Synthesis and characterization of Reishi mushroom-mediated green synthesis of silver nanoparticles for the biochemical applications

Green Synthesis of Superparamagnetic Iron Oxide Nanoparticles with Eucalyptus globulus Extract and Their Application in the Removal of Heavy Metals from Agricultural Soil

The green synthesis of metal oxide nanoparticles is presented as an excellent sustainable alternative for achieving nanostructures, with potential applications. This research provides important information regarding the influence of the type of solvent used in extracting organic reducing agents from E. globulus on the FeO NPs green synthesis protocol. A broad approach to characterization is presented, where UV-vis spectrophotometry suggests the presence of this type of nanoparticulate material. Likewise, the reduction mechanism was evaluated by FT-IR and the magnetic properties were evaluated by PPSM. In addition, characterizations were linked via elemental analysis (EDX), crystallographic characterization (XRD), electron microscopy (SEM/STEM), and Z potential to evaluate colloidal stability. The results show the influence of the type of solvent used for the extraction of organic reducing agents from E. globulus, and the effect on the synthesis of FeO NPs. In addition, the nanostructure material obtained showed excellent efficiency in the remediation of agricultural soil, eliminating metals such as Cr-VI, Cd, and, to a lesser extent, Pb.

Green synthesis, characterization of Radix Hedysari-mediated silver nanoparticles and their use for sensitive colorimetric detection of Pb2+ in the Yellow River medium

In this study, a safe, rapid, and environment-friendly green synthesis of silver nanoparticles using the alcohol extract of Radix Hedysari (RH-AgNPs) was developed, the alcohol extract of Radix Hedysari (RH) acted as the reducing agent, stabilizer, and modifier. The main components of RH were determined using high-performance liquid chromatography (HPLC). The particle size and morphology of RH-AgNPs were optimized and characterized by a series of techniques. The size distribution, zeta potential, element distribution, and crystalline nature of RH-AgNPs were all determined. It was indicated that RH-AgNPs showed great sensitivity for lead ion (Pb²⁺) detection with a limit of detection (LOD) of 1.5 μM with a wide range of 10-500 μM. The selectivity was also explored for common metal ions. RH-AgNPs were then applied to the detection of Pb²⁺ in spiked Yellow River samples, and the possible mechanism is based on the crosslinking reaction between the hydroxide radical, carboxylate radical and Pb²⁺.

Silver Nanoparticles for Conductive Inks: From Synthesis and Ink Formulation to Their Use in Printing Technologies

Currently, silver nanoparticles have attracted large interest in the photonics, electrics, analytical, and antimicrobial/biocidal fields due to their excellent optical, electrical, biological, and antibacterial properties. The versatility in generating different sizes, shapes, and surface morphologies results in a wide range of applications of silver nanoparticles in various industrial and health-related areas. In industrial applications, silver nanoparticles are used to produce conductive inks, which allows the construction of electronic devices on low-cost and flexible substrates by using various printing techniques. In order to achieve successful printed patterns, the necessary formulation and synthesis need to be engineered to fulfil the printing technique requirements. Additional sintering processes are typically further required to remove the added polymers, which are used to produce the desired adherence, viscosity, and reliable performance. This contribution presents a review of the synthesis of silver nanoparticles via different methods (chemical, physical and biological methods) and the application of silver nanoparticles under the electrical field. Formulation of silver inks and formation of conductive patterns by using different printing techniques (inkjet printing, screen printing and aerosol jet printing) are presented. Post-printing treatments are also discussed. A summary concerning outlooks and perspectives is presented at the end of this review.

Phyto-Capped Ag Nanoparticles: Green Synthesis, Characterization, and Catalytic and Antioxidant Activities

Using a simple approach, silver nanoparticles (Ag NPs) were synthesized from green coffee bean extract. The optical color change from yellowish to reddish-brown of the green-produced Ag NPs was initially observed, which was confirmed by the UV-Visible spectrophotometer’s surface plasmonic resonance (SPR) bands at 329 and 425 nm. The functional groups of green coffee-capped Ag NPs (GC-capped Ag NPs) were studied using a Fourier transform infrared spectrometer, revealing that Ag NPs had been capped by phytochemicals, resulting in excellent stability, and preventing nanoparticle aggregation. The presence of elemental silver is confirmed by energy dispersive X-ray analysis. In addition to the measurement of the zeta potential of the prepared GC-capped Ag NPs, the size distribution is evaluated by the dynamic light scattering. Depending on the nano-morphological study, the particle diameter of Ag NPs is 8.6 ± 3.5 nm, while the particle size of GC-capped Ag NPs is 29.9 ± 4.3 nm, implying the presence of well-dispersed nanospheres with an average capsulation layer of thickness 10.7 nm. The phyto-capped Ag NPs were found to be crystalline, having a face-centered cubic (FCC) lattice structure and Ag crystallite size of ~7.2 nm, according to the XRD crystallographic analysis. The catalytic performance of phyto-capped Ag NPs in the removal of methylene blue dye by sodium borohydride (NaBH₄) was investigated for 12 min to reach a degradation efficiency of approximately 96%. The scavenging activities of 2,2-Diphenyl-1-picrylhydrazyl (DPPH) free radicals are also examined in comparison to previously reported Ag-based nano-catalysts, demonstrating a remarkable IC₅₀ of 26.88 µg/mL, which is the first time it has been recorded.

Biogenic Synthesis of Silver Nanoparticles, Characterization and Their Applications—A Review

With the growing awareness for the need of sustainable environment, the importance of synthesizing and the application of green nanoparticles has gained special focus. Among various metal nanoparticles, silver nanoparticles (AgNPs) have gain significant attention. AgNPs are synthesized conventionally by physical and chemical methods using chemicals such as reducing agents, which are hazardous to environment due to their toxic properties, provoking a serious concern to create and develop environment friendly methods. Thus, biological alternatives are emerging to fill gaps, such as green syntheses that use biological molecules taken from plant sources in the form of extracts, which have shown to be superior to chemical and physical approaches. These biological molecules derived from plants are assembled in a highly regulated manner to make them suitable for metal nanoparticle synthesis. The current review outlines the wide plant diversity that may be used to prepare a rapid and single-step procedure with a green path over the traditional ones, as well as their antifungal activity.

Fungi as veritable tool in current advances in nanobiotechnology

Fungi have great prospects for synthesis, applications and developing new products in nanotechnology. In recent times, fungi use in nanotechnology is gaining more attention because of the ecological friendly state of their metabolite-mediated nanoparticles, their safety, amenability and applications in diverse fields. The diversity of the metabolites such as enzymes, polysaccharide, polypeptide, protein and other macro-molecules has made fungi a veritable tool for nanoparticles synthesis. Mechanism of fungal nano-biosynthesis from the molecular perspective has been extensively studied through various investigations on its green synthesized metal nanoparticles. Fungal nanobiotechnology has been applied in agricultural, medical and industrial sectors for goods and services improvement and delivery to mankind. Agriculturally, it has found applications in plant disease management and production of environmentally friendly, non-toxic insecticides, fungicides to enhance agricultural production in general. Medically, diagnosis and treatment of diseases, especially of microbial origin have been improved with fungal nanoparticles through more efficient drug delivery systems with great benefits to pharmaceutical industries. This review therefore explored fungal nanobiotechnology; mechanism of synthesis, characterization and potential applications in various fields of human endeavours for goods and services delivery.

Green Synthesis of Metal and Metal Oxide Nanoparticles: Principles of Green Chemistry and Raw Materials

Increased request for metal and metal oxide nanoparticles nanoparticles has led to their large-scale production using high-energy methods with various toxic solvents. This cause environmental contamination, thus eco-friendly “green” synthesis methods has become necessary. An alternative way to synthesize metal nanoparticles includes using bioresources, such as plants and plant products, bacteria, fungi, yeast, algae, etc. “Green” synthesis has low toxicity, is safe for human health and environment compared to other methods, meaning it is the best approach for obtaining metal and metal oxide nanoparticles. This review reveals 12 principles of “green” chemistry and examples of biological components suitable for “green” synthesis, as well as modern scientific research of eco-friendly synthesis methods of magnetic and metal nanoparticles. Particularly, using extracts of green tea, fruits, roots, leaves, etc., to obtain Fe3O4 NPs. The various precursors as egg white (albumen), leaf and fruit extracts, etc., can be used for the „green” synthesis of spinel magnetic NPs. “Green” nanoparticles are being widely used as antimicrobials, photocatalysts and adsorbents. “Green” magnetic nanoparticles demonstrate low toxicity and high biocompatibility, which allows for their biomedical application, especially for targeted drug delivery, contrast imaging and magnetic hyperthermia applications. The synthesis of silver, gold, platinum and palladium nanoparticles using extracts from fungi, red algae, fruits, etc., has been described.

Heterodimers of metal nanoparticles: synthesis, properties, and biological applications

Heterodimers of metal nanoparticles consist of two metals, come in many sizes and adopt various shapes. They offer unique properties due to the presence of two metals and have the extraordinary flexibility needed to serve as a multipurpose platform for diverse applications in areas including photonics, sensing, and catalysis. Heterodimer nanoparticles contain different metals that contribute to extraordinary surface plasmon resonance (SPR), surface-enhanced Raman scattering (SERS), and catalytic properties. These properties make them versatile molecules that can be used in intracellular imaging, as antibacterial agents, as photocatalytic and biological macromolecules and for the detection of chemical substances. Moreover, heterodimer nanoparticles are composed of the two metals within larger molecules that provide more choices for modification and application. In this review, we briefly summarize the lesser-known aspects of heterodimers, including some of their properties, and present concrete examples of recent progress in synthesis and applications. This review provides a perspective on achievements and suggests a framework for future research with a focus on the synthesis and application of heterodimers. We also explore the possible applications of heterodimer nanoparticles based on their unique properties.

Antioxidants: Classification, Natural Sources, Activity/Capacity Measurements, and Usefulness for the Synthesis of Nanoparticles

Natural extracts are the source of many antioxidant substances. They have proven useful not only as supplements preventing diseases caused by oxidative stress and food additives preventing oxidation but also as system components for the production of metallic nanoparticles by the so-called green synthesis. This is important given the drastically increased demand for nanomaterials in biomedical fields. The source of ecological technology for producing nanoparticles can be plants or microorganisms (yeast, algae, cyanobacteria, fungi, and bacteria). This review presents recently published research on the green synthesis of nanoparticles. The conditions of biosynthesis and possible mechanisms of nanoparticle formation with the participation of bacteria are presented. The potential of natural extracts for biogenic synthesis depends on the content of reducing substances. The assessment of the antioxidant activity of extracts as multicomponent mixtures is still a challenge for analytical chemistry. There is still no universal test for measuring total antioxidant capacity (TAC). There are many in vitro chemical tests that quantify the antioxidant scavenging activity of free radicals and their ability to chelate metals and that reduce free radical damage. This paper presents the classification of antioxidants and non-enzymatic methods of testing antioxidant capacity in vitro, with particular emphasis on methods based on nanoparticles. Examples of recent studies on the antioxidant activity of natural extracts obtained from different species such as plants, fungi, bacteria, algae, lichens, actinomycetes were collected, giving evaluation methods, reference antioxidants, and details on the preparation of extracts.

Potential Usage of Edible Mushrooms and Their Residues to Retrieve Valuable Supplies for Industrial Applications

Currently, the food and agricultural sectors are concerned about environmental problems caused by raw material waste, and they are looking for strategies to reduce the growing amount of waste disposal. Now, approaches are being explored that could increment and provide value-added products from agricultural waste to contribute to the circular economy and environmental protection. Edible mushrooms have been globally appreciated for their medicinal properties and nutritional value, but during the mushroom production process nearly one-fifth of the mushroom gets wasted. Therefore, improper disposal of mushrooms and untreated residues can cause fungal disease. The residues of edible mushrooms, being rich in sterols, vitamin D2, amino acids, and polysaccharides, among others, makes it underutilized waste. Most of the published literature has primarily focused on the isolation of bioactive components of these edible mushrooms; however, utilization of waste or edible mushrooms themselves, for the production of value-added products, has remained an overlooked area. Waste of edible mushrooms also represents a disposal problem, but they are a rich source of important compounds, owing to their nutritional and functional properties. Researchers have started exploiting edible mushroom by-products/waste for value-added goods with applications in diverse fields. Bioactive compounds obtained from edible mushrooms are being used in media production and skincare formulations. Furthermore, diverse applications from edible mushrooms are also being explored, including the synthesis of biosorbent, biochar, edible films/coating, probiotics, nanoparticles and cosmetic products. The primary intent of this review is to summarize the information related to edible mushrooms and their valorization in developing value-added products with industrial applications.

Silver nanoparticles synthesized by Nigrospora oryzae showed antifungal activity

In this investigation, an alternate green-route based on myco-synthesised silver nanoparticles (Ag NPs) was evaluated to control plant disease to reduce the usage of synthetic chemicals. Here, we described biologically synthesised Ag NPs using the corn grain contaminant, Nigrospora oryzae, and were well-characterised by UV-visible spectrophotometer, X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Energy Dispersive Spectroscopy (EDS) and particle size analyzer. The pathogenic behaviour of the Fusarium spp. were checked on Giza 86 and Giza 90 cultivars under greenhouse conditions. F. moniliforme and F. oxysporum exhibited high pathogenecity against Giza 90 and Giza 86 cultivars respectively. The antifungal activity of biosynthesised Ag NPs was evaluated against eight species of Fusaria causing damping-off of cotton seedlings. In vitro treatments with different concentrations of Ag NPs were achieved on Czapek Dox agar and Potato dextrose agar plates. Fungal growth was drastically retarded from 25 to 200 ppm of Ag NPs interaction. The antifungal activity of Ag NPs against the Fusarium spp. was clearly proven.

Biogenic synthesis and cytotoxic effects of silver nanoparticles mediated by white rot fungi

Silver nanoparticles (AgNPs) were successfully synthesized using silver nitrate via the biological route using the culture filtrate of Ganoderma enigmaticum as well as Trametes ljubarskyi white rot fungi materials at room temperature. The proposed synthetic technique was applied for the first time for AgNPs preparation via the biological route through a low-cost pathway, which considered as an adequate direction of preparation compared to the commercial methods. This study reports the in vitro cytotoxic effect of biologically synthesized AgNPs in disposing of the human lung cancer cell line (A549) and human breast cancer cell (MCF-7) by using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. In addition, the viability of the tested cell lines was tested after treatment for 24 h in the presence of the prepared nanoparticles. The obtained results indicated the reduced viability of cancer cell lines with improving concentrations of AgNPs (40-120 μg/mL) at 24 h. Furthermore, at 120 μg/mL concentration, the fungal nanoparticles showed substantial cytotoxic effects toward the treated cells. Consequently, the results designated that the biologically synthesized silver nanoparticles have effective behavior for treating A549 and MCF-7 cancer cells from the laboratory experiment approach; however, additional studies are required to validate these results in vivo models as anticancer agents depending on their cytotoxic activity.

Biogenic Silver Nanoparticles Synthesized by Lysinibacillus xylanilyticus MAHUQ-40 to Control Antibiotic-Resistant Human Pathogens Vibrio parahaemolyticus and Salmonella Typhimurium

The present study highlights a simple and eco-friendly method for the biosynthesis of silver nanoparticles (AgNPs) using Lysinibacillus xylanilyticus strain MAHUQ-40. Also, the synthesized AgNPs were used to investigate their antibacterial activity and mechanisms against antibiotic-resistant pathogens. Biosynthesis of AgNPs was confirmed by ultraviolet-visible spectroscopy, and then, they were characterized by field emission-transmission electron microscopy (FE-TEM), X-ray diffraction (XRD), dynamic light scattering (DLS), and fourier transform-infrared (FTIR). The toxicity of AgNPs against two pathogenic bacteria was evaluated. The UV-vis spectral scanning showed the peak for synthesized AgNPs at 438 nm. Under FE-TEM, the synthesized AgNPs were spherical with diameter ranges from 8 to 30 nm. The XRD analysis revealed the crystallinity of synthesized AgNPs. FTIR data showed various biomolecules including proteins and polysaccharides that may be involved in the synthesis and stabilization of AgNPs. The resultant AgNPs showed significant antibacterial activity against tested pathogens. The MICs (minimum inhibitory concentrations) and MBCs (minimum bactericidal concentrations) of the AgNPs synthesized by strain MAHUQ-40 were 3.12 and 12.5 μg/ml, respectively, against Vibrio parahaemolyticus and 6.25 and 25 μg/ml, respectively, against Salmonella Typhimurium. FE-TEM analysis showed that the biogenic AgNPs generated structural and morphological changes and damaged the membrane integrity of pathogenic bacteria. Our findings showed the potentiality of L. xylanilyticus MAHUQ-40 to synthesis AgNPs that acted as potent antibacterial material against pathogenic bacterial strains.

The first and low cost copper Schiff base/manganese oxide bio nanocomposite from unwanted plants as a robust industrial catalyst

In this paper, the first bio-nano colloid including manganese oxide nanoparticles and copper nanocomplex in the presence of Amaranthus spinosus as one unwanted plant was prepared (Mn₃O₄/CuL bio-nanocolloid). As-prepared bio nanocolloid was analysed completely by different techniques such as FT-IR, ICP-AES, SEM, EDX, TEM and elemental analysis to have the size, structure, morphology and elements in this compound. This bio-nanocolloid showed high catalytic activity towards green oxidation reactions of alcohols using hydrogen peroxide under solvent free conditions. The longevity, easy and practical recoverability of the solid catalyst was also confirmed for six times. The natural starting material for a long-term stability catalyst preparation, using ideal oxidant (H₂O₂), solventless and easy work up show the great potential in scalability for actual industries applications.

Ganoderma lucidum inspired silver nanoparticles and its biomedical applications with special reference to drug resistant Escherichia coli isolates from CAUTI

In the search for alternative therapy for infections and other ailments, metallic nanoparticles, mainly silver nanoparticles (AgNPs) synthesized through bioengineered sources are extensively explored. Fungal bioactive compounds and their nanoparticles were reported with the potential biomedical application. A medicinal mushroom Ganoderma lucidum was reported as a repository of rich medicinal properties. In the current study, silver nanoparticles were synthesized using the extracts of G. lucidum and its antimicrobial activity was tested against drug-resistant Escherichia coli isolated from the catheter used for urinary tract infection (CAUTI). The GC-MS study of G. lucidum extracts showed the presence of ethyl acetoacetate ethylene acetal with the highest area percentage of 72.2% and retention time (RT 5873). Pyridine-3-ol is the second primary compound with a peak height of 6.44% and a retention time of 2.143. The third compound is l,4-Dioxane-2,3-diol, with an area of 8.09% and RT 5450. Butylated Hydroxy Toluene [BHT] is the fourth major compound with an area of 3.32%, and 9-Cedranone constitutes the fifth position in occupying the area percentage [1.88] and height 1.56%. Pyrrole is the sixth primary compound registering an area size of 0.96% and height 2.06%. The AgNPs synthesized using G. lucidum extract were in size range 23 and 58 nm as per SEM analysis and within the range wavelength 0.556-0.796 nm as per UV-Vis spectral study. FTIR Spectroscopy and X-ray diffraction analysis (XRD) were made to characterize the formed nanoparticles. The AgNPs synthesized effectively inhibited the growth of E. coli isolated from catheter-associated urinary tract infection and showed resistance to many drugs. The antioxidant potential of the synthesized nanoparticles assessed using DPPH radical scavenging activity, EC50 (µg/ml), and ARP data showed that the prepared nanoparticles were more potent in free radical scavenging activity than the standard quercetin. The cytotoxicity effect of Ag-NPs on breast cancer cell line- MDA-MB-231 confirmed its anticancer potential. The half-maximal inhibitory concentration (IC50) of Ag-NPs to inhibit 50% of the tumor was 9.2 g/mL. The synthesized GL-AgNPs was exhibited a multifocal biomedical potential.

Green Synthesis and Antibacterial Activity of HAp@Ag Nanocomposite Using Centella asiatica (L.) Urban Extract and Eggshell

In recent years, the green synthesis of nanoparticles via biological processes has attracted considerable attention. Herein, we introduce a facile and green approach for the synthesis of poriferous silver nanoparticles (Ag-NPs) decorated hydroxylapatite (HAp@Ag) nanoparticles with excellent antibacterial properties. All the nanocomposites were fully characterized in the solid state via various techniques such as X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and energy-dispersive X-ray spectrometer (EDX), in which the synthesized Ag-NPs (24 nm in diameter) and their homogeneous incorporation on HAp have been studied by ultraviolet-visible (UV-vis) technique, transmission electron microscopy (TEM), and dynamic light scattering (DLS) analysis. The obtained results indicate that the structure and morphology of HAp have no significant changes after the incorporation of Ag-NPs on its surface. Moreover, an impressive antibacterial activity of HAp@Ag nanocomposite against Gram-positive bacterium Staphylococcus aureus and Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa has been recorded by using the agar well diffusion method. As a result, the HAp@Ag nanocomposite promises to be a great biomedical material with high antibacterial properties.

Antimicrobial metal-based nanoparticles: a review on their synthesis, types and antimicrobial action

The investigation of novel nanoparticles with antimicrobial activity has grown in recent years due to the increased incidence of nosocomial infections occurring during hospitalization and food poisoning derived from foodborne pathogens. Antimicrobial agents are necessary in various fields in which biological contamination occurs. For example, in food packaging they are used to control food contamination by microbes, in the medical field the microbial agents are important for reducing the risk of contamination in invasive and routine interventions, and in the textile industry, they can limit the growth of microorganisms due to sweat. The combination of nanotechnology with materials that have an intrinsic antimicrobial activity can result in the development of novel antimicrobial substances. Specifically, metal-based nanoparticles have attracted much interest due to their broad effectiveness against pathogenic microorganisms due to their high surface area and high reactivity. The aim of this review was to explore the state-of-the-art in metal-based nanoparticles, focusing on their synthesis methods, types, and their antimicrobial action. Different techniques used to synthesize metal-based nanoparticles were discussed, including chemical and physical methods and "green synthesis" methods that are free of chemical agents. Although the most studied nanoparticles with antimicrobial properties are metallic or metal-oxide nanoparticles, other types of nanoparticles, such as superparamagnetic iron-oxide nanoparticles and silica-releasing systems also exhibit antimicrobial properties. Finally, since the quantification and understanding of the antimicrobial action of metal-based nanoparticles are key topics, several methods for evaluating in vitro antimicrobial activity and the most common antimicrobial mechanisms (e.g., cell damage and changes in the expression of metabolic genes) were discussed in this review.

Hetta H, Shaheen TI. Endophytic Streptomyces laurentii Mediated Green Synthesis of Ag-NPs with Antibacterial and Anticancer Properties for Developing Functional Textile Fabric Properties

Improvement of the medical textile industry has received more attention recently, especially with widespread of microbial and viral infections. Medical textiles with new properties, such as bacterial pathogens self-cleaning, have been explored with nanotechnology. In this study, an endophytic actinomycetes strain of Streptomyces laurentii R-1 was isolated from the roots of the medicinal plant Achillea fragrantissima. This is used as a catalyst for the mediated biosynthesis of silver nanoparticles (Ag-NPs) for applications in the textile industry. The biosynthesized Ag-NPs were characterized using UV-vis spectroscopy, Fourier transform infrared (FT-IR), transmission electron microscopy (TEM), and X-ray Diffraction (XRD), which confirmed the successful formation of crystalline, spherical metal nanoparticles. The biosynthesized Ag-NPs exhibited broad-spectrum antibacterial activity. Our data elucidated that the biosynthesized Ag-NPs had a highly cytotoxic effect against the cancerous caco-2 cell line. The selected safe dose of Ag-NPs for loading on cotton fabrics was 100 ppm, regarding their antibacterial activity and safe cytotoxic efficacy. Interestingly, scanning electron microscope connected with energy dispersive X-ray spectroscopy (SEM-EDX) of loaded cotton fabrics demonstrated the smooth distribution of Ag-NPs on treated fabrics. The obtained results highlighted the broad-spectrum activity of nano-finished fabrics against pathogenic bacteria, even after 5 and 10 washing cycles. This study contributes a suitable guide for the performance of green synthesized NPs for utilization in different biotechnological sectors.

Zizyphus mauritiana Fruit Extract-Mediated Synthesized Silver/Silver Chloride Nanoparticles Retain Antimicrobial Activity and Induce Apoptosis in MCF-7 Cells through the Fas Pathway

Recently, green synthesis of silver/silver chloride nanoparticles (Ag/AgCl-NPs) has gained a lot of interest because of the usage of natural resources, rapidness, eco-friendliness, and benignancy. Several researchers reported that silver-based biogenic NPs have both antimicrobial and anticancer properties. In the present study, Ag/AgCl-NPs were synthesized from Zizyphus mauritiana fruit extract, and their antibacterial, antifungal, and antiproliferative mechanisms against human MCF-7 cell lines were evaluated. Synthesis of Ag/AgCl-NPs from the Z. mauritiana fruit extract was confirmed by the changes of color and a peak of the UV-visible spectrum at 428 nm. The nanoparticles were characterized by transmission electron microscopy, energy dispersive X-ray, X-ray powder diffraction, thermal gravimetric analysis, atomic force microscope, and Fourier transform infrared. Antibacterial activity was checked against four pathogenic bacteria and two fungi. Cytotoxicity was checked against human breast cancer cell line (MCF-7) and mice Ehrlich ascites carcinoma (EAC) cells by MTS assay and clonogenicity assay. Cell morphology of the control and nanoparticle-treated MCF-7 cells were checked by Hoechst 33342, YF488-Annexin V, and caspase-3 substrates. The level of reactive oxygen species (ROS) was studied by using 2',7'-dichlorofluorescein-diacetate staining. Real-time polymerase chain reaction was used for gene expression. Synthesized nanoparticles were heat stable cubic crystals with an average size of 16 nm that contain silver and chlorine with various functional groups. The synthesized Ag/AgCl-NPs inhibited the growth of three pathogenic bacteria (Bacillus subtilis, Shigella boydii, and Escherichia coli) and two fungi (Aspergillus niger and Trichoderma spp.). Ag/AgCl-NPs inhibited the growth of MCF-7 and EAC cells with the IC₅₀ values of 28 and 84 μg/mL, respectively. No colony was formed in MCF-7 cells in the presence of these nanoparticles as compared with control. Ag/AgCl-NPs induced apoptosis and generated ROS in MCF-7 cells. The expression level of FAS, FADD, and caspase-8 genes increased several folds with the decrease of PARP gene expression. These results demonstrated that the anti-proliferation activity of Ag/AgCl-NPs against MCF-7 cells resulted through ROS generation and induction of apoptosis through the Fas-mediated pathway.

Antioxidant Functionalized Nanoparticles: A Combat against Oxidative Stress

Numerous abiotic stresses trigger the overproduction of reactive oxygen species (ROS) that are highly toxic and reactive. These ROS are known to cause damage to carbohydrates, DNA, lipids and proteins, and build the oxidative stress and results in the induction of various diseases. To resolve this issue, antioxidants molecules have gained significant attention to scavenge these free radicals and ROS. However, poor absorption ability, difficulty in crossing the cell membranes and degradation of these antioxidants during delivery are the few challenges associated with both natural and synthetic antioxidants that limit their bioavailability. Moreover, the use of nanoparticles as an antioxidant is overlooked, and is limited to a few nanomaterials. To address these issues, antioxidant functionalized nanoparticles derived from various biological origin have emerged as an important alternative, because of properties like biocompatibility, high stability and targeted delivery. Algae, bacteria, fungi, lichens and plants are known as the producers of diverse secondary metabolites and phenolic compounds with extraordinary antioxidant properties. Hence, these compounds could be used in amalgamation with biogenic derived nanoparticles (NPs) for better antioxidant potential. This review intends to increase our knowledge about the antioxidant functionalized nanoparticles and the mechanism by which antioxidants empower nanoparticles to combat oxidative stress.

Antibacterial effect of silver nanorings

Background

The emergence and expansion of antibiotic resistance makes it necessary to have alternative anti-infective agents, among which silver nanoparticles (AgNPs) display especially interesting properties. AgNPs carry out their antibacterial action through various molecular mechanisms, and the magnitude of the observed effect is dependent on multiple, not fully understood, aspects, particle shape being one of the most important. In this article, we conduct a study of the antibacterial effect of a recently described type of AgNP: silver nanorings (AgNRs), making comparisons with other alternative types of AgNP synthesized in parallel using the same methodology.

Results

When they act on planktonic forms, AgNRs produce a smaller effect on the viability of different bacteria than nanoparticles with other structures although their effect on growth is more intense over a longer period. When their action on biofilms is analyzed, AgNRs show a greater concentration-dependent effect. In both cases it was observed that the effect on inhibition depends on the microbial species, but not its Gram positive or negative nature. Growth patterns in silver-resistant Salmonella strains suggest that AgNRs work through different mechanisms to other AgNPs. The antibacterial effect is also produced to some extent by the conditioning of culture media or water by contact with AgNPs but, at least over short periods of time, this is not due to the release of Ag ions.

Conclusions

AgNRs constitute a new type of AgNP, whose antibacterial properties depend on their shape, and is capable of acting efficiently on both planktonic bacteria and biofilms.

A hybrid lipid membrane coating "shape-locks" silver nanoparticles to prevent surface oxidation and silver ion dissolution

The controlled synthesis of stable silver nanoparticles (AgNPs), that do not undergo surface oxidation and Ag+ ion dissolution, continues to be a major challenge. Here the synthesis of robust hybrid lipid-coated AgNPs, comprised of l-α-phosphatidylcholine (PC) membranes anchored by a stoichiometric amount of long-chained hydrophobic thiols and sodium oleate (SOA) as hydrophobic binding partners, that do not undergo surface oxidation and Ag+ ion dissolution, is described. UV-Visible (UV-Vis) spectroscopy, transmission electron microscopy (TEM), and inductively coupled plasma mass spectrometry (ICP-MS) demonstrate that in the presence of strong oxidants, such as potassium cyanide (KCN), the hybrid lipid-coated AgNPs are stable and do not undergo surface oxidation even in the presence of membrane destabilizing surfactants. UV-Vis studies show that the stability of hybrid lipid-coated AgNPs of various sizes and shapes is dependent on the length of the thiol hydrocarbon chain and can be ranked in the order of increasing stability as follows: propanethiol (PT) < hexanethiol (HT) ≤ decanethiol (DT). UV-Vis and ICP-MS studies show that the hybrid lipid-coated AgNPs do not change in size or shape confirming that the AgNPs do not undergo surface oxidation and Ag+ ion dissolution when placed in the presence of strong oxidants, chlorides, thiols, and low pH. Long-term stability studies, over 21 days, show that the hybrid lipid-coated AgNPs do not release Ag+ ions and are more stable. Overall, these studies demonstrate hybrid membrane encapsulation of nanomaterials is a viable method for stabilizing AgNPs in a "shape-locked" form that is unable to undergo surface oxidation, Ag+ ion release, aging, or shape conversion. More importantly, this design strategy is a simple approach to the synthesis and stabilization of AgNPs for a variety of biomedical and commercial applications where Ag+ ion release and toxicity is a concern. With robust and shielded AgNPs, investigators can now evaluate and correlate how the physical features of AgNPs influence toxicity without the confounding factor of Ag+ ions present in samples. This design strategy also provides an opportunity where the membrane composition can be tuned to control the release rate of Ag+ ions for optimizing antimicrobial activity.

Synthesis of Silver Nanoparticles Using a Novel Cyanobacteria Desertifilum sp. extract: Their Antibacterial and Cytotoxicity Effects

BACKGROUND

The emergence of multi drug-resistant (MDR) bacterial infections and cancer has necessitated the development and discovery of alternative eco-safe antibacterial and anticancer agents. Biogenic fabrication of metallic nanoparticles is an emerging discipline for production of nanoproducts that exert potent anticancer and antibacterial activity, and do not suffer from the limitations inherent in physiochemical synthesis methods.

METHODOLOGY

In this study, we isolated, purified, and characterized a novel cyanobacteria extract (Desertifilum IPPAS B-1220) to utilize in biofabrication of silver nanoparticles (D-SNPs). D-SNPs were produced by adding Desertifilum extract to silver nitrate solution under controlled conditions. Biofabrication of D-SNPs was confirmed using a UV-Vis spectrophotometer. The resultant D-SNPs were characterized using XRD, FTIR, SEM, and TEM. The toxicity of D-SNPs against five pathogenic bacteria and three cancer cell lines (MCF-7, HepG2, and Caco-2) was evaluated.

RESULTS

Formation of D-SNPs was indicated by a color change from pale yellow to dark brown. The peak of the surface plasmon resonance of the D-SNPs was at 421 nm. The XRD detected the crystallinity of D-SNPs. FTIR showed that polysaccharides and proteins may have contributed to the biofabrication of D-SNPs. Under SEM and TEM, the D-SNPs were spherical with diameter ranges from 4.5 to 26 nm. The D-SNPs significantly suppressed the growth of five pathogenic bacteria, and exerted cytotoxic effects against MCF-7, HepG2, and Caco-2 cancer cells with IC50 values of 58, 32, and 90 µg/mL, respectively.

CONCLUSION

These findings showed for the first time the potentiality of novel cyanobacteria strain Desertifilum IPPAS B-1220 to fabricate small SNPs that acted as potent anticancer and antibacterial material against different cancer cell lines and pathogenic bacterial strains. These findings encourage the researchers to focus on cyanobacteria in general and especially Desertifilum sp. IPPAS B-1220 for synthesizing different NPs that opening the window for new applications.

Silver nanoparticles stabilized by a metal–organic framework (MIL-101(Cr)) as an efficient catalyst for imine production from the dehydrogenative coupling of alcohols and amines

In this paper, we present silver nanoparticles supported on a metal–organic framework (Ag@MIL-101) as a catalyst for the one-pot tandem synthesis of imines from alcohols and amines.