Extracellular biosynthesis of silver nanoparticles using the fungus Fusarium oxysporum

Role of Protein in Fungal Biomineralization of Copper Carbonate Nanoparticles

Biomineralization processes are of key importance in the biogeochemical cycling of metals and other elements by microorganisms, and several studies have highlighted the potential applications of nanoparticle synthesis via biomineralization. The roles played by proteins in the transformation and biologically induced biomineralization of metals by microorganisms is not well understood, despite the interactions of protein and nanoparticles at mineral interfaces attracting much interest in various emerging fields for novel biomaterial synthesis. Here, we have elucidated the association and involvement of fungal proteins in the formation of biogenic copper carbonate nanoparticles (CuNPs) using a carbonate-enriched biomass-free ureolytic fungal culture supernatant. Proteomic analysis was conducted that identified the major proteins present in the culture supernatant. Of the proteins identified, triosephosphate isomerase (TPI) exhibited a strong affinity to the CuNPs, and the impact of purified TPI on CuNP formation was studied in detail. The combined use of scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) confirmed that TPI played an important role in controlling the morphology and structure of the nanomaterials. Fourier transform infrared spectroscopy (FTIR) was applied to examine conformational changes of the proteins to further clarity the interaction mechanisms with CuNPs during biomineralization. Such analyses revealed unfolding of proteins on the mineral surface and an increase in β sheets within the protein structure. These results extend understanding of how microbial systems can influence biomineral formation through protein secretion, the mechanisms involved in formation of complex protein/inorganic systems, and provide useful guidelines for the synthesis of inorganic-protein based nanomaterials.

Cellulose nanocrystal assisted trace silver nitrate to synthesize green silver nanocomposites with antibacterial activity

Cellulose nanocrystals (CNCs) with silver nanoparticles (AgNPs) are used for applications ranging from chemical catalysis to environmental remediation, and generation of smart electronics and biological medicine such as antibacterial agents. To reduce the synthesis cost of AgNPs and environmental pollution, microwave-assisted generation of AgNPs on the CNC surface (AgNPs@CNC) has been found to be useful, because microwave reaction has the advantages of simple reaction conditions, short reaction time and high reaction efficiency. The silver ions (Ag⁺) could be added to the CNC suspension and placed in the microwave reactor for a few minutes to produce AgNPs. AgNP generation was affected by factors such as the concentrations of Ag⁺ and CNC, and the power of the microwave, as well as the time of reaction. In this study, we used trace amounts of AgNO₃ to rapidly synthesize AgNPs using a green microwave-based method instead of Tollen's reagent, and the antibacterial activity of the T1 sample showed that only using 0.03 mM (∼0.01 wt%) AgNO₃ to synthesize AgNPs@CNC could achieve good antibacterial properties.

Cellulose nanocrystals (CNCs) with silver nanoparticles (AgNPs) are used for applications ranging from chemical catalysis to environmental remediation, and generation of smart electronics and biological medicine such as antibacterial agents.

Antibacterial efficacy of facile cyanobacterial silver nanoparticles inferred by antioxidant mechanism

Nanoparticles (NPs) have gained importance in technological advances owing to their user friendly enhanced and efficient physical, chemical, and biological characteristics compared to their bulk counterparts. Biological synthesis of NPs by using a microorganism, enzymes, or plant extracts offers a greener and eco-friendly approach besides many advantages over physical or chemical approaches. This study reports the biosynthesis of silver nanoparticles (AgNPs) using Nostoc muscorum NCCU 442 aqueous extract as the reducing and capping agent for AgNPs synthesis. The synthesized nanoparticles were characterized by UV-VIS spectrum, SEM, EDS, TEM, AFM, DLS and XRD. Results showed distinguishing polycrystalline nature of synthesized AgNPs with surface plasmon significant band in the size range of 6-45nm with average 30 size nm. FT-IR study revealed the role of secondary metabolites present in aqueous extract for the synthesis of AgNPs. Biological activities of purified AgNPs as antioxidant and antibacterial potential showed the highest antibacterial activity against Staphylococcus aureus MTCC 902.

Integrating biometallurgical recovery of metals with biogenic synthesis of nanoparticles

Industrial activities, such as mining, electroplating, cement production, and metallurgical operations, as well as manufacturing of plastics, fertilizers, pesticides, batteries, dyes or anticorrosive agents, can cause metal contamination in the surrounding environment. This is an acute problem due to the non-biodegradable nature of metal pollutants, their transformation into toxic and carcinogenic compounds, and bioaccumulation through the food chain. At the same time, platinum group metals and rare earth elements are of strong economic interest and their recovery is incentivized. Microbial interaction with metals or metals-bearing minerals can facilitate metals recovery in the form of nanoparticles. Metal nanoparticles are gaining increasing attention due to their unique characteristics and application as antimicrobial and antibiofilm agents, biocatalysts, in targeted drug delivery, for wastewater treatment, and in water electrolysis. Ideally, metal nanoparticles should be homogenous in shape and size, and not toxic to humans or the environment. Microbial synthesis of nanoparticles represents a safe, and environmentally friendly alternative to chemical and physical methods. In this review article, we mainly focus on metal and metal salts nanoparticles synthesized by various microorganisms, such as bacteria, fungi, microalgae, and yeasts, as well as their advantages in biomedical, health, and environmental applications.

Silver Nanoparticles: Mechanism of Action and Probable Bio-Application

This review is devoted to the medical application of silver nanoparticles produced as a result of "green" synthesis using various living organisms (bacteria, fungi, plants). The proposed mechanisms of AgNPs synthesis and the action mechanisms on target cells are highlighted.

Biosynthesis, characterization, and in vitro assessment on cytotoxicity of actinomycete-synthesized silver nanoparticles on Allium cepa root tip cells

Background

The industrial production of silver nanoparticles (AgNPs) and its commercial applications are being considerably increased in recent times, resulting in the release of AgNPs in the environment and enhanced probability of contaminations and their adverse effects on living systems. Based on this, the present study was conducted to evaluate the in vitro cytotoxicity of actinomycete-synthesized AgNPs on Allium cepa (A. cepa) root tip cells. A green synthesis method was employed for biosynthesis of AgNPs from Streptomyces sp. NS-33. However, morphological, physiological, biochemical, and molecular analysis were carried out to characterize the strain NS-33. Later, the synthesized AgNPs were characterized and antibacterial activity was also carried out against pathogenic bacteria. Finally, cytotoxic activity was evaluated on A. cepa root tip cells.

Results

Results showed the synthesis of spherical and polydispersed AgNPs with a characteristic UV-visible (UV-Vis.) spectral peak at 397 nm and average size was 32.40 nm. Energy dispersive spectroscopy (EDS) depicted the presence of silver, whereas Fourier transform infrared (FTIR) studies indicated the presence of various functional groups. The phylogenetic relatedness of Streptomyces sp. NS-33 was found with Streptomyces luteosporeus through gene sequencing. A good antibacterial potential of AgNPs was observed against two pathogenic bacteria. Concerning cytotoxicity, a gradually decreased mitotic index (MI) and increased chromosomal aberrations were observed along with the successive increase of AgNPs concentration.

Conclusions

Therefore, the release of AgNPs into the environment must be prevented, so that it cannot harm plants and other beneficial microorganisms.

Silver nanoparticles: synthesis, characterisation and biomedical applications

Nanotechnology is a rapidly growing field due to its unique functionality and a wide range of applications. Nanomedicine explores the possibilities of applying the knowledge and tools of nanotechnology for the prevention, treatment, diagnosis and control of disease. In this regard, silver nanoparticles with diameters ranging from 1 to 100 nm are considered most important due to their unique properties, ability to form diverse nanostructures, their extraordinary range of bactericidal and anticancer properties, wound healing and other therapeutic abilities and their cost-effectiveness in production. The current paper reviews various types of physical, chemical and biological methods used in the production of silver nanoparticles. It also describes approaches employing silver nanoparticles as antimicrobial and antibiofilm agents, as antitumour agents, in dentistry and dental implants, as promoters of bone healing, in cardiovascular implants and as promoters of wound healing. The paper also explores the mechanism of action, synthesis methods and morphological characterisation of silver nanoparticles to examine their role in medical treatments and disease management.

Photo-mediated optimized synthesis of silver nanoparticles using the extracts of outer shell fibre of Cocos nucifera L. fruit and detection of its antioxidant, cytotoxicity and antibacterial potential

Presently, photo-mediated optimized synthesis of SNPs (CS-AgNPs) was carried out with the help of aqueous extracts of coconut (Cocos nucifera) outer shell fibre. Green synthesis of CS-AgNPs was undertaken under laboratory light conditions and characterized by several standard techniques such as UV–visible spectrophotometer (UV–Vis), X-ray diffraction pattern (XRD), Fourier transform infrared (FT-IR), and scanning electron microscopy (SEM) images and energy dispersive spectroscopy (EDX). UV–Vis spectra displayed a surface plasmon resonance peak at 468 nm equivalent to CS-AgNPs, and the FT-IR spectra confirmed the association of biological molecules from the extract in the synthesis process. The SEM image data confirmed the round and circular nature of CS-AgNPs. The EDX data presented the elemental configuration with a solid peak at 3 KeV that matched with the Ag. The synthesized CS-AgNPs exhibited substantial cytotoxicity potential against the HepG2 cells with (effective concentration (IC₅₀) value of 15.28 µg/ml along with robust antioxidant potential, with respect to its 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging (IC₅₀ of 96.39 µg/ml) and reducing assay (IC_0.5 of 209.96 µg/ml). The CS-AgNPs demonstrated encouraging antimicrobial potential against four different pathogenic bacteria and one Candida sp. with inhibition zone diameter ranged between 8.87 and 13.07 mm. Overall, the existing investigation suggested that CS-AgNPs can be an attractive, cost-effective, and environment-friendly candidate for its possible uses in the food, cosmetics, and therapeutic fields.

A Concise Review on Multidimensional Silver Nanoparticle Health Aids and Threats

Benefits and Risk:

AgNps have beneficial approaches for cancer treatment and angiogenesisrelated diseases like rheumatoid arthritis, atherosclerosis, diabetic psoriasis, retinopathy, endometriosis, and adiposity.

Result:

The advancing nanotechnology-based therapy needs to be devised better, and it should offload the hitches of prevailing treatment approaches. Essential studies are required to explain the synergistic effect of two different cytotoxic agents.

Green synthesis of silver nanoparticles using Citrus limon peels and evaluation of their antibacterial and cytotoxic properties

The present work aimed to synthesis silver nanoparticles (AgNPs) using biological waste products Citrus limon peels, its characterization, antimicrobial activities and the cytotoxic effect of the synthesized green AgNPs. Characterization of the prepared AgNPs showed the formation of spherical, and few agglomerated AgNPs forms as measured by UV–visible spectrophotometer. The average size of the prepared AgNPs was 59.74 nm as measured by DLS technique. The spectrum of the synthesized AgNPs was observed at 3 KeV using the EDX. On the other hand, FTIR analysis of the green synthesized AgNPs showed the presence of alcohols, phenolics, mono-substituted alkynes, aliphatic primary amines, sodium salt, amino acid, or SiOH alcohol groups. The antimicrobial studies of the formed AgNPs showed positive activity against most of the studied human pathogenic bacteria with varying degrees. Finally, the evaluation of the cytotoxic effect of the green synthesized AgNPs were done using two types of cell lines, human breast cancer cell line (MCF-7) and human colon carcinoma cell line (HCT-116). The results revealed the concentration has a direct correlation with cell viability. The 50% inhibitory concentration (IC₅₀) of MCF-7 cell line was in of 23.5 ± 0.97 µL/100 µL, whereas the HCT-116 cell line was in 37.48 ± 5.93 µL/100 µL.

Therapies and Vaccines Based on Nanoparticles for the Treatment of Systemic Fungal Infections

Treatment modalities for systemic mycoses are still limited. Currently, the main antifungal therapeutics include polyenes, azoles, and echinocandins. However, even in the setting of appropriate administration of antifungals, mortality rates remain unacceptably high. Moreover, antifungal therapy is expensive, treatment periods can range from weeks to years, and toxicity is also a serious concern. In recent years, the increased number of immunocompromised individuals has contributed to the high global incidence of systemic fungal infections. Given the high morbidity and mortality rates, the complexity of treatment strategies, drug toxicity, and the worldwide burden of disease, there is a need for new and efficient therapeutic means to combat invasive mycoses. One promising avenue that is actively being pursued is nanotechnology, to develop new antifungal therapies and efficient vaccines, since it allows for a targeted delivery of drugs and antigens, which can reduce toxicity and treatment costs. The goal of this review is to discuss studies using nanoparticles to develop new therapeutic options, including vaccination methods, to combat systemic mycoses caused by Candida sp., Cryptococcus sp., Paracoccidioides sp., Histoplasma sp., Coccidioides sp., and Aspergillus sp., in addition to providing important information on the use of different types of nanoparticles, nanocarriers and their corresponding mechanisms of action.

Myco-decontamination of azo dyes: nano-augmentation technologies

Effluents of textile, paper, and related industries contain significant amounts of synthetic dyes which has serious environmental and health implications. Remediation of dyes through physical and chemical techniques has specific limitations. Augmented biological decontamination strategies 'microbial remediation' may involve ring-opening of dye molecules besides the reduction of constituent metal ions. Both bacterial and fungal genera are known to exhibit metabolic versatility which can be harnessed for effective bio-removal of the toxic dye contaminants. Ascomycetous/basidiomycetes fungi can effectively decontaminate azo dyes through laccase/peroxidase enzyme-mediated catalysis. The extent, efficacy, and range of fungal dye decontamination can be enhanced by the conjugated application of nanomaterials, including nanoparticles (NPs) and their composites. Fungal cell-enabled NP synthesis- 'myco-farmed NPs', is a low-cost strategy for scaled-up fabrication of a variety of metal, metal oxide, non-metal oxide NPs through oxidation/reduction of dissolved ions/molecules by extracellular biomolecules. Augmented and rapid decontamination of azo dyes at high concentrations can be achieved by the use of myco-farmed NPs, NPs adsorbed fungal biomass, and nano-immobilized fungi-derived bio-catalytical agents. This manuscript will explore the opportunities and benefits of mycoremediation and application of fungus-NP bionanoconjugate to remediate dye pollutants in wastewaters and land contaminated with the effluent of textile industries.

Utilization of Morchella esculenta-mediated green synthesis golden nanoparticles in biomedicine applications

This study aimed to synthesize gold nanoparticles (AuNPs) by hot water extract in room conditions using edible Morchella esculenta (ME) and investigate the bioactive properties of the synthesized Morchella esculenta-based gold nanoparticles (ME-AuNPs). The characterization of the biologically synthesized ME-AuNPs was made using the ultraviolet-visible spectrophotometry, X-ray crystallography, scanning electron microscopy, Fourier transforms infrared spectroscopy, and energy dispersive X-ray spectrum methods. The ME-AuNPs, with a particle size of 16.51 nm, were found to have strong bioactive properties. The antioxidant activity of the ME-AuNPs attempted by metal chelating activity, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity and the β-carotene linoleate model system. The activities at 10 mg/mL were 82, 85, and 77% for the chelation of ferrous ions, DPPH scavenging, and β-carotene linoleate tests, respectively. The ME-AuNPs also showed strong antimicrobial activity against various pathogen microorganisms and strong cytotoxic activity in the A549 and HepG2 cell lines. This study demonstrated the possibility of using a cheap and nontoxic fungal extract as a reducing and stabilizing agent for the synthesis of size-controlled, large-scale, and biocompatible AuNPs that could be used in future diagnostic and therapeutic applications.

In Vivo Biosynthesis of Inorganic Nanomaterials Using Eukaryotes-A Review

Bionanotechnology, the use of biological resources to produce novel, valuable nanomaterials, has witnessed tremendous developments over the past two decades. This eco-friendly and sustainable approach enables the synthesis of numerous, diverse types of useful nanomaterials for many medical, commercial, and scientific applications. Countless reviews describing the biosynthesis of nanomaterials have been published. However, to the best of our knowledge, no review has been exclusively focused on the in vivo biosynthesis of inorganic nanomaterials. Therefore, the present review is dedicated to filling this gap by describing the many different facets of the in vivo biosynthesis of nanoparticles (NPs) using living eukaryotic cells and organisms-more specifically, live plants and living biomass of several species of microalgae, yeast, fungus, mammalian cells, and animals. It also highlights the strengths and weaknesses of the synthesis methodologies and the NP characteristics, bio-applications, and proposed synthesis mechanisms. This comprehensive review also brings attention to enabling a better understanding between the living organisms themselves and the synthesis conditions that allow their exploitation as nanobiotechnological production platforms as these might serve as a robust resource to boost and expand the bio-production and use of desirable, functional inorganic nanomaterials.

Synthesis of Metal Nanoparticles by Microorganisms

Metal nanoparticles (NPs), with sizes ranging from 1–100 nm, are of great scientific interest because their functions and features differ greatly from those of bulk metal. Chemical or physical methods are used to synthesize commercial quantities of NPs, and green, energy-efficient approaches generating byproducts of low toxicity are desirable to minimize the environmental impact of the industrial methods. Some microorganisms synthesize metal NPs for detoxification and metabolic reasons at room temperature and pressure in aqueous solution. Metal NPs have been prepared via green methods by incubating microorganisms or cell-free extracts of microorganisms with dissolved metal ions for hours or days. Metal NPs are analyzed using various techniques, such as ultraviolet-visible spectroscopy, electron microscopy, X-ray diffraction, electron diffraction, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. Numerous publications have focused on microorganisms that synthesize various metal NPs. For example, Ag, Au, CdS, CdSe, Cu, CuO, Gd2O3, Fe3O4, PbS, Pd, Sb2O3, TiO2, and ZrO2 NPs have been reported. Herein, we review the synthesis of metal NPs by microorganisms. Although the molecular mechanisms of their synthesis have been investigated to some extent, experimental evidence for the mechanisms is limited. Understanding the mechanisms is crucial for industrial-scale development of microorganism-synthesized metal NPs.

Eco Friendly Approach for Synthesis, Characterization and Biological Activities of Milk Protein Stabilized Silver Nanoparticles

Today, the overall occurrence of re-emerging and rising illnesses has been a serious load on economies as well as public health. Here, we describe a simple, nontoxic and eco-friendly method for the synthesis of milk protein (MP)-stabilized silver nanoparticles (MP-s-AgNPs) using ultrahigh-temperature full cream milk. Highly stable AgNPs were prepared with a fair control over their size, without using any reducing or stabilizing agent, and their formation was attributed to the presence of the MP casein. Ag⁺ ion reduction was possibly caused by the MPs. The synthesized MP-s-AgNPs were characterized in detail by ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and dynamic light scattering. MP-s-AgNPs showed inhibitory activity against both Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative microorganisms (Salmonella typhi and Escherichia coli). Moreover, MP-s-AgNPs were found to be more toxic to bacteria than to fungi (Aspergillus fumigatus, Aspergillus ochraceus and Penicillium chrysogenum).

Biophysical insights into the interaction of human serum albumin with Cassia fistula leaf extracts inspired biogenic potent antibacterial and anticancerous gold nanoparticles

In the present investigation, the characterization of Cassia fistula leaf extracts (CFLE) mediated gold nanoparticles (CF-GNPs) and its binding features with human serum albumin (HSA) through interaction have been probed. The results from UV-visible, TEM and EDX analysis proved the formation of CF-GNPs. The functional groups like OH, NH, CN etc present in the phytochemicals of CFLE were mainly acted as reducing and protecting agent which was confirmed by FTIR study. The zeta potential (-17.8 mV) and hydrodynamic size (20.4 nm) of the CF-GNPs were also measured by DLS. The microbicidal effect of the CF-GNPs was estimated against gram negative bacterium, Escherichia coli (DH5-Alpha) and MIC was found to be 2.8 nM. Anticancer activity of the CF-GNPs was also checked against A375 (skin melanoma) cell lines where IC₅₀ was 6.5 nM. The interaction study of CF-GNPs with HSA and conformational alteration of HSA upon interaction were investigated by the fluorescence, lifetime, synchronous, circular dichroism spectrum and zeta potential measurement. The negative value of Gibb's free energy indicated spontaneity of the CF-GNPs-HSA complex formation. The fluorescence lifetime measurement confirmed the construction of ground state CF-GNPs-HSA complex passing through static quenching mechanism and determined the distance from donor to acceptor also. Circular dichroism spectroscopy signified unchangeable native structure of HSA with minor decrease of alpha helix structure (54.5% to 51.1%) upon interaction. The more negative zeta potential value (-25.9 mV) of CF-GNPs-HSA system than the CF-GNPs (-17.8 mV) proved the adsorption of HSA on the outer surface of CF-GNPs.Communicated by Ramaswamy H. Sarma.

Single-step green route synthesis of Au/Ag bimetallic nanoparticles using clove buds extract: Enhancement in antioxidant bio-efficacy and catalytic activity

In present work, we demonstrate a single step environmentally benign approach to synthesize Au/Ag bimetallic nanoparticles (BMNPs) using aqueous extract of Clove buds for the first time. Clove bud's (CB) extract has proficiency to act as a reducing and stabilizing agent for the formation of Au/Ag BMNPs. In presence of extract, Au^III and Ag^I are reduced competitively within same solution and produce Au/Ag alloy NPs. The kinetics besides the formation of NPs was studied using UV-visible spectroscopy and efficiency of the extract was monitored by varying contact time, temperature, pH and extract concentration. The electron microscopic studies revealed the presence of NPs with peculiar morphology at alkaline pH. Further, the existence of Au and Ag atoms was investigated using energy dispersive X-ray (EDX), X-ray diffraction (XRD) and cyclic voltammetry (CV) techniques. Fourier transform infrared spectroscopy (FTIR) showed that Eugenol in the extract is mainly responsible for the production of NPs which are also surrounded by various phytochemicals. Zeta potential of all the NPs is found to be negative which prevents their agglomeration due to inter-repulsion and the biosynthesized Au/Ag BMNPs revealed greater catalytic efficiency for the degradation of methyl orange (MO), methylene blue (MB) and reduction of p-nitrophenol (p-NP). Significant enhancement induced by BMNPs compared to individual monometallic nanoparticles (MMNPs) was assigned to the synergistic effect of MMNPs and coating of phytochemicals present in the CB extract.

Metal-derived nanoparticles in tumor theranostics: Potential and limitations

Initially, metal derived nanoparticles have been used exclusively as contrasting agents in magnetic resonance imaging. Today, green routes of chemical synthesis together with numerous modifications of the core and surface gave rise to a plethora of biomedical applications of metal derived nanoparticles including tumor imaging, diagnostics, and therapy. These materials are an emerging class of tools for tumor theranostics. Nevertheless, the spectrum of clinically approved metal nanoparticles remains narrow, as the safety, specificity and efficiency still have to be improved. In this review we summarize the major directions for development and biomedical applications of metal based nanoparticles and analyze their effects on tumor cells and microenvironment. We discuss the advantages and possible limitations of metal nanoparticle-based tumor theranostics, as well as the potential strategies to improve the in vivo performance of these unique materials.

Silver nanoparticles stabilized with propolis show reduced toxicity and potential activity against fungal infections

Aim: Elucidate the antifungal efficacy of biologically synthesized silver nanoparticles with ethanolic propolis extract (AgNPs PE) against the planktonic forms and biofilms of clinically important fungi. Materials & methods: AgNPs were synthesized, characterized and evaluated for cytotoxicity, mutagenicity and antimicrobial activity. Results: AgNPs PE displayed a colloidal appearance, good stability and size of 2.0–40.0 nm. AgNPs PE demonstrated lower cytotoxicity and nonmutagenic potential. In addition, AgNPs PE displayed antifungal properties against all tested isolates, inhibiting growth at concentrations lower than the cytotoxic effect. Mature biofilms treated for 48 h with AgNPs PE showed significant reduction of viable cells, metabolic activity and total biomass. Conclusion: This is the first time that AgNPs have been synthesized from an ethanolic extract of propolis only, proving antifungal, antibiofilm, atoxic and nonmutagenic properties.

Toxicological impact of green synthesized silver nanoparticles and protective role of different selenium type on Oreochromis niloticus: hematological and biochemical response

BACKGROUND

The present work aimed to detect the toxicological effects of green synthesized silver nanoparticles (Ag-NPs) by using Moringa Oleifera leaves extract on hematological and biochemical parameters of Oreochromis niloticus.

METHODS

Adult fish were exposed to two sublethal concentrations (1.95 and 3.9 ppm) of Ag-NPs against sodium selenite (0.1 ppm) and biosynthesized selenium nanoparticles (Se-NPs); 0.1 ppm; protection role for 2 and 4 weeks. Hematological parameters; erythrocyte count (RBCs), hemoglobin content (Hb), haematocrit value (Hct), mean corpuscular volume (MCV), Mean Corpuscular Hemoglobin Concentration (MCHC), leucocytes (WBCs), with differential count Micronucleus (MN) and alerted cells and biochemical parameters; aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) enzyme activities, serum protein (total protein, albumin and globulin) concentration, urea, creatinine, glucose, cholesterol (Cho) and triglyceride (Tg) were detected.

RESULTS

The present investigation showed that Ag-NPs in different doses led to a significant reduction (p < 0.05) in RBCs, Hb, Hct, MCV, WBCs, LYM and serum proteins concentration. However, MCHC, MN, alerted cells, NEUT, AST, ALT, ALP enzyme activities, urea, creatinine, glucose, Cho and Tg showed a significant increases (p < 0.05) when compared with control group. Sodium selenite (Se) and biosynthesized selenium nanoparticles (Se-NPs) play an optimistic role in detoxification of Ag-NPs toxicity.

CONCLUSION

The results suggest the negative impact of Ag-NPs on hematology and biochemical parameters of fish. Moreover, Se-NPs showed a full improvement of hematological and biochemical parameters more than that of sodium selenite in elimination of Ag-NPs toxicity.

Synthesis of Biogenic Silver Nanoparticles (AgCl-NPs) Using a Pulicaria vulgaris Gaertn. Aerial Part Extract and Their Application as Antibacterial, Antifungal and Antioxidant Agents

In this study, very simple and fast one-step synthesis of biogenic silver chloride nanoparticles (AgCl-NPs) using a Pulicaria vulgaris Gaertn. aerial part extract from an aqueous solution of silver nitrate at room temperature is proposed. The proceedings of the reaction were investigated by UV-Vis spectroscopy. AgCl-NPs were characterized using X-ray diffraction spectroscopy (XRD), Fourier-transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). Antibacterial and antifungal activities of these nanoparticles were evaluated by disk diffusion and microdilution methods against Staphylococcus aureus, Escherichia coli, Candida albicans, and C. glabrata. In addition, the antioxidant activity of the synthesized AgCl-NPs was determined by the DPPH radical scavenging assay. The antimicrobial test confirmed the bactericidal activity of biosynthesized AgCl-NPs against Gram-positive and Gram-negative bacteria. They also exhibited good antifungal activities with minimum inhibitory concentration (MIC) values ranging from 40 to 60 µg/mL against Candida glabrata and Candida albicans, respectively. In addition, biosynthesized AgCl-NPs were established to have remarkable antioxidant activity. All this pointed out that the proposed new biosynthesis approach resulted in production of AgCl-NPs with convenient biomedical applications.

Microwave-Assisted Green Synthesis and Characterization of Silver Nanoparticles Using Melia azedarach for the Management of Fusarium Wilt in Tomato

These days, research in agriculture is focusing on the theme of sustainability along with protection of agriculture produce. Nanotechnology in the agriculture sector aims for the enhancement of agricultural produce and the reduction of pesticides through providing innovative agrochemical agents and their novel delivery mechanisms. The current investigation involved the green synthesis of silver nanoparticles (AgNPs) from the aqueous leaf extract of Melia azedarach by following a microwave-assisted method to control Fusarium oxysporum, the causal agent of tomato wilt. Biosynthesized Melia leaf extract (MLE)-AgNPs were characterized by UV-visible spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), energy dispersive X-ray (EDX) spectrometry, dynamic light scattering (DLS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and zeta potential analysis. The intensity of the peak at 434 nm in UV-vis spectra, attributed to the surface plasmon resonance of MLE-AgNPs, changes with reaction parameters. TEM exhibits spherical shaped nanoparticles with an average particle size range from 12 to 46 nm. Efficient inhibition of F. oxysporum, the causal agent of tomato wilt, was achieved after exposure to MLE-AgNPs both in vivo and in vitro. In vitro studies exhibited repressed fungal mycelial growth with 79-98% inhibition as compared to the control. Significant increases in growth parameters of tomato seedlings were observed after treatment with biosynthesized nanoparticles as compared to F. oxysporum-infected plants grown without them under greenhouse conditions. Furthermore, SEM imaging was done to reveal the prominent damage on the cell wall of hyphae and spores after MLE-AgNP treatment. Propidium iodide (PI) staining of mycelium indicated the extent of cell death, causing irretrievable damage and disintegration of cellular membranes by altering the membrane permeability. Also, 2',7'-dichlorofluorescin diacetate (DCFH-DA) fluorescence specifies intracellular reactive oxygen species (ROS) production in F. oxysporum after treatment with MLE-AgNPs. The current investigation suggested that biosynthesized nanoparticles can revolutionize the field of plant pathology by introducing an environment-friendly approach for disease management and playing a potential part in agriculture industry. However, to date, little work has been done to integrate nanotechnology into phytopathology so, this area of research is in need of adoption and exploration for the management of plant diseases.

Production, extraction and characterization of Chlorella vulgaris soluble polysaccharides and their applications in AgNPs biosynthesis and biostimulation of plant growth

Chlorella vulgaris, like a wide range of other microalgae, are able to grow mixotrophically. This maximizes its growth and production of polysaccharides (PS). The extracted polysaccharides have a complex monosaccharide composition (fructose, maltose, lactose and glucose), sulphate (210.65 ± 10.5 mg g-1 PS), uronic acids (171.97 ± 5.7 mg g-1 PS), total protein content (32.99 ± 2.1 mg g-1 PS), and total carbohydrate (495.44 ± 8.4 mg g-1 PS). Fourier Transform infrared spectroscopy (FT-IR) analysis of the extracted polysaccharides showed the presence of N-H, O-H, C-H, -CH3, >CH2, COO-1, S=O and the C=O functional groups. UV-Visible spectral analysis shows the presence of proteins, nucleic acids and chemical groups (ester, carbonyl, carboxyl and amine). Purified polysaccharides were light green in color and in a form of odorless powder. It was soluble in water but insoluble in other organic solvents. Thermogravimetric analysis demonstrates that Chlorella vulgaris soluble polysaccharide is thermostable until 240°C and degradation occurs in three distinct phases. Differential scanning calorimetry (DSC) analysis showed the characteristic exothermic transition of Chlorella vulgaris soluble polysaccharides with crystallization temperature peaks at 144.1°C, 162.3°C and 227.7°C. The X-ray diffractogram illustrated the semicrystalline nature of these polysaccharides. Silver nanoparticles (AgNPs) had been biosynthesized using a solution of Chlorella vulgaris soluble polysaccharides. The pale green color solution of soluble polysaccharides was turned brown when it was incubated for 24 hours with 100 mM silver nitrate in the dark, it showed peak maximum located at 430 nm. FT-IR analysis for the biosynthesized AgNPs reported the presence of carbonyl, -CH3, >CH2, C-H,-OH and -NH functional groups. Scanning and transmission electron microscopy show that AgNPs have spherical shape with an average particle size of 5.76. Energy-dispersive X-ray (EDX) analysis showed the dominance of silver. The biosynthesized silver nanoparticles were tested for its antimicrobial activity and have positive effects against Bacillus sp., Erwinia sp., Candida sp. Priming seeds of Triticum vulgare and Phaseolus vulgaris with polysaccharides solutions (3 and 5 mg mL-1) resulted in significant enhancement of seedling growth. Increased root length, leaf area, shoot length, photosynthetic pigments, protein content, carbohydrate content, fresh and dry biomass were observed, in addition these growth increments may be attributed to the increase of antioxidant activities.