Sonochemical synthesis of silver nanoparticles using starch: a comparison

Effects of copper, and aluminium in ionic, and nanoparticulate form on growth rate and gene expression of Setaria italica seedlings

This study aims to determine the effects of copper, copper oxide nanoparticles, aluminium, and aluminium oxide nanoparticles on the growth rate and expression of ACT-1, CDPK, LIP, NFC, P5CR, P5CS, GR, and SiZIP1 genes in five days old seedling of Setaria italica ssp. maxima, cultivated in hydroponic culture. Depending on their concentration (ranging from 0.1 to 1.8 mg L-1), all tested substances had both stimulating and inhibiting effects on the growth rate of the seedlings. Copper and copper oxide-NPs had generally a stimulating effect whereas aluminium and aluminium oxide-NPs at first had a positive effect but in higher concentrations they inhibited the growth. Treating the seedlings with 0.4 mg L-1 of each tested toxicant was mostly stimulating to the expression of the genes and reduced the differences between the transcript levels of the coleoptiles and roots. Increasing concentrations of the tested substances had both stimulating and inhibiting effects on the expression levels of the genes. The highest expression levels were usually noted at concentrations between 0.4 and 1.0 mg/L of each metal and metal nanoparticle, except for SiZIP1, which had the highest transcript amount at 1.6 mg L-1 of Cu2+ and at 0.1-0.8 mg L-1 of CuO-NPs, and LIP and GR from the seedling treated with Al2O3-NPs at concentrations of 0.1 and 1.6 mg L-1, respectively.

Chemical background of silver nanoparticles interfering with mammalian copper metabolism

The rapidly increasing application of silver nanoparticles (AgNPs) boosts their release into the environment, which raises a reasonable alarm for ecologists and health specialists. This is manifested as increased research devoted to the influence of AgNPs on physiological and cellular processes in various model systems, including mammals. The topic of the present paper is the ability of silver to interfere with copper metabolism, the potential health effects of this interference, and the danger of low silver concentrations to humans. The chemical properties of ionic and nanoparticle silver, supporting the possibility of silver release by AgNPs in extracellular and intracellular compartments of mammals, are discussed. The possibility of justified use of silver for the treatment of some severe diseases, including tumors and viral infections, based on the specific molecular mechanisms of the decrease in copper status by silver ions released from AgNPs is also discussed.

Greener design and characterization of biochar/Fe3O4@SiO2-Ag magnetic nanocomposite as efficient catalyst for synthesis of bioactive benzylpyrazolyl coumarin derivatives

The study aimed to develop an efficient catalyst, biochar/Fe₃O₄@SiO₂-Ag magnetic nanocomposite, to synthesize bioactive benzylpyrazolyl coumarin derivatives through a one-pot multicomponent reaction. The catalyst was prepared using Ag nanoparticles synthesized with Lawsonia inermis leaf extract and carbon-based biochar obtained through pyrolysis of Eucalyptus globulus bark. The nanocomposite contained a silica-based interlayer, highly dispersed Ag nanoparticles, and a central magnetite core, which responded well to external fields. The biochar/Fe₃O₄@SiO₂-Ag nanocomposite showed excellent catalytic activity and could be easily recovered using an external magnet and reused five times without significant loss of performance. The resulting products were tested for antimicrobial activity and showed significant activity against various microorganisms.

Green Synthesis of Silver Nanoparticles Using Datura metel Flower Extract Assisted by Ultrasound Method and Its Antibacterial Activity

BACKGROUND

Green synthesis method of nanoparticles has been developed for several years. Besides providing environmental-friendly process, green synthesis of nanoparticles using plant extract provides synergistic effect of the secondary metabolite in such antibiotic activity. The study with an intensification process in nanoparticles formation is also gaining great attention. This research deals with the green synthesis of silver nanoparticles using Datura metel flower extract for the antibacterial agent. The use of ultrasound-assisted method for the synthesis was investigated.

METHODS

Synthesis of silver nanoparticles (AgNPs) using Datura metel flower extract under ultrasound- assisted method has been conducted. Evaluation of the successful synthesis was done using UV-visible spectrophotometry, particle size analyzer, x-ray diffraction, and transmission electron microscopy. The prepared AgNPs were tested as an antibacterial against S. aureus, K. pneumoniae, S. pyogenes, and E. coli.

RESULTS

The ultrasound-assisted synthesis of AgNPs produces particles ranging from 25-70 nm in size; meanwhile, the reflux method demonstrated the size of 50-170 nm. These particles size represents the effect on the antibacterial activity as the ultrasound-assisted synthesized Ag NPs have higher inhibition zone towards all tested bacteria. Subsequently, these data presented the applicability of Ag NPs synthesis using an ultrasound method as a potential candidate for biomedical applications.

CONCLUSION

The profile of UV-Visible spectra and particle size analyses demonstrated the applicability of the ultrasound technique to produce a smaller size of the nanoparticles with higher antibacterial activity.

Impact of Starch Coating Embedded with Silver Nanoparticles on Strawberry Storage Time

The strawberry has a very short postharvest life due to its fast softening and decomposition. The goal of this research is to see how well a starch-silver nanoparticle (St-AgNPs) coating affects the physical, chemical, and microbiological qualities of strawberries during postharvest life. Additionally, the effect of washing with running water on silver concentration in coated strawberry fruit was studied by an inductively coupled plasma-optical emission spectrometer (ICP-OES). Furthermore, the shelf-life period was calculated in relation to the temperature of storage. Fourier transform infrared-attenuated total reflectance (FTIR-ATR), UV-Visible, and Transmission Electron Microscopic (TEM) were used to investigate the structure of starch-silver materials, the size and shape of AgNPs, respectively. The AgNPs were spherical, with an average size range of 12.7 nm. The coated samples had the lowest weight loss, decay, and microbial counts as compared to the uncoated sample. They had higher total acidity and anthocyanin contents as well. The washing process led to the almost complete removal of silver particles by rates ranging from 98.86 to 99.10%. Finally, the coating maintained strawberry qualities and lengthened their shelf-life from 2 to 6 days at room storage and from 8 to 16 days in cold storage.

A Review on Plants and Microorganisms Mediated Synthesis of Silver Nanoparticles, Role of Plants Metabolites and Applications

Silver nanoparticles are one of the most extensively studied nanomaterials due to their high stability and low chemical reactivity in comparison to other metals. They are commonly synthesized using toxic chemical reducing agents which reduce metal ions into uncharged nanoparticles. However, in the last few decades, several efforts were made to develop green synthesis methods to avoid the use of hazardous materials. The natural biomolecules found in plants such as proteins/enzymes, amino acids, polysaccharides, alkaloids, alcoholic compounds, and vitamins are responsible for the formation of silver nanoparticles. The green synthesis of silver nanoparticles is an eco-friendly approach, which should be further explored for the potential of different plants to synthesize nanoparticles. In the present review we describe the green synthesis of nanoparticles using plants, bacteria, and fungi and the role of plant metabolites in the synthesis process. Moreover, the present review also describes some applications of silver nanoparticles in different aspects such as antimicrobial, biomedicine, mosquito control, environment and wastewater treatment, agricultural, food safety, and food packaging.

Synthesis, Characterization and Biomedical Application of Silver Nanoparticles

Silver nanoparticles (AgNPs) have been employed in various fields of biotechnology due to their proven properties as an antibacterial, antiviral and antifungal agent. AgNPs are generally synthesized through chemical, physical and biological approaches involving a myriad of methods. As each approach confers unique advantages and challenges, a trends analysis of literature for the AgNPs synthesis using different types of synthesis were also reviewed through a bibliometric approach. A sum of 10,278 publications were analyzed on the annual numbers of publication relating to AgNPs and biological, chemical or physical synthesis from 2010 to 2020 using Microsoft Excel applied to the Scopus publication database. Furthermore, another bibliometric clustering and mapping software were used to study the occurrences of author keywords on the biomedical applications of biosynthesized AgNPs and a total collection of 224 documents were found, sourced from articles, reviews, book chapters, conference papers and reviews. AgNPs provides an excellent, dependable, and effective solution for seven major concerns: as antibacterial, antiviral, anticancer, bone healing, bone cement, dental applications and wound healing. In recent years, AgNPs have been employed in biomedical sector due to their antibacterial, antiviral and anticancer properties. This review discussed on the types of synthesis, how AgNPs are characterized and their applications in biomedical field.

Synthesis of Hollow PVP/Ag Nanoparticle Composite Fibers via Electrospinning under a Dense CO2 Environment

Polyvinylpyrrolidone (PVP) is used in a wide variety of applications because of its unique chemical and physical features, including its biocompatibility and low toxicity. In this study, hollow PVP/silver nanoparticle (PVP/Ag NP) composite fibers were synthesized. Stable, spherical Ag NPs, with an average size of 14.4 nm, were produced through a facile sonochemical reduction method. A small amount of starch as a potent reducing and stabilizing agent was used during the reduction of Ag ions to Ag NPs. The fabricated Ag NPs were then added to a 10 wt% PVP-dichloromethane (DCM) solution, which was utilized as an electrospinning feed solution under a dense carbon dioxide (CO₂) environment at 313 K and 5 MPa and an applied voltage of 15 kV. The dense CO₂ enabled rapid extraction of DCM from the PVP-Ag NPs-DCM solution, which was then dissolved into PVP/Ag NPs, resulting in a hollow structure. Scanning electron microscopy, Fourier-transform infrared (FT-iR) spectroscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses, and thermogravimetric analysis (TGA), were used to characterize the electrospinning products.

Biosynthesized silver nanoparticles induce phytotoxicity in Vigna radiata L

With the recent developments in the field of nanotechnology, the biosynthesis of nanoparticles has increased tremendously. Silver nanoparticles (SNPs) are among the most synthesized nanoparticles and this extensive synthesis can elevate the amounts of SNPs in the environment, which, consequently, pose a serious threat to the ecosystem and can bring unwanted environmental effects. As plants are an important part of ecosystem, investigation of toxic effects of SNPs on plants is particularly interesting. This study evaluates the potential risk of SNPs interaction with plants. For this, seeds of Vigna radiata L. were screened in presence of SNPs (20 mgL^-1) using the germination, growth, and biochemical parameters as a phototoxicity criterion. The 19.57 nm average-sized SNPs were synthesized via the biosynthesis method. These biosynthesized SNPs were then applied on two varieties of V. radiata (Azri and High cross 404) and found to have variety dependent toxic effects on seed germination, growth, and biochemical parameters. Seed germination, root length, shoot length, fresh weight, chlorophyll, carotenoid, sugar content, and total proteins were reduced by 20, 46, 50, 18, 55, 62, 82, and 67%, respectively, in High cross 404, when compared with control (distilled water). The variety Azri was less sensitive than the variety High cross 404. In conclusion, the results demonstrated that SNPs affect seed germination and seedling growth when internalized and accumulated in plants, revealing that SNPs were responsible for the side effects. More in-depth research is required, in the form of different concentrations of SNPs or different plant species, to draw a logical conclusion and develop legislation about the safe use of biosynthesized SNPs.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s12298-021-01073-4.

Silver Micro-Nanoparticle-Based Nanoarchitectures: Synthesis Routes, Biomedical Applications, and Mechanisms of Action

Silver has become a potent agent that can be effectively applied in nanostructured nanomaterials with various shapes and sizes against antibacterial applications. Silver nanoparticle (Ag NP) based-antimicrobial agents play a major role in different applications, including biomedical applications, as surface treatment and coatings, in chemical and food industries, and for agricultural productivity. Due to advancements in nanoscience and nanotechnology, different methods have been used to prepare Ag NPs with sizes and shapes reducing toxicity for antibacterial applications. Studies have shown that Ag NPs are largely dependent on basic structural parameters, such as size, shape, and chemical composition, which play a significant role in preparing the appropriate formulation for the desired applications. Therefore, this review focuses on the important parameters that affect the surface interaction/state of Ag NPs and their influence on antimicrobial activities, which are essential for designing future applications. The mode of action of Ag NPs as antibacterial agents will also be discussed.

A Green, Simple and Facile Way to Synthesize Silver Nanoparticles Using Soluble Starch. pH Studies and Antimicrobial Applications

Along with the progress of nanoscience and nanotechnology came the means to synthesize nanometric scale materials. While changing their physical and chemical properties, they implicitly changed their application area. The aim of this paper was the synthesis of colloidal silver nanoparticles (Ag-NPs by ultrasonic disruption), using soluble starch as a reducing agent and further as a stabilizing agent for produced Ag-NPs. In this context, an important parameter for Ag-NPs preparation is the pH, which can determine the particle size and stability. The physical-chemical behavior of the synthesized Ag-NPs (shape, size, dispersion, electric charge) is strongly influenced by the pH value (experiment being conducted for pH values in the range between 8 and 13). The presence of a peak located at 412 nm into the UV-VIS spectra demonstrates the presence of silver nano-spheres into the produced material. In UV/VIS spectra, we observed a specific peak for yellow silver nano-spheres located at 412 nm. Samples characterization was performed by scanning electron microscopy, SEM, energy-dispersive X-ray spectroscopy, EDX, Fourier-transform infrared spectroscopy, and FT-IR. For all Ag-NP samples, we determined the zeta and observed that the Ag-NP particles obtained at higher pH and have better stability. Due to the intrinsic therapeutic properties and broad antimicrobial spectrum, silver nanoparticles have opened new horizons and new approaches for the control of different types of infections and wound healing abilities. In this context, the present study also aims to confirm the antimicrobial effect of prepared Ag-NPs against several bacterial strains (indicator and clinically isolated strains). In this way, it was confirmed that the antimicrobial activity of synthesized Ag-NPs was good against Staphylococcus aureus (ATCC 25923 and S. aureus MSSA) and Escherichia coli (ATTC 25922 and clinically isolated strain). Based on this observation, we conclude that the prepared Ag-NPs can represent an alternative or auxiliary material used for controlling important nosocomial pathogens. The fungal reference strain Candida albicans was more sensitive at Ag-NPs actions (zone of inhibition = 20 mm) compared with the clinically isolated strain (zone of inhibition = 10 mm), which emphasizes the greater resistance of fungal strains at antimicrobial agent’s action.

Green Synthesis of Gold, Silver, and Iron Nanoparticles for the Degradation of Organic Pollutants in Wastewater

The green synthesis of nanoscale materials is of special interest to researchers all over the world. We describe a simple, robust, inexpensive, and environmentally friendly approach to the synthesis of gold, silver, and iron nanoparticles using a variety of biomolecules/phytochemicals as potential reducers and stabilizers. The green approach to the controlled synthesis of nanoparticles with different morphologies is based on the use of plant extracts. Green synthesized nanoparticles can be used as catalysts, photocatalysts, adsorbents, or alternative agents for the elimination of various organic dyes. The kinetic enhancement of nanoparticles for the degradation/removal of dyes could provide significant and valuable insights for the application of biochemically functionalized nanoparticles in engineering. In this review, current plant-mediated strategies for preparing nanoparticles of gold, silver, and iron are briefly described, and morphologically dependent nanoparticles for the degradation of organic pollutants in wastewater are highlighted. Overall, the approach presented in the article supports environmental protection and is a promising alternative to other synthesis techniques.

Recent Advances in Inorganic Nanomaterials Synthesis Using Sonochemistry: A Comprehensive Review on Iron Oxide, Gold and Iron Oxide Coated Gold Nanoparticles

Sonochemistry uses ultrasound to improve or modify chemical reactions. Sonochemistry occurs when the ultrasound causes chemical effects on the reaction system, such as the formation of free radicals, that intensify the reaction. Many studies have investigated the synthesis of nanomaterials by the sonochemical method, but there is still very limited information on the detailed characterization of these physicochemical and morphological nanoparticles. In this comprehensive review, recent advances in the sonochemical synthesis of nanomaterials based on iron oxide nanoparticles (Fe3O4NP), gold nanoparticles (AuNP) and iron oxide-coated gold nanoparticles (Fe3O4@Au NP) are discussed. These materials are the most studied materials for various applications, such as medical and commercial uses. This review will: (1) address the simple processing and observations on the principles of sonochemistry as a starting point for understanding the fundamental mechanisms, (2) summarize and review the most relevant publications and (3) describe the typical shape of the products provided in sonochemistry. All in all, this review's main outcome will provide a comprehensive overview of the available literature knowledge that promotes and encourages future sonochemical work.

Green Synthesis of Silver Nanoparticles from the Extracts of Fruit Peel of Citrus tangerina, Citrus sinensis, and Citrus limon for Antibacterial Activities

Wide application of nanoparticles motivates the need for synthesising them. Here, a nontoxic, eco-friendly, and cost-effective method has been established for the synthesis of silver nanoparticles using extracts of lemon peel (Citrus limon), green orange peel (Citrus sinensis), and orange peel (Citrus tangerina). The synthesised nanoparticles have been characterised using UV-visible absorptionspectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy (TEM). The UV-visible absorption spectrum of these synthesised silver nanoparticles shows an absorption peak at around 440 nm. TEM images show different shaped particles with various sizes. Furthermore, the antibacterial activity of silver nanoparticles was appraised by a well-diffusion method and it was observed that the green synthesised silver nanoparticles have an effective antibacterial activity against Escherichia coli and Staphylococcus aureus. The outcome of this study could be beneficial for nanotechnology-based biomedical applications.

A review on the green and sustainable synthesis of silver nanoparticles and one-dimensional silver nanostructures

The significance of silver nanostructures has been growing considerably, thanks to their ubiquitous presence in numerous applications, including but not limited to renewable energy, electronics, biosensors, wastewater treatment, medicine, and clinical equipment. The properties of silver nanostructures, such as size, size distribution, and morphology, are strongly dependent on synthesis process conditions such as the process type, equipment type, reagent type, precursor concentration, temperature, process duration, and pH. Physical and chemical methods have been among the most common methods to synthesize silver nanostructures; however, they possess substantial disadvantages and short-comings, especially compared to green synthesis methods. On the contrary, the number of green synthesis techniques has been increasing during the last decade and they have emerged as alternative routes towards facile and effective synthesis of silver nanostructures with different morphologies. In this review, we have initially outlined the most common and popular chemical and physical methodologies and reviewed their advantages and disadvantages. Green synthesis methodologies are then discussed in detail and their advantages over chemical and physical methods have been noted. Recent studies are then reviewed in detail and the effects of essential reaction parameters, such as temperature, pH, precursor, and reagent concentration, on silver nanostructure size and morphology are discussed. Also, green synthesis techniques used for the synthesis of one-dimensional (1D) silver nanostructures have been reviewed, and the potential of alternative green reagents for their synthesis has been discussed. Furthermore, current challenges regarding the green synthesis of 1D silver nanostructures and future direction are outlined. To sum up, we aim to show the real potential of green nanotechnology towards the synthesis of silver nanostructures with various morphologies (especially 1D ones) and the possibility of altering current techniques towards more environmentally friendly, more energy-efficient, less hazardous, simpler, and cheaper procedures.

Sugar-Mediated Green Synthesis of Silver Selenide Semiconductor Nanocrystals under Ultrasound Irradiation

Silver selenide (Ag2Se) is a promising nanomaterial due to its outstanding optoelectronic properties and countless bio-applications. To the best of our knowledge, we report, for the first time, a simple and easy method for the ultrasound-assisted synthesis of Ag2Se nanoparticles (NPs) by mixing aqueous solutions of silver nitrate (AgNO3) and selenous acid (H2SeO3) that act as Ag and Se sources, respectively, in the presence of dissolved fructose and starch that act as reducing and stabilizing agents, respectively. The concentrations of mono- and polysaccharides were screened to determine their effect on the size, shape and colloidal stability of the as-synthesized Ag2Se NPs which, in turn, impact the optical properties of these NPs. The morphology of the as-synthesized Ag2Se NPs was characterized by transmission electron microscopy (TEM) and both α- and β-phases of Ag2Se were determined by X-ray diffraction (XRD). The optical properties of Ag2Se were studied using UV-Vis spectroscopy and its elemental composition was determined non-destructively using scanning electron microscopy-energy-dispersive spectroscopy (SEM-EDS). The biological activity of the Ag2Se NPs was assessed using cytotoxic and bactericidal approaches. Our findings pave the way to the cost-effective, fast and scalable production of valuable Ag2Se NPs that may be utilized in numerous fields.

Simple Approaches for the Synthesis of AgNPs in Solution and Solid Phase Using Modified Methoxypolyethylene Glycol and Evaluation of Their Antimicrobial Activity

Purpose

Simple methodology for preparation of metal nanoparticles such as AgNPs uses an methanolic aqueous medium at room temperature or a solvent-free procedure under microwave irradiation. The prepared AgNPs showed a significant antimicrobial effect against Gram-positive bacteria, Gram-negative bacteria, and fungi.

Methods

The modified methoxypolyethylene glycol bishydrazino-s-triazine (mPEGTH2) showed remarkable activity for reducing Ag⁺ to Ag⁰ in an aqueous methanolic solution and using a solvent-free method (solid phase) under microwave irradiation. In the solid phase synthesis, the size and shape of the AgNPs can be controlled by varying the weight ratio of mPEGTH2 to AgNO₃ used. In addition, the antimicrobial activity depends on the ratio of mPEGTH2 to AgNO₃. The mPEGTH2-AgNPs (2:1) demonstrated higher antimicrobial activity compared to mPEGTH2-AgNPs (1:1) against Gram-positive bacteria, Gram-negative bacteria, and C.albicans.

Results

This work presents simple methods for the synthesis of AgNPs using modified methoxypolyethylene glycol with bishydrazino-s-triazine (mPEGTH2); a solution method, using methanol-water medium at room temperature, and a solvent-free (solid phase) method, employing microwave irradiation or direct heating which could be used for the preparation of AgNPs on large scale. In the solid phase, ratios of mPEGTH2 to AgNO₃ (1:1 or 2:1, respectively) are very important to control the size and shape of AgNPs. While in solution phase is not necessary where the molar ratio used is 10:1. Most of the experimental methods resulted in AgNPs ranging in size from 7 to 10 nm as observed from XRD and TEM characterization. The antimicrobial activity of the AgNPs was also dependent on the weight ratio of mPEGTH2 to AgNO₃, with a large effect as observed when using the solvent-free method. The mPEGTH2-AgNPs (2:1) demonstrated higher antimicrobial activities compared to mPEGTH2-AgNPs (1:1) against S. aureus, S. epidermidis, E. faecalis, E. coli, P. aeruginosa, S. typhimurium, and C. albicans. In all cases, the MICs and MBCs of mPEGTH2-AgNPs (1:1) were lower than those of mPEGTH2-AgNPs (2:1).

Conclusion

In summary, mPEGTH2-AgNPs (2:1) is a promising candidate to kill pathogenic microbes. In particular, the method used for the preparation of AgNPs by using polyethylene glycol polymer modified with bishydrazino-s-triazine has the most potential and would be the most cost-effective method. This method of the synthesis of nanoparticles may be suitable for the preparation of other metal nanoparticles, which would allow for numerous applications in medicinal and industrial.

Polymer scaffold layers of screen-printed electrodes for homogeneous deposition of silver nanoparticles: application to the amperometric detection of hydrogen peroxide

A method is described for electrochemical oxidation of polymers on the surface of screen-printed electrodes (SPCE). These act as scaffold layers for homogeneous deposition of silver nanoparticles (AgNPs). Hexamethylenediamine (HMDA) and poly(ethylene glycol) were immobilized on the SPCE surface via electrochemical oxidation. AgNPs were then electrodeposited on the scaffolds on the SPCE. This type of different carbon chain containing materials like PEG and HMDA act as big tunnels for electron mobility and are useful for the homogenous deposition of AgNPs on the SPCE surface without agglomeration. The resulting sensor was applied to the determination of hydrogen peroxide (H₂O₂) as a model analyte. It is found to display favorable catalytic and conductive properties towards the reduction of H₂O₂. Cyclic voltammetry and amperometry revealed that the modified electrode performs better than other modified SPCEs. Best operated at a potential of around -0.61 V (vs Ag|AgCl), the amperometric response is linear in the 10-180 μM H₂O₂ concentration range and the detection limit is 1.5 μM. The sensor is stable and reproducible. The resultant sensor was appplied to toothpaste analysis, and good recovery values were gained. Graphical abstractSchematic representation of electropolymerization of poly(ethylene glycol) and hexamethylenediamine scaffold layers on screen-printed electrodes for homogeneous electrodeposition of silver nanoparticles. This electrode was applied for the amperometric determination of hydrogen peroxide.

Green Synthesis and Characterization of Pullulan Mediated Silver Nanoparticles through Ultraviolet Irradiation

Nanoparticles (NPs) are, frequently, being utilized in multi-dimensional enterprises. Silver nanoparticles (AgNPs) have attracted researchers in the last decade due to their exceptional efficacy at very low volume and stability at higher temperatures. Due to certain limitations of the chemical method of synthesis, AgNPs can be obtained by physical methods including sun rays, microwaves and ultraviolet (UV) radiation. In the current study, the synthesis of pullulan mediated silver nanoparticles (P-AgNPs) was achieved through ultraviolet (UV) irradiation, with a wavelength of 365 nm, for 96 h. P-AgNPs were formed after 24 h of UV-irradiation time and expressed spectra maxima as 415 nm, after 96 h, in UV-vis spectroscopy. The crystallographic structure was “face centered cubic (fcc)” as confirmed by powder X-ray diffraction (PXRD). Furthermore, high resolution transmission electron microscopy (HRTEM) proved that P-AgNPs were covered with a thin layer of pullulan, with a mean crystalline size of 6.02 ± 2.37. The average lattice fringe spacing of nanoparticles was confirmed as 0.235 nm with quasi-spherical characteristics, by selected area electron diffraction (SAED) analysis. These green synthesized P-AgNPs can be utilized efficiently, as an active food and meat preservative, when incorporated into the edible films.

Green synthesis of silver nanoparticles using terrestrial fern (Gleichenia Pectinata (Willd.) C. Presl.): characterization and antimicrobial studies

Novel silver nanoparticles from Gleichenia Pectinata (Willd.) C. Presl. was synthesized. A combination of spectroscopic and microscopic techniques were utilized to characterize the newly synthesized Gleichenia Pectinata Silver Nanoparticles (GPAgNPs) vis-à-vis UV-Vis Spectroscopy, Fourier Transform Infra-Red (FTIR) Spectroscopy, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy Dispersive X-ray Spectroscopy (EDX) and X-Ray Diffraction (XRD) Analyses. Significant absorption was observed at 460 nm resulting from the surface Plasmon resonance (SPR). A rapid rate of synthesis was observed and the best surface plasmon resonance was obtained at 105 minutes contact time. SEM and TEM showed an spherical shape of GPAgNPs with an average size of 7.51 nm. The XRD result revealed a crystalline and polydispersed GPAgNPs. GPAgNPs were effective against four antibiotic resistant pathogens and they exhibited excellent antimicrobial activity against Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae and Candida albicans. GPAgNPs favorably competed with standard antibiotics. This therefore enlisted GPAgNPs as potential antimicrobial and therapeutic agents against multidrug resistant micro-organisms (MDRM).

Synthesis and characterization of size- and shape-controlled silver nanoparticles

Silver nanoparticles (AgNPs) have application potential in diverse areas ranging from wound healing to catalysis and sensing. The possibility for optimizing the physical, chemical and optical properties for an application by tailoring the shape and size of silver nanoparticles has motived much research on methods for synthesis of size- and shape-controlled AgNPs. The shape and size of AgNPs are reported to vary depending on choice of the Ag precursor salt, reducing agent, stabilizing agent and on the synthesis technique used. This chapter provides a detailed review on various synthesis approaches that may be used for synthesis of AgNPs of desired size and shape. Silver nanoparticles may be synthesized using diverse routes, including, physical, chemical, photochemical, biological and microwave -based techniques. Synthesis of AgNPs of diverse shapes, such as, nanospheres, nanorods, nanobars, nanoprisms, decahedral nanoparticles and triangular bipyramids is also discussed for chemical-, photochemical- and microwave-based synthesis routes. The choice of chemicals used for reduction and stabilization of nanoparticles is found to influence their shape and size significantly. A discussion on the mechanism of synthesis of AgNPs through nucleation and growth processes is discussed for AgNPs of varying shape and sizes so as to provide an insight on the various synthesis routes. Techniques, such as, electron microscopy, spectroscopy, and crystallography that can be used for characterizing the AgNPs formed in terms of their shape, sizes, crystal structure and chemical composition are also discussed in this chapter.

Graphical Abstract:

Sonochemical-assisted magnesium borate synthesis from different boron sources

In this study, sonochemical-assisted magnesium borate synthesis is studied from different boron sources. Various reaction parameters are successfully applied by a simple and green method. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and Raman spectroscopies are used to characterize the synthesized magnesium borates on the other hand surface morphologies are investigated by using scanning electron microscope (SEM). The XRD analyses showed that the products were admontite [MgO(B2O3)3 · 7(H2O)] with JCPDS (Joint Committee on Powder Diffraction Standards) no. of 01-076-0540 and mcallisterite [Mg2(B6O7(OH)6)2 · 9(H2O)] with JCPDS no. of 01-070-1902. The results that found in the spectroscopic studies were in a good agreement with characteristic magnesium borate bands in both regions of infra-red and visible. According to SEM results, obtained borates were in micro and sub-micro scales. By the use of ultrasonication, reaction yields were found between 84.2 and 97.9%. As a result, it is concluded that the sonochemical approach is a practicable synthesis method to get high efficiency and high crystallinity in the synthesis magnesium borate compounds.

Silver Nanoparticles: Synthesis, Characterization, Properties, Applications, and Therapeutic Approaches

Recent advances in nanoscience and nanotechnology radically changed the way we diagnose, treat, and prevent various diseases in all aspects of human life. Silver nanoparticles (AgNPs) are one of the most vital and fascinating nanomaterials among several metallic nanoparticles that are involved in biomedical applications. AgNPs play an important role in nanoscience and nanotechnology, particularly in nanomedicine. Although several noble metals have been used for various purposes, AgNPs have been focused on potential applications in cancer diagnosis and therapy. In this review, we discuss the synthesis of AgNPs using physical, chemical, and biological methods. We also discuss the properties of AgNPs and methods for their characterization. More importantly, we extensively discuss the multifunctional bio-applications of AgNPs; for example, as antibacterial, antifungal, antiviral, anti-inflammatory, anti-angiogenic, and anti-cancer agents, and the mechanism of the anti-cancer activity of AgNPs. In addition, we discuss therapeutic approaches and challenges for cancer therapy using AgNPs. Finally, we conclude by discussing the future perspective of AgNPs.

In vitro evaluation of silver nanoparticles cytotoxicity on Hepatic cancer (Hep-G2) cell line and their antioxidant activity: Green approach for fabrication and application

In this article, biosynthesis of silver nanoparticles (AgNPs) using Andean Mora (Rubus glaucus Benth.) leaf has been reported. Different analytical techniques including UV-vis spectroscopy, dynamic light scattering (DLS), transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used for the characterization of AgNPs. The initial appearance of color change with the intense surface plasmon resonance (SPR) bands around 440-455 in UV-visible spectra revealing the formation of AgNPs. The TEM image showed the AgNPs to be anisotropic, quasi-spherical in shape with sizes in the range of 12-50nm. On the other hand, XRD studies revealed the formation of face-centered cubic structure for AgNPs. The surface modified AgNPs showed no cytotoxicity at the concentration ranging from 0.01μM to 1.0μM on the Hepatic cancer (Hep-G2) cell line and observed antioxidant efficacy >70% at the concentration 0.05mM/0.20mL against 1, 1-diphenyl-2-picrylhydrazyl. From the results obtained it is suggested that AgNPs could be used effectively in future drug delivery systems and other biomedical concerns.

Green synthesis of silver nanoparticles using Andean blackberry fruit extract

Green synthesis of nanoparticles using various plant materials opens a new scope for the phytochemist and discourages the use of toxic chemicals. In this article, we report an eco-friendly and low-cost method for the synthesis of silver nanoparticles (AgNPs) using Andean blackberry fruit extracts as both a reducing and capping agent. The green synthesized AgNPs were characterized by various analytical instruments like UV–visible, transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The formation of AgNPs was analyzed by UV–vis spectroscopy at λ_max = 435 nm. TEM analysis of AgNPs showed the formation of a crystalline, spherical shape and 12–50 nm size, whereas XRD peaks at 38.04°, 44.06°, 64.34° and 77.17° confirmed the crystalline nature of AgNPs. FTIR analysis was done to identify the functional groups responsible for the synthesis of the AgNPs. Furthermore, it was found that the AgNPs showed good antioxidant efficacy (>78%, 0.1 mM) against 1,1-diphenyl-2-picrylhydrazyl. The process of synthesis is environmentally compatible and the synthesized AgNPs could be a promising candidate for many biomedical applications.

Green approach for fabrication and applications of zinc oxide nanoparticles

Zinc oxide nanoparticles (ZnO-NPs) are known to be one of the multifunctional inorganic compounds which are widely used in everyday applications. This study aims to fabricate ZnO-NPs using grapefruit (Citrus paradisi) peel extract with particle size ranging from 12 to 72 nm. Structural, morphological, and optical properties of the synthesized nanoparticles have been characterized by using UV-Vis spectrophotometer, TEM, DLS, and FTIR analysis. They show the significant photocatalytic degradation efficiency (>56%, 10 mg/L, 6 h) against methylene blue and antioxidant efficacy (≥80% for 1.2 mM) against 1,1-diphenyl-2-picrylhydrazyl. From the results obtained it is suggested that green ZnO-NPs could be used effectively in environmental safety applications and also can address future medical concerns.

Synthesis of silver nanoparticles using Sacha inchi (Plukenetia volubilis L.) leaf extracts

Silver nanoparticles (AgNPs) are fabricated using Sacha inchi (SI) or (Plukenetia volubilis L.) leaf extract as non-toxic reducing agent with particle size ranging from 4 to 25 nm. Optical, structural and morphological properties of the synthesized nanoparticles have been characterized by using Visual, UV-Vis spectrophotometer, transmission electron microscopy (TEM) and dynamic light scattering (DLS) analysis. Selected area electron diffraction (SAED) confirmed the formation of metallic Ag. Infrared spectrum measurement was carried out to hypothesize the possible phytochemicals responsible for stabilization and capping of the AgNPs. It shows the significant antioxidant efficacy in comparison with SI leaf extracts against 1,1-diphenyl-2-picrylhydrazyl. From the results obtained it is suggested that green AgNPs could be used effectively in future engineering and medical concerns.