جستجوی مقالات مرتبط با کلیدواژه « agnps » در نشریات گروه « علوم پایه »

Today, the production and use of materials with nanometer diversity is increasing day by day due to the unique and fascinating features of these materials. Until now, various physical and chemical methods have been used for the synthesis of silver nanoparticles (AgNPs), but the use of plants for the synthesis of AgNPs is very fast, simple, non-toxic, and environmentally friendly. In this research, the aqueous extract (AE) of Capparis plants was used for the biosynthesis of AgNPs. The color of the silver nitrate solution changed to reddish color after adding the extract. The Antimicrobial activity of AgNPs against Streptococcus pyogenes, Streptococcus pneumoniae, S. saprophyticus, Hafnia alvei,  Acinetobacter. baumannii, Enterococcus faecalis, Proteus mirabilis, Serratia marcescens, Staphylococcus aureus bacteria were investigated by minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) using microdilution method. The amount of total phenol and flavonoids in the methanolic extract (ME) of capparis leaves was equal to 229.9- 28.09 mg per gram of dry matter. The antioxidant properties of the ME of capparis were 85.18%. The greatest effect of the ME of the medicinal plant capparis was 0.2315 on the inactivity of E. coli and the greatest effect of green AgNPs synthesized from the AE of the medicinal plant Capparis with ELISA of 0.3740 was on the inactivity of S. mutanis. The maximum diameter of the inhibitor zone (MDIZ) was 5.5 mm due to the inactivity of H. alvi bacteria. The results of this research showed that the leaf extract of the Capparis spinosa f. inermis Knocheplant is capable of synthesizing AgNPs and the synthetic nanoparticles showed good antimicrobial activity against pathogenic strains in vitro.

The present work describes the corrosion inhibition of one of the widely used alloys in the industrial process, i.e., Mild Steel in Fresh water and demineralized water using acrylic polymer coating, Acrylic/8% Zn3(PO4)2 coatings, and Acrylic/8% Zn3(PO4)2/ 5mM AgNPs coating. The efficiency of coating on mild steel in fresh water and demineralized water was studied using suitable gravimetric and electrochemical techniques and the surface texture of mild steel after coating was studied by Scanning Electron Microscope. The electrochemical study reveals that the coating efficiency was found to decrease with an increase in temperature and Acrylic/8% Zn3(PO4)2/5mM AgNPs exhibited the highest inhibition efficiency of 94% and 95% in fresh water and demineralized water respectively at 303K. The excellent corrosion coating performance is attributed to the physisorption process of adsorption of the coatings on the metal surface which in turn followed the Langmuir adsorption isotherm. The results obtained by both Tafel polarization and electrochemical impedance spectroscopy methods were in good agreement with each other. The density functional theory in the study of acrylic coating also supported the obtained experimental results. To sum up, the acrylic coating with and without 8% Zn3(PO4)2/ 5mM AgNPs is an efficient corrosion coating material.

Lactuca undulata Ledeb. is a medicinal plant belonging to the Asteraceae family. Chicoric acid is one of the main derivatives of caffeic acid, with various pharmacological and biological properties. This study was conducted to optimize cell suspension culture and enhance chicoric acid production in L. undulata by eliciting secondary metabolites using silver nitrate (AgNO3) and silver nanoparticles (AgNPs). Seeds were cultured on ½ MS medium to produce sterile seedlings. In order to produce callus, leaf and root explants were obtained from 2 months old sterile seedlings and placed on ½ MS medium containing 2 mg/L 2,4-D/ plus 0.5 mg/L Kin and 2 mg/L 2,4-D/ plus 2 mg/L Kin, respectively. Cell suspension cultures from leaf and root-derived calluses were established and treated with different concentrations (0, 2, and 4 mg/L) of AgNO3 and AgNPs during the logarithmic growth phase. Then cells were harvested after 24, 48, and 72 hours. Overall, elicitation by AgNPs was more effective on chicoric acid production compared to AgNO3. The highest amounts of chicoric acid (9.7 ± 0.48 mg/g DW) and caffeic acid (15.3 ± 0.8 mg/L) were found in leaf and root cell suspension cultures after 48 hours of exposure to 4 and 2 mg/L AgNPs, respectively. In contrast, 4 mg/L of AgNO3 stimulated the greatest accumulation of chlorogenic acid (4.56 ± 0.3 mg/g DW) in root cell culture at 72 h after elicitation. The current results revealed that the use of AgNPs can be an efficient strategy to improve cichoric acid accumulation in cell suspension culture.

Euphorbia helioscopia, a traditional medicinal herb, possesses various pharmaceutical applications for human diseases. In the present study, the ethanol and hexane extracts of E. helioscopia leaves were subjected to phytochemical screening to identify the presence of secondary metabolites. The concentrations of alkaloids, phenols, and flavonoids were determined quantitatively to evaluate the medicinal properties of the plant extracts. The ethanolic extract showed a higher yield of various secondary metabolites, specifically, phenol showed a high degree of precipitation. Silver nanoparticles (AgNPs) were then green synthesized from the leaf extract and characterized by UV–Visible spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscope (SEM). The presence of elemental silver is confirmed by the sharp peaks in the UV-Visible at 442 nm. The FTIR spectrum showed the presence of various functional groups from the plant extract that fabricated and activated the AgNPs. The synthesized NPs were found to be spherical with slight aggregation in the SEM micrograph. The crude plant extracts and AgNPs were compared for antibacterial activity at various concentrations. AgNPs exhibited higher inhibitory activity against selected Gram-positive and Gram-negative pathogens than the crude extracts. The enhanced activity of AgNPs may be attributed to the phenolic content of the plant extracts. Hence, the present study confirms that E. helioscopia leaves have potential antimicrobial activity and also act as an efficient source for AgNPs with remarkable pharmacological properties that can be further evaluated to develop them as a promising drug candidate.

We herein report the green synthesis of a reduced Graphene Oxide/Silver nanoparticle (rGO/AgNP) nanocomposite by simultaneously reduction of graphene oxide and silver ions using an aqueous extract of cinnamon (Cinnamomum verum) plant bark. Methylene blue dye removal capacity and efficiency of the nanocomposite was evaluated.  The synthesized nanocomposites were characterized by using UV‑DRS, SEM, P‑XRD, and FTIR spectroscopy. The XRD results showed the average particle sizes Ag NPs, rGO, and rGO/Ag NPs nanocomposite to 29.9 nm, 0.67 nm, and 13.35 nm respectively. The UV-DRS analysis result showed that rGO/Ag nanocomposite exhibited two absorbance peaks at 272 & 334 nm which corresponds to rGO and Ag NPs respectively. The FTIR spectral data revealed the functional groups characteristics of phytochemicals in the plant extract, rGO and rGO/AgNP nanocomposite. The surface morphology from SEM result obtained indicated that Ag NPs showed non-homogeneity and different shapes, rGO had thin flat layer sheet morphology whereas Ag NPs were deposited on rGO nanosheets in the form of clusters in the rGO/AgNP nanocomposite. The rGO/AgNP nanocomposite had highest methylene blue removal efficiency of 99.98% at optimum pH 2, adsorbent dose 80 mg, contact time 50 min and initial concentration of 10 mg/l. The Adsorption isotherms were well fitted to Langmuir isotherm for all synthesized adsorbents. The adsorption kinetics results were best fitted to the pseudo-second-order model. The green synthesized rGO/AgNP nanocomposite has the potential to be used as an adsorbent in wastewater treatment applications.

Measuring the heavy metals in environmental and food samples to evaluate the decontamination of toxic pollutants in the environment is vital for human health. In the current project, a new colorimetric method based on the aggregation of 1,3-dimethyl benzotriazolium iodide (BTAIL) stabilized silver nanoparticles (AgNPs) for detection of copper (Cu2+) ion was developed. Aggregation of AgNPs induced by coordinative coupling between Cu2+ and triazole ring of BTAIL. Cu2+ AgNPs aggregates with a color change from yellow to red and a decrease in UV-vis absorption peak at 400 nm. Under the optimized experimental conditions (pH=9, reaction time= 3 min, BTAIL volume= 600 µL (0.01 M)) a linear range of 20-100 nM was obtained. Good selectivity and sensitivity toward Cu2+ among the other ions were observed. Finally, real sample results such as green tea, Rosa damascene, Chamaemelum nobile, and Thymus vulgaris indicated that the proposed method could apply precisely for practical applications.

Nanoparticles (NPs) have received much attention recently in various areas of industry, biomedical, and agricultural sectors worldwide. It is important to recognize the consequences of the use and application of NPs and their interaction with ecosystems components including plants, whether in the environmental area or in physiology and crop production. The present study aimed to investigate the changes in essential oil content and composition of Thymus daenensis Celak., Thymus fedtschenkoi Ronniger and Thymus vulgaris L. under silver nanoparticles (AgNPs) and silicon nanoparticles (SiNPs) in four levels (0, 30, 60, 100 ppm). The essential oil content increased at all stress levels and in all three species. The amount of monoterpene hydrocarbons in T. fedtschenkoi increased, while it decreased in other two species. The amount of sesquiterpentes, except for oxygenated sesquiterpenes in T. daenensis, increased slightly. Compared to other factors, the type of plant species was more determinative in response to treatments. Overall, both AgNPs and SiNps treatments had a distinct effect. However, no interpretable results were observed between the different levels of both treatments.

This paper presents removal of some polycyclic aromatic hydrocarbons (PAHs) by silver nanoparticles (AgNPs) which were synthesised by garlic based green route method. Allivum sativum (Garlic) extract was used for the synthesis of silver nanoparticles Ag(P) as a green route process while synthetic chemical method was adopted for preparation of silver nanoparticles Ag(W). The synthesis of AgNPs was studied as a function of variation in volume of garlic extract, temperature and time. Solution of pyrene, anthracene and phenanthrene was prepared in n-hexane, and their removal efficiencies were studied. PAHs were removed successfully with optimal efficiency of more than 80% with the affinity order of removal, which followed Phenanthrene > Pyrene > Anthracene. The adsorption of PAHs on AgNPs is attributed to the occurrence of hydrophobic interactions. Ag (P) nanoparticles synthesized were found relatively better adsorbent than Ag (W), for removal of PAHs. It may be ascribed owing to the presence of more functional groups in the garlic extract participating in binding of PAH to the surface. The adsorption property of the AgNPs synthesized by both ways was studied and comparative results were obtained based on adsorption efficiency of PAHs. Further, FTIR and XRD were used to characterize the properties of garlic extract with binding and interaction taking place between AgNPs and PAHs. UV-Vis confirmed the formation of Ag(P) and Ag(W) by biological method and chemical wet co-precipitation method, respectively. Ag(P)can be applied over a wide range of temperature, due to stability of compounds present in Allivum sativum at high temperatures.

Particles with the size of 1-100 nm are known as nanoparticles (NPs). The widespread use of silver NPs (AgNPs) makes it familiar in different industries. They have unique properties as a result of their high surface to volume ratio, although aggregation of NPs interferes with their functions. This phenomenon has several side effects on the environment, the amount of which may depend on the stability of AgNPs. Stability of colloids depends on various agents, such as capping agents and environmental conditions, including pH and ionic strength. In this study, the effects of a variety of electrolytes, such as NaCl (10mM), NaNO3 (10 and 100mM), andCa (NO3)2 (10mM)at different values of pH were investigated on the aggregation of AgNPs synthesized using an aqueous extract of dried Juglans regia green husk. In NaNO3 10mM pH 9, NPs were more stable than in other media. Therefore, the special optical and electronic properties of AgNPs in such a medium as well as in water were investigated. The UV-visible extinction spectra of AgNPs in both water and NaNO3 (10 mM, pH 9.0) showed a surface plasmon resonance (SPR) at 445 nm as well as a broad peak at shorter wavelengths (255 nm). The fluorescence emission spectra of AgNPs at different excitation wavelengths in the range of 245-290 nm revealed emission peaks that were red-shifted in the range of 487-580 nm by the increase in the excitation wavelength. This behavior is attributed to the existence of a variety of emission centers with different energy levels.

The purpose of this study was to expand a trouble free biological method for the synthesis of silver nanoparticles (AgNPs) using the leaves extract of Rosa ChinensisL. to act as reducing and stabilizing agent. Water soluble phytochemicals played a vital role for the reduction silver ions into silver nanoparticles. The leaves extract was exposed to silver ions and the resultant biosynthesized AgNPs characterized by X-ray diffraction (XRD) spectrum showed crystalline structure while morphological shape, average size and the crystalline nature of the nanoparticles were determined by field emission scanning electron microscopy (FESEM), transmission electron microscopic with selected area electron diffraction (TEM-SAED). The elemental analysis displayed strong signal at 3 keV that agrees to silver ions and confirms the presence of metallic silver. FTIR analysis exhibits the possible reducing bio-molecules within the leaf extract. Moreover, AgNPs nanoparticles evinced excellent antibacterial activity against Staphylococcus aureus and Streptococcus pyogenus bacterial pathogens. The studies describing the synthesis of AgNPs nanoparticles by efficient and green method followed by the investigation of antibacterial activities may be opened new horizons to scientists and researchers for the medicinal purposes.

An ultrasensitive electrochemical immunosensor for the detection of tumor marker human chorionic gonadotropin (hCG) was developed with a limit of detection as low as 2 pg mL-1 in phosphate buffer. The Platinum nanoparticles (PtNPs) were electrodeposited to modify the gold surface and to increase enlarging the electrochemically active sites, resulting in the facilitation of electron exchange. Cysteamine (Cys) self-assembled monolayer was chemisorbed spontaneously on Pt substrates via the Pt-S bond and the amine groups array exposed on the electrode surface was used to anchor AgNPs through electrostatic interaction. AgNPs increased the immobilized amount of antibodies on the electrode to enhance the sensitivity of the sensor. Under optimal experimental parameters, Differential pulse voltammetry (DPV) signal changes of the [Fe(CN)6]3-/4- are used to detect hCG with two broad linear ranges: 0.007 to 1.11 and 1.11 to 68 ng mL-1. The reported strategy has provided a promising platform for highly sensitive and selective detection of hCG. Finally, the proposed immunosensor is successfully used in detecting hCG in a human serum samples.

The field of nanobiotechnology mainly encompasses with physics, biology, chemistry and material sciences and it develops novel therapeutic nano-scale materials for biomedical, drug delivery, cancer therapy and pharmaceutical applications. Silver nanoparticles (AgNPs) have unique physiochemical, biological and environmental properties which make them useful in a wide range of applications, so AgNPs was synthesized using mustard plant. The formation and characterization of AgNPs were investigated using UV-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR),X-ray diffraction (XRD) and transmission electron microscopy (TEM). UV-visible spectroscopy showed surface plasmon resonance peak at about 411 nm. FTIR indicated the role of different functional groups (carboxyl, amine, aromatic and hydroxyl) in the formation process of AgNPs. TEM analysis showed spherical particles with size range 1-35 nm and an average size 14 nm. Our measurements showed that mustard seed exudates could mediate facile and eco-friendly biosynthesis of colloidal spherical AgNPs. Also, we studied influence of concentrations of silver nitrate on stability of biosynthesized AgNPs. The results clearly showed that the stability of biosynthesized AgNPs strongly depended on the concentration of used silver ions and increased with increasing the concentration of silver ions in the biosynthesis process. Our results indicated that AgNPs synthesized at higher concentrations of silver nitrate were more stable.

Dermatophytosis is the common cutaneous infections in humans and animals, which is caused by the keratinophylic fungus called dermatophytes. In recent years, drug-resistance in pathogenic fungi, including dermatophytes to the current antifungal have been increased. The aim of this study was to evaluate the antifungal efficacy of AgNPs against Microsporum canis, Trichophyton mentagrophytes, and Microsporum gypseum. The antifungal susceptibility of nano-silver particles (AgNPs) compared with Griseofulvin (GR). Its efficacy was investigated against three strains of dermatophytes by both agar dilution and broth microdilution test (BMD). The average minimum inhibitory concentration (MIC) of Ag-NPs on M. canis, T. mentagrophytes and M. gypseum were 200, 180, and 170 μg/ml, respectively. Whereas these strains showed MIC of 25, 100 and 50 μg/ml for Griseofulvin (GR). Our finding indicated that the AgNPs was less active than Griseofulvin (GR) but it had anti-dermatophytic effect.