Biofabrication of Silver Nanoparticles Using Nostoc muscorum Lukesova 2/91: Optimization, Characterization, and Biological Applications.

Purpose: The biological synthesis of nanoparticles (NPs) has become a new methodology for the eco-friendly production of NPs with high scalability and biocompatibility. Cyanobacteria are one of the most widespread microorganisms on Earth and have been proven to be successful biofactories for synthesizing NPs. It is challenging to discover new microalgae with the potential to synthesize NPs of small size with high stability. Methods: Nostoc muscorum Lukesova 2/91 was isolated, purified, and identified morphologically and genetically using microscopy and DNA sequencing. Volatile biomolecules in aqueous algal extracts were assessed using gas chromatography-mass spectroscopy (GC-MS). Results: Data showed that the main biomolecules were fatty acids and their esters, followed by secondary metabolites. Algal extract was used to convert silver nitrate (AgNO3) into silver NPs under various optimized parameters. 1 mM of AgNO3, 1:1 (V/V ratio of algal extract to AgNO3), 25 °C, under light illumination, for 24 h, at pH 7.4 were the optimum conditions for NP production (Nos@AgNPs). Nos@AgNPs were characterized using UV-VIS spectroscopy, FTIR, TEM, SEM, EDx, mapping, and a Zetasizer. The wavelength of Nos@AgNPs was 401.4 nm and their shapes were cubic to oval, with an average diameter of 11.8 ± 0.5 nm. FTIR spectroscopy revealed that proteins/polysaccharides could be the main reductants, whereas these molecules and/or fatty acids could be stabilizers for NP synthesis. Nos@AgNPs (86.15%) was silver and had a hydrodynamic diameter of 10.7 nm with a potential charge of -19.7 mV. Antiproliferative and antimicrobial activities of Nos@AgNPs were evaluated. Nos@AgNPs exhibited significant inhibitory activity against lung, colon, and breast cancer cells and considerable biocidal activity against Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia, and Pseudomonas aeruginosa. Conclusion: N. muscorum Lukesova 2/91 is an excellent source for the biofabrication of small and stable AgNPs with potent inhibitory effects against cancer and bacterial cells.

Planophila laetevirens-Mediated Synthesis of Silver Nanoparticles: Optimization, Characterization, and Anticancer and Antibacterial Potentials.

Algal-mediated synthesis of nanoparticles (NPs) opens the horizon for green and sustainable synthesis of NPs that can be used in many fields, such as medicine and industry. We extracellularly synthesized silver NPs (Ag-NPs) using the novel microalgae Planophila laetevirens under optimized conditions. The isolate was collected from freshwater/soil, purified, morphologically identified, and genetically identified using light, inverted light, scanning electron microscopy, and 18S rRNA sequencing. The phytochemicals in the algal extract were detected by GC-MS. Aqueous biomass extracts and cell-free media were used to reduce silver nitrate to Ag-NPs. To get small, uniformly shaped, and stable Ag-NPs, various abiotic parameters, including precursor concentration, the ratio between the reductant and precursor, temperature, time of temperature exposure, pH, illumination, and incubation time, were controlled during the synthesis of Ag-NPs. B-P@Ag-NPs and S-P@Ag-NPs (Ag-NPs synthesized using biomass and cell-free medium, respectively) were characterized using UV-vis spectroscopy, transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray analysis (EDX) and mapping, Fourier transform infrared (FTIR) spectroscopy, and a zeta sizer. S-P@Ag-NPs had a smaller size (10.8 ± 0.3 nm) than B-P@Ag-NPs (19.0 ± 0.6 nm), while their shapes were uniform quasispherical (S-P@Ag-NPs) and spherical to oval (B-P@Ag-NPs). EDX and mapping analyses demonstrated that Ag was the dominant element in the B-P@Ag-NP and S-P@Ag-NP samples, while FTIR revealed the presence of O-H, C-H, N-H, and C-O groups, indicating that polysaccharides and proteins acted as reductants, while polysaccharides/fatty acids acted as stabilizers during the synthesis of NPs. The hydrodynamic diameters of B-P@Ag-NPs and S-P@Ag-NPs were 37.7 and 28.3 nm, respectively, with negative charges on their surfaces, suggesting their colloidal stability. Anticancer activities against colon cancer (Sw620 and HT-29 cells), breast cancer (MDA-MB231 and MCF-7 cells), and normal human fibroblasts (HFs) were screened using the MTT assay. B-P@Ag-NPs and S-P@Ag-NPs had a greater antiproliferative effect against colon cancer than against breast cancer, with biocompatibility against HFs. The biocidal effects of the B-P@Ag-NPs and S-P@Ag-NPs were evaluated against Escherichia coli, Bacillus cereus, and Bacillus subtilis using agar well diffusion and resazurin dye assays. B-P@Ag-NPs and S-P@Ag-NPs caused higher growth inhibition of Gram-negative bacteria than of Gram-positive bacteria. B-P@Ag-NPs and S-P@Ag-NPs synthesized by P. laetevirens are promising antitumor and biocidal agents.

One-pot facile synthesis of hexagonal Bi2Te3 nanosheets and its novel nanocomposites: Characterization, anticancer, antibacterial, and antioxidant activities.

Bismuth Telluride (Bi2Te3) layered structure results in extraordinary features in diagnostic and therapeutic applications. However, Bi2Te3 synthesis with reliable stability and biocompatibility in biological systems was the major challenge that limited its biological application. Herein, reduced graphene oxide (RGO) or graphitic carbon nitride (CN) nanosheets were incorporated into Bi2Te3 matrix to improve exfoliation. Bi2Te3 nanoparticles (NPs) and its novel nanocomposites (NCs): CN@Bi2Te3 and CN-RGO@Bi2Te3 were solvothermally synthesized, physiochemically characterized and assessed for their anticancer, antioxidant, and antibacterial activities. X-ray diffraction depicted Bi2Te3 rhombohedral lattice structure. Fourier-transform infrared and Raman spectra confirmed NC formation. Scanning and transmission electron microscopy revealed 13 nm thickness and 400-600 nm diameter of hexagonal, binary, and ternary nanosheets of Bi2Te3-NPs/NCs. Energy dispersive X-ray Spectroscopy revealed the presence of Bi, Te, and carbon atoms in the tested NPs with negatively charged surfaces as depicted by zeta sizer. CN-RGO@Bi2Te3-NC displayed the smallest nanodiameter (359.7 nm) with the highest Brunauer-Emmett-Teller surface area and antiproliferative activity against MCF-7, HepG2 and Caco-2. Bi2Te3-NPs had the greatest scavenging activity (96.13 ± 0.4%) compared to the NCs. The NPs inhibitory activity was greater against Gram-negative bacteria than that of Gram-positive bacteria. Integration of RGO and CN with Bi2Te3-NPs enhanced their physicochemical properties and therapeutic activities giving rise to their promising capacity for future biomedical applications.

One-Step Phytofabrication Method of Silver and Gold Nanoparticles Using Haloxylon salicornicum for Anticancer, Antimicrobial, and Antioxidant Activities.

Among various routes of metallic nanoparticle (NPs) fabrication, phytosynthesis has significant advantages over other conventional approaches. Plant-mediated synthesis of NPs is a fast, one-step, ecobenign, and inexpensive method with high scalability. Herein, silver (Ag) and gold (Au)-NPs were extracellularly synthesized using aqueous Haloxylon salicornicum (H@Ag-, H@Au-NPs) leaf extracts. GC-MS was performed to analyze the chemical compositions of H. salicornicum extract. H@Ag- and H@Au-NPs were characterized via UV-Vis spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, transmission and scanning electron microscopy, and Zetasizer. H@Ag- and H@Au-NPs have surface plasmon resonance at 435.5 and 530.3 nm, respectively. FTIR and GC-MS data suggest that secondary plant metabolites and hydrocarbons might be responsible for the reduction and stabilization of NPs. XRD demonstrated that both NPs have a crystalline nature. H@Ag-NPs have a uniform spherical shape, whereas H@Au-NPs are spherical with few oval and triangular shapes, and their average nanosizes were 19.1 ± 0.8 and 8.1 ± 0.3 nm, respectively. Hydrodynamic diameters of H@Ag-NPs and H@Au-NPs were 184.7 nm, 56.4, and 295.4 nm, and their potential charges were -24.0 and -24.4 mV, respectively. The inhibitory activity of 500 µg/mL H@Ag- and H@Au-NPs was tested against Sw480, Sw620, HCT-116, and Caco-2 colon cancer cell lines and two normal cell lines, including HFs and Vero. H@Ag-NPs revealed potent anticancer activity against all cancer cells at low concentrations. Sw480 was the most sensitive cell to H@Ag-NPs, whereas Sw620 was the least permeable one. These findings suggested that the antiproliferative activity of H@Ag-NPs is cell-response-dependent and may be influenced by a variety of factors, including the cellular metabolic state, which influences cellular charge and interactions with charged NPs. Although H@Au-NPs were smaller, their reactivity against cancer cells was weak, suggesting that the chemical properties, metal structure, quantity and chemistry of the functional groups on the NP surface may influence their reactivity. The biocidal activity of 1 mg/mL H@Ag- and H@Au-NPs against Staphylococcus aureus, Bacillus cereus, Escherichia coli and Klebsiella pneumoniae was assessed. H@Ag-NPs showed biocidal activity against Gram-positive bacteria compared to Gram-negative bacteria, whereas H@Au-NPs showed no inhibitory activity. FRAP and DPPH assays were used to determine the scavenging activity of the plant extracts and both NPs. H@Ag-NPs (1 mg/mL) had the greatest scavenging activity compared to tested drugs. These findings suggest that H@Ag-NPs are potent anticancer, antibacterial, and antioxidant agents, while H@Au-NPs may be used as a drug vehicle for pharmaceutical applications.

Green Synthesis of Hexagonal Silver Nanoparticles Using a Novel Microalgae Coelastrella aeroterrestrica Strain BA_Chlo4 and Resulting Anticancer, Antibacterial, and Antioxidant Activities.

Microalgae-mediated synthesis of nanoparticles (NPs) is an emerging nanobiotechnology that utilizes the biomolecular corona of microalgae as reducing and capping agents for NP fabrication. This study screened a novel microalgal strain for its potential to synthesize silver (Ag)-NPs and then assayed the biological activities of the NPs. Coelastrella aeroterrestrica strain BA_Chlo4 was isolated, purified, and morphologically and molecularly identified. Chemical composition of the algal extract was determined by GC-MS analysis. Ag-NPs were biosynthesized by C. aeroterrestrica BA_Chlo4 (C@Ag-NPs) and characterized using various techniques. Antiproliferative activity and the biocidal effect of C@Ag-NPs, C. aeroterrestrica algal extract, and chemically synthesized Ag-NPs (Ch@Ag-NPs) were explored, and the scavenging activity of C@Ag-NPs against free radicals was investigated. C@Ag-NPs were hexagonal, with a nanosize diameter of 14.5 ± 0.5 nm and a maximum wavelength at 404.5 nm. FTIR and GC-MS analysis demonstrated that proteins and polysaccharide acted as capping and reducing agents for C@Ag-NPs. X-ray diffraction, energy diffraction X-ray, and mapping confirmed the crystallinity and natural structure of C@Ag-NPs. The hydrodynamic diameter and charge of C@Ag-NPs was 28.5 nm and -33 mV, respectively. C@Ag-NPs showed significant anticancer activity towards malignant cells, with low toxicity against non-cancerous cells. In addition, C@Ag-NPs exhibited greater antioxidant activity and inhibitory effects against Gram-positive and -negative bacteria compared with the other tested treatments. These findings demonstrate, for first time, the potential of a novel strain of C. aeroterrestrica to synthesize Ag-NPs and the potent antioxidant, anticancer, and biocidal activities of these NPs.

Algal-Derived Synthesis of Silver Nanoparticles Using the Unicellular ulvophyte sp. MBIC10591: Optimisation, Characterisation, and Biological Activities.

Algal-mediated synthesis of nanoparticles (NPs) is an eco-friendly alternative for producing NPs with potent physicochemical and biological properties. Microalgae represent an ideal bio-nanofactory because they contain several biomolecules acting as passivation and stabilising agents during the biogenesis of NPs. Herein, a novel microalgae sp. was isolated, purified, and identified using light and electron microscopy and 18s rRNA sequencing. The chemical components of their watery extract were assessed using GC-MS. Their dried biomass was used to synthesise silver (Ag) NPs with different optimisation parameters. Ag-NPs were physiochemically characterised, and their anticancer and antibacterial effects were examined. The data showed that the isolated strain was 99% similar to the unicellular ulvophyte sp. MBIC10591; it was ellipsoidal to spherical and had a large cup-shaped spongiomorph chloroplast. The optimum parameters for synthesising Ag-NPs by unicellular ulvophyte sp. MBIC10591 (Uv@Ag-NPs) were as follows: mixture of 1 mM of AgNO3 with an equal volume of algal extract, 100 °C for 1 h, and pH of 7 under illumination for 24 h. TEM, HRTEM, and SEM revealed that Uv@Ag-NPs are cubic to spherical, with an average nanosize of 12.1 ± 1.2 nm. EDx and mapping analysis showed that the sample had 79% of Ag, while FTIR revealed the existence of several functional groups on the NP surface derivatives from the algal extract. The Uv@Ag-NPs had a hydrodynamic diameter of 178.1 nm and a potential charge of -26.7 mV and showed marked antiproliferative activity against PC3, MDA-MB-231, T47D, and MCF-7, with IC50 values of 27.4, 20.3, 23.8, and 40 µg/mL, respectively, and moderate toxicity against HFs (IC50 of 13.3 µg/mL). Uv@Ag-NPs also showed marked biocidal activity against Gram-negative bacteria. Escherichia coli was the most sensitive bacteria to the NPs with an inhibition zone of 18.9 ± 0.03 mm. The current study reports, for the first time, the morphological appearance of the novel unicellular ulvophyte sp., MBIC10591, and its chemical composition and potential to synthesise Uv@Ag-NPs with smaller sizes and high stability to act as anti-tumour and microbial agents.

Anticandidal Potential of Two Cyanobacteria-Synthesized Silver Nanoparticles: Effects on Growth, Cell Morphology, and Key Virulence Attributes of Candida albicans.

Candida albicans is an opportunistic human fungal pathogen responsible for 90-100% of mucosal and nosocomial infections worldwide. The emergence of drug-resistant strains has resulted in adverse consequences for human health, including numerous deaths. Consequently, there is an urgent need to identify and develop new antimicrobial drugs to counter these effects. Antimicrobial nanoagents have shown potent inhibitory activity against a number of pathogens through targeting their defense systems, such as biofilm formation. Here, we investigated the anticandidal activity of silver nanoparticles biosynthesized by the cyanobacterial strains Desertifilum sp. IPPAS B-1220 and Nostoc Bahar_M (D-SNPs and N-SNPs, respectively), along with that of silver nitrate (AgNO3), and examined the mechanisms underlying their lethal effects. For this, we performed agar well diffusion and enzyme activity assays (lactate dehydrogenase, adenosine triphosphatase, glutathione peroxidase, and catalase) and undertook morphological examinations using transmission electron microscopy. The effects of the three treatments on Hwp1 and CDR1 gene expression and protein patterns were assessed using qRT-PCR and SDS-PAGE assays, respectively. All of the three treatments inhibited C. albicans growth; disrupted membrane integrity, metabolic function, and antioxidant activity; induced ultrastructural changes in the cell envelope; and disrupted cytoplasmic and nuclear contents. Of the three agents, D-SNPs showed the greatest biocidal activity against C. albicans. Additionally, the D-SNP treatment significantly reduced the gene expression of Hwp1 and CDR1, suggestive of negative effects on biofilm formation ability and resistance potential of C. albicans, and promoted protein degradation. The mechanism involved in the biocidal effects of both D-SNPs and N-SNPs against C. albicans could be attributed to their ability to interfere with fungal cell structures and/or stimulate oxidative stress, enabling them to be used as a robust antimycotic agent.

Lichens-A Potential Source for Nanoparticles Fabrication: A Review on Nanoparticles Biosynthesis and Their Prospective Applications.

Green synthesis of nanoparticles (NPs) is a safe, eco-friendly, and relatively inexpensive alternative to conventional routes of NPs production. These methods require natural resources such as cyanobacteria, algae, plants, fungi, lichens, and naturally extracted biomolecules such as pigments, vitamins, polysaccharides, proteins, and enzymes to reduce bulk materials (the target metal salts) into a nanoscale product. Synthesis of nanomaterials (NMs) using lichen extracts is a promising eco-friendly, simple, low-cost biological synthesis process. Lichens are groups of organisms including multiple types of fungi and algae that live in symbiosis. Until now, the fabrication of NPs using lichens has remained largely unexplored, although the role of lichens as natural factories for synthesizing NPs has been reported. Lichens have a potential reducible activity to fabricate different types of NMs, including metal and metal oxide NPs and bimetallic alloys and nanocomposites. These NPs exhibit promising catalytic and antidiabetic, antioxidant, and antimicrobial activities. To the best of our knowledge, this review provides, for the first time, an overview of the main published studies concerning the use of lichen for nanofabrication and the applications of these NMs in different sectors. Moreover, the possible mechanisms of biosynthesis are discussed, together with the various optimization factors influencing the biological synthesis and toxicity of NPs.

Kefir: A protective dietary supplementation against viral infection.

Coronavirus disease 2019 (COVID-19) is an infectious disease caused by a recently discovered coronavirus termed 'severe acute respiratory syndrome coronavirus 2' (SARS-CoV-2). Several scholars have tested antiviral drugs and compounds to overcome COVID-19. 'Kefir' is a fermented milk drink similar to a thin yogurt that is made from kefir grains. Kefir and its probiotic contents can modulate the immune system to suppress infections from viruses (e.g., Zika, hepatitis C, influenza, rotaviruses). The antiviral mechanisms of kefir involve enhancement of macrophage production, increasing phagocytosis, boosting production of cluster of differentiation-positive (CD4+), CD8+, immunoglobulin (Ig)G+ and IgA+ B cells, T cells, neutrophils, as well as cytokines (e.g., interleukin (IL)-2, IL-12, interferon gamma-γ). Kefir can act as an anti-inflammatory agent by reducing expression of IL-6, IL-1, TNF-α, and interferon-γ. Hence, kefir might be a significant inhibitor of the 'cytokine storm' that contributes to COVID-19. Here, we review several studies with a particular emphasis on the effect of kefir consumption and their microbial composition against viral infection, as well as discussing the further development of kefir as a protective supplementary dietary against SARS-CoV-2 infection via modulating the immune response.

Cyanobacteria - A Promising Platform in Green Nanotechnology: A Review on Nanoparticles Fabrication and Their Prospective Applications.

Green synthesis of nanoparticles (NPs) is a global ecofriendly method to develop and produce nanomaterials with unique biological, physical, and chemical properties. Recently, attention has shifted toward biological synthesis, owing to the disadvantages of physical and chemical synthesis, which include toxic yields, time and energy consumption, and high cost. Many natural sources are used in green fabrication processes, including yeasts, plants, fungi, actinomycetes, algae, and cyanobacteria. Cyanobacteria are among the most beneficial natural candidates used in the biosynthesis of NPs, due to their ability to accumulate heavy metals from their environment. They also contain a variety of bioactive compounds, such as pigments and enzymes, that may act as reducing and stabilizing agents. Cyanobacteria-mediated NPs have potential antibacterial, antifungal, antialgal, anticancer, and photocatalytic activities. The present review paper highlights the characteristics and applications in various fields of NPs produced by cyanobacteria-mediated synthesis.

Oxidative Stress and Apoptotic Responses Elicited by Nostoc-Synthesized Silver Nanoparticles against Different Cancer Cell Lines.

Green nanoparticles represent a revolution in bionanotechnology, providing opportunities to fight life-threatening diseases, such as cancer, with less risk to the environment and to human health. Here, for the first time, we systematically investigated the anticancer activity and possible mechanism of novel silver nanoparticles (N-SNPs) synthesized by Nostoc Bahar M against the MCF-7 breast cancer cells, HCT-116 colorectal adenocarcinoma cells, and HepG2 liver cancer cells, using cell viability assays, morphological characterization with inverted light and transmission electron microscopy, antioxidants and enzymes (glutathione peroxidase (GPx), glutathione (GSH), adenosine triphosphatase (ATPase), and lactate dehydrogenase (LDH)), and western blotting (protein kinase B (Akt), phosphorylated-Akt (p-Akt), mammalian target of rapamycin (mTOR), B-cell lymphoma 2 (Bcl-2), tumor suppressor (p53), and caspase 3). N-SNPs decreased the viability of MCF-7, HCT-116, and HepG2 cells, with half-maximal inhibitory concentrations of 54, 56, and 80 µg/mL, respectively. They also significantly increased LDH leakage, enhanced oxidative stress via effects on antioxidative markers, and caused metabolic stress by significantly decreasing ATPase levels. N-SNPs caused extensive ultrastructural alterations in cell and nuclear structures, as well as in various organelles. Furthermore, N-SNPs triggered apoptosis via the activation of caspase 3 and p53, and suppressed the mTOR signaling pathway via downregulating apoptosis-evading proteins in MCF-7, HCT-116, and HepG2 cells. Ultrastructural analysis, together with biochemical and molecular analyses, revealed that N-SNPs enhanced apoptosis via the induction of oxidative stress and/or through direct interactions with cellular structures in all tested cells. The cytotoxicity of Nostoc-mediated SNPs represents a new strategy for cancer treatment via targeting various cell death pathways. However, the potential of N-SNPs to be usable and biocompatible anticancer drug will depend on their toxicity against normal cells.

Novel Biogenic Silver Nanoparticle-Induced Reactive Oxygen Species Inhibit the Biofilm Formation and Virulence Activities of Methicillin-Resistant Staphylococcus aureus (MRSA) Strain.

Emerging antibiotic-resistant bacteria result in increased mortality and have negative economic impacts. It is necessary to discover new strategies to create alternative antibacterial agents that suppress the bacterial resistance mechanism and limit the spread of serious infectious bacterial diseases. Silver nanoparticles may represent a new medicinal agents as alternative antibiotics affect different bacterial mechanisms such as virulence and resistance. In addition to that of silver nitrate (AgNO3) and ampicillin, for the first time, the inhibitory effect of silver nanoparticles synthesized using Desertifilum sp. (D-SNPs) was evaluated against five pathogenic bacteria using the agar well diffusion method. Also, the influence of D-SNPs and AgNO3 on bacterial antioxidant and metabolic activities was studied. The antibacterial activity of D-SNPs and AgNO3 against methicillin-resistant Staphylococcus aureus (MRSA) strains was studied at the morphological and molecular level. D-SNPs and AgNO3 have the ability to inhibit the growth of the five bacterial strains and resulted in an imbalance in the CAT, GSH, GPx and ATPase levels. MRSA treated with D-SNPs and AgNO3 showed different morphological changes such as apoptotic bodies formation and cell wall damage. Moreover, both caused genotoxicity and denaturation of MRSA cellular proteins. Additionally, TEM micrographs showed the distribution of SNPs synthesized by MRSA. This result shows the ability of MRSA to reduce silver nitrate into silver nanoparticles. These data indicate that D-SNPs may be a significant alternative antibacterial agent against different bacteria, especially MDR bacteria, by targeting the virulence mechanism and biofilm formation, leading to bacterial death.

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.

Cytotoxic effect of green silver nanoparticles against ampicillin-resistant Klebsiella pneumoniae.

Considering the harmful effects and high spread of drug-resistant Klebsiella pneumoniae, many researchers have been trying to produce new antibacterial agents to combat the emergence of multidrug-resistant (MDR) strains of this bacterium. Recent progress in the nanomedicine field has provided opportunities for synthesizing unique nanoagents to battle MDR bacteria by targeting virulence and resistance signalling. The biocidal effects of 14.9 nm silver nanoparticles fabricated using Nostoc sp. Bahar M (N-SNPs) and AgNO3 were examined against drug-resistant K. pneumoniae using the agar well diffusion method. Transmission electron microscopy (TEM) was used to detect the ultrastructural changes caused by N-SNPs and AgNO3. To address the mode of action of N-SNPs and AgNO3, CAT, GPx, LDH and ATPase levels were assessed. The toxicity of N-SNPs and AgNO3 was evaluated against the mfD, flu, hly, 23S, hns, hcp-1, VgrG-1 and VgrG-3 genes as well as cellular proteins. N-SNPs showed the greatest inhibitory activity against K. pneumoniae, with MIC and MBC values of 0.9 and 1.2 mg mL-1, respectively. Furthermore, N-SNPs and AgNO3 induced apoptotic features, including cell shrinkage and cell atrophy. N-SNPs were more potent bactericidal compounds than AgNO3, causing increased leakage of LDH and GPx activities and depletion of ATPase and CAT activities, resulting in induced oxidative stress and metabolic toxicity. Compared to AgNO3, N-SNPs exhibited the highest toxicity towards the selected genes and the greatest damage to bacterial proteins. N-SNPs were the most potent agents that induced bacterial membrane damage, oxidative stress and disruption of biomolecules such as DNA and proteins. N-SNPs may be used as effective nanodrugs against MDR bacteria.

Lethal Mechanisms of Nostoc-Synthesized Silver Nanoparticles Against Different Pathogenic Bacteria.

BACKGROUND: Increasing antibiotic resistance and the emergence of multidrug-resistant (MDR) pathogens have led to the need to develop new therapeutic agents to tackle microbial infections. Nano-antibiotics are a novel generation of nanomaterials with significant antimicrobial activities that target bacterial defense systems including biofilm formation, membrane permeability, and virulence activity. PURPOSE: In addition to AgNO3, the current study aimed to explore for first time the antibacterial potential of silver nanoparticles synthesized by Nostoc sp. Bahar_M (N-SNPs) and their killing mechanisms against Streptococcus mutans, methicillin-resistant Staphylococcus aureus, Escherichia coli, and Salmonella typhimurium. METHODS: Potential mechanisms of action of both silver species against bacteria were systematically explored using agar well diffusion, enzyme (lactate dehydrogenase (LDH) and ATPase) and antioxidant (glutathione peroxidase and catalase)   assays, and morphological examinations. qRT-PCR and SDS-PAGE were employed to investigate the effect of both treatments on mfD, flu, and hly gene expression and protein patterns, respectively. RESULTS: N-SNPs exhibited greater biocidal activity than AgNO3 against the four tested bacteria. E. coli treated with N-SNPs showed significant surges in LDH levels, imbalances in other antioxidant and enzyme activities, and marked morphological changes, including cell membrane disruption and cytoplasmic dissolution. N-SNPs caused more significant upregulation of mfD expression and downregulation of both flu and hly expression and increased protein denaturation compared with AgNO3. CONCLUSION: N-SNPs exhibited significant inhibitory potential against E. coli by direct interfering with bacterial cellular structures and/or enhancing oxidative stress, indicating their potential for use as an alternative antimicrobial agent. However, the potential of N-SNPs to be usable and biocompatible antibacterial drug will evaluate by their toxicity against normal cells.

Biofabrication And Antitumor Activity Of Silver Nanoparticles Utilizing Novel Nostoc sp. Bahar M.

BACKGROUND: Over recent years, green chemistry procedures have been developed to synthesize nanoparticles in eco-friendlier and less expensive ways. These procedures use natural sources such as bacteria, fungi, yeast, plants, actinomycetes, algae, or cyanobacteria, or use biomolecules such as proteins, vitamins, or pigments instead of chemical materials to fabricate salt precursors into nanoparticles. METHODOLOGY: In the current investigation, we developed an effective, inexpensive, nontoxic method to synthesize silver nanoparticles (SNPs) using the cellular extract of a novel strain of cyanobacterium, Nostoc sp. Bahar M. SNPs were characterized using ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The antitumor properties of the biogenic SNPs were tested against Caco-2 cells using a cell proliferation assay and inverted light microscopy. RESULTS: The new strain Nostoc sp. Bahar M was able to fabricate small SNPs from silver nitrate through an eco-friendly and inexpensive biosynthesis process. SNPs synthesis was accompanied by a color transformation from pale yellow to dark brown. Ultraviolet spectroscopy showed an absorption peak at 403 nm, confirming SNPs formation. X-ray diffraction analysis indicated that the SNPs had a face-centered cubic crystalline structure. Fourier-transform infrared spectroscopy was used to identify a protein that may play an important role in SNPs biosynthesis. Scanning and transmission electron micrographs showed that the SNPs were uniformly distributed and spherical in shape, with an average diameter of 14.9 nm. Cytotoxicity assays showed that SNPs exhibited a significant dose-dependent cytotoxic activity against human colon cancer cells with an IC50 of 150 µg/mL. CONCLUSION: Nostoc sp. Bahar M provided an eco-friendly route for fabricating SNPs, which have cytotoxic activity toward Caco-2 cells.