Generation Of Metal Nanoparticles Research Articles

Effect of nanoparticles on morphological parameters of wheat

This work is devoted to studying the features of the generation of metal nanoparticles (NPs) by underwater discharges and their use in the technology of growing grain crops. The purpose of the study is to use the latest nano-containing preparations based on NPs of biofunctional metals, which will allow the introduction of modern technologies and technological processes for environmentally friendly crop production while simultaneously increasing the quality indicators of the final wheat harvest. To obtain NPs, metals of the biogenic group were chosen, the content of which in known agrochemical preparations is at least 0.01%. Metal NPs were obtained in discharge chambers filled with deionized water. As a result of underwater electric spark discharges, metal colloids were obtained as a preparative form of nanomaterials for further use and processing of wheat crops. To carry out the certification of NPs by the methods of electron microscopy (SEM and TEM) and X-ray structural analysis, the metal phase of the colloidal solutions was separated from the dispersion medium by drying. We determined the composition, structure, and average size of the target NPs. A complex preparation was studied, the composition of which included metal NPs, in particular Fe − 1800 ppm; Cu − 400 ppm; Zn − 1000 ppm; Mn − 800 ppm. Testing of the drug was carried out in field conditions during the cultivation of winter wheat at various stages of organogenesis. The application rate of the drug was 1–1.5 L/ha, accordingly, 1.0–1.5 L of the drug was diluted in 250 L of water. Foliar treatment of wheat plants was carried out. The analysis of grain quality indicators showed a 30% increase in the total protein content and a more than two-fold increase in gluten, which indicates the extraordinary prospects of using the obtained preparations.

Nanocomposite Materials based on Metal Nanoparticles for the Electrochemical Sensing of Neurotransmitters

Neurotransmitters (NTs) are known as endogenous chemical messengers with important roles in the normal functioning of central and peripheral nervous systems. Abnormal levels of certain NTs, such as dopamine, serotonin and epinephrine, have been linked with several neurodegenerative diseases (such as Alzheimer’s disease, Parkinson’s disease and Huntington’s disease). To date, various strategies have been employed for the quantitative determination of NTs, and nanocomposite materials based on conducting polymers and metal nanoparticles constitute a cornerstone for the development of electrochemical sensors with low costs, stability, fast response rates and high selectivity and sensitivity. The preparation and analytical applications of nanocomposite materials based on metal nanoparticles in the electrochemical sensing of neurotransmitters are discussed in this paper. Recent developments in the electrochemical sensing of neurotransmitters are also discussed with emphasis on the benefits brought by metal nanoparticles in improving the sensitivity of the analytical measurements. The electrochemical synthesis methods for the in situ generation of metal nanoparticles within conducting polymer layers are reviewed. The analytical applications of the nanocomposite-sensing materials towards the detection of neurotransmitters such as dopamine, epinephrine and serotonin are discussed in terms of detection and quantification limits, linear response range, sensitivity and selectivity.

Mo3Ni2N Nanoparticle Generation by Spark Discharge.

Spark ablation is an advantageous method for the generation of metallic nanoparticles with defined particle sizes and compositions. The reaction of the metal particles with the carrier gas during the synthesis and, therefore, the incorporation of those light elements into structural voids or even compound formation was confirmed for hydrides and oxides but has only been suspected to occur for nitrides. In this study, dispersed nanoparticles of Mo3Ni2N and Mo with Janus morphology, and defined particle sizes were obtained by spark discharge generation as a result of carrier gas ionization and characterized using transmission electron microscopy and powder X-ray diffraction. Metal nitrides possess beneficial catalytic and thermoelectric properties, as well as high hardness and wear resistance. Therefore, this method offers the possibility of controlled synthesis of materials which are interesting for numerous applications.

Influence of an external magnetic field on laser-induced plasma and cavitation bubbles in submerged targets

A pulsed Nd:YAG laser is tightly focussed on a metal target immersed in distilled de-ionized water. The resultant laser-induced plasma and subsequent cavitation bubble behavior are studied under the influence of an external magnetic field that is varied from 700 to 1000 Gauss. The study is conducted using a beam deflection probe arrangement. In addition, laser-induced breakdown spectroscopy is also employed to study the plasma spectrum. Furthermore, three different magnetic materials are employed for this investigation: ferromagnetic nickel, paramagnetic gadolinium, and diamagnetic copper. The studies revealed that cavitation bubble radii and collapse durations increased considerably as the magnitude of the external magnetic field was increased. This effect was prominent in the case of nickel and less so in the case of gadolinium and copper. For nickel, collapse times increase when the magnetic field was applied, whereas for gadolinium and copper, significant changes were not observed. The differences observed in collapse times showed that magnetic properties of the targets played a vital role in this phenomenon. The process of pulsed laser ablation in liquid also led to the respective generation of metallic nanoparticles from individual materials. Characterization of the generated nanoparticles revealed size reduction when synthesized under the influence of an external magnetic field. These characterizations were performed using transmission electron microscopy and UV-Vis spectroscopy.

Vacuum as a continuum medium forming energy inhomogeneities with high energy density in the liquid phase

A method for the formation of metal nanoparticles in a localized volume with a high energy density due to the flow of a pulsed electric discharge and the effect of cavitation has been studied. The mechanism of formation of energy inhomogeneities, which provides the generation of nanoparticles with high specific energy intensity, is considered. The formation of dynamic heterogeneity is carried out in three stages. There is a breakdown of the interelectrode space and the formation of a vacuum volume, which is filled with a vapor-gas medium. As a result of an increase in pressure in the bubble, a pulsed gas discharge is ignited, which leads to the generation of metal nanoparticles. As a result, there is a localized volume in which the energy in the discharge reaches a value of up to 106 K. The growth of energy in the bubble leads to its collapse and metal nanoparticles pass from a medium with high energy (106) into water at room temperature, which leads to their hardening. Particularly pure nanoparticles of various metals with a size of 5–15 nm are obtained, which can be grown on a single-crystal silicon surface at room temperature and positioned on the surface of porous materials and products of complex configuration.

Bis(acyl)phosphine Oxides as Stoichiometric Photo‐Reductants for Copper Nanoparticle Synthesis: Efficiency and Kinetics

AbstractBis(acyl)phospine oxide (BAPO) photo‐initiators show excellent properties in photo‐induced radical polymerization. Furthermore, in aqueous or alcoholic solutions, the primary phosphorus‐centred radical forms a solvent adduct, which acts as a reductant for metal cations. Here, we present the mechanism, stoichiometry and kinetics of this reduction process. Moreover, we address the controlled production of copper nanoparticles. This is accomplished using optical spectroscopy in conjunction with in‐depth kinetic analysis. This study opens the door for the application of BAPOs as a light‐activated reducing agents, allowing a facile, mild and controlled generation of metal nanoparticles and of metal/polymer nanocomposites.

Azadirachta indica-Derived Silver Nanoparticle Synthesis and Its Antimicrobial Applications

Advancement of biologically driven experimental procedure for the generation of metal nanoparticles is a major aspect in the domain of nanotechnology. Herein, we synthesized one pot silver nanoparticles (AgNPs) using Azadirachta indica (Neem plant) via green synthesis method. The alkaloids and flavonoids in the plant extract served as capping and reducing agent to develop silver nanoparticles. The characterization of synthesized AgNPs was performed using analytical techniques such as UV-visible spectroscopy, FTIR, and SEM. The synthesized AgNPs were further impregnated onto a cotton cloth and the antimicrobial studies were performed. The AgNPs embedded in cotton fabric were found to show zone of inhibition against the fungi Candida albicans, gram-negative bacteria Escherichia coli, and gram-positive bacteria Staphylococcus aureus. This experimental study suggests that the AgNPs impregnated on cotton cloth could have great potential for application in smart nanobandages for wound dressing, medical textiles, sports clothing, etc.

Sonochemical synthesis of electrocatalysts for low-temperature water electrolysers

An important step in the process of producing hydrogen a viable method is to improve the efficiency and reduce the cost of low-temperature water electrolysers. One of the most crucial components is the catalyst used to drive the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Traditionally, the nanosized electrocatalysts are synthesized through a chemical reduction method involving a strong reducing agent like sodium borohydride, polyol, etc. Being able to control the nucleation and growth and therefore the size of the nanocatalysts, however, is not straightforward with the chemical reduction method where the use of surfactants is heavily relied upon, thus complicating the method for the industry. An alternative synthesis route involves the in-situ generation of radicals to serve as reducing agents through high power ultrasound (20 kHz–1 MHz) in a process where water is split into OH- and H-radicals referred to as water sonolysis. This presentation highlights the effects of ultrasonication frequencies, ultrasonication, times, pH solutions, reducing agents, and different saturation gasses on the generation of metallic nanoparticles and their subsequent electrocatalytic activities towards the HER and OER in mild acidic and alkaline environments. A series of physical characterizations on these sonochemically prepared nanoelectrocatalysts will be shown and discussed.

In-situ synthesis of metal nanoparticle embedded soft hybrid materials via eco-benign approach

Abstract The unique optical and electronic properties of metal nanoparticles and tunable properties of the organic templates encourage the scientific community to generate metal nanoparticle embedded soft hybrid materials for various novel utilities. Here, we discuss the in-situ synthesis of metal nanoparticle embedded soft hybrid materials via eco-benign approach which exclude the use of toxic reducing/capping agents or toxic reaction media. In this protocol, the gel matrix composed of benign organic templates act as reducing as well as stabilizing agent for the in-situ generation and stabilization of metal nanoparticles. As the incorporation of metal salts (as nanoparticle precursor) in the gel medium is required in this process, in most of the cases aqueous media were used for the generation of metal nanoparticle embedded soft hybrid materials. This discussion includes interesting findings from our laboratory where hybrid gel matrix composed of renewable chemicals was utilized for the in-situ synthesis of palladium nanoparticle embedded soft trihybrid material. The hybrid gel matrix rich in polyphenols/flavonoids was exploited to generate palladium nanoparticle embedded trihybrid gel through in-situ reduction of doped Pd (II) salts to stable PdNPs. The xerogel of this trihybrid material was utilized as recyclable heterogeneous catalyst for C-C coupling reaction in air under phosphene free condition and reduction reaction.

Highlighting the DCO‐SCF 2020 Award Winners – A Valuable Collaboration with EurJOC

Highlighting the DCO‐SCF 2020 Award Winners – A Valuable Collaboration with EurJOC

Reaction–Diffusion Assisted Synthesis of Gold Nanoparticles: Route from the Spherical Nano-Sized Particles to Micrometer-Sized Plates

The design of nanoparticles of desired sizes and shapes and 2D nanostructured materials is challenging and important due to their unique physical and chemical properties. One of the most common methods for the generation of metal nanoparticles is the wet synthetic route in which metal ions are reduced and the formed particles are stabilized in the liquid phase. Here we show a facile and powerful method to synthesize gold nanoparticles in a solid agarose gel utilizing the diffusion of reagents using the Turkevich method at room temperature. Our technique yields particles spatially separated by their sizes and shapes (spheres and plates) in the gel column. We have achieved 4 orders of magnitude difference in the sizes of the synthesized particles with a linearly increasing trend in the function of their spatial position. We have also generated micrometer-sized nanoplates with triangle, truncated triangle, or hexagon shapes attaining almost the length-to thickness ratio of 500, representing the magnificent power of the reaction–diffusion assisted synthesis.

Ecotoxicity Evaluation of Pristine and Indolicidin-coated Silver Nanoparticles in Aquatic and Terrestrial Ecosystem.

BackgroundMetallic nanoparticles (NPs) are highly exploited in manufacturing and medical processes in a broad spectrum of industrial applications and in the academic sectors. Several studies have suggested that many metallic nanomaterials including those derived by silver (Ag) are entering the ecosystem to cause significant toxic consequences in cell culture and animal models. However, ecotoxicity studies are still receiving limited attention when designing functionalized and non.-functionalized AgNPs.ObjectiveThis study aimed to investigate different ecotoxicological profiles of AgNPs, which were analyzed in two different states: in pristine form uncoated AgNPs and coated AgNPs with the antimicrobial peptide indolicidin. These two types of AgNPs are exploited for a set of different tests using Daphnia magna and Raphidocelis subcapitata, which are representatives of two different levels of the aquatic trophic chain, and seeds of Lepidium sativum, Cucumis sativus and Lactuca sativa.ResultsEcotoxicological studies showed that the most sensitive organism to AgNPs was crustacean D. magna, followed by R. subcapitata and plant seeds, while AgNPs coated with indolicidin (IndAgNPs) showed a dose-dependent decreased toxicity for all three.ConclusionThe obtained results demonstrate that high ecotoxicity induced by AgNPs is strongly dependent on the surface chemistry, thus the presence of the antimicrobial peptide. This finding opens new avenues to design and fabricate the next generation of metallic nanoparticles to ensure the biosafety and risk of using engineered nanoparticles in consumer products.

Liquid Spreading Induced by In Situ Generation of Metallic Nanoparticles.

Spreading or pinning of a liquid drop on a solid substrate is determined by the surface energy of solid and liquid, topography of substrate surface, and different external forces like electric field, magnetic field, and vibration. Here we present a novel mechanism of depinning, driven by in situ generation of a species following reaction between a constituent of the droplet and one in the substrate. In particular, fluoro-carbon (FC) functionalized agarose and pHEMA gels are used as the substrates; the substrate is soaked with chloroauric acid. A drop of poly(dimethylsiloxane) (PDMS) mixed with the cross-linking agent is dispensed on it. The drop does not spread in absence of the salt, but as the salt concentration increases, the spreading diameter increases with decrease in the contact angle. The Si-H group, present as a constituent in the cross-linking agent, reduces the salt, leading to in situ generation of gold nanoparticles, that mitigates the pinning effect of the drop and the drop spreads.

Eco-Friendly Methods of Gold Nanoparticles Synthesis

Background:Owing to the importance of metallic nanoparticles, different researches and studies have been induced to synthesize them in many ways. One of the ways that paid attention last years is the green synthesis methods of nanoparticles or the so-called ''eco-friendly methods''. The most common sources that has been used for green synthesis of nanoparticles are plants, leaves, fungi and microorganisms. The green synthesis methods are widely used because they are inexpensive, usable, and nontoxic. Moreover, plant extracts are rich in reducing and capping agents.Methods:In the present review, green synthesis methods of gold nanoparticles (AuNps) using Chitosan, Klebsiella pneumoniae, Magnolia Kobus, Elettaria cardamomum (Elaichi) aqueous extract and other agents as a reducing/capping agents will be discussed in details. Moreover, we will make a comparison between different green routes of synthesis and the characterization of the obtained nanoparticles from each route.Results:The characterization and applications of the prepared GNPs from different routes are reviewed.Conclusion:The utilization of gold nanoparticles has been advocated because of their high biocomptability, administration in clinical applicability and in diverse aspects of life. It seems that plants are good candidates for nanoparticles production because they are inexpensive, available and renewable sources in addition, it is too simple to prepare extracts from them. Moreover, the great diversity in the types and amounts of reducing agents from plant extracts is responsible for the effortless generation of metallic nanoparticles of various shapes and morphologies.

Optimization of process parameters influencing the sustainable construction of iron oxide nanoparticles by a novel tropical wetlands Streptomyces spp.

A Streptomyces strain isolated from the soil sediments of tropical freshwater wetlands in Malaysia demonstrated promising attributes to be developed into a versatile microbial nanofactory for the sustainable synthesis of ferric oxide nanoparticles (IONP). Process parameters such as temperature, ferric salt precursor concentration, cell free extract (CFE) concentration and biomass harvesting times are serious players in the extracellular generation of metallic nanoparticles. A statistical approach using One-Variable-At-A-Time (OVAT) Analysis followed by Response Surface Methodology (RSM) was employed towards the optimization of the microbial bioprocess and modulation of nanoparticle size dimensions. OVAT revealed that IONP production increased with increasing temperature, precursor concentration, harvesting time and CFE concentration with highest yield at 65 °C, 2 mM precursor concentration, 68 h harvesting time and 100% CFE concentration. A detailed statistical analysis using RSM (RSM) showed significantly strong negative interactive effects between temperature and CFE concentration (p = 0.0037), temperature and precursor concentration (p = 0.0093) and mild interactive effects between CFE and precursor concentration (p = 0.0301). Taking into account the interactive influence of these variables, numerical analysis using RSM proposed that for optimal generation of microbial mediated IONP, a CFE concentration of 55.58%, temperature of 55.75 °C and precursor concentration of 2.46 mM FeCl3.6H2O would be required.

Synthesis of Metal Nanoparticles in Metal-Phenolic Networks: Catalytic and Antimicrobial Applications of Coated Textiles.

The synthesis of metal nanoparticle (NP)-coated textiles (nanotextiles) is achieved by a dipping process in water without toxic chemicals or complicated synthetic procedures. By taking advantage of the unique nature of tannic acid, metal-phenolic network-coated textiles serve as reducing and stabilizing sites for the generation of metal nanoparticles of controllable size. The textiles can be decorated with various metal nanoparticles, including palladium, silver, or gold, and exhibit properties derived from the presence of the metal nanoparticles, for example, catalytic activity in water (>96% over five cycles using palladium nanoparticles) and antibacterial activity against Gram-negative bacteria (inhibition of Escherichia coli using silver nanoparticles) that outperforms a commercial bandage. The reported strategy offers opportunities for the development of hybrid nanomaterials that may have application in fields outside of catalysis and antimicrobials, such as sensing and smart clothing.

Wolfberry fruit (Lycium barbarum) extract mediated novel route for the green synthesis of silver nanoparticles

A green, simple and low cost process for production of well dispersed, small size silver nanoparticles with narrow distribution from 3nm to 15nm was described. In this method, silver nanoparticles were prepared in aqueous medium by employing wolfberry fruit extract as both reducing and stabilizing agent without utilizing any other capping and reducing agent. The generation of metallic nanoparticles was observed by change of color and the UV–vis absorption spectroscopy. The obtained silver nanoparticles were analyzed by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results show that the as-synthesized silver nanoparticles are highly crystalline in nature, spherical in shape. The reaction times, silver nitrate concentrations and wolfberry fruit extract amounts play crucial roles in the synthesis of small silver nanoparticles. The method displayed in this paper offers a very hopeful mean to prepare other noble nanoparticles using renewable materials as reducing and capping agent.

Development of highly efficient Cu versus Pd catalysts supported on graphitic carbon materials for the reduction of 4-nitrophenol to 4-aminophenol at room temperature

In this work we report a simple procedure for synthesis of Cu and Pd catalysts supported on high surface area graphite (HSAG) by wetness impregnation technique, and further generation of metal nanoparticles using NaBH4 as reducing agent. The catalysts have been tested in the reduction of 4-nitrophenol to 4-aminophenol, at room temperature, in presence of NaBH4 as hydrogen source. Both Cu and Pd catalysts exhibited exceptionally high catalytic activity with the total degradation of 4-nitrophenol in less than 45 s. Taking into account that Cu is cheaper than Pd, we focused our investigation on studying the catalytic properties of Cu nanoparticles supported over two lab prepared graphene-materials (one N-doped and other undoped) and the commercial HSAG. The maximum catalytic activity was obtained with Cu supported on undoped graphene due to the combination of two parameters: small metal particle size and the unique properties of graphene generated by its electron transference ability. However, recyclability of both Cu/graphene-materials fell after 5 consecutive runs, while Cu/HSAG displayed high stability even after 10 cycles. In order to rationalize these findings, it is postulated that copper nanoparticles in Cu/HSAG are located at the edges of the graphite layers, where a stronger metal-support interaction takes place.

Determination of Antioxidant Capacity of Chinese Rice Wine and Zhuyeqing Liquor Using Nanoparticle-Based Colorimetric Methods

In this work, three nanoparticle-based methods, namely gold nanoparticle (AuNP) method, silver nanoparticle (AgNP) method, and iron oxide nanoparticle (IONP) method, were used to measure the antioxidant capacities of Chinese rice wine (CRW) and Zhuyeqing liquor (ZYQL). The formed nanoparticles were characterized by the UV-Vis spectroscopy and transmission electron microscopy, which conformed the generation of metal nanoparticles. In addition, it was found that the colorimetric response of AuNPs, AgNPs, and IONPs was all dependent on the amount of antioxidants contained in wine samples. Furthermore, the colorimetric methods reported in this study all showed good correlations with ferric reducing antioxidant power (FRAP) (the correlation coefficients were 0.952, 0.948, and 0.969, respectively, for AuNPs, AgNPs, and IONPs). Moreover, the formation process of nanoparticles was shown by the plots of the absorbance at absorption peak as a function of the volume of wine sample, which was a sigmoidal curve, and gave two new indexes to report the antioxidant capacity of CRW and ZYQL. Compared with traditional methods, the precision of the novel method maybe slightly lower; however, it does not require the use of expensive radical compounds and organic solvents. The overall results indicated that these three nanoparticle-based methods developed can be used as alternative methods for the determination of the antioxidant capacity in CRW and ZYQL.

In Situ Synthesis of Metal Nanoparticle Embedded Hybrid Soft Nanomaterials.

The allure of integrating the tunable properties of soft nanomaterials with the unique optical and electronic properties of metal nanoparticles has led to the development of organic-inorganic hybrid nanomaterials. A promising method for the synthesis of such organic-inorganic hybrid nanomaterials is afforded by the in situ generation of metal nanoparticles within a host organic template. Due to their tunable surface morphology and porosity, soft organic materials such as gels, liquid crystals, and polymers that are derived from various synthetic or natural compounds can act as templates for the synthesis of metal nanoparticles of different shapes and sizes. This method provides stabilization to the metal nanoparticles by the organic soft material and advantageously precludes the use of external reducing or capping agents in many instances. In this Account, we exemplify the green chemistry approach for synthesizing these materials, both in the choice of gelators as soft material frameworks and in the reduction mechanisms that generate the metal nanoparticles. Established herein is the core design principle centered on conceiving multifaceted amphiphilic soft materials that possess the ability to self-assemble and reduce metal ions into nanoparticles. Furthermore, these soft materials stabilize the in situ generated metal nanoparticles and retain their self-assembly ability to generate metal nanoparticle embedded homogeneous organic-inorganic hybrid materials. We discuss a remarkable example of vegetable-based drying oils as host templates for metal ions, resulting in the synthesis of novel hybrid nanomaterials. The synthesis of metal nanoparticles via polymers and self-assembled materials fabricated via cardanol (a bioorganic monomer derived from cashew nut shell liquid) are also explored in this Account. The organic-inorganic hybrid structures were characterized by several techniques such as UV-visible spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Utilization of silver nanoparticle-based hybrid nanomaterials as an antimicrobial material is another illustration of the advantage of hybrid nanomaterials. We envision that the results summarized in this Account will help the scientific community to design and develop diverse organic-inorganic hybrid materials using environmentally benign methods and that these materials will yield advanced properties that have multifaceted applications in various research fields.