Sucrose ester micellar-mediated synthesis of Ag nanoparticles and the antibacterial properties

Green synthesis and characterization of silver nanoparticles and its efficacy against Rhizoctonia solani, a fungus causing sheath blight disease in rice

Rice (Oryza sativa) stands as a crucial staple food worldwide, especially in Bangladesh, where it ranks as the third-largest producer. However, intensified cultivation has made high-yielding rice varieties susceptible to various biotic stresses, notably sheath blight caused by Rhizoctonia solani, which inflicts significant yield losses annually. Traditional fungicides, though effective, pose environmental and health risks. To address this, nanotechnology emerges as a promising avenue, leveraging the antimicrobial properties of nanoparticles like silver nanoparticles (AgNPs). This study explored the green synthesis of AgNPs using Ipomoea carnea leaf extract and silver nitrate (AgNO3), and also examined their efficacy against sheath blight disease in rice. The biosynthesized AgNPs were characterized through various analytical techniques such as UV-vis spectrophotometer, X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Particle size analyzer, Zeta potential, Scanning Electron Microscope (SEM), Field Emission Scanning Electron Microscope (FESEM), Transmission Electron Microscope (TEM) for confirming their successful production and crystalline nature of nanoparticles. The results of UV-visible spectrophotometers revealed an absorption peak ranging from 421 to 434 nm, validated the synthesis of AgNPs in the solution. XRD, DLS, and TEM estimated AgNPs sizes were ~45 nm, 66.2nm, and 46.38 to 73.81 nm, respectively. SEM and FESEM demonstrated that the synthesized AgNPs were spherical in shape. In vitro assays demonstrated the significant inhibitory effects of AgNPs on mycelial growth of Rhizoctonia solani, particularly at higher concentrations and pH levels. Further greenhouse and field experiments validated the antifungal efficacy of AgNPs against sheath blight disease in rice, exhibiting comparable effectiveness to commercial fungicides. The findings highlight the potential of AgNPs as a sustainable and effective alternative for managing rice sheath blight disease, offering a safer solution amidst environmental concerns associated with conventional fungicides.

Metal nanoparticles as inhibitors of enzymes and toxins of multidrug-resistant Staphylococcus aureus

Staphylococcus aureus is an aerobic Gram-positive spherical bacterium known to cause a broad range of infections worldwide. It is a major cause of infective skin and soft infections and severe and life-threatening conditions, such as pneumonia, bloodstream infections, and endocarditis. The emergence of drug-resistant strains of S aureus, particularly methicillin-resistant S aureus (MRSA), has become a significant concern in the healthcare community. Antibiotic-resistant S aureus is commonly acquired in hospitals and long-term care facilities. It often affects patients with weakened immune systems, those undergoing invasive medical procedures, or those who have been hospitalized for extended periods. In the US, S aureus is known to cause potentially fatal illnesses, such as toxic shock syndrome (TSS) and acute-onset toxic shock syndrome (TSS), which are characterized by fever and hypotension. It develops resistance to antibiotics through several mechanisms, such as the production of enzymes that inactivate antibiotics, target site modification, efflux pumps, and plasmid-mediated resistance. Therefore, preventing the spread of drug-resistant S aureus is needed, and there is an urgent need to explore novel approaches in the development of anti-staphylococcal agents. This article reviews the principal infections caused by S aureus, major virulence factors, mechanisms of resistance development, and nanotechnology-based solutions for the control of drug-resistant S aureus.

Green Synthesis, Characterization and Antimicrobial Activity of Silver Nanoparticles Using Aqueous Extracts of Allium cepa and Raphanus sativus

Green synthesis of nanoparticles is rapidly evolving because it is cost-effective and eco-friendly, this also contributes to its preference over nanoparticles from other sources. In this study, silver nanoparticles were synthesized from Allium cepa (AC) and Raphanus sativus (RS) aqueous extracts and the biological activities were evaluated. The silver nanoparticles AgNPs@AC and AgNPS@RS were synthesized from AC and RS extracts, respectively, using silver nitrate and characterized using UV–visible spectroscopy (UV–Vis), Fourier transform infrared (FT-IR) spectroscopy, Powder X-ray diffraction (PXRD), scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX). The FT-IR spectra of AgNPs@AC and AgNPS@RS showed characteristic groups pertaining to active molecules of the respective extracts indicating their surface functionalization. The XRD pattern of AgNPs@AC revealed diffraction peaks at 38.26, 44.39, 64.65, 77.54 and 81.64 that were indexed to (1 1 1), (2 0 0), (2 2 0), (3 1 1) and (2 2 2) planes of face-centered cubic (FCC) crystalline structure, respectively. The XRD pattern of AgNPs@RS revealed diffraction peaks at 38.24, 44.32, 64.62, 77.46 and 81.65 that was indexed to (1 1 1), (2 0 0), (2 2 0), (3 1 1) and (2 2 2) planes of face-centered cubic (FCC) crystalline structure, respectively. The SEM images indicate that the particles are spherical in shape and have particle size in the range of 25–35[Formula: see text]nm. The nanoparticles demonstrated substantial antimicrobial activity against Gram [Formula: see text]ve and Gram [Formula: see text]ve harmful bacteria species, such as S. aureus, E. coli and fungal species C. albicans. This study shows that A. cepa (Onion) and R. sativus (Radish) aqueous extracts can be used as an effective reducing and capping agent for the green synthesis of silver nanoparticles (AgNP). AgNPS@RS showed acceptable size and shape of nanoparticles and could therefore be a potential source of antimicrobial agents.

L-Cysteine as a reducing/capping/gel-forming agent for the preparation of silver nanoparticle composites with anticancer properties

The present article reports the in situ preparation of silver nanoparticles (AgNPs) homogeneously distributed in the gel matrix formed using only L-cysteine (CYS) as a bio-reducing agent. The physicochemical methods of analysis confirmed the formation of a gel-network from aggregates consisting of spherical/elliptical cystine-stabilized AgNPs (core) and cysteine/Ag⁺ complexes (shell) regardless of the used silver salt - AgNO₃, AgNO₂ or AgOOCCH₃. CYS/AgNO₃ and CYS/AgOOCCH₃ aqueous solution systems needed the addition of electrolytes (Cl^- and SO₄^2-) for the gelation process, but the gel-formation in CYS/AgNO₂ occurred in one stage without any additional components. The AgNP sizes were about 1-5 nm in diameter for CYS/AgNO₃, 5-10 nm for CYS/AgOOCCH₃ and 20-40 nm for CYS/AgNO₂ systems. The zeta-potential values varied from +60 mV for CYS/AgNO₃ to +25 mV for the CYS/AgNO₂ system. The MTT-test showed that the obtained composites suppressed the MCF-7 breast cancer cells and the CYS/AgNO₃ system possessed the highest activity. Flow cytofluorimetry confirmed that the cell death occurred by apoptosis and this effect was the strongest for the CYS/AgNO₃ system. All systems were non-toxic to fibroblast cells. The novel simplest "green chemistry" approach, combining the knowledge of organic, inorganic, physical and supramolecular chemistry could open possibilities for the creation of the newest soft gel materials used in various fields of our life.

Facile synthesis of metal nanoparticle-loaded polymer nanocomposite with highly efficient an optically enhanced biocidal and anticancer agents

In this work, we prepared silver nanoparticles (AgNPs)-loaded poly(2,5-dimethoxyaniline;PDMA) nanocomposite via a simple chemical oxidative method to develop new effective biocidal and anticancer agents systems. In situ UV-vis and fluorescence spectroscopy has been used to monitor the formation of PDMA/Ag is strongly dependent on the concentration of PDMA in the present system. The FTIR and XRD studies exhibit that the rate of polymer formation and oxidation state of PDMA/Ag nanocomposite, which confirmed the AgNPs is strongly binding with the PDMA matrix. SEM and EDAX analysis revealed the presence of uniform size and the highest percentage of AgNPs (42.1%) in the PDMA/Ag nanocomposite. TEM and size distribution analysis revealed the presence of spherical AgNPs with an average diameter of 25 nm in the PDMA/Ag nanocomposite. In addition, the PDMA polymer with embedded AgNPs exhibited excellent antibacterial performance against Escherichia coli and Staphylococcus aureus. Interestingly, the prepared PDMA/Ag nanocomposite exhibited enhanced bactericidal performance compared with the PDMA polymer, presumably because of the antibacterial properties of the AgNPs substrate. The anticancer effects of combined treatment with PDMA polymer and AgNPs were evaluated using a series of cellular and biochemical assays. The findings from this study revealed that the PDMA/Ag nanocomposite treatment significantly inhibited cell viability and proliferation of the human cervical cancer cell line (HeLa). The PDMA/Ag nanocomposite exhibits better antibacterial and anticancer activities compare to pristine PDMA.

In Vivo and In Vitro Assessments of the Antibacterial Potential of Chitosan-Silver Nanocomposite Against Methicillin-Resistant Staphylococcus aureus-Induced Infection in Rats

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most threatening multidrug-resistant bacteria worldwide. Owing to their efficient antimicrobial properties, nanoparticles have been widely used as an alternative approach for combating the antibiotic-resistant bacteria. Consequently, this study was designed to compare in between the bactericidal effect of low doses (5 mg/kg bwt) of nanoparticles of chitosan (Ch-NPs), silver (Ag-NPs), and chitosan-silver nanocomposites (Ch-Ag NCs) both in vitro and in vivo against experimentally chronic infection induced by methicillin-resistant Staphylococcus aureus (MRSA). The three forms of nanoparticles were tested for their in vitro antimicrobial potential against MRSA by detection of MICs and MBCs using microdilution method. In vivo, thirty-five male albino Wistar rats were used and divided into five groups (n = 7). Group l (negative control), group 2 (MRSA infected and untreated), groups 3, 4, and 5 (MRSA infected then treated with Ch-NPs, Ag-NPs, and Ch-Ag NCs respectively for 7 days). After 6 weeks, blood samples were collected then rats were euthanized to collect different organs (liver, spleen, lungs, and kidneys). Some of them were kept in 10% formalin for histopathological investigations while others used for bacterial re-isolation. Ch-Ag NCs showed the lowest MIC and MBC among the tested nanoparticles. Moreover, the highest histopathological scoring was observed in the infected and untreated group while the lowest scoring was detected in groups treated with Ch-Ag NCs in comparison with the negative control group. The highest bacterial count was noticed in the infected and untreated group followed by those treated with Ch-NPs while the lowest count was observed in group treated with Ch-Ag NCs. Depending on these results, it can be concluded that Ch-Ag NCs have a strong bactericidal effect against MRSA and may be used as alternative option to antibiotics.

Synthesis of combinatorial Janus nanoparticles based on EpCAM-PEG/PCL for targeted therapy of human colorectal adenocarcinoma

Active targeted nanotechnology-based drug delivery systems have gained significant favor because they have the ability to decrease side effects, improve drug bioavailability, and the potency of anticancer treatment. In this study, functional amphiphilic Janus nanoparticles (JNPs), consisting of hydrophilic and hydrophobic biocompatible polymers as two distinct sides, have been prepared via a robust and simple synthesis method. The surface-active hydrophilic side of this Janus platform is functionalized with an aptamer against epithelial cell adhesion molecule (EpCAM) to deliver Doxorubicin (DOX) for the treatment of metastasis colorectal adenocarcinoma HT29 cells. The Janus morphology of the nanoparticles and their cell penetration behavior are shown in microscopic evaluations. By evaluating the prepared DOX-loaded aptamer-modified JNPs by cell-toxicity assay and confocal microscopy, it was determined that the utilization of an internalization strategy to enhance cell uptake would increase the anticancer effect of the Janus nanocarrier and improve the capacity to deliver the chemotherapeutical drug site-specifically.

Exploring the potentials of halophilic prokaryotes from a solar saltern for synthesizing nanoparticles: The case of silver and selenium

Halophiles are the organisms that thrive in extreme high salt environments. Despite the extensive studies on their biotechnological potentials, the ability of halophilic prokaryotes for the synthesis of nanoparticles has remained understudied. In this study, the archaeal and bacterial halophiles from a solar saltern were investigated for the intracellular/extracellular synthesis of silver and selenium nanoparticles. Silver nanoparticles were produced by the archaeal Haloferax sp. (AgNP-A, intracellular) and the bacterial Halomonas sp. (AgNP-B, extracellular), while the intracellular selenium nanoparticles were produced by the archaeal Halogeometricum sp. (SeNP-A) and the bacterial Bacillus sp. (SeNP-B). The nanoparticles were characterized by various techniques including UV-Vis spectroscopy, XRD, DLS, ICP-OES, Zeta potentials, FTIR, EDX, SEM, and TEM. The average particle size of AgNP-A and AgNP-B was 26.34 nm and 22 nm based on TEM analysis. Also, the characteristic Bragg peaks of face-centered cubic with crystallite domain sizes of 13.01 nm and 6.13 nm were observed in XRD analysis, respectively. Crystallographic characterization of SeNP-A and SeNP-B strains showed a hexagonal crystallite structure with domain sizes of 30.63 nm and 29.48 nm and average sizes of 111.6 nm and 141.6 nm according to TEM analysis, respectively. The polydispersity index of AgNP-A, AgNP-B, SeNP-A, and SeNP-B was determined as 0.26, 0.28, 0.27, and 0.36 and revealed high uniformity of the nanoparticles. All of the synthesized nanoparticles were stable and their zeta potentials were calculated as (mV): -33.12, -35.9, -31.2, and -29.34 for AgNP-A, AgNP-B, SeNP-A, and SeNP-B, respectively. The nanoparticles showed the antibacterial activity against various bacterial pathogens. The results of this study suggested that the (extremely) halophilic prokaryotes have great potentials for the green synthesis of nanoparticles.

NePCM Based on Silver Dispersions in Poly(Ethylene Glycol) as a Stable Solution for Thermal Storage

The main objective of this study is to design and characterize silver suspensions based on poly(ethylene glycol) PEG400, Ag/PEG400, as energy storage media for low-temperature applications. A polyvinylpyrrolidone (PVP) treatment was applied to ~22 nm silver nanoparticles to ensure good stability in poly(ethylene glycol). An array of different experimental techniques was utilized to analyze the molecular mass and purity of base poly(ethylene glycol), morphology of dry PVP-capped Ag nanoparticles, hydrodynamic average size of dispersed Ag particles, as well as thermal stability of PEG400 and Ag/PEG400 dispersions. Samples exhibited good temporal stabilities with average hydrodynamic diameter around 50 nm according to dynamic light scattering analyses. Melting and solidification transitions were investigated in terms of temperature and enthalpy from differential scanning calorimeter (DSC) thermograms. The thermophysical characterization was completed with thermal conductivity (k), dynamic viscosity (η), isobaric heat capacity (Cp), density (ρ), and surface tension (σ) measurements of designed materials using a Hot Disk thermal conductivimeter, a rotational rheometer, a DSC calorimeter working with a quasi-isothermal modulated method, a U-tube densimeter and a drop shape analyzer, respectively. For a nanoparticle loading of only 1.1% in mass, sub-cooling reduced by 7.1% and thermal conductive improved by 3.9%, with almost no penalization in dynamic viscosity (less than 5.4% of increase). Maximum modifications in Cp, ρ, and σ were 0.9%, 2.2%, and 2.2%, respectively. Experimental results were compared with the values provided by using different theoretical or semi-empirical equations. In particular, good descriptions of dynamic viscosity as functions of temperature and nanoparticle volume concentration were obtained by using the Vogel-Fulcher-Tammann equation and a first-order polynomial η( ϕ v , n p ) correlation, with absolute average deviations of 2.2% and 0.55%, respectively.

Anti-Methicillin-Resistant Staphylococcus aureus Nanoantibiotics

Nanoparticle-based antibiotic constructs have become a popular area of investigation in the biomedical sciences. Much of this work has pertained to human diseases, largely in the cancer therapy arena. However, considerable research has also been devoted to the nanochemistry for controlling infectious diseases. Among these are ones due to bacterial infections, which can cause serious illnesses leading to death. The onset of multi-drug-resistant (MDR) infections such as those caused by the human pathogen Staphylococcus aureus has created a dearth of problems such as surgical complications, persistent infections, and lack of available treatments. In this article, we set out to review the primary literature on the design and development of new nanoparticle materials for the potential treatment of S. aureus infections, and areas that could be further expanded upon to make nanoparticle antibiotics a mainstay in clinical settings.

Characterization and Cytotoxicity Evaluation of Biologically Synthesized Silver Nanoparticles from Albuca setosa Aqueous Bulb Extract

Biologically synthesized nanoparticles are rapidly evolving because it is cost effective and eco-friendly, this also contributes to its preference over nanoparticles from other sources. In this study, silver nanoparticles were synthesized from Albuca setosa aqueous bulb (ASB) extracts and the biological activities evaluated. The silver nanoparticles were synthesized from ASB extracts using silver nitrate and characterized using UV–visible spectroscopy (UV–Vis), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The antioxidant activity was determined by evaluating the effect on 2,2-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity, 2,2[Formula: see text]-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid diammonium salt (ABTS). The antibacterial potential was investigated on selected Gram positive and Gram negative bacteria while the cytotoxicity was evaluated on MDA-MB-231 breast cancer cells (ATCC HTB-26). Albuca setosa silver nanoparticles (AS-AgNPs) was formed within 60 min reaction time of UV–Vis absorption. The FTIR showed that acid anhydride, alkene, amine, aldehyde, ester, ketone and carbonyl groups contributed to the synthesis of the AS-AgNPs, while SEM and TEM showed stable irregular shaped monodispersed silver nanoparticles with average size of 7 nm. The XRD patterns revealed diffraction peaks at [Formula: see text] and 92.37∘ that was indexed to (1 1 0), (1 1 0), (1 0 0), (1 0 0) and (1 0 0) planes of face-centered cubic (fcc) crystalline structure respectively. The synthesized nanoparticles possess good antioxidant activity with IC50 of [Formula: see text] and [Formula: see text][Formula: see text][Formula: see text]g/ml for DPPH and ABTS, respectively, and inhibit the growth of Staphylococcus faecalis and Bacillus cereus with MIC of 25 and 15[Formula: see text][Formula: see text]g/ml respectively. AS-AgNPs also revealed higher cytotoxic efficacy against MDA-MB-231 breast cancer cells with IC50 of [Formula: see text][Formula: see text][Formula: see text]g/ml. AS-AgNPs showed acceptable size and shape of nanoparticles and could therefore be a potential source of antimicrobial and anticancer agents. It can be concluded that the synthesized AS-AgNPs is a good source of anticancer agent with broad spectrum of antibiotic activity.

Green synthesis and inhibitory effects against oral pathogens of silver nanoparticles mediated by rice extracts

Rice is staple food for people in many countries for centuries. It is therefore considered as safe and environmental friendly material for pharmaceutical formulations. In the present study, aqueous extracts of three different parts of rice grain; rice bran (RB), rice husk (RH), and rice germ (RG) were compared for their use as reducing agents in synthesis of silver nanoparticles (AgNPs). AgNPs from those three different parts of rice, RB-AgNPs, RH-AgNPs, and RG-AgNPs, respectively showed different reducing activity, which the highest capacity was RB. RG-AgNPs and RB-AgNPs showed the maximum absorption of AgNPs at 440 nm whereas that of RH-AgNPs was at 480 nm. FTIR spectra of all AgNPs indicated the presence of different functional groups from rice attached to the nanoparticles and these groups prevented the particle agglomeration. Size analysis using dynamic light scattering revealed that RB-AgNPs was the smallest particles (346.4 ± 36.8 nm) and possessed the highest negative zeta potential. Antimicrobial test showed that the AgNPs obtained from green synthesis mediated by rice extracts have great antimicrobial activity against Streptococcus mutans, the severe oral pathogenic bacteria causing dental caries. These results suggest that aqueous extracts of RB, RH, and RG have potential to be used as reducing agents in synthesis of silver nanoparticles.

Recyclable magnetite-silver heterodimer nanocomposites with durable antibacterial performance

There is a significant need for magnetite-silver nanocomposites that exhibit durable and recyclable antimicrobial activity. In this study, magnetic iron oxide nanoparticles (Fe₃O₄ NPs) coated with ethylenediamine-modified chitosan/polyacrylic acid copolymeric layer (Fe₃O₄@ECS/PAA) were fabricated. Subsequently, directly deposited silver (Ag) NPs procedure was carried out to form the antibacterial heterodimers of Fe₃O₄@ECS/PAA-Ag NPs. The composition and morphology of the resultant nanostructures were confirmed by FT-IR, XRD, TEM and TGA. The overall length of the heterodimers was approximately 45 nm, in which the mean diameter of Fe₃O₄@ECS/PAA NPs reached up to 35 nm, and that of Ag NPs was around 15 nm. The mass fraction of silver NPs in the nanocomposites was about 63.1%. The obtained Fe₃O₄@ECS/PAA NPs exhibited good colloidal stability, and excellent response to additional magnetic field, making the NPs easy to recover after antibacterial tests. In particular, the Fe₃O₄@ECS/PAA-Ag NPs retained nearly 100% biocidal efficiency (10⁶–10⁷ CFU/mg nanoparticles) for both Gram-negative bacteria E. coli and Gram-positive bacteria S. aureus throughout ten cycles without washing with any solvents or water, exhibiting potent and durable antibacterial activity.

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Recyclable dual functional antibacterial heterodimer nanocomposites were fabricated.

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The nanostructures realized the combination of antibacterial ability and recyclable function.

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Biocidal efficiency retained nearly 100% throughout ten cycles.

Phytochemical constituents of fucoidan (Padina tetrastromatica) and its assisted AgNPs for enhanced antibacterial activity

Biological synthesis of nanomaterials is a growing innovative approach and it was broadly utilised in the field of nanotechnology and nanomedicine. This study illustrates that biosynthesis of silver nanoparticles (AgNPs) using fucoidan extracted from seaweed Padina tetrastromatica. The functional groups of extracted fucoidan were characterised by Fourier transform infrared spectroscopy (FTIR) and used to NPs synthesis. Synthesised AgNPs were characterised by ultraviolet-visible spectra, scanning electron microscope, energy dispersive X-ray, transmission electron microscope, selected area electron diffraction and FTIR. In this study, their main focus is enhancement antibacterial activity of AgNPs coated antibiotics against antibiotic resistant bacteria. Among the microorganisms, Serratia nematodiphila was resistant to novobiocin and penicillin, but it was sensitive to AgNPs impregnated antibiotic discs. The zone of inhibition was 12 and 15 mm. The synergistic effect of combined antibiotics and AgNPs resulted in increased fold area which was greater than the sum of their separate effects. It reveals that AgNPs are highly sought in the medicinal field due to their broad spectrum of antibacterial activity and relatively cheaper. This enhanced synergistic effect potentially superior to control the growth of bacteria and it is the budding process for the development of new remedial agents for severe diseases.

Antioxidant activity of chemically synthesized AgNPs and biosynthesized Pongamia pinnata leaf extract mediated AgNPs - A comparative study

Biosynthesis of metal nanoparticles is the present research in the limb of nanotechnology which reduces the toxicity of metal nanoparticles. Green chemistry approach emphasizes that the usage of plant material has offered a reliable, simple, nontoxic and eco-friendly that links Nanotechnology and Biotechnology. Increasing environmental concerns over chemical synthesis routes have resulted in attempts to develop bio-mimetic approaches. The current study deals with novel method for biosynthesis of AgNPs using Pongamia pinnata leaf extract as reducing agent. These biosynthesized nanoparticles were characterized with the help of UV-vis Spectroscopy, Photoluminescence (PL) and Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Atomic force microscopy (AFM), Dynamic light scattering (DLS) and Zeta Potential (ZP). Free radical scavenging potential of P. pinnata synthesized silver nanoparticles was evaluated in vitro by using five different assays viz., DPPH, ABT^+S, Hydroxyl, Superoxide anion and Nitric oxide scavenging assays are also adopted. Capping of AgNPs by various polyphenolic compounds present in P. pinnata leaf extract appears to be a major contributor to lower toxicity compared to chemically synthesized AgNPs. The surface plasmon resonance shows 425nm and grain size of the AgNPs was measured from XRD and FTIR revealed the bioconjucation of AgNPs. The in vitro antioxidant activity of AgNPs showed a significant effect on scavenging of free radicals. The results suggest that the silver nanoparticles from P. pinnata can be potent natural antioxidants and can be essential for health preservation against oxidative stress related degenerative diseases, such as cancer. The vitality of this study lies in the formation of silver nanoparticles by utilizing the wealth of global ecological resources, eliminating obnoxious and toxic reagents which are hazardous to be handled as well as to be applied.

Green synthesis of ZnO nanoparticles by Olive (Olea europaea)

Green synthesis of nanoparticles is superior to physical and chemical methods as it is environment-friendly and cost-effective. The present study was carried out for inducing nanoparticles synthesis by zinc nitrate in the leaves extracts of olive. Further leaves extracts were evaluated for antiradical scavenging activity by 1, 1-diphenyl-2-picryl-hydrazyl assay. Morphological and structural properties of the synthesised ZnO nanoparticles have been characterised using UV-Vis spectrophotometer, FTIR, TEM, XRD and dynamic light scattering (DLS) analysis. Further, zinc oxide nanoparticles were evaluated for antiradical scavenging activity by capacity of total antioxidant assay. Synthesised ZnO nanoparticles were confirmed by the absorption maxima at the wavelength of 370 nm. TEM image revealed that ZnO nanoparticles were spherical with average size 41 nm. FTIR investigation suggested that the flavonoids, glycosides, proteins and phenols molecules can play an important role in the stabilisation of ZnO nanoparticles.

RETRACTED: Green synthesis of zinc oxide nanoparticles using Moringa oleifera leaf extract and evaluation of its antimicrobial activity

The development of semiconductor materials made a considerable progress of catalytic technologies. In the present study, a simple and eco-friendly chemical direction for the synthesis of zinc oxide nanoparticles (ZnO NPs) using leaf extract of Moringa oleifera has been used. The prepared ZnO NPs were characterized various techniques such as UV-Vis absorption spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray analysis (EDX), Fourier transform infrared spectroscopy (FT-IR) and photoluminescence spectroscopy (PL). XRD analysis revealed the wurtzite hexagonal structure of ZnO NPs. FT-IR confirmed the presence of functional groups of both leaf extract and ZnO NPs. The particles size, morphology and topography determined from FE-SEM. The intense and narrow width of zinc and oxygen have high purity and crystalline were identified using EDX. UV-Vis absorption showed the characteristic absorption peak of ZnO NPs. The results of antimicrobial activities revealed that maximum zones of inhibition was observed Gram (+ve) positive bacteria and followed by the Gram (-ve) negative bacteria and fungal at concentration of 200μg/mL of ZnO NPs.

Synthesis of antibacterial and magnetic nanocomposites by decorating graphene oxide surface with metal nanoparticles

Simple method for preparation of Ag NPs and GO + IO + Ag nanocomposites using cinnamon extract developed. The nanocomposites developed are magnetic and as effective as Ag NPs against bacteria and are cheaper due to less amount of Ag.

Green synthesis of silver nanoparticles using Eucalyptus leucoxylon leaves extract and evaluating the antioxidant activities of extract

This study was designed to examine the in vitro antioxidant activity of essential oil and methanol extracts of Eucalyptus leucoxylon. Furthermore, the polar fraction of the extract was used as a reducing agent for the green synthesis of silver nanoparticles (Ag NPs). Antioxidant activities of the samples were determined by using three different test systems, namely DPPH and β-carotene/linoleic acid and reducing power. The structure and composition of the prepared Ag NPs were characterised by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and UV-vis spectroscopy. Synthesised Ag NPs were almost spherical in shape with an average diameter of about ∼ 50 nm and synthesised within 120 min reaction time at room temperature.

Biomolecule-mediated synthesis of selenium nanoparticles using dried Vitis vinifera (raisin) extract

Biomolecule-mediated nanoparticle synthesis has recently the gained attention of researchers due to its ecofriendly and non-toxic nature. Metabolites from plant extracts represent a better alternative to chemical methods to fulfill the growing demand for non-hazardous nanoparticle synthesis routes. Selenium and its nanoparticles have an extensive range of applications. Thus, biofabrication of selenium nanoparticles can be potentially useful in various fields. This study reports a green approach to biosynthesize selenium nanoparticles (Se-np) using dried Vitis vinifera (raisin) extracts. The biosynthesized selenium nanoparticles were characterized using transmission electron microscope (TEM), dynamic light scattering (DLS), X-ray diffraction (XRD), energy dispersive X-ray (EDX) spectroscopy and Fourier transform infrared spectroscopy (FTIR). Transmission electron microscopic images revealed the spherical shape of biosynthesized selenium nanoparticles and a size range of 3–18 nm. Dynamic light scattering also confirmed the average particle size of 8.12 ± 2.5 nm with 0.212 PDI. The crystalline nature of selenium nanoparticles was confirmed by the X-ray diffraction study. Moreover, as inferred from the FTIR spectrum, the presence of highly stable lignin biopolymer on the surface of selenium nanoballs suggests a possible role as capping agent.

Sonochemical synthesis of silver nanoparticles using starch: a comparison

A novel approach was applied to synthesize silver nanoparticles using starch under sonication. Colloidal silver nanoparticles solution exhibited an increase of absorption from 420 to 440 nm with increase starch quantity. Transmission electron microscopy followed by selected area electron diffraction pattern analysis indicated the formation of spherical, polydispersed, amorphous, silver nanoparticles of diameter ranging from 23 to 97 nm with mean particle size of 45.6 nm. Selected area electron diffraction (SAED) confirmed partial crystalline and amorphous nature of silver nanoparticles. Silver nanoparticles synthesized in this manner can be used for synthesis of 2-aryl substituted benzimidazoles which have numerous biomedical applications. The optimized reaction conditions include 10 ml of 1 mM AgNO3, 25 mg starch, 11 pH range, and sonication for 20 min at room temperature.

Characterization and antimicrobial property of poly(acrylic acid) nanogel containing silver particle prepared by electron beam

In this study, we developed a one step process to synthesize nanogel containing silver nanoparticles involving electron beam irradiation. Water-soluble silver nitrate powder is dissolved in the distilled water and then poly(acrylic acid) (PAAc) and hexane are put into this silver nitrate solution. These samples are irradiated by an electron beam to make the PAAc nanogels containing silver nanoparticles (Ag/PAAc nanogels). The nanoparticles were characterized by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). In addition, the particle size and zeta-potential were confirmed by a particle size analyzer (PSA). The antibacterial properties of the nanogels were evaluated by paper diffusion test. The Ag/PAAc nanogels had an antibacterial effect against Escherichia coli and Staphylococcus aureus. The nanogels also demonstrated a good healing effect against diabetic ulcer. The size of the Ag/PAAc nanogels decreased with increasing irradiation doses, and the absolute value of the zeta potential increased with increasing irradiation doses. Also, the Ag/PAAc nanogels exhibited good antibacterial activity against both Gram-negative and Gram-positive bacteria. In in vivo wound healing, the Ag/PAAc nanogels have a good healing effect.

Room Temperature Synthesis and Catalytic Properties of Surfactant-Modified Ag Nanoparticles

Well-dispersed Ag nanoparticles with size of 20–30 nm were synthesized in water at room temperature with a self-made novel imidazoline Gemini surfactant quaternary ammonium salt of di (2-heptadecyl-1-formyl aminoethyl imidazoline) hexanediamine. Transmission electron microscopy, X-ray powder diffraction, ultraviolet-visible absorption spectra, and Fourier transform infrared ray were used to characterize the Ag nanoparticles. Results showed that the micellized aggregation of imidazoline Gemini surfactant in water, the growth of Ag initial particles, and the interaction (adsorption and coordination) between surfactant and Ag+/Ag nanoparticles took place simultaneously to form the well-dispersed Ag nanoparticles. Catalytic results show that the surface-modified Ag product was an active metal catalyst for methyl orange reduction reaction due to the effective adsorption between Ag nanoparticles and methyl orange molecules, which was of promising application in environmental protection.

Size-controlled green synthesis of silver nanoparticles mediated by gum ghatti (Anogeissus latifolia) and its biological activity

BACKGROUND

Gum ghatti is a proteinaceous edible, exudate tree gum of India and is also used in traditional medicine. A facile and ecofriendly green method has been developed for the synthesis of silver nanoparticles from silver nitrate using gum ghatti (Anogeissus latifolia) as a reducing and stabilizing agent. The influence of concentration of gum and reaction time on the synthesis of nanoparticles was studied. UV-visible spectroscopy, transmission electron microscopy and X-ray diffraction analytical techniques were used to characterize the synthesized nanoparticles.

RESULTS

By optimizing the reaction conditions, we could achieve nearly monodispersed and size controlled spherical nanoparticles of around 5.7 ± 0.2 nm. A possible mechanism involved in the reduction and stabilization of nanoparticles has been investigated using Fourier transform infrared spectroscopy and Raman spectroscopy.

CONCLUSIONS

The synthesized silver nanoparticles had significant antibacterial action on both the Gram classes of bacteria. As the silver nanoparticles are encapsulated with functional group rich gum, they can be easily integrated for various biological applications.

Microwave-assisted green synthesis of silver nanostructures

Over the past 25 years, microwave (MW) chemistry has moved from a laboratory curiosity to a well-established synthetic technique used in many academic and industrial laboratories around the world. Although the overwhelming number of MW-assisted applications today are still performed on a laboratory (mL) scale, we expect that this enabling technology may be used on a larger, perhaps even production, scale in conjunction with radio frequency or conventional heating. Microwave chemistry is based on two main principles, the dipolar mechanism and the electrical conductor mechanism. The dipolar mechanism occurs when, under a very high frequency electric field, a polar molecule attempts to follow the field in the same alignment. When this happens, the molecules release enough heat to drive the reaction forward. In the second mechanism, the irradiated sample is an electrical conductor and the charge carriers, ions and electrons, move through the material under the influence of the electric field and lead to polarization within the sample. These induced currents and any electrical resistance will heat the sample. This Account summarizes a microwave (MW)-assisted synthetic approach for producing silver nanostructures. MW heating has received considerable attention as a promising new method for the one-pot synthesis of metallic nanostructures in solutions. Researchers have successfully demonstrated the application of this method in the preparation of silver (Ag), gold (Au), platinum (Pt), and gold-palladium (Au-Pd) nanostructures. MW heating conditions allow not only for the preparation of spherical nanoparticles within a few minutes but also for the formation of single crystalline polygonal plates, sheets, rods, wires, tubes, and dendrites. The morphologies and sizes of the nanostructures can be controlled by changing various experimental parameters, such as the concentration of metallic salt precursors, the surfactant polymers, the chain length of the surfactant polymers, the solvents, and the operation reaction temperature. In general, nanostructures with smaller sizes, narrower size distributions, and a higher degree of crystallization have been obtained more consistently via MW heating than by heating with a conventional oil-bath. The use of microwaves to heat samples is a viable avenue for the greener synthesis of nanomaterials and provides several desirable features such as shorter reaction times, reduced energy consumption, and better product yields.