Stabilization Of Metal Nanoparticles Research Articles

Green Synthesis of Silver Nanoparticles Using Aqueous Fruit Peel Extract of Citrus aurantifolia: Optimization, Its Characterization and Stability Test

In this present study, silver nanoparticles were synthesized by green biological synthesis method using plant extract from fruit peel of Citrus aurantifolia as reducing agents. All the parameters in the synthesis of silver nanoparticles (AgNPs) were optimized to achieve a better yield, controlled size and stability of the particles. The biosynthesis of silver nanoparticles was monitored via UV-vis spectrophotometer and stability test was done. The resulting UV-Vis spectra of synthesized AgNPs from C. aurantifoliafruit peel extract (CAFPE) showed standard surface plasmon resonance band at 420 nm which indicated the presence of AgNPs. The optimum result was obtained with an optimum concentration at 4 mM AgNO3, leaving in a dark room temperature for 24 h and using a concentration 1:3 ratio (extract: silver nitrate). Moreover, the stability of the CAFPE-AgNPs was also observed after 30 days of synthesis and even up to 10 months, indicating optimization plays major role towards the stability fate of nanoparticles. The FTIR analysis showed possible functional groups of biomolecules that play roles in the bioreduction and capping of silver nanoparticles. In addition, it is believed that these parameters are highly suitable for bulk production of single spherical AgNPs with diameter 29.6- 45.2 nm confirmed via FESEM. Thus, the obtained results clearly suggest that optimization of silver nanoparticles may have important role in attaining a better yield and stability of metal nanoparticles, refraining back to its original structure or particles.

Carbonized cellulose microspheres loaded with Pd NPs as catalyst in p-nitrophenol reduction and Suzuki-Miyaura coupling reaction

Catalytic reduction of p-nitrophenol is usually carried out using transition metal nanoparticles such as gold, palladium, silver and copper, especially palladium nanoparticles, which are characterized by fast reaction rate, high turnover frequency, good selectivity and high yield. However, the aggregation and precipitation of the metals lead to the decomposition of the catalyst, which results in a significant reduction of the catalytic activity. Therefore, the preparation of homogeneous stabilized palladium nanoparticle catalysts has been widely studied. Stabilized palladium nanoparticles mainly use synthetic polymers. Cellulose microspheres, as a natural polymer material with low cost and porous fiber network structure, are excellent carriers for stabilizing metal nanoparticles. Cellulose microspheres impregnated with palladium metal nanoparticles were carbonized to have a larger specific surface area and highly dispersed palladium nanoparticles, which exhibited excellent catalytic activity in the catalytic reduction of 4-nitrophenol. In this aspect, cellulose carbon-based microspheres Pd nanoparticles (Pd@CCM) catalysts were designed and characterized by SEM, TEM, EDS, XRD, FTIR, XPS, TGA, BET and so on. Furthermore, the catalytic performance of Pd@CCM catalysts were investigated via 4-nitrophenol reduction, which showed high catalytic activity. This catalyst also exhibited excellent catalytic performance in Suzuki-Miyaura coupling reaction. Linking aromatic monomer and benzene through Suzuki-Miyaura coupling was presented as an effective route to obtain polymeric substrate with low-cost and simple synthesis method. In addition, cellulose carbon-based microspheres Pd nanoparticles catalyst showed desirable recyclability with maintaining its catalytic activity even after five recycles. This work is highly suggestive on the heterogeneous catalysts design and application.

Scaling-Up Microwave-Assisted Synthesis of Highly Defective Pd@UiO-66-NH2 Catalysts for Selective Olefin Hydrogenation under Ambient Conditions.

The need to develop green and cost-effective industrial catalytic processes has led to growing interest in preparing more robust, efficient, and selective heterogeneous catalysts at a large scale. In this regard, microwave-assisted synthesis is a fast method for fabricating heterogeneous catalysts (including metal oxides, zeolites, metal-organic frameworks, and supported metal nanoparticles) with enhanced catalytic properties, enabling synthesis scale-up. Herein, the synthesis of nanosized UiO-66-NH2 was optimized via a microwave-assisted hydrothermal method to obtain defective matrices essential for the stabilization of metal nanoparticles, promoting catalytically active sites for hydrogenation reactions (760 kg·m-3·day-1 space time yield, STY). Then, this protocol was scaled up in a multimodal microwave reactor, reaching 86% yield (ca. 1 g, 1450 kg·m-3·day-1 STY) in only 30 min. Afterward, Pd nanoparticles were formed in situ decorating the nanoMOF by an effective and fast microwave-assisted hydrothermal method, resulting in the formation of Pd@UiO-66-NH2 composites. Both the localization and oxidation states of Pd nanoparticles (NPs) in the MOF were achieved using high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and X-ray photoelectron spectroscopy (XPS), respectively. The optimal composite, loaded with 1.7 wt % Pd, exhibited an extraordinary catalytic activity (>95% yield, 100% selectivity) under mild conditions (1 bar H2, 25 °C, 1 h reaction time), not only in the selective hydrogenation of a variety of single alkenes (1-hexene, 1-octene, 1-tridecene, cyclohexene, and tetraphenyl ethylene) but also in the conversion of a complex mixture of alkenes (i.e., 1-hexene, 1-tridecene, and anethole). The results showed a powerful interaction and synergy between the active phase (Pd NPs) and the catalytic porous scaffold (UiO-66-NH2), which are essential for the selectivity and recyclability.

Efficient removal of environmental pollutants by green synthesized metal nanoparticles of Clitoria ternatea

Prevention and management of water pollution are becoming a great challenge in the present scenario. Different conventional methods like carbon adsorption, ion exchange, chemical precipitation, evaporation, and biological treatments remove water pollutants. Nowadays, the requirement for effective, non-toxic and safe waste management strategies is very high. Nanomaterials have been explored in various fields due to their unique characteristics. Green synthesis of nanomaterial is becoming more popular due to their safety, non-toxicity, and ease of scale-up technology. Metal nanoparticles can be synthesized using a green synthesis method using biological sources provided by eco-friendly, non-hazardous nanomaterials with superior properties to bulk metals. Hence, this study has designed a green synthesis of magnetic (cobalt oxide) and noble (gold) nanoparticles from the fresh flowers of Clitoria ternatea. The flavonoids and polyphenols in the extract decreased the energy band gap of cobalt oxide and gold nanoparticles; hence, the capping of the natural constituents in Clitoria ternatea helped form stable metal nanoparticles. The cobalt oxide and gold nanoparticles are evaluated for their potential for eliminating organic pollutants from industrial effluent. The novelty of this present work represents the application of cobalt oxide nanoparticles in the removal of organic pollutants and a comparative study of the catalytic behaviour of both metal nanoparticles. The degradation of bromophenol blue, bromocresol green, and 4–nitrophenol in the presence of gold nanoparticles was completed in 120, 45, and 20 min with rate constants of 3.7 × 10−3/min, 6.9 × 10−3/min, and 16.5 × 10−3/min, respectively. Similarly, the photocatalysis of bromophenol blue, bromocresol green, and 4–nitrophenol in the presence of cobalt oxide nanoparticles was achieved in 60, 90, and 40 min with rate constants of 2.3 × 10−3/min, 1.8 × 10−3/min, and 1.7 × 10−3/min, respectively. The coefficient of correlation (R2) values justify that the degradation of organic pollutants follows first-order kinetics. The significance of the study is to develop green nanomaterials that can be used efficiently to remove organic pollutants in wastewater using a cost-effective method with minimal toxicity to aquatic animals. It has proved to be useful in environmental pollution management.

Amphiphilic Dendronized Copolymer-Encapsulated Au, Ag and Pd Nanoparticles for Catalysis in the 4-Nitrophenol Reduction and Suzuki-Miyaura Reactions.

The branched structures of dendronized polymers can provide good steric stabilization for metal nanoparticle catalysts. In this work, an amphiphilic dendronized copolymer containing hydrophilic branched triethylene glycol moieties and hydrophobic branched ferrocenyl moieties is designed and prepared by one-pot ring-opening metathesis polymerization, and is used as the stabilizer for metal (Au, Ag and Pd) nanoparticles. These metal nanoparticles (Au nanoparticles: 3.5 ± 3.0 nm; Ag nanoparticles: 7.2 ± 4.0 nm; Pd nanoparticles: 2.5 ± 1.0 nm) are found to be highly active in both the 4-nitrophenol reduction and Suzuki-Miyaura reactions. In the 4-nitrophenol reduction, Pd nanoparticles have the highest catalytic ability (TOF: 2060 h-1). In addition, Pd nanoparticles are also an efficient catalyst for Suzuki-Miyaura reactions (TOF: 1980 h-1) and possess good applicability for diverse substrates. The amphiphilic dendronized copolymer will open a new door for the development of efficient metal nanoparticle catalysts.

An evaluation of the pharmacological responses of metal nanoparticles derived from aqueous extract of Caralluma adscendens R. Brown var. Bicolor

Nanomaterials employed in nanomedicine have the potential to function as both diagnostic and therapeutic tools for individuals. Over the past few decades, significant efforts have been made to synthesize a range of metal nanoparticles through the utilization of different plant extracts. Caralluma adscendens R. Brown var. bicolor leaves (CABL) extract was employed in this study as a reducing/capping agent for the synthesis of gold/silver nanoparticles (CABL@AgNPs/CABL@AuNPs) and explore their pharmacological properties. The successful synthesis of CABL@AgNPs and CABL@AuNPs was confirmed through the observation of surface plasmon resonance (SPR) at 439 and 522 nm using ultraviolet–visible spectrophotometer (UV–Vis). High resolution-transmission electron microscopy (HR-TEM) and energy dispersive X-ray (EDX) techniques were employed to evaluate the shape, size, and chemical composition of the as-synthesized CABL@AgNPs and CABL@AuNPs. Fourier-transform infrared spectroscopy (FTIR) was used to determine the biomolecules responsible for the reduction of metal ions and the stability of metal nanoparticles generated using plant extract. An evaluation was performed to assess the antibacterial and antifungal efficacy of the prepared aqueous CABL extract, CABL@AgNPs, and CABL@AuNPs through the implementation of the disc diffusion technique. The results demonstrated that CABL@AgNPs exhibited greater efficiency when compared to both CABL extract and CABL@AuNPs. The dose-dependent nature of antimicrobial activities was clearly demonstrated through the results of antioxidant and anti-inflammatory experiments. The wound healing activity of the prepared nanomaterials was evaluated using a variety of techniques, including MTT assay, fluorescence staining test, and in vitro scratch assay. The wound-healing capacity of prepared nanomaterials was evaluated using an in vitro scratch assay with Fibroblast L929 cells. The impact of nanoparticles at the IC50 concentration range was analysed through a fluorescence staining experiment and MTT assay to determine toxicity levels. The environmentally friendly approach of current study shown that both nanoparticles have the potential to be effective therapeutic agents for treating different illnesses.

Regenerated silk fibroin coating stable liquid metal nanoparticles enhance photothermal antimicrobial activity of hydrogel for wound infection repair

The integration of liquid metal (LM) and regenerated silk fibroin (RSF) hydrogel holds great potential for achieving effective antibacterial wound treatment through the LM photothermal effect. However, the challenge of LM's uncontrollable shape-deformability hinders its stable application. To address this, we propose a straightforward and environmentally-friendly ice-bath ultrasonic treatment method to fabricate stable RSF-coated eutectic gallium indium (EGaIn) nanoparticles (RSF@EGaIn NPs). Additionally, a double-crosslinked hydrogel (RSF-P-EGaIn) is prepared by incorporating poly N-isopropyl acrylamide (PNIPAAm) and RSF@EGaIn NPs, leading to improved mechanical properties and temperature sensitivity. Our findings reveal that RSF@EGaIn NPs exhibit excellent stability, and the use of near-infrared (NIR) irradiation enhances the antibacterial behavior of RSF-P-EGaIn hydrogel in vivo. In fact, in vivo testing demonstrates that wounds treated with RSF-P-EGaIn hydrogel under NIR irradiation completely healed within 14 days post-trauma infection, with the formation of new skin and hair. Histological examination further indicates that RSF-P-EGaIn hydrogel promoted epithelialization and well-organized collagen deposition in the dermis. These promising results lay a solid foundation for the future development of drug release systems based on photothermal-responsive hydrogels utilizing RSF-P-EGaIn.

Porous Poly(ionic Liquid) Membrane with Metal Nanoparticle Gradient: A Smart Actuator for Visualizing Chemical Reactions.

Poly(ionic liquid) (PIL)-based porous membranes are extensively investigated as soft polymer actuators. While PILs have shown significant advancements in membrane fabrication and stabilization of metal nanoparticles (MNPs), research on integrating MNPs into porous membranes to achieve actuation behavior under multiple stimuli is limited. Herein, this work presents a new paradigm for designing a porous PIL-polyacrylic acid (PAA) membrane with a distinct MNP gradient via a top-bottom diffusion approach involving a metal salt precursor solution and NaBH4 as a reducing agent. The strong binding sites provided by PILs, combined with the gradient distribution of -COO- groups across the membrane cross-section, play a significant role in controlling the MNPs' gradient distribution. Interestingly, the MNPs within the membrane display excellent catalytic activity in exothermic reactions such as H2O2 decomposition, dissipating uneven heat that quickly permeates the membrane network. This induces asymmetrical swelling of polymer chains, resulting in rapid membrane bending. Furthermore, such MNP-loaded membrane could serve as a portable test paper for visually monitoring H2O2. This advancement paves the way for the development of intricate smart actuation materials and expands their practical applications in various real-life scenarios.

Facile and size-controllable fabrication of copper nanoparticles on nitrogen-doped carbon dots using an N,N-dimethylformamide-based reduction approach

Nitrogen-doped carbon dots (NCDs) have been recognized as a promising supporting material for stabilizing metal nanoparticles. In this study, copper nanoparticles (CuNPs) decorated onto NCDs were easily prepared under mild conditions. Two types of Cu fabricated NCDs were prepared by using different Cu precursors – CuCl2 and N,N-dimethylformamide (DMF)-protected CuNPs, where DMF was employed as a multifunctional reagent serving as a reducing agent, stabilizer, and solvent for the synthesis of the CuNPs. The resulting NCDs with Cu species were characterized using ICP-AES, FT-IR, XPS, XRD, and STEM. We found that the Cu precursor greatly influence the fabrication of Cu species on NCDs, with the Cu content of the CuNPs/NCDs being almost twice that of CuCl2/NCDs. Furthermore, when DMF-protected CuNPs were used, nano-sized Cu particles ranging from 4 to 11 nm were immobilized on NCDs surface, whereas single-atom Cu were observed when using CuCl2. This indicates that DMF-protected CuNPs are a suitable source of Cu for the preparation of nano-sized Cu on NCDs.

Polyhydroxy Fullerene for Synthesizing Noble Metal Nanoparticles

The redox properties of fullerene and its derivatives enable them to function as electron relays through either oxidation or reduction. Polyhydroxy fullerene (PHF), also known as fullerol or fullerenol, is highly water-soluble derivative and a well-known antioxidant. We have found that PHF is also very effective in reducing noble metal precursors and stabilizing metal nanoparticles by forming covalent M-O bonds. Traditionally, noble metal nanoparticles, such as gold are synthesized using a reducing agent like sodium borohydride (NaBH4) or sodium citrate at elevated temperatures and alkaline pH, with stabilizers added during nucleation to control the size and dispersion of the nanoparticles. While sodium citrate is sometimes used as a single reducing and stabilizing agent, it is not an effective stabilizer and is often replaced with polymers to improve colloidal dispersion. In contrast, PHF can be used as a single reducing and stabilizing agent for metal nanoparticles. The nanoparticles were synthesized by simply mixing the metal precursors with PHF in an aqueous phase and stirring at room temperature. The size and morphology of synthesized nanoparticles were characterized with high-resolution transmission electron microscopy, aberration corrected TEM, and dynamic light scattering. These nanoparticles were monodisperse with size ranging from 2 nm to 100 nm in diameter, which could be controlled by changing the concentration of the two reactants. We utilized multiple tools to investigate the mechanism of reduction and nanoparticle formation. We propose a kinetic agglomerate-dissociation mechanism to describe the formation of gold nanoparticles using PHF. Kinetic agglomerates form instantaneously upon mixing the two reactants due to electrostatic interactions. During the reduction process reactive carbonyl peaks were observed with electron energy loss spectroscopy. The carbonyl moieties were observed only after agglomerate formation and subsequently changed to Au-O bonds between PHF and synthesized gold nanoparticles, which was confirmed with Fourier-transform infrared spectroscopy and density-functional theory calculations, and X-ray photoelectron spectroscopy. Further, we demonstrated that the synthesis of gold nanoparticles using PHF can be affected by pH due to changes in hemiketal structure of PHF. Compared to citrate ions, PHF-coated gold nanoparticles are more stable, remaining so for over two years. The novel PHF-mediated synthesis method can also be applied to other noble metals like platinum, palladium, and silver and create bimetallic nanoparticles. The surface PHF coating on noble metal nanoparticles integrates the properties of both metal and carbon nanoparticles, resulting in superior functional applications. Our findings open up new opportunities for metallic nanoparticle preparation methods, properties, and applications.

Electrochemical stability of metal nanoparticles: The role of size-distribution broadness

In this article, we develop a thermodynamic and an electrochemical kinetic model to study the stability of metal nanoparticles (MNPs) supported on an inert substrate and in contact with an electrolyte. Regardless of the model, we find that the redox potential is a property of the entire MNPs’ size distribution, which has to be characterized by, at least, its mean and variance. The thermodynamic model, which considers only the excess free energy due to the increased surface-to-volume ratio on MNPs, predicts an increase in surface effects as the size distribution becomes broader. On the other hand, the electrochemical kinetic approach models the MNPs as reactive systems considering the changes in the heterogeneous-rate constants due to surface effects. This allows the use of the mixed potential theory to evaluate the electrode potential, which would be experimentally accessible, showing a tendency contrary to that predicted by the thermodynamic model for closed systems. Then, the electrochemical boundary conditions –i.e., charge conservation- have to be considered rather than just the thermodynamic criteria. Also, it is analyzed under which circumstances the charge-transfer processes control the electrode potential, instead of mass-transfer. Hence, it is shown that the electrochemical kinetic approach is applicable to the study of the electrochemical Ostwald ripening among many other processes.

Fenugreek seeds extract mediated nickel oxide nanoparticles and their potential biomedical applications

The biogenic nanoparticle synthesis is much interest in the field of modern science and technology because of their excellent inhibition of potential pathogens. A quick, dependable, and efficient way to create very stable metal nanoparticles is by Phytosynthesis. Hence, Fenugreek seeds extract-mediated nickel oxide nanoparticles (NF) are synthesized by an eco-friendly, greener approach. Numerous characterization methods, including X-ray diffraction (XRD), Fourier transform infrared (FT-IR), ultraviolet visible (UV–Vis), photoluminescence (PL), scanning electron microscope (SEM), transmission electron microscope (TEM), and energy-dispersive X-ray spectroscopy (EDX), were used to confirm the as-prepared nanoparticles. Powder X-ray diffraction (PXRD) and selected area electron diffraction (SAED) show the prepared NiO NPs crystallinity. The FT-IR spectrum ensures the vibrational modes present in the prepared compound. The formation of NiO NPs is confirmed from the ultraviolet–visible (UV–Vis) spectrum analysis with the surface plasmon resonance (SPR) band at 320 nm. The morphological behavior is shown by the field emission-scanning electron microscope (FE-SEM) and high-resolution transmission electron microscope (HR-TEM). This prepared Fenugreek seeds extract assisted NiO NPs were examined with different biomedical studies such as anti-diabetic, anti-oxidant, and anti-inflammatory. The green approach to NiO NPs shows 82.21 % anti-diabetic, 79.82 % anti-oxidant, and 94.54 % anti-inflammatory and anti-bacterial activities. Moreover, it can act as an excellent inhibitor with the potential to cure various diseases like diabetes, oxidative stress, and inflammation.

Hydroformylation of olefins over a novel active rhodium catalyst supported on a melamine–cyanuric acid co-crystal

Hydroformylation, or oxo synthesis, is one of the most important industrial petrochemical processes involving homogeneous catalysts. The development of efficient and stable phosphorus-free heterogeneous catalytic systems for this process is of great interest because it can solve the problem of separation and recycling of expensive metals and reduce the amount of phosphorus-containing waste. Macromolecular compounds containing triazine rings can be promising candidates for supports for the stabilization of metal nanoparticles and subsequent use in heterogeneous catalytic reactions. Herein, it was shown that the interaction of cyanuric chloride with melamine produces cyanuric acid–melamine (CAM) co-crystal, which was used as a support for stabilizing rhodium nanoparticles. The obtained catalyst (CAM/Rh) exhibits high activity and stability in the hydroformylation of olefins of various structures. After completion of the reaction, the catalyst is easily separated from the reaction mixture and can be used repeatedly with virtually no loss of activity.

Strong Metal‐support Interactions in Photocatalysis: Fundamentals and Design Methods

AbstractEngineering the composition and geometry of metallic sites has become a popular manner to boost reaction rate and control reaction selectivity in heterogeneous catalysis. Many studies have been devoted to enhancing the stability of metallic nanoparticles during catalytic reactions by dispersion on metal oxide supports such as TiO2, CeO2 or Nb2O5. These supports not only modulate electronic properties and dispersion/stabilization of metallic nanoparticle but also influence catalytic selectivity, resulting in the so‐called “strong metal‐support interaction” (SMSI). In this minireview, we outlined the discovery and fundamentals of SMSI, as well as its extensive development over years. In addition, we summarized recent approaches developed to induce the construction of SMSI between different metal nanoparticles and metal oxide supports. Associated characterization microscopic and spectroscopic techniques were emphasized. Despite being a prevalent concept in catalysis, the number of studies on SMSI in heterogeneous photocatalysis has been even in limitation. Herein, we highlighted the beneficial effects of SMSI on boosting photocatalytic activity for CO2 reduction and H2 evolution reactions. In general, despite some controversial aspects of the SMSI, this concept offers wide opportunities ahead and encourages researchers to rethink the local active site localization and photocatalyst design.

Multi-Functional Applications of H-Glass Embedded with Stable Plasmonic Gold Nanoislands.

Metal nanoparticles (MNPs) are synthesized using various techniques on diverse substrates that significantly impact their properties. However, among the substrate materials investigated, the major challenge is the stability of MNPs due to their poor adhesion to the substrate. Herein,it isdemonstrated how a newly developed H-glass can concurrently stabilize plasmonic gold nanoislands (GNIs) and offer multifunctional applications. The GNIs on the H-glassaresynthesized using a simple yet, robust thermal dewetting process. The H-glass embedded with GNIs demonstrates versatility in its applications, such as i) acting as a room temperature chemiresistive gas sensor (70% response for NO2 gas); ii) serving as substrates for surface-enhanced Raman spectroscopy for the identifications of Nile blue (dye) and picric acid (explosive) analytes down to nanomolar concentrations with enhancement factors of 4.8 × 106 and 6.1 × 105 , respectively; and iii) functioning as a nonlinear optical saturable absorber with a saturation intensity of 18.36 × 1015 Wm-2 at 600nm, and the performance characteristics are on par with those of materials reported in the existing literature. This work establishes a facile strategy to develop advanced materials by depositing metal nanoislands on glass for various functional applications.

SbPh3-based organic molecular cage for size-controlled preparation and stabilization of palladium nanoparticles

Group 15 triphenyl compounds with coordination ability such as triphenylamine (NPh3) and triphenylphosphine (PPh3) have been widely investigated for the construction of functional porous organic materials. In this work, a SbPh3-based organic molecular cage (Sb-cage) was unprecedently synthesized. The spatial configuration of Sb-cage was precisely analyzed by single crystal X-ray diffraction, showing a trigonal–bipyramidal [2 + 3] assembly. Sb-cage was employed to the mediated growth of palladium nanoparticles (PdNPs) with an average diameter of 0.70 nm. As-synthesized utrafine PdNPs exhibits good catalytic activity in Suzuki-Miyaura coupling reaction between aryl halides and phenylboronic acid, where the PdNPs could grow up in situ to a stable size distribution of 1.71 ± 0.30 nm. Furthermore, the advantages of the trigonal bipyramidal configuration in the stabilization of metal nanoparticles during the catalytic reaction cycles were demonstrated via the control experiments on SbPh3-based unclosed semicage.

Synthesis of Silver Nano-particle with Poly-herbal Plant Extracts for Anti-fungal and Anti-microbial Activity on Candida Albicans and E. Coli

In this study, we have developed a method to synthesize silver nanoparticles by mixing the silver solution with the leaf extract of Pisum sativum without using any surfactant or external energy. In this method, physiologically steady, bio-compatible Ag nanoparticles were set up. These functionalized POLY HERBAL Ag-NPs could be used for targeted drug delivery with enhanced therapeutic efficacy and minimal side effects. Extracellular synthesis of metal nanoparticles using extracts of plants like Pisum sativum (Pea), Zingiber officinale (Ginger) Curcuma longa (turmeric) has been successfully carried out. In this article, Ag-NPs formation using Pisum sativum (Pea), Zingiber officinale (Ginger) and Curcuma longa (turmeric) has been thoroughly discussed. It is well recognized that on treating the metallic salt solution with some plant extracts, a rapid reduction take place leading to the origination of highly stable metal nanoparticles. With this method quick synthesis of nanoparticles was noticed to occur; i.e., reaction time was 1–2 h as contrasted to 2–4 days required by microorganisms. These nanoparticles were examined by various characterization techniques to disclose their morphology, chemical composition, and antimicrobial activity. TEM image of these NPs shows the evolution of spherical, non-uniform, poly-dispersed nanoparticles. A comprehensive study of the anti-microbial activity of nanoparticles was performed.

Surface Borate-Derived Highly Dispersed and Stable Metal Nanoparticles on Nitrogen-Vacancy Boron Nitride Support Promoting CO Methanation

Surface Borate-Derived Highly Dispersed and Stable Metal Nanoparticles on Nitrogen-Vacancy Boron Nitride Support Promoting CO Methanation

Silver-platinum nanoparticles and nanodroplets supported on silica surfaces: Structure and chemical ordering

Stable and metastable metallic nanoparticles exhibit unique properties compared to the bulk, with potentially important applications for catalysis. This is in particular the case for the AgPt alloy that can exhibit the ordered L11 structure (alternation of pure Ag and Pt (111) planes) in nanometer size particles. However, for such small systems, the interfaces play an important role. Therefore, the support used to elaborate the nanoparticles in ultrahigh vacuum experiments may influence their properties, even in the case of weakly interacting substrates like amorphous carbon or silica. This work focuses on the AgPt nanoparticles deposited on silica, and investigates the effect of the support disorder and roughness on the structure and chemical ordering, in particular at the interface with the substrate, by Monte Carlo calculations of the atomic density profiles with semi-empiric potentials.

Synthesis and characterization of tetraphenylethylene-functionalized N-heterocyclic carbene-stabilized gold nanoparticles with aggregation-induced emission

Gold nanoparticles (AuNPs) have found use in broad range of applications such as in catalysis and nanomedicine. Despite the fact that thiol-based AuNPs have been widely studied, they suffer from relative instability in various conditions, such as high and low temperatures, pH variations, and are prone to oxidation. Over the last decade, N-heterocyclic carbenes (NHCs) have been under spotlight as suitable ligands to stabilize metal nanoparticles and surfaces. Although NHC-functionalized AuNPs have been shown to outperform their thiol-based analogs in terms of stability, their applications in nanomedicine have not been realized. Hybrid nanomaterials, such as AuNPs tagged with π-conjugated molecules with aggregation-induced emission (AIE) property, are promising candidates to develop fluorescent materials for cellular imaging. The combination of NHC-stabilized AuNPs with AIE to form stable, fluorescent hybrid AuNPs is of significant interest to open the door to develop new NHC-based nanomaterials. Herein, we report the synthesis and characterization of water-soluble fluorescent NHC-decorated AuNPs for potential applications in nanomedicine. Their stability in biologically relevant conditions is investigated.