solution. TEM images revealed the average size of Ag-NPs were prepared to be 28.8 nm and the shape was spherical. Green synthesized Ag-NPs have the ability to combat multi-drug-resistant E. faecalis via reducing virulence factors, which is considered a good approach toward resolving the multidrug resistance crisis.

Synthesis of silver nanoparticles (AgNPs) of leaves extract of Rhynchoglossum notonianum wall. for enhancing its bioavailability and antibacterial activity

Objective: Silver nanoparticles (AgNPs) derived from Rhynchoglossum notonianum Wall. leaf were the subject of this investigation to examine their synthesis, characterisation, and biological activity. Materials and Methods: Aqueous extracts of Rhynchoglossum notonianum Wall leaves and 0.1 M silver nitrate were used to make AgNPs. Particle size, Zeta potential, UV-Vis spectroscopy, and SEM were used to determine the AgNPs properties. Results: Rapid and homogeneous size and shape silver nanoparticles were synthesised utilising Rhynchoglossum notonianum Wall. extract. When methanolic leaf extracts of Rhynchoglossum notonianum Wall. were combined with an aqueous silver ion complex solution, the surface Plasmon vibrations were excited, resulting in the production of MERNAgNPs. UV-Visible spectroscopy was used to characterise the nanoparticles. The widening of the peak in the UV-visible spectrum suggested polydispersion. The silver nanoparticles in solution have a surface Plasmon band of 420nm. Aqueous silver nitrate solution is diffused throughout the reaction time, with no signs of agglomeration. The average particle size (z-average) was “132.6nm”, the polydispersity index was “0.248”, and the zeta values were -25.1mV with a 100% peak area. This implies a stable silver nanoparticle.

Green Synthesis and Antibacterial Activities of Silver Nano particles Mediated by Extract of Cucurbita maxima (Pumpkin) Fruit Pith

Synthesis of silver nanoparticles (AgNPs) has become a necessary field of applied science. Biological method for synthesis of AgNPs by cucurbita maxima fruit pith extracts was used. The AgNPs were identified by UV–visible spectrometry; X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectrometry (FT-IR). The presence of surface plasmon band around 420 nm indicates AgNPs formation. Parameter optimization showed the smallest size of AgNPs (2.86 ± 0.3 nm) was obtained with 0.1 M AgNO3 at 40oC. The present study provides the proof that the molecules within aqueous cucurbita maxima fruit pith extracts facilitate synthesis of AgNPs and highlight on value-added from cucurbita maxima fruit pith and fruit peel extracts for cost effectiveness. Also, eco-friendly medical and nanotechnologybased industries could also be provided. Size of prepared AgNPs could be controlled by temperature and AgNO3 concentration. Further studies are required to study effect of more parameters on size and morphology of AgNPs as this will help in the control of large scale production of biogenic AgNPs. The synthesized silver nanoparticles are screened antibacterial activities

Sunlight-Mediated Green Synthesis of Silver Nanoparticles Using the Berries of Ribes rubrum (Red Currants): Characterisation and Evaluation of Their Antifungal and Antibacterial Activities.

Plants are a treasure trove of several important phytochemicals that are endowed with therapeutic and medicinal properties. Ribes rubrum L. (red currants) are seasonal berries that are widely consumed for their nutritional value and are known for their health benefits. Red currants are a rich source of secondary metabolites such as polyphenols, tocopherols, phenolic acids, ascorbic acid, and flavonoids. In this study, sunlight-mediated synthesis of silver nanoparticles (AgNPs) was successfully accomplished within 9 min after adding the silver nitrate solution to the aqueous extract of red currant. The synthesised AgNPs were characterised with UV–Vis, transmission electron microscopy (TEM), dynamic light scattering (DLS), Fourier transform infrared spectrum (FTIR), and energy-dispersive X-ray spectrum (EDX). The efficacy of aqueous extracts of red currants and AgNPs in controlling the growth of some pathogenic fungi and bacteria was also investigated. The UV–visible (UV–Vis) spectrum displayed an absorption peak at 435 nm, which corresponded to the surface plasmon band. The strong silver signal on the EDX spectrum at 3 keV, authenticated the formation of AgNPs. The several peaks on the FTIR spectrum of the aqueous extract of red currant and the nanoparticles indicated the presence of some important functional groups such as amines, carbonyl compounds, and phenols that are vital in facilitating the process of capping and bioreduction, besides conferring stability to nanoparticles. The TEM microphotographs showed that the nanoparticles were well dispersed, roughly spherical, and the size of the nanoparticles ranged from 8 to 59 nm. The red currant silver nanoparticles were highly potent in inhibiting the growth and proliferation of some fungal and bacterial test isolates, especially Alternaria alternata, Colletotrichum musae, and Trichoderma harzianum. Based on the robust antifungal and antibacterial activity demonstrated in this study, red currant nanoparticles can be investigated as potential replacements for synthetic fungicides and antibiotics.