As-synthesized Silver Nanoparticles Research Articles

Facile synthesis of silver chloride-polyaniline nanocomposites and its photocatalytic activity for the degradation of methylene blue

Herein, we report a green and an effective strategy for the synthesis of polyaniline-silver chloride (AgCl@PANI) nanocomposites by using facile in-situ chemical oxidative polymerization method in the presence of as-synthesized silver nanoparticles (Ag NPs) for the study of their photocatalytic activity towards the photodegradation of methylene blue (MB) under UV irradiation. The contents of Ag NPs varied from 2% to 6% during polymerization reaction to get AgCl@PANI nanocomposites. These synthesized polymer nanocomposites were characterized for their structural and optical properties, thermal stability, dc conductivity and photocatalytic activity by FT-IR spectroscopy, XRD, UV–Vis spectroscopy, TGA, SEM, standard four probe method and the photodegradation activity of MB, respectively. XRD analysis confirm the successful formation of AgCl@PANI nanocomposites without the presence of additional phases. TGA shows that AgCl@PANI nanocomposites have excellent thermal stability due to the barrier effect of AgCl moieties bounded with in the polymer chain and the strong physiochemical interactions between PANI and AgCl as inferred from FT-IR and UV–vis analysis. Under UV irradiation, the AgCl@PANI nanocomposite, with 4 wt% of Ag NPs (AgCl@PANI-4%), demonstrated excellent photocatalytic activity for MB degradation with the photodegradation percentage of ∼ 99 % in 20 min. The experimental findings illustrate that the superior photocatalytic activity of AgCl@PANI nanocomposites is owing to incorporation of AgCl moieties in the polymer structure, less needed energy for the formation of electron-hole pairs in the quinoid ring of PANI in the UV-region, enhanced light absorption owing to smaller grain size morphology, high surface area of the nanocomposite and high electrical conductivity (128 mS.cm−2). These results suggest the potential of these synthesized conjugated polymer-based nanocomposites as a photocatalyst for cost-effective and efficient wastewater treatment for the industrial applications.

Antimicrobial and Antiproliferative Activity of Green Synthesized Silver Nanoparticles Using Bee Bread Extracts.

Bee bread (BB) is a fermented mixture of bee pollen, is rich in proteins, amino acids, fatty acids, polyphenols, flavonoids, as well as other bioactive compounds, and is considered functional food for humans. In this study, we explored an innovative green synthesis of colloidal silver nanoparticles, using BB extracts as reducing and stabilizing agents. A preliminary chemical characterization of the BB extracts was conducted. The plasmonic response of the as-synthesized silver nanoparticles (BB-AgNPs) was evaluated by UV-Vis spectroscopy, while their hydrodynamic diameter and zeta potential were investigated by dynamic light spectroscopy (DLS). Transmission electron microscopy (TEM) analysis pointed out polydisperse NPs with quasi-spherical shapes. The newly synthesized nanoparticles showed good antioxidant activity against the tested free radicals, DPPH, ABTS•+, and FRAP, the best results being obtained in the case of ABTS•+. BB-AgNPs exhibited good antibacterial activity on the tested Gram-positive and Gram-negative bacterial strains: herein S. aureus, B. cereus, E. faecalis, E. coli, P. aeruginosa, S. enteritidis, and on yeast C. albicans, respectively. The inhibition diameters varied between 7.67 ± 0.59 and 22.21 ± 1.06 mm, while the values obtained for minimum inhibitory concentration varied between 0.39 and 6.25 µg/mL. In vitro antiproliferative activity was tested on colon adenocarcinoma, ATCC HTB-37 cell line, and the results have shown that the green synthetized BB-AgNPs induced a substantial decrease in tumor cell viability in a dose-dependent manner with an IC50 ranging from 24.58 to 67.91 µg/mL. Consequently, more investigation is required to comprehend the processes of the cytotoxicity of AgNPs and develop strategies to mitigate their potentially harmful effects while harnessing their antimicrobial properties.

GREEN-SYNTHESIS OF SILVER NANOPARTICLES: SPECTRAL, OPTICAL, AND ANTIBACTERIAL CHARACTERIZATION STUDIES

A green approach was used for synthesizing Silver-NPs by the extract of Artocarpus heterophyllus leaves. The effect of Artocarpus heterophyllus leaf extract was investigated. A powder XRD study has been used to analyze the structure and particle size of as-synthesized Ag-NPs. According to the powder-XRD study, the as-prepared Silver-NPs possess an FCC structure and have a particle size of 23nm. The possible bio-reducing agents within the leaf extracts were confirmed using FTIR spectral analysis. The characteristic surface plasmon resonance signal of the as-synthesized silver nanoparticles was detected at 418 nm using UV–Vis spectroscopic analysis between the wavelength range of 300 and 800nm. An emission peak was observed at 472nm in the PL investigation, indicating the fluorescent emission of Ag-NPs. The FESEM analysis has been exploited to inspect the morphological aspect of biosynthesized silver-NPs. According to FESEM micrographs, the biosynthesized NPs were found to have spherical shapes. Using the agar-well process, the antibacterial efficacy of biosynthesized Silver-NPs was examined. The prepared Silver-NPs exhibited a better antibacterial efficacy against E.coli than against S.typhi. It's also been observed that when the concentration increased, the antibacterial activity increased as well.

Green Synthesis of Silver Nanoparticles Using Juniperus procera Extract: Their Characterization, and Biological Activity

Plant extract-based green synthesis of metal nanoparticles (NPs) has become a popular approach in the field of nanotechnology. In this present investigation, silver nanoparticles were prepared by an efficient and facile approach using Juniperus procera extract as a bioreducing and stabilizing agent. The as-synthesized silver nanoparticles (JP-AgNPs) were characterized by several characterization techniques such as UV–Vis, XRD, FT-IR, HR-TEM, and EDX analysis. The XRD analysis evidently confirms that the as-synthesized Ag nanoparticles (NPs) from Juniperus procera plant extract (JP-AgNPs) are crystalline in nature. FT-IR analysis confirms that the plant extract plays a dual role as a bioreducing and capping agent, while HR-TEM revealed the spherical morphology of as-synthesized JP-AgNPs with the size of ~23 nm. Furthermore, the synthesized JP-AgNPs were evaluated for antibacterial properties against several bacterial and fungal strains such as Staphylococcus aureus (ATCC 12228), Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), Proteus mirabilis (ATCC 4753), Cryptococcus neoformans (ATCC 16620), and Candida albicans (ATCC 885-653). The JP-AgNPs displayed an efficient mean zone of inhibition (MZI) at 50.00 µL for bacterial associated with fungal pathogens than the plant extract. Mainly, MZI values against microbial pathogens were as follows; E. coli (17.17 ± 0.72 mm), P. mirabilis (14.80 ± 0.17 mm), and C. albicans (14.30 ± 0.60 mm), whereas JP-AgNPs showed moderate activity against P. aeruginosa (11.50 ± 0.29 mm) and C. neoformans (9.83 ± 0.44 mm). Notably, the tested JP-AgNPs have displayed almost similar antimicrobial activities with that of standard antimicrobial drugs, such as streptomycin and nystatin. The enhanced antimicrobial activity of JP-AgNPs can be ascribed to the quality of resultant NPs including, uniform size, shape, and aqueous colloidal stability of nanoparticles.

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

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

Sustainable-green synthesis of silver nanoparticles using safflower (Carthamus tinctorius L.) waste extract and its antibacterial activity

Silver nanoparticles have high potential for application in food industry, as they have the ability to inhibit a wide range of bacteria of pathogenic and spoilage origin. They can be obtained from different methods classified in physical and chemical and which are aggressive with the environment since they produce toxic waste. Nowadays, environmentally friendly methods such as green synthesis can be used, through the use of agri-food waste. The use of these wastes is a more sustainable method, because it reduces the environmental pollution, at the same time that silver nanoparticles are obtained. The aim of the present study is the green synthesis of silver nanoparticles using safflower (Carthamus tinctorius L.) aqueous extract from waste and its antibacterial activity on Staphylococcus aureus (Gram positive) and Pseudomonas fluorescens (Gram negative). The analyses by TEM showed that the as-synthesized silver nanoparticles were uniform and spherical particles with an average diameter of 8.67 ± 4.7 nm and confirmed by SEM. The electron diffraction and TEM analyses showed the characteristic crystallinity of silver nanoparticles. FTIR spectroscopy confirmed that various functional groups were responsible for reducing and stabilizing during the biosynthesis process. Nanoparticles inhibited the growth of both types of bacteria from the lowest concentration evaluated (0.9 μg/mL). We conclude that silver nanoparticles synthesized in the present study have potential application as antibacterial agents in food and medicine industry.

Plant-mediated green synthesis and characterization of silver nanoparticles using Phyllanthus emblica fruit extract

Abstract A cost-effective and non-hazardous approach was carried out for the plant-mediated green synthesis of metallic nanomaterials utilizing the fruit extract of Indian gooseberry (Amla) or Phyllanthus emblica. In this study, silver nanoparticles were effectively synthesized from silver nitrate precursors through a facile and eco-friendly method using the fruit extract of Phyllanthus emblica as a reducing and stabilizing agent. The ultraviolet–visible (UV–Vis) spectroscopy, x-ray diffraction analysis, field emission scanning electron microscopy (FESEM), and energy dispersive x-ray analysis (EDX) were employed to characterize the synthesized nanoparticles. A face-centered cubic crystalline structure and elemental silver phase were identified by x-ray diffraction analysis. The Rietveld refinement determined the average crystallite size (Lvol-IB) of the silver nanoparticles’ as 16.29 nm. The microstructural analysis revealed the spherical shape of the as-synthesized silver nanoparticles and the average grain size ranged between 60 and 80 nm. The development of elemental silver was affirmed by the EDX spectrum. The bio-reduction of silver ions and the formation of silver nanoparticles were ascertained by the UV–Vis spectral analysis. A surface plasmon resonance peak was found at 453 nm. The well-balanced size and shape of the synthesized elemental silver nanoparticles suggested the Phyllanthus emblica fruit extract as an effective reducing agent.

Synthesis of silver/hydroxyapatite/tryptophan nanocomposite particles by biological method

The inorganic calcium phosphate compound hydroxyapatite (HAP) is widely used in bone and teeth proxy applications in the biomedical field. The efficacy of this material depends on size and absolutely morphology. Synthesis of hydroxyapatite nanoparticles with appreciable size and morphology is considered as a significant technology. However, post-surgery bacterial infections were also accounted that could be a crucial and challengeable for a good biomaterial. To compensate, all issues, synthesis of Silver/Hydroxyapatite/Tryptophan nanocomposite was reported in the present study. Initially synthesis of silver nanoparticles (AgNPs) was done by the cost effective green method using the flower extract of Aerva lanata. The alkaloids, flavonoids, tannin and polyphenols present in the flower extract were acting as reducing agent for Ag ions. In the synthesis of HAP, Calcium Nitrate Tetrahydrate [CaNO3·4H2O] (0.05 M) and Diammonium Hydrogen Phosphate [(NH4)2 HPO4] were used as precursors and the amino acid tryptophan as a template. The as-synthesized silver nanoparticles, HAP/Tryptophan nanocomposite and Silver/HAP/Tryptophan nanocomposite were characterized by UV–Visible, FT-IR, XRD, SEM and antibacterial studies. All the results were authenticated that the Ag/HAP/Tryptophan nanocomposite can perform as a good biomaterial for bone and tooth replacement applications.

Bio-inspired synthesis of silver nanoparticles using Hibiscus Tiliaceus L. flower extracts for improved optical characteristics

In this work, we report a simple, facile, environment friendly and green approach to synthesize silver nanoparticles using aqueous flower extracts of Hibiscus Tiliaceus L. The morphology (shape/size) and crystal structure of as-synthesized silver nanoparticles (NPs) were determined by transmission electron microscopy and x-ray diffraction. The UV–Vis spectroscopy was used to record the surface plasmon resonance peak, while spectro-fluorophotometry was used to examine the fluorescence emission spectra of silver NPs. Moreover, the optical nonlinearities of silver NPs were investigated using z-scan technique with low power argon laser beam at wavelengths 488 nm and 514 nm in continuous-wave regime and at 532 nm in the pulsed laser regime. Our results indicate that the nonlinear absorption in silver NPs is reverse saturation absorption of the order of 10–3 cm/W and the negative nonlinear refractive index was determined as of the order of 10–8 cm2/W. Moreover, the optical nonlinear properties were used to demonstrate optical limiting abilities of the synthesized silver NPs. The results presented in this study indicate that bio-synthesized silver NPs are excellent candidates as a nonlinear material and can be widely used for waveguide applications.

Design and development of porous terracotta disc: An eco-friendly novel control agent for mosquito larvae

In the present work, we synthesized silver nanoparticles supported by rice husk by hydrothermal treatment, as-synthesized silver nanoparticles rice husk (AgNPs-RH) bio-composite mixed with potter clay thoroughly, molded, dried into a disc-shaped before firing and applying as a point of use larvicidal agent. As designed, porous terracotta disc (PTD) infused with AgNPs-RH-biocomposite were characterized by UV spectrophotometer, Fourier-transform infrared spectroscopy, transmission electron microscopy, X-ray diffraction analysis and energy-dispersive X-ray spectroscopy. The amount of silver ions released from the PTD was also found to be within the prescribed limit of 0.1 ppm-level. Later we dropped the PTD and tested its larvicidal activity against the IVth instar larva stage of Aedes, Anopheles and Culex species. We found 100% larvicidal mortality in 24 h of exposure to the designed PTD and the amount of silver released from the porous disc was found to be 0.0343 ppm. Further from the histopathological studies of dead larvae revealed that the silver ions from the PTD have substantially damaged the exoskeleton of larvae.

Biosynthesis of AgNPs and their synergistic effect in combination with ultrasound waves on breast cancer cells

Silver nitrate (AgNO3) was used to prepare Silver nanoparticles (Ag NPs), where polyphenols obtained from leaf extract of Cocos nucifera were used as capping and reducing agents. Furthermore, Characterization techniques like HRTEM, UV–Vis, XRD and FT-IR were used to study the as-prepared Ag NPs. With the help of various spectroscopic and microscopic techniques, the as-synthesized silver nanoparticles were characterized. Various analyses like HRTEM, EDS, FT-IR, XRD and UV–Vis have confirmed the synthesis of silver nanoparticles. Images from HRTEM microscope confirmed the formation of small, spherical and poly dispersive AgNPs having 10 nm average size. In the current paper, the possible synergistic impact of silver nanoparticles and ultrasound waves was examined as a potential route to cancer therapy. Eventually, AgNPs were produced, characterized and then exposed to MCF-7 cell lines in various concentrations. Cells were administrated with ultrasonic waves after 24 h, and the viability of cells after treatment was recorded at 72, 48 and 24 h. Ultrasound was noticed to have the potential to promote ROS development in the cells causing to cell death. In addition, although the results of current study revealed that Ag NPs at higher concentrations (100 μg/mL) function as sonosensitizer, and reinforce the production of ROS, yet, further research and study in vitro and particularly in vivo are required to prove the assumption.

Bio-Inspired Localized Surface Plasmon Resonance Enhanced Sensing of Mercury Through Green Synthesized Silver Nanoparticle

We report sensing of mercury ion through localized surface plasmon resonance based intensity modulation. A U-shaped probe is utilized for this purpose that is functionalized with Chitosan mediated silver nanoparticles. The nanoparticles have been synthesized through a green route. The as-synthesized silver nanoparticles are found to be ~44 nm, as affirmed by absorption curves and DLS experiment. Subject to the dipping of as- fabricated probe in various heavy metal ion solutions, we attain excellent selectivity towards mercury. The sensing offers a limit of detection of 1.5 ppb with an excellent linearity ~0.97. The eco-friendly as well as cost-effective with simplistic design approach has enough potential for the application in real time monitoring of heavy metal contaminants in aqueous solutions.

Preparation of silver nanoparticles and application in water-based conductive inks

We reported a simple, high yield and large-scale preparation method for silver nanoparticles. Silver nanoparticles with 8–13 nm in diameter were successfully synthesized by silver nitrate as raw material, sodium borohydride as reducing agent, dispersan-5040 (polycarboxylate sodium salt) as surface modifier in aqueous solution. The effects of sodium borohydride and dispersan-5040 on the morphologies of silver nanoparticles were investigated. Further, the conductive inks were prepared with as-synthesized silver nanoparticles as conductive fillers in the presence of deionized (DI) water and additives. The effects of conductive fillers and additives on the pH, conductivity, surface tension and viscosity of the inks were investigated. The conductive patterns were fabricated by inkjet printer and their performances were studied. The sheet resistances of the printed pattern with seven-layer was 1.2 [Formula: see text] when the printed pattern was heat-treated at 120[Formula: see text]C for 60 min. We succeeded in printing a simple conductive circuit on photographic paper, which can light three 0.06 W LED beads. The successful fabrication of the functional circuit proves the feasibility of the ink and provides some ideas for future paper-based circuits.

Facile green synthesis and characterization of Crataegus microphylla extract-capped silver nanoparticles (CME@Ag-NPs) and its potential antibacterial and anticancer activities against AGS and MCF-7 human cancer cells

A facile, fast and inexpensive method to preparation of silver nanoparticles (CME@Ag-NPs) with very favorable efficiency in biological assay has been expanded utilizing Crataegus microphylla fruit extract as reducing agent. Some parameters such as pH, time, AgNO3 concentration and temperature on the biological assay efficiency and morphological characteristics of CME@Ag-NPs were investigated to reach optimum condition. FT-IR, XRD, TEM, DLS, FESEM, EDS and UV/Vis analysis were used to investigate the properties of the as-synthesized CME@Ag-NPs. Regular, homogeneous and spherical-like morphology of CME@Ag-NPs with a mean particle size of 30–50 nm was obtained from FESEM and TEM images. The antibacterial activity of CME@Ag-NPs was explored on Acinetobacter baumannii, Staphylococcus aureus, Enterococcus, Pseudomonas, Escherichia coli, Klebsiella and Proteus mirabilis bacteria by MIC and MBC test. Investigation of the antibacterial activity showed that as-obtained nanoparticles have significant activity against Proteus mirabilis (MIC value of 3.5 μg/ml and MBC value of 7 μg/ml) than other bacterial strains. Further, antibacterial activity of CME@Ag-NPs was determined against multidrug-resistant. Interestingly, as-synthesized silver nanoparticles displayed considerable antibacterial activity against all the test strains. In vitro cytotoxicity of nanoparticles on MCF-7 and AGS cell lines was assayed in different concentration of CME@Ag-NPs and doxorubicin as positive control. As the results show, CME@Ag-NPs is excellent effective in inhibiting the growth of MCF-7 and AGS cell lines.

Phytosynthesis of silver nanoparticles using Zingiber officinale extract: evaluation of their catalytic and antibacterial activities

Aqueous extract of the rhizome of ginger (Zingiber officinale) has been used to prepare silver nanoparticles. The aqueous dispersion of as-synthesized silver nanoparticles was stable. Almost spherical particles having average diameter 5.28 ± 1.29 nm along with few large aggregates have been revealed from transmission electron microscopic image. Evidence of the existence of such small nanoparticles has also been demonstrated by their UV-Vis spectral analysis where characteristic Surface Plasmon Resonance Band (SPR) of silver nanoparticles appeared at 432 nm. Cyclic voltammetry (CV) study was performed to know the reducing ability of the aqueous extract of the rhizome. The interaction of the ingredients present in the extract with the surface of nanoparticles was studied using FT-IR spectroscopy. Catalysis and antibacterial activity, two very important applications of such nanoparticles were studied. The silver nanoparticles exhibited antibacterial activity against Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. Catalytic efficiency of the nanoparticles was evaluated and reported in terms of catalytic activity parameter (κ), against the degradation of common environmental pollutants 4-nitrophenol (4-NP) and common organic dyes like Eosine blue (EB), Brilliant Cresyl Blue (BCB), Eriochrome Black T (EBT). The obtained κ values are 549, 218, 1054, 280 s−1 g−1 for 4-NP, EB, BCB and EBT, respectively and some of these values are comparable with the values of κ reported in literature suggesting the good catalytic efficiency of nanoparticles.

Anticancer Activity of Green Silver Nanoparticles against He-La Cervical Cancer Cell Lines

Abstract In the present work, green nanotechnology was used to synthesize silver nanoparticles of different sizes to study their anti-cancer activity against He-La cervical. The synthesis method is easy, simple, environment friendly and does not require any sophisticated labs. This method utilizes principles of green chemistry. Silver nanoparticles were synthesized using electrolytic deposition technique with black tea leaf extract as capping agent. The as-synthesized nanoparticles were characterized using XRD, TEM, and UV-Visible and FTIR spectroscopy techniques. Elemental analysis of the X-ray graphs reveals that highly pure silver nanoparticles are synthesized. Activity of the Ag NPs against cell lines was observed in a dose-dependent manner using MTT assay and it was found that as-synthesized silver nanoparticles inhibited the growth of He-La cervical cancer cell lines almost up to 70-75% respectively. The IC50 value of sample against He-La cervical cancer cell lines were obtained at 30-fold dilutions of concentration of 178 ppm

Potential of bacterial culture media in biofabrication of metal nanoparticles and the therapeutic potential of the as-synthesized nanoparticles in conjunction with artemisinin against MDA-MB-231 breast cancer cells.

In the recent past, various groups have proposed diverse biocompatible methods for the synthesis of metal nanoparticles (NPs). Besides culture biomass, culture supernatants (CS) are increasingly being explored for the synthesis of NPs; however, with the ever-increasing exploration of various CS in the biofabrication of NPs, it is equally important to explore the potential of various culture media (CMs) in the synthesis of metal NPs. Considering these aspects, in the present investigation, we explore the possible applicability of various CMs in the biofabrication of metal NPs. The synthesis of NPs was primarily followed by UV/VIS spectroscopy, and, thereafter, the NPs were characterized by various physiochemical techniques, including EM, EDX, FT_IR, X-ray diffraction, and DLS measurements, and finally, their anticancer potentialities were investigated against breast cancer. In addition, the NPs were examined in conjunction with artemisinin for therapeutic benefits against aggressive and highly metastatic MDA-MB-231 breast cancer cells. Cumulatively, the results of the present study collated the potentials of various bacterial CMs in the biofabrication of metal NPs and ascertained the efficacy of the as-synthesized silver nanoparticles, especially the combinatorial entity as intriguing breast cancer therapeutics. The data of the presentstudy plausibly assist in advancing the therapeutic applicability of the combinatorial amalgam against aggressive and highly metastatic MDA-MB-231 breast cancer cells.

Green Synthesis of Silver Nanoparticles Using Aqueous Extract of Rosa brunonii Lindl and Their Morphological, Biological and Photocatalytic Characterizations

In this work, silver (Ag) nanoparticles were synthesized by simple, eco-friendly chemical reaction using aqueous extract of Rosa brunonii Lindl as a reducing agent. The characterizations using scanning electron microscopy, X-ray diffraction (XRD), energy dispersive spectrometry, UV–Vis spectrum and photo luminance spectroscopy confirmed the successful synthesis of Ag nanoparticles. The suitable antioxidant properties of as-synthesized silver nanoparticles using three assays; DPPH, FRAP and ferrous chelation potential, were confirmed. Various in vitro biological parameters of biosynthesized nanoparticles suggested an excellent antimicrobial activity against different (five bacterial and four fungal) microbial strains viz. Escherichia coli, Kleibsella pnemoniae, Campylobacter jejunii, Bacillus cereus, Alcaligenes denitrificans, Bipolaris specifera, Fusarium oxysporum, Aspergillus niger and Curvularia lunata. The as-synthesized silver nanoparticles were found most susceptible to C. jejunii (bacteria) at 47.11 µg/mL and A. niger (fungal) at 70.9 µg/mL. Further, photocatalytic property of silver nanoparticles showed a gradual increase of degradation (%) of Congo red dye under direct sunlight with respect to time for 3 h in the interval of 1 h each. The results confirmed that green synthesized silver nanoparticles are highly efficient for the photocatalytic degradation of the Congo red dye.

Surface characterisation and reaction kinetics of silver nanoparticles mediated by the leaf and flower extracts of French marigold (Tagetes patula).

In this study, French marigold's leaf and flower were used for the synthesis of silver nanoparticles (SNPs) in order to explore their potentials towards bioreduction of Ag+ to Agᵒ. The as-synthesised SNPs were characterised using UV-Vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, powder X-ray diffraction, transmission electron microscopy, and zeta-potential analysis. The results obtained showed that the particles are polydispersed with sizes in the range 15.8-42.8 nm. The bioreduction was believed to be due to the amides, aldehyde functional groups, and essential oils present in the extracts as confirmed by the FTIR analysis. The growth mechanism involved in the reaction was studied which revealed oriented attachment (OA) onwards Ostwald ripening in the case of the flower-mediated synthesis and typical OA in the leaf-mediated synthesis. The studied kinetics of the particle formation showed that the reaction is possibly a pseudo-first-order reaction with some diffusion-controlled mechanism which is driven by high surface area to volume ratio in both the leaf- and flower-mediated synthesis.

Synthesis of highly stable silver nanoparticles through a novel green method using Mirabillis jalapa for antibacterial, nonlinear optical applications

Green synthesis techniques are developing as more simplistic and eco-friendly approach for the synthesis of metal nanoparticles compared to chemical reduction methods. Herein we report Synthesis of highly stable silver nanoparticles using Mirabillis jalapa seed extract as a reducing and capping agent. The as-prepared silver nanoparticles were characterized by UV–vis spectroscopy (UV–vis) to confirm the formation of silver nanoparticles by its characteristic surface plasmon resonance peak observed at 420 nm. The Powder X-ray diffraction (P-XRD) revealed the structure and crystalline nature of synthesized silver nanoparticles, The Fourier transform infra-red spectroscopic (FT-IR) revealed the presence of the biomolecules in the extract that acted as reducing as well stabilizing agent. The high resolution transmission electron microscopic (HRTEM) images divulged that the synthesized silver nanoparticles were spherical in shape and poly dispersed. The energy dispersive X-ray diffraction (EDX) profile revealed the elements present in the as-synthesized colloidal silver nanoparticles and its percentages. The Zeta potential measured for silver nanoparticles evidenced that the prepared silver nanoparticles owned high stability in room temperature itself. The as-synthesized silver nanoparticles (AgNPs) in colloidal form were showed good antimicrobial effects and it's were found to exhibit third order optical nonlinearity as studied by Z-scan technique using 532 nm Nd:YAG (SHG) CW laser beam (COHERENT—Compass 215 M-50 diode pumped) output as source. The negative nonlinearity observed was well utilized for the study of optical limiting behavior of the silver nanoparticles.