Crystalline Silver Nanoparticles Research Articles

Stoichiometry crystallographic phase analysis and crystallinity integration of silver nanoparticles: A Rietveld refinement study

A highly crystalline phase of silver nanoparticles was successfully synthesized using silver nitrate as the precursor and trisodium citrate dihydrate as the chelating agent. Rietveld refinement analysis revealed that approximately 95.0 % of the synthesized material consisted of crystalline silver nanoparticles, with the remaining 5.0 % being unreacted starting material. XRD characterized the prominent crystalline phase, providing insights into lattice parameters were α = β = γ = 90.0°, a = b = c = 4.08871 Å; lattice strain 0.290 %, lattice volume 68.353 Å3 and average dislocation density 9.6 9× 10-4 nm−2. The most intense diffraction peak was attributed to the (111) plane at 2θ = 38.18°. The average crystallite size was determined to be 32.12 nm, confirming the formation of crystalline silver nanoparticles. The specific surface area of the synthesized silver nanoparticles was 18 m2/g Notably, the synthesized silver nanoparticles exhibited a higher degree of crystallinity (59.35 %) compared to the standard silver nitrate (38.46 %), indicating a highly crystalline nature. The crystallographic data confirmed the successful synthesis of highly crystalline silver nanoparticles with improved crystallinity over the reference material.

A facile cleaner approach towards the synthesis of silver-doped cardanol-based hydrophobic antimicrobial and anticorrosive polymeric coating material

This work reports the solvent, catalyst and cross-linker free green synthesis of silver (Ag)-doped cardanol-based multifunctional polymer nanocomposite (PNC) coatings. The interaction of Ag ions with the polymeric backbone and in-situ formation of nanoparticles (NP) was confirmed by various characterization techniques. The optimum curing temperature (120–160 °C) and Ag concentration (1%) required for the free-standing film/coating with durable mechanical and chemical resistant properties in acidic/basic/salt solutions was studied. The high gel content (degree of crosslinking, 98%) and thermal stability up to 345 °C endorse the formulation of a well-cross-linked polymeric film/coating. XRD (approx. 27 nm) indicated the formation of crystalline silver nanoparticles within the polymer matrix, whereas SEM and TEM explored the distribution (200–700 nm). EIS studies for three weeks in 3.5% NaCl solution showed the exceptional corrosion inhibition efficiency (98-91%) of the coatings on steel substrate. The stable coating resistance value (MΩ.cm−2) throughout the study highlights the formation of a hydrophobic barrier with good resistance against the corrosive ions. Additionally, the potent antibacterial impact against Gram-positive, and Gram-negative bacteria, and the antifungal activity of the nanocomposite were attributed to the presence of Ag in the PNC. The multifunctional properties arise from the in-situ formed nanostructure and its synergistic effect with the biopolymer matrix projects its versatile industrial application.

Molecular insights into quercetin-enhanced crystalline silver nanoparticles: Implications for breast cancer cell cytotoxicity and antibacterial action in Kyllinga nemoralis

Amidst the ongoing global health crisis posed by cancer and antibiotic-resistant infections, innovative solutions are in high demand. The utilization of Kyllinga nemoralis leaf (KNL) extracts for synthesizing silver nanoparticles (AgNPs) represents a novel approach, with the potential to deliver profound advancements in healthcare, benefitting society on a broad scale. Successful synthesis of AgNPs by KNL extracts for treating breast cancer cells, specifically MDA-MB-231 cells, is recorded in this report. The adsorption mechanism of quercetin (Q) on Ag and its optimized structural characteristics were computed at the DFT level. According to FTIR analysis, quercetin, one of the flavonoids found in KNL extract, acts as a reducing and stabilizing agent for the conversion of Ag+ ions to Ag0, and carboxylates serve as ligands that cap the AgNPs. The small-sized (7 nm), spherical particles, which are uniform in size and monodispersed, exhibit regulation over the size of the AgNPs due to being shielded by enough flavonoids and gallic acid absorbed into the extract. The observed negative zeta potential of −20 mV indicates the moderate stability of the AgNPs colloid. It is noted that AgNPs prepared at higher concentrations of KNL extract showed lower minimum inhibitory concentration (MIC) values (80 µg/mL) and larger inhibition zones (22 mm) against Pseudomonas aeruginosa. The cell viability rate of MDA-MB-231 cell lines decreases with increasing concentration of AgNPs. The antibacterial and anticancer activity of AgNPs is observed in a size-dependent manner. This research raises the possibility of using plant-based, small-sized AgNPs therapeutically for breast cancer and as antibacterial agents.

Bactericidal effect of nanosilver synthesized with Neolitsea cassia mucilaginous extract

This study focused on green synthesis of silver nanoparticles using mucilaginous leaf extracts of Neolitsea cassia and demonstrating the bactericidal effect of the product against Staphylococcus aureus and Escherichia coli, which are common in polluted water. A concentration series of silver nitrate was subjected to four treatments by mixing with separate (a) aqueous and (b) 80% methanol extracts of N. cassia leaves in (c) atmospheric and (d) nitrogen gaseous environments, for comparison. A linear increment of the dry weight of silver nanoparticles was observed with increasing silver nitrate concentration (r = 0.99, p = 0), resulting in higher yields from 80% methanol extracts in an atmospheric environment. As characterized by surface plasmon resonance absorption, energy-dispersive X-ray spectroscopy and scanning electron microscopy, quasi-spherical crystalline silver nanoparticles of 11.7 nm average diameter were synthesized. The disk diffusion method showed that the growth of E. coli and S. aureus in culture media was increasingly inhibited with increasing nanoparticle concentration (r = 0.95, p = 0 and r = 0.93, p = 0, respectively). It was concluded that 80% methanol extract in an atmospheric environment was the most productive way to green-synthesize silver nanoparticles from the mucilaginous sap of N. cassia.

Simple and additive-free synthesis of highly reflective thin silver films and their application on large-scale surfaces

There is a growing demand for highly reflective coatings especially on non-conducting surfaces for use in various industries. Additionally, focus is arising on green production and cost reduction in terms of energy, time, etc., which require detailed investigation of coating process parameters. Therefore, in this work, silver thin films with high reflectance were synthesized on glass substrates in short durations at room temperature by electroless plating (ELP) method in one-step and without using any additives. Effects of deposition time, concentration of the reactants (AgNO3, Glucose, NaOH), and also the surface pretreatment and activation steps were investigated in detail to improve the reflectance and structural properties of silver films. Contact angle measurements were realized to examine the effects of each surface modification step. Surfaces subjected to etching, sensitization and Ag activation were found to yield more homogeneously distributed nanoparticles in short deposition period. Scanning electron microscopy (SEM) also showed smaller-sized spherulite-shaped crystals, forming a close packed structure with an optimum film thickness of ∼110 nm. The continuity of the silver coatings on the surface was verified by the low sheet resistance of 0.18 Ωsq−1. Atomic force microscopy (AFM) analysis revealed a smoother film structure with an RMS of 10.7 nm after sensitization. X-ray diffraction analysis (XRD) and X-ray photoelectron spectroscopy analysis (XPS) analysis proved the growth of highly crystalline silver nanoparticles with high purity. All these morphological improvements led to high values of light (∼97%), near-infrared (99%) and solar (96%) reflectance for the coatings. Finally, based on the optimized concentrations and bath conditions, large-scale (700×500 mm2) first-surface mirrors were successfully produced (96.2%R and 0.25 Ωsq−1) by spray coating technique combined with ELP. Overall, the results indicate that the obtained films have potential usage in applications such as solar energy, electronics and aeronautics.

Silver zirconium oxide cermet coatings spray deposited onto galvanized steel sheet for low temperature solar applications

A new type of cermet coating, with potential use as low-cost solar thermal absorber has been developed using spray pyrolysis. It consists of crystalline silver nanoparticles embedded in amorphous zirconia and was obtained by spraying aqueous precursor solutions onto aluminized carbon steel sheets at 200 °C. It was found that simultaneous spraying of silver and zirconium solutions led to a considerable reduction, in the nanometer range, of silver particle size distribution. Hence, we comparatively studied the cermet coatings obtained by A) sequentially or B) simultaneously spraying silver and zirconium solutions. For the latter case, a zirconia anti-reflection layer was sprayed on top. Both coating systems were studied by SEM, AFM, HRTEM/EDS and UV-VIS-IR spectroscopy with respect to silver particle size distribution. Optical parameters like solar absorptance (AM 1.5) and thermal emittance (373 K) were determined from absolute hemispherical reflectance, and a performance coefficient was calculated in order to evaluate the solar selectivity of the coatings. The comparison showed that smaller silver particles lead to an increase in solar selectivity and that the size reduction is due to an effective encapsulation by zirconia of the silver particles when spraying silver and zirconium precursors simultaneously. Furthermore, HRTEM confirmed the metallic and crystalline state of the silver nanoparticles embedded in amorphous zirconia.

Retracted: Eco-Friendly Synthesis of Multishaped Crystalline Silver Nanoparticles Using Hill Garlic Extract and Their Potential Application as an Antifungal Agent

Retracted: Eco-Friendly Synthesis of Multishaped Crystalline Silver Nanoparticles Using Hill Garlic Extract and Their Potential Application as an Antifungal Agent

Silver nanoparticles production mediated by natural tetraploid Trifolium pratense L.: Characterization and potential biological activity

Abstract This study was aimed to present the green synthesis of silver nanoparticles through natural tetraploid Trifolium pratense L. containing high amounts of phenolic compounds and glycosidic bioactive macromolecules. Combinatorial optimization of AgNPs was achieved thanks to the stabilizing and reducing properties of the natural tetraploid T. pratense L. flowering herb extract. The biologically synthesized AgNPs were visualized by color change in UV–Vis spectroscopy. UV–Vis spectroscopy proved to be a fast and simple method to determine the synthesis of AgNPs. In addition, TEM, XRD, and FTIR analyses were performed to confirm and characterize the formation of crystalline silver nanoparticles. It was shown by the TEM analysis that AgNPs changed their size and shape when biosynthesized in different conditions. It was determined that smaller AgNPs were spherical and larger AgNPs had a truncated octahedron shape. The XRD analysis proved the presence of Ag0 in nanoparticles and showed its crystal structure and faced cubic shapes for AgNPs. Interactions between the plant bioactive compounds and the AgNPs were distinctly visible in the FTIR spectra. The biosynthesized AgNPs showed strong antioxidant activity against DPPH and ABTS; furthermore, the total phenol content was also high.

Dielectric barrier discharge plasma synthesis of Ag/γ-Al2O3 catalysts for catalytic oxidation of CO

In this study, Ag/γ-Al2O3 catalysts were synthesized by an Ar dielectric barrier discharge plasma using silver nitrate as the Ag source and γ-alumina (γ-Al2O3) as the support. It is revealed that plasma can reduce silver ions to generate crystalline silver nanoparticles (AgNPs) of good dispersion and uniformity on the alumina surface, leading to the formation of Ag/γ-Al2O3 catalysts in a green manner without traditional chemical reductants. Ag/γ-Al2O3 exhibited good catalytic activity and stability in CO oxidation reactions, and the activity increased with increase in the Ag content. For catalysts with more than 2 wt% Ag, 100% CO conversion can be achieved at 300 °C. The catalytic activity of the Ag/γ-Al2O3 catalysts is also closely related to the size of the γ-alumina, where Ag/nano-γ-Al2O3 catalysts demonstrate better performance than Ag/micro-γ-Al2O3 catalysts with the same Ag content. In addition, the catalytic properties of plasma-generated Ag/nano-γ-Al2O3 (Ag/γ-Al2O3-P) catalysts were compared with those of Ag/nano-γ-Al2O3 catalysts prepared by the traditional calcination approach (Ag/γ-Al2O3-C), with the plasma-generated samples demonstrating better overall performance. This simple, rapid and green plasma process is considered to be applicable for the synthesis of diverse noble metal-based catalysts.

Green synthesis of multifunctional MgO@AgO/Ag2O nanocomposite for photocatalytic degradation of methylene blue and toluidine blue.

Introduction: In this paper, MgO@AgO/Ag2O nanoparticles were greenly synthesized, the current idea is to replace the harmful chemical technique with an ecofriendly synthesis of metal oxide nanoparticles (NPs) utilizing biogenic sources. Methods: The current investigation was conducted to create silver oxide NPs decorated by MgO NPs (namely, MgO@AgO/Ag2O nanocom-posite) using the leaves extract of Purslane (Portulaca Oleracea) as the reducing and capping agent. The nanopowder was investigated by means of X-ray diffraction, scanning electron mi-croscope, BET surface area, Fourier transform infrared, and UV-vis spectrophotom-eter studies. XRD studies reveal the monophasic nature of these highly crystalline silver nano-particles. SEM studies the shape and morphology of the synthesis AgO/Ag2O and MgO@AgO/Ag2O NPs. The presence of magnesium and oxygen was further confirmed by EDS profile. Results and discussion: The surface area was found to be 9.1787 m2/g and 7.7166 m2/g, respectively. FTIR analysis showed the presence of specific functional groups. UV-vis spectrophotometer studies show the absorption band at 450nm due to surface plasmon resonance. The results have also indicated the high performance of the greenly synthesized AgO/Ag2O NPs and MgO@AgO/Ag2O NPs for photocatalytic activity dye degradation (methylene blue and toluidine blue).

Bulk Level Synthesis of Solid Silver Nanocatalyst: Green Mediated Approach

The synthesis of silver nano particles has acquired more attention in terms of its applicability in various fields including medicine, environmental, electronics and energy. Owing to its exceptionally good catalytic activity, this particular study is focused on the synthesis of silver nanoparticles in bulk scale, free from capping agents. Apart from the conventional colloidal green synthesis, the silver nanoparticles were synthesized in solid form using a cheap green medium lime fruit extract. The green mediated sol-gel auto combustion method eliminates the use of hazardous reducing agents and tedious purification processes. The structure, morphology and purity of the synthesized material were explored through various analytical techniques. TEM studies revealed that the synthesized silver nanoparticles were spherical in shape with average particle size of 8 nm. The potential of the silver nanoparticle as a catalyst towards reduction of organic compounds and dye degradation was established by conducting nitrophenol reduction and methylene blue degradation as a basic reaction. The nanoparticles were found to have effectively catalysed the reduction of p-nitrophenol and degradation of methylene blue with the aid of sodium borohydride as reducing agent. It may open up new path for the chemical free synthesis of crystalline silver nanoparticles with enhanced catalytic property.

Green Synthesis of Silver Nanoparticles Using Aqueous Citrus limon Zest Extract: Characterization and Evaluation of Their Antioxidant and Antimicrobial Properties.

The current work concentrated on the green synthesis of silver nanoparticles (AgNPs) through the use of aqueous Citrus limon zest extract, optimizing the different experimental factors required for the formation and stability of AgNPs. The preparation of nanoparticles was confirmed by the observation of the color change of the mixture of silver nitrate, after the addition of the plant extract, from yellow to a reddish-brown colloidal suspension and was established by detecting the surface plasmon resonance band at 535.5 nm, utilizing UV-Visible analysis. The optimum conditions were found to be 1 mM of silver nitrate concentration, a 1:9 ratio extract of the mixture, and a 4 h incubation period. Fourier transform infrared spectroscopy spectrum indicated that the phytochemicals compounds present in Citrus limon zest extract had a fundamental effect on the production of AgNPs as a bio-reducing agent. The morphology, size, and elemental composition of AgNPs were investigated by zeta potential (ZP), dynamic light scattering (DLS), SEM, EDX, X-ray diffraction (XRD), and transmission electron microscopy (TEM) analysis, which showed crystalline spherical silver nanoparticles. In addition, the antimicrobial and antioxidant properties of this bioactive silver nanoparticle were also investigated. The AgNPs showed excellent antibacterial activity against one Gram-negative pathogens bacteria, Escherichia coli, and one Gram-positive bacteria, Staphylococcus aureus, as well as antifungal activity against Candida albicans. The obtained results indicate that the antioxidant activity of this nanoparticle is significant. This bioactive silver nanoparticle can be used in biomedical and pharmacological fields.

Pine Needle (Pinus densiflora) Extract-Mediated Synthesis of Silver Nanoparticles and the Preparation of Carrageenan-Based Antimicrobial Packaging Films

Silver nanoparticles (AgNPs) were prepared using a pine needle extract-mediated synthesis method. The X-ray diffraction (XRD) spectrum showed a characteristic peak of silver, indicating that crystalline silver nanoparticles were formed. The synthesized AgNPs were spherical and had a uniform size of 63.9 ± 2.1 nm with a narrow size distribution. The AgNPs have been used as functional nanofillers in the manufacture of carrageenan-based functional nanocomposite films. Field emission scanning electron microscopy (FE-SEM) confirmed that AgNPs were uniformly dispersed in the carrageenan polymer matrix. The addition of AgNPs to the Carr film affected the surface color, mechanical, water vapor barrier, and surface wettability properties and significantly improved the UV blocking properties of the nanocomposite films. In addition, the carrageenan/AgNP composite films showed strong antioxidant activity and potent antibacterial activity against both Gram-positive (S. aureus) and Gram-negative (E. coli O157: H7) bacteria. The carrageenan/AgNP film with UV protection, antioxidant, and antibacterial activity can be used as active food packaging material to extend the shelf life of packaged food.

Eco-Friendly Synthesis of Multishaped Crystalline Silver Nanoparticles Using Hill Garlic Extract and Their Potential Application as an Antifungal Agent

Antimicrobial resistance is a global health challenge, and the large loads of biocides dumped into the environment augment the spread of antifungal resistance and environmental contamination. Therefore, eco-friendly antifungal agents must be developed to combat antibiotic resistance and to reduce environmental contamination. In the present investigation, Allium sativum (Hill garlic-Malai Poondu) extract was used as a green resource to achieve silver nanoparticle (AgNP) production. AgNPs were characterized by various spectral and microscopic analyses. In vitro free radical scavenging assays were instigated to determine the antioxidant capacity of the AgNPs, and the antifungal activity was assessed using Agar well-diffusion assay again pathogenic fungal strains. The mean particle size of the AgNPs was calculated as 35.1 nm with face-centered cubic (FCC) structure. AgNPs exhibited free radical scavenging activity against 2,2-diphenyl-1-picrylhydrzyl (DPPH), 2,2-azino-bis (3-etilbenzotiazolin)-6-sulfonic acid (ABTS), and hydrogen peroxide (H2O2) radicals. Scavenging of DPPH radicals by AgNPs was impressive, and an IC50 value of 6.3 ± 0.4 μg/ml was obtained in this assay. Among the tested Candida strains, the order of the least susceptibility on exposure to AgNPs synthesized using Hill garlic extract was as follows: C . g l a b r a t a ≤ C . t r o p i c a l i s ≤ C . p a r a p s i l o s i s ≤ C . k r u s e i ≤ C . a l b i c a n s . The study highlights the synthesis of environment-friendly nanoparticles using Hill garlic extract with enhanced antifungal properties.

Biogenic Synthesis of Silver Nanoparticles using Aspergillus Aureoles (Endophyte) and Demonstration of their Anti- microbial Activity

The nanoparticles have been recognized to play vital coating roles in electronics, energy contact actions, biology, and medicine due to their unique properties for two decades. In the present study, silver nanoparticles were synthesized using an endophytic fungus, Aspergillus aureoles, and subjected to antimicrobial activity. The treatment of an aqueous solution of silver nitrate (3 mM) with cell-free filtrate of Aspergillus aureoles resulted in the production of stable and crystalline silver nanoparticles. Silver nanoparticles were characterized using different studies, such as Ultraviolet-Visible Spectroscopy, High-Resolution Transmission Electron Microscopy, X-ray Diffraction Spectroscopy, Fourier Transform Infrared Spectroscopy, and Dynamic Light Scattering. The antimicrobial activity was carried out by the well diffusion method. The nanoparticles were in a spherical shape with an average particle size of 12-15 nm as observed in a High-Resolution Transmission Electron Microscope. The crystalline nature and size of nanoparticles were confirmed by the X-ray Diffraction Spectroscopy and Selected Area Electron Diffraction, respectively. The Fourier Transform Infrared Spectroscopic study revealed the involvement of various functional groups of Aspergillus aureoles extract in stabilizing the nanoparticles. These nanoparticles exhibited potent antimicrobial activity against both gram-positive and negative bacteria, which was comparable to the standard antibiotic. Thus, the study established the possible use of green silver nanoparticles in controlling microbial infections and developing a novel broad-spectrum antimicrobial agent/s.

Fabrication and characterization of noble crystalline silver nanoparticles from Pimenta dioica leave extract and analysis of chemical constituents for larvicidal applications

The current works report the bio-efficacy of Pimenta dioica leaf derived silver nanoparticles (Pd@AgNPs) and leaf extract obtained trough different solvents against the larvae of malaria, filarial and dengue vectors. Synthesis of silver nanoparticles (AgNPs) was done by adding 10 ml of P. dioica leaf extract into 90 ml of 1 mM silver nitrate solution, a slow colour change was observed depicting the formation of AgNPs. Further, Pd@AgNPs was confirmed through Ultraviolet–visible spectroscopy which exhibited characteristic absorption peak at 422 nm wavelength. X-ray diffraction and selected area electron diffraction analysis confirmed monodispersed and crystalline nature of Pd@AgNPs with 32 nm an average size. Scanning electron microscopy and transmission electron microscopy showed the most of Pd@AgNPs were spherical and triangular in shape and energy-dispersive X-ray spectroscopy revealed silver elemental nature of nanoparticles. Zeta potential of Pd@AgNPs is highly negative which confirmed its stable nature. Pd@AgNPs showed prominent absorption peaks at 1015, 1047, 1243, 1634, 2347, 2373, 2697 and 3840 cm−1 which are corresponding to following compounds polysaccharides, carboxylic acids, water, alcohols, esters, ethers, amines, amides and phenol, respectively as reported by Fourier-transform infrared spectroscopy analysis. Gas chromatography–mass spectrometry and Liquid chromatography–mass spectrometry analysis revealed 39 and 70 compounds, respectively, which might be contributed for bio-reduction, capping, stabilization and larvicidal behavior of AgNPs. A comparable lethality (LC50 and LC90) was observed in case of Pd@AgNPs over leaf extract alone. The potential larvicidal activity of Pd@AgNPs was observed against the larvae of Aedes aegypti,(LC50, 2.605; LC90, 5.084 ppm) Anopheles stephensi (LC50, 3.269; LC90, 7.790 ppm) and Culex quinquefasciatus (LC50, 5.373; LC90, 14.738 ppm without affecting non-targeted organism, Mesocyclops thermocyclopoides after 72 hr of exposure. This study entails green chemistry behind synthesis of AgNPs which offers effective technique for mosquito control and other therapeutic applications.

Biosynthesis of silver nanoparticles using the Falcaria Vulgaris (Alisma Plantago-Aquatica L.) extract and optimum synthesis

There are many reports about the use of medicinal plants in traditional medicine, as well as the application of metal nanoparticles in various biomedical fields. The purpose of the present study is bio synthesize of silver nanoparticles, using the aqueous extract of Alisma Plantago-Aquatica L plant and to achieve optimal conditions for the synthesis of these nanoparticles. For this reason, the effect of different parameters such as pH, extract volume, concentration of silver nitrate solution, temperature and reaction time were studied and their optimal amount was determined. Then, the nanoparticles synthesized in optimum conditions, were evaluated (UV-Vis), X-ray diffraction (XRD), Field-Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscope (TEM) and Fourier-Transform Infrared spectroscopy (FTIR). Strong and width peak of the visible UV spectrophotometer, at 438 nm wavelength, showed the formation of silver nanoparticles. The X-ray diffraction pattern confirmed the formation of crystalline silver nanoparticles at a size of about 25 nm. The results of FESEM showed nanoparticle shape in a spherical and monodisperse, with a particle size range of 20 to 58 nm. The TEM analysis also yielded a nanoparticle size of about 20 nm. The results of the Fourier transform infrared spectroscopy (FTIR), indicate the involvement of hydroxyl, amine and carboxyl groups in the plant extract in the synthesis of silver nanoparticles. The results of this study showed that theAlisma Plantago-Aquatica L. plant extract can be introduced as an appropriate, affordable and safe alternate in terms of green chemistry, instead of toxic and high-risk chemicals.

In situ green synthesis of MnFe2O4@EP@Ag nanocomposites using Epilobium parviflorum green tea extract: An efficient magnetically recyclable catalyst for the reduction of hazardous organic dyes

The present paper introduces a plant‐mediated green synthesis of highly stable MnFe2O4@EP@Ag magnetically recyclable nanocomposites (MRNCs) using Epilobium parviflorum (EP) tea extract as a coating material on MnFe2O4 nanoparticles (NPs) for the Ag immobilization. Fourier transform infrared spectroscopy‐attenuated total reflectance (ATR‐FTIR) studies confirmed the presence of the polyphenolics in EP extract, including tannic, gallic, and other derivatives, which can enhance the complexation properties with silver ions on MnFe2O4 NPs. Thus, the capacity and the surface properties of the resulting nanosorbent (MnFe2O4@EP) can also improve their ability to form magnetic nanocatalyts without using any additional chemicals, toxic or extra‐reducing agents. The transmission electron microscopy (TEM) verified the successful coating of EP extract on MnFe2O4 core as a 5 nm shell. X‐ray diffraction (XRD) patterns and scanning electron microscope/energy‐dispersive X‐ray spectroscopy (SEM–EDX) confirmed the presence of both MnFe2O4 and crystalline silver nanoparticles in the core‐shell structure of the MnFe2O4@EP@Ag MRNCs. The obtained MnFe2O4@EP@Ag MRNCs displayed high efficiency and catalytic activity for the reduction of various azo dyes like methyl orange (MO), methyl red (MR), congo red (CR), alizarin yellow (AY), nitro aromatic compound, 4‐Nitrophenol (4 NP), and a common tracer, rhodamine B (RhB). Results displayed that the MnFe2O4@EP@Ag MRNCs revealed higher catalytic activity with the normalized rate constant (knor) of 350.47 s−1 g−1 for RhB reduction. Furthermore, they were highly efficient in the reduction of other azo dyes and nitro compound in the order of MO (85.51 s−1 g−1) > CR (70.09 s−1 g−1) > 4 NP (62.15 s−1 g−1) > AY (54.67 s−1 g−1) > MR (46.73 s−1 g−1). In addition, the MnFe2O4@EP@Ag MRNCs exhibited an excellent unchanged recovery efficiency even after several cycles; therefore, they can be good potential candidates for the treatment of organic pollutants in wastewater and a wide range of applications in heterogeneous catalysis.

Collagen-Carboxymethylcellulose Biocomposite Wound-Dressings with Antimicrobial Activity.

Microbial infections associated with skin diseases are frequently investigated since they impact on the progress of pathology and healing. The present work proposes the development of freeze-dried, glutaraldehyde cross-linked, and non-cross-linked biocomposite dressings with a porous structure, which may assist the reepithelization process through the presence of collagen and carboxymethylcellulose, along with a therapeutic antimicrobial effect, due to silver nanoparticles (AgNPs) addition. Phisyco-chemical characterization revealed the porous morphology of the obtained freeze-dried composites, the presence of high crystalline silver nanoparticles with truncated triangular and polyhedral morphologies, as well as the characteristic absorption bands of collagen, silver, and carboxymethylcellulose. In vitro tests also assessed the stability, functionality, and the degradability rate of the obtained wound-dressings. Antimicrobial assay performed on Gram-negative (Escherichia coli), Gram-positive (Staphyloccocus aureus) bacteria, and yeast (Candida albicans) models demonstrated that composite wound dressings based on collagen, carboxymethylcellulose, and AgNPs are suitable for skin lesions because they prevent the risk of infection and have prospective wound healing capacity. Moreover, the cell toxicity studies proved that the obtained materials can be used in long time treatments, with no cytotoxic effects.

Colorimetric Detection of Ammonia Using Synthesized Silver Nanoparticles from Durian Fruit Shell

There has been increased interest in the production of nanoparticles (NP) through green chemistry. This article used durian fruit shell aqueous solution that acts as a reductive preparation of silver NPs. The silver nanoparticles have a size of approximately 25 nm. The NP size uniformity was determined by the SEM and TEM analysis. X-ray diffraction technique was used to characterize crystalline silver nanoparticles face-centered cubic structure. XPS spectrum showed distinct silver peaks on the nanoparticles’ surface. An optical method that was based on surface plasmon resonance (SPR) was used to perform the green Ag NPs aqueous ammonia sensing study. Optical measurement facilitated the ammonia sensing study of Ag NPs that had been prepared. The study also investigated the performance of the optical sensor, thus adding validity to the study. Also, the research sought to determine how the concentration of ammonia in ammonia sensing affects the Ag NPs that had been obtained. The study observed a linear relationship with R2 as the correlation factor which was equal to 0.9831. This was observed from the ammonia concentration plot versus absorption ratio that suggested that there was a linear increase in absorption ratio with increase in ammonia concentration. The study significance is that the room temperature optical ammonia sensor can be used in future for medical diagnosis in the detection of low levels of ammonia in biological fluid like sweat, cerebrospinal fluid, saliva, plasma, or biological samples. This enhances the application of the technique in human biomedical applications.