Biosynthesis Of AgNPs Research Articles

Biological Synthesis of Silver Nanoparticles from Lavandula mairei Humbert: Antibacterial and Antioxidant Activities.

Hospital-acquired infections involving carbapenem-resistant Acinetobacter baumannii (A. baumannii) and extended spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae pose significant challenges in the intensive care units. The lack of novel antimicrobial drugs amplifies the urgency to explore innovative management strategies. Nanotechnology, with its ability to generate nanoparticles possessing specific properties beneficial in drug delivery and nanomedicine, stands as a pivotal research domain. The objective of this study was to synthesize, for the first time, biologically silver nanoparticles (Ag-NPs) from Lavandula mairei Humbert (L. mairei) plant. The biosynthesized Ag-NPs were characterized by UV-visible spectral analysis, X-Ray diffraction Analysis, Fourier transform infrared spectroscopy analysis, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy. Subsequently, the antibacterial and antioxidant activities of Ag-NPs were assessed using the micro-dilution method, DPPH test and FRAP assay, respectively. The green-synthesized Ag-NPs exhibited high antibacterial activity against ESBL-producing multidrug-resistant (MDR) strains and against carbapenem-resistant and non-carbapenem-resistant strains of A. baumannii, as well as a very interesting antioxidant activity. The present study suggests that these results hold very promising for the potential application of biologically synthesized Ag-NPs from L. mairei (Ag-LM-NPs) in the invention of novel antibacterial and antioxidant agents.

Green synthesis of bio-mediated silver nanoparticles from Persea americana peels extract and evaluation of their biological activities: In vitro and in silico insights

In this article, Persea americana aqueous peels extract was used to synthesize silver nanoparticles in a simple and environmentally friendly manner. The properties of synthesized silver nanoparticles (AV-AgNPs) were studied via several techniques, including UV–vis spectroscopy, DLS, TEM, EDX, and FTIR. The UV–Vis spectra analysis revealed that the highest absorption peak occurred at 428 nm, providing strong evidence for forming AV-AgNPs. The TEM results indicate that the synthesized AV-AgNPs were uniformly dispersed, exhibiting a spherical shape with an average size of 24 nm. EDX imaging also confirmed the presence of AgNPs. FTIR analysis shows P. americana's phenolic compounds and proteins significantly contribute to AV-AgNP synthesis and stabilization. In addition, the antimicrobial activity of AV-AgNPs was assessed against pathogenic bacteria commonly found in humans, exhibiting a moderate zone of inhibition against the selected pathogens. Additionally, AV-AgNPs were used in antioxidant studies with the robust antioxidant properties 2, 2 diphenyl-1-picrylhydrazyl (DPPH). In vitro studies have shown that AV-AgNPs can remarkably inhibit α-amylase in a dose-dependent manner, indicating their potential as antidiabetic agents. In silico research, it was revealed that naringenin derived from P. americana exhibited a strong binding to S. typhi and B. cereus (−8.7 and −7.5 kcal/mol, respectively). At the same time, quercetin demonstrated a high binding affinity and energy to α-Amylase (−8.9 kcal/mol). This study presents the first investigation into the biosynthesis of AgNPs utilizing the aqueous peel extract derived from P. americana with multiple uses, including antioxidant, antimicrobial, and antidiabetic activity.

Sunlight and microwave catalyzed comparative biosynthesis of silver nanoparticles using in-vitro and in-vivo biomass of Fagonia schweinfurthii Hadidi, its antibacterial activity and phytotoxicity

In the present study, we explore the potential of Fagonia schweinfurthii Hadidi (FS) in-vivo plant material and in-vitro-grown callus as a bio-template for AgNPs synthesis, highlighting its eco-friendly and bio-inspired sustainable approach. The comparative efficacy of natural plant material and its callus culture was assessed for AgNP synthesis by employing both sunlight and microwave irradiation as separate synthesis methods. This yielded four distinct types of AgNPs denoted as CS-AgNPs, PS-AgNPs, CM-AgNPs, and PM-AgNPs. Sunlight-irradiated AgNP synthesis optimized at near to neutral pH (6.6), whereas microwave-assisted synthesis needed a basic pH for synthesis. Optimization of these AgNPs involved varying concentrations of AgNO3, plant aqueous extract (PAE), and callus aqueous extract (CAE) of FS, exposure time to sunlight and microwave radiation, as well as pH adjustments. The particle size of these AgNPs ranged from 5 to 30 nm, having a crystalline nature with a similar fringe width of 0.22 nm, as observed from HR-TEM analysis. These AgNPs showed significant antibacterial properties against the clinical isolates with λmax 420 nm. Importantly, CAE outperformed PAE for the biosynthesis of AgNPs, mainly in the presence of sunlight-producing CS-AgNPs. These CS-AgNPs are rapidly synthesized, well dispersed and stable, showing significant antibacterial activity, and the least environmental phytotoxicity. It promoted the number of secondary roots, seedling DW, and TWC with 100% seed germination. This highlights their sustainable features for exploring industrial eco-friendly nonmanufacturing of AgNPs using callus culture and sunlight irradiation.

Catalytic Degradation Efficacy of Silver Nanoparticles Fabricated Using Actinidia deliciosa Peel Extract

The preparation of metallic nanoparticles using green synthetic approaches and its application toward the efficient degradation of environmentally hazardous dyes constitutes an attractive alternative to currently employed methods. In the current report, the green synthesis of silver nanoparticles (AgNPs) was successfully achieved using Actinidia deliciosa (kiwifruit) peel aqueous extract as a bioreducing agent under optimized synthesis conditions. The experimental parameters were optimized in terms of reactant ratio, reaction temperature, and reaction time. The biogenic nanoparticles exhibited SPR absorption band at λmax 480 nm. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images revealed quasispherical monodisperse nanoparticles which were 36 nm in diameter. The hydrodynamic diameter of the nanoparticles was 106 nm as determined by dynamic light scattering, and the highly negative ζ-potential (−34 mV) supported its superior colloidal stability. Energy dispersive X-ray confirmed that silver is a major constituent of the nanoparticles. X-ray diffraction (XRD) diffractograms confirmed the crystallinity of the nanoparticles and its face-centered cubic (fcc) lattice structure. The functional groups in the plant’s phytochemicals facilitating the reduction of Ag+ ions and stabilization of the formed AgNPs were identified by fourier transform infrared (FTIR) spectroscopy. In specific, the bands in the FTIR spectra at 3,412, 1,618, 1,419, and 1,237 cm−1 suggested the presence of phenolic compounds. Phytochemical analysis by colorimetric assays revealed that the kiwifruit peel extract was rich in phenolic compounds. When evaluated in the catalytic degradation of organic dyes, the biosynthesized AgNPs induced instant and complete discoloration of the methylene blue dye when 1.6 mg of nanoparticles was used. At a lower dose of AgNPs (0.4 mg), 80% degradation of the dye occurred after 3 hr of treatment. The degradation reaction followed second-order kinetics with a rate constant of 0.01083 mM−1s−1. The current study highlights the immense potential of the prepared nanoparticles as efficient catalysts for the degradation of hazardous organic dyes such as methylene blue and presents an intriguing argument for investigating the catalytic efficiency of the biogenic AgNPs for the degradation of other structurally different dye pollutants.

Green synthesis of silver nanoparticles using mature-pseudostem extracts ofAlpinia nigraand their bioactivities

AbstractGreen synthesis of silver nanoparticles (AgNPs) employing agricultural wastes as plant extracts to improve environmental benignity and also economic value added is the highlight of this research. The mature pseudostem ofAlpinia nigrais an unbeneficial raw material discarded from several food ingredients and medicinal formulas. Therefore, this research focused on condition optimization for AgNP synthesis with ecofriendly techniques usingA. nigramature-pseudostem extracts and evaluation of their antioxidant, antibacterial activities, and toxicity with brine shrimp lethality assay (BSLA). The optimal reaction conditions were achieved by using 5 mM silver nitrate (AgNO3) solution with a volume ratio of 2:8 for the extract to AgNO3at pH 12 under room temperature. The morphology and crystalline phase of the generated AgNPs were characterized using UV–visible spectrophotometry, field emission-scanning electron microscope (FE-SEM), energy dispersive X-ray, X-ray diffraction, and Fourier transform-infrared (FTIR) techniques. The FE-SEM analysis exposed spherical shapes with an average diameter of approximately 49 nm. The XRD analysis indicated their face center cubic structure, and the FTIR spectra confirmed that phytochemicals fromA. nigraextract promoted the synthesis of AgNPs. In particular, the biosynthesized AgNPs presented potential antibacterial activity against bothStaphylococcus aureusandEscherichia coliand effective antioxidant capacity using the DPPH radical scavenging assay. Additionally, non-toxic desired AgNPs were confirmed with BSLA.

Eco-friendly Biosynthesis of Ag-NPs by Streptomyces griseus With Anti- Candida albicans and Antitumor Activity.

The most significant sexually transmissible fungal disease, semen candidiasis, is caused by Candida albicans and impacts male reproductive potential. Actinomycetes are a group of microorganisms that could be isolated from various habitats and used for the biosynthesis of various nanoparticles with biomedical applications. Testing antifungal activity of biosynthesized Ag nanoparticles versus isolated C. albicans from semen as well as its anticancer activity versus the Caco-2 cell line. Screening 17 isolated actinomycetes for the biosynthesis of Ag nanoparticle biosynthesis. Characterization of biosynthesized nanoparticles, testing its anti-Candida albicans, and antitumor activity. Streptomyces griseus was the isolate that identified silver nanoparticles using UV, FTIR, XRD and TEM. Biosynthesized nanoparticles have promising anti-Candida albicans with MIC (125 ± 0.8) µg/ml and accelerate apoptotic rate versus Caco-2 cells (IC50 = 7.30 ± 0.54 µg/ml) with minimal toxicity (CC50 = 142.74 ± 4.71 µg/ml) versus Vero cells. Certain actinomycetes could be used for the biosynthesis of nanoparticles with successive antifungal and anticancer activity to be verified by in vivo studies.

Trachyspermum copticum aqueous seed extract-derived silver nanoparticles: Exploration of their structural characterization and comparative antibacterial performance against gram-positive and gram-negative bacteria

Abstract In this study, the aqueous seed extract of Trachyspermum copticum was employed to fabricate silver nanoparticles (AgNPs) for their antibacterial performance. The structural characteristics of the phytofabricated AgNPs were investigated using ultraviolet–visible, energy dispersive X-ray, dynamic light scattering, zeta potential, field emission scanning electron microscope, and Fourier transform infrared spectroscopy. Further, the antibacterial effects of AgNPs were evaluated against two standard gram-positive strains of Staphylococcus aureus and Streptococcus pyogenes and two standard gram-negative strains of Escherichia coli and Klebsiella pneumoniae. The findings showed the phytofabrication of spherical-shaped AgNPs with a Z-average diameter of 119.7 nm and the polydispersity index of 0.56. The minimum inhibitory concentration of AgNPs against S. aureus, S. pyogenes, E. coli, and K. pneumoniae strains was 0.25, 1, 0.5, and 0.5 μg·mL−1, respectively. In addition, the minimum bactericidal concentration of these nanoparticles (NPs) against the mentioned strains was 8, 16, 4, and 4 μg·mL−1, respectively. Furthermore, the AgNPs enhanced the generation of reactive oxygen species significantly in all studied bacteria compared to the control (P < 0.05) suggesting an oxidative-associated antibacterial mechanism of AgNPs. Moreover, a dose-dependent cell death was found in all bacterial samples based on flow cytometry analysis. Overall, this study showed a biological approach for the biosynthesis of AgNPs with significant antibacterial effects.

Deinococcus wulumuqiensis R12 synthesized silver nanoparticles with peroxidase-like activity for synergistic antibacterial application.

The use of a combination of several antibacterial agents for therapy holds great promise in reducing the dosage and side effects of these agents, improving their efficiency, and inducing potential synergistic therapeutic effects. Herein, this study provides an innovative antibacterial treatment strategy by synergistically combining R12-AgNPs with H2O2 therapy. R12-AgNPs were simply produced with the supernatant of an ionizing radiation-tolerant bacterium Deinococcus wulumuqiensis R12 by one-step under room temperature. In comparison with chemically synthesized AgNPs, the biosynthesized AgNPs presented fascinating antibacterial activity and peroxidase-like properties, which endowed it with the capability to catalyze the decomposition of H2O2 to generate hydroxyl radical. After the combination of R12-AgNPs and H2O2, an excellent synergistic bacteriostatic activity was observed for both Escherichia coli and Staphylococcus aureus, especially at low concentrations. In addition, in vitro cytotoxicity tests showed R12-AgNPs had good biocompatibility. Thus, this work presents a novel antibacterial agent that exhibits favorable synergistic antibacterial activity and low toxicity, without the use of antibiotics or a complicated synthesis process.

Untargeted metabolomics and molecular docking studies on green silver nanoparticles synthesized by Sarocladium subulatum: Exploring antibacterial and antioxidant properties

The biological synthesis of silver nanoparticles (Ag-NPs) with fungi has shown promising results in antibacterial and antioxidant properties. Fungi generate metabolites (both primary and secondary) and proteins, which aid in the formation of metal nanoparticles as reducing or capping agents. While several studies have been conducted on the biological production of Ag-NPs, the exact mechanisms still need to be clarified. In this study, Ag-NPs are synthesized greenly using an unstudied fungal strain, Sarocladium subulatum AS4D. Three silver salts were used to synthesize the Ag-NPs for the first time, optimized using a cell-free extract (CFE) strategy. Additionally, these NPs were assessed for their antimicrobial and antioxidant properties. Various spectroscopic and microscopy techniques were utilized to confirm Ag-NP formation and analyze their morphology, crystalline properties, functional groups, size, stability, and concentrations. Untargeted metabolomics and proteome disruption were employed to explore the synthesis mechanism. Computational tools were applied to predict metabolite toxicity and antibacterial activity. The study identified 40 fungal metabolites capable of reducing silver ions, with COOH and OH functional groups playing a pivotal role. The silver salt type impacted the NPs' size and stability, with sizes ranging from 40 to 52 nm and zeta potentials from −0.9 to −30.4 mV. Proteome disruption affected size and stability but not shape. Biosynthesized Ag-NPs using protein-free extracts ranged from 55 to 62 nm, and zeta potentials varied from −18 to −27 mV. Molecular docking studies and PASS results found no role for the metabolome in antibacterial activity. This suggests the antibacterial activity comes from Ag-NPs, not capping or reducing agents. Overall, the research affirmed the vital role of specific reducing metabolites in the biosynthesis of Ag-NPs, while proteins derived from biological extracts were found to solely affect their size and stability.

Potent antibacterial nanocomposites from okra mucilage/chitosan/silver nanoparticles for multidrug-resistant Salmonella Typhimurium eradication

Abstract The polymeric nanocomposites (NCs), constructed from okra (Abelmoschus esculentus) fruits mucilage (OM), silver nanoparticles (AgNPs), and chitosan (Ch), were fabricated as potential candidates to overcome drug-resistant Salmonella Typhimurium bacteria. AgNPs were directly mediated by OM, with 4.2 nm mean diameters. The composed NCs from Ch/OM/AgNPs were innovatively synthesized and the various ratios of Ch:OM/AgNPs affected the NCs particles’ size and charges. The infrared analysis of employed materials/NCs validated their interactions and conjugations. The antibacterial assays of NCs against different resistant S. Typhimurium strains indicated the efficiency of polymeric NCs to inhibit bacteria with significant superiority over standard antibiotics. The NCs that contained equal ratios from Ch and OM/AgNPs were the best formulation (mean diameter, 47.19 nm and surface charge, +16.9 mV) to exhibit the strongest actions toward S. Typhimurium. The NCs caused severe deformation, destruction, and lysis in exposed bacteria, as traced with scanning microscopy. The biosynthesis of AgNPs using OM and their nanoconjugation with Ch provided effectual natural biopolymers NCs with enhanced expected biosafety and efficiency against drug-resistant S. Typhimurium strains, which supports their potential applications as disinfectant, sterilizing, and curative antibacterial agents.

Green synthesis of silver nanoparticles from Hibiscus tiliaceus L. Leaves and their applications in dye degradation, antioxidant, antimicrobial, and anticancer activities

The present study reports the green synthesis of silver nanoparticles (AgNPs) from aqueous extract of Hibiscus tiliaceus L. leaves and their application in dye degradation, antioxidant, antimicrobial, and anticancer activities. Analysis using Fourier transform infrared (FT-IR) spectroscopy revealed that plant metabolite functional groups had a role in the reduction and stability of AgNPs, and X-ray crystallography (XRD) demonstrated that the AgNPs were in crystal form. The UV–vis spectroscopy, dynamic light scattering (DLS), and zeta potential investigations revealed that the AgNPs were formed with an average size of 88.10 nm in colloidal form and were stable (-49 mV). The field emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM) confirmed the shape and size of the AgNPs as spherical with a particle size of 30 - 35 nm, respectively. The AgNPs exhibited potential antioxidant activity by total antioxidant, DPPH, and reducing power assays. The biosynthesized AgNPs displayed a wide range of antibacterial activity on Gram-ve and Gram+ve bacteria by the zone of inhibition assay. AgNPs showed good anticancer activity on MCF-7 cells with an IC50 value of 65.83 µg/mL. Furthermore, AgNPs acted as potential catalysts in combination with the reducing agent sodium borohydride (NaBH4) for the degradation of methylene blue (MB), methylene orange (MO), and methylene green (MG) dyes. The degradation efficiency of catalyst AgNPs in the attendance of NaBH4 for 15 min was noted to be 12.8 %, 26.92 %, and 47.56 % for MO, MB, and MG, respectively. The study concluded that green synthesized AgNPs could be highly applicable as an antioxidant, antimicrobial, and anticancer agents in the biomedical field. Furthermore, AgNPs could be helpful in the remediation of dye effluents.

Unravelling the Antimicrobial, Antibiofilm, Suppressing Fibronectin Binding Protein A (fnba) and cna Virulence Genes, Anti-Inflammatory and Antioxidant Potential of Biosynthesized Solanum lycopersicum Silver Nanoparticles.

Background and Objectives: Urinary tract infections [UTIs] are considered the third most known risk of infection in human health around the world. There is increasing appreciation for the pathogenicity of Gram-positive and Gram-negative strains in UTIs, aside from fungal infection, as they have numerous virulence factors. Materials and Methods: In this study, fifty urine samples were collected from patients suffering from UTI. Among the isolates of UTI microbes, six isolates were described as MDR isolates after an antibiotic susceptibility test carried out using ten different antibiotics. An alternative treatment for microbial elimination involved the use of biosynthesized silver nanoparticles (AgNPs) derived from Solanum lycopersicum [S. cumin]. Results: The sizes and shapes of AgNPs were characterized through TEM imaging, which showed spherical particles in a size range of 35-80 nm, of which the average size was 53 nm. Additionally, the silver nanoparticles (AgNPs) demonstrated inhibitory activity against Staphylococcus aureus (OR648079), exhibiting a 31 mm zone of inhibition at a minimum inhibitory concentration (MIC) of 4 mg/mL and a minimum bactericidal concentration (MBC) of 8 mg/mL. This was followed by Aspergillus niger (OR648075), which showed a 30 mm inhibition zone at an MIC of 16 mg/mL and a minimum fungicidal concentration (MFC) of 32 mg/mL. Then, Enterococcus faecalis (OR648078), Klebsiella pneumoniae (OR648081), and Acinetobacter baumannii (OR648080) each displayed a 29 mm zone of inhibition at an MIC of 8 mg/mL and an MBC of 16 mg/mL. The least inhibition was observed against Candida auris (OR648076), with a 25 mm inhibition zone at an MIC of 16 mg/mL and an MFC of 32 mg/mL. Furthermore, AgNPs at different concentrations removed DPPH and H2O2 at an IC50 value of 13.54 μg/mL. Also, AgNPs at 3 mg/mL showed remarkable DNA fragmentation in all bacterial strains except Enterococcus faecalis. The phytochemical analysis showed the presence of different active organic components in the plant extract, which concluded that rutin was 88.3 mg/g, garlic acid was 70.4 mg/g, and tannic acid was 23.7 mg/g. Finally, AgNPs concentrations in the range of 3-6 mg/mL showed decreased expression of two of the fundamental genes necessary for biofilm formation within Staphylococcus aureus, fnbA (6 folds), and Cna (12.5 folds) when compared with the RecA gene, which decreased by one-fold when compared with the control sample. These two genes were submitted with NCBI accession numbers [OR682119] and [OR682118], respectively. Conclusions: The findings from this study indicate that biosynthesized AgNPs from Solanum lycopersicum exhibit promising antimicrobial and antioxidant properties against UTI pathogens, including strains resistant to multiple antibiotics. This suggests their potential as an effective alternative treatment for UTIs. Further research is warranted to fully understand the mechanisms of action and to explore the therapeutic applications of these nanoparticles in combating UTIs.

Unveiling the silver lining: examining the effects of biogenic silver nanoparticles on the growth dynamics of in vitro olive shoots

The current study aimed to evaluate the effects of biogenic silver nanoparticles (AgNPs) on growth behavior and leaf anatomy of in vitro growing shoots of ‘Picual’ and ‘Dolce’ olive cultivars. Biosynthesis of AgNPs was carried out using the cell-free filtrate of Fusarium oxysporum. The dimension and shape of the synthesized AgNPs have been analyzed using spectroscopy and topography analysis tools, confirming that the biosynthesis of AgNPs is a crystalline nanostructure with an average particle size of 37 nm. The shoots of the selected olive cultivars were cultured on Rugini olive medium-supplemented AgNPs at 0, 10, 20, and 30mg L− 1. The effect of genotypes on shoot multiplication was significant, ‘Picual’ recorded higher values of shoot growth parameters compared with ‘Dolce’ cultivar. Adding AgNPs to the culture medium significantly affected the growth of in vitro olive shoots. AgNPs at 20 and 30mg L− 1 produced higher values of the number of shoots, shoot length, and leaf number of Picual cv. compared with the control treatments, but the higher AgNPs concentration harmed the growth parameters of Dolce cv. and recorded lower growth values compared with the lower concentration (10mg L− 1). AgNPs had a significant effect on leaf morphology and their anatomical structure. The current results showed that the stimulatory effect of AgNPs on shoot growth of in vitro olive shoots is highly dependent on plant genotype and nanoparticle concentration.

Endophytic Aspergillus hiratsukae mediated biosynthesis of silver nanoparticles and their antimicrobial and photocatalytic activities.

In the current study, endophytic Aspergillus hiratsukae was used for the biosynthesis of silver nanoparticles (Ag-NPs) for the first time. The characterizations were performed using X ray diffraction (XRD), Transmission electron microscopy (TEM), Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), Dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FT-IR), and UV-Vis spectroscopy. The obtained results demonstrated the successful formation of crystalline, spherical Ag-NPs with particle diameters ranging from 16 to 31 nm. The FT-IR studied and displayed the various functional groups involved, which played a role in capping and reducing agents for Ag-NPs production. The SEM-EDX revealed that the main constituent of the AS-formed sample was primarily Ag, with a weight percentage of 64.2%. The mycosynthesized Ag-NPs were assessed for antimicrobial as well as photocatalytic activities. The antimicrobial results indicated that the synthesized Ag-NPs possess notable antibacterial efficacy against Staphylococcus aureus, Bacillus subtilis, and Escherichia coli, with minimum inhibitory concentrations (MICs) of Ag-NPs ranging from 62.5 to 250 μg/mL. Moreover, the biosynthesized Ag-NPs demonstrated weak antifungal activity against Aspergillus brasiliensis and Candida albicans, with MICs of 500 and 1,000 μg/mL, respectively. In addition, the mycosynthesized Ag-NPs exhibited photocatalytic activity toward acid black 2 (nigrosine) dye under both light and dark stimulation. Notably, After 300 min exposure to light, the nigrosine dye was degraded by 93%. In contrast, 51% degradation was observed after 300 min in darkness. In conclusion, Ag-NPs were successfully biosynthesized using endophytic A. hiratsukae and also exhibited antimicrobial and photocatalytic activities that can be used in environmental applications.

Biosynthesis, Characterization and Optimization of Silver Nanoparticles with Strong Antibacterial Activity Using Cell Extracts of Cyanobacterial Chroococcus sp.

AbstractThe synthesis of Cyanobacteria‐mediated nanoparticles has attracted great attention due to its ecofriendly, cost‐effective and biocompatible properties. Silver nanoparticles (AgNPs) are used in different areas such as medicine, household products, disinfectants or food storage. The present study aimed the biosynthesis of AgNPs from Cyanobacterial Chroococcus sp. and their antimicrobial activities on some important pathogen bacterial species. According to the obtained data, optimal conditions for synthesis of AgNPs were extract rate 3 : 1 v/v (cell extract/AgNO3), silver salt concentration 10 mM, pH 7, temperature 60 °C and time 30 minutes. The surface plasmon resonance peak of AgNPs was observed at 420–430 nm, and AgNPs were well‐dispersed spherical with an average size of 11–13 nm in diameter by TEM. SEM‐EDX analysis revealed a strong signal of silver. With FTIR analyzes, shift in the absorption bands after the AgNPs formation was confirmed. X‐ray diffraction analysis exhibited that the AgNPs were cubic crystalline shape. Zeta potential of AgNPs showed ‐ 20 mV. The AgNPs strong showed antibacterial activity on an opportunistic bacterial pathogens of Micococcus luteus, Bacillus subtilis and Pseudomonas aeroginosa. The effective and rapid synthesis of Chroococcus‐mediated AgNPs and their strong antimicrobial effects can create an important potential for their use in biomedical and environmental applications.

Improving the optical, thermal, mechanical, electrical properties and antibacterial activity of PVA-chitosan by biosynthesized Ag nanoparticles: Eco-friendly nanocomposites for food packaging applications

In this study, nanocomposite films were produced by blending polyvinyl alcohol (PVA) and chitosan (Cs) polymers with 70 % PVA and 30 % Cs, incorporating silver nanoparticles (Ag NPs) via a solution-casting method. The research aims to investigate the impact of the biosynthesized Ag NPs by Chenopodium murale leaf extract on optical, morphological, mechanical, thermal, electrical, and antibacterial properties. XRD analysis showed a decrease in crystallinity degree with Ag NPs addition. TEM revealed Ag NPs in cubic and spherical shapes with an average size of 23.4 nm. SEM and AFM indicated surface morphology changes. FT-IR spectra showed interaction between Ag ions and the blend. The energy gap decreased with increasing Ag NPs concentration. TGA exhibited enhanced thermal stability. Mechanical properties improved significantly. AC electrical conductivity and dielectric parameters were studied. Antibacterial activity against Gram-positive and Gram-negative bacteria was observed. Overall, PVA/Cs-Ag NPs films show promise for food packaging and optoelectronic applications.

Ecofriendly Synthesis of Silver Nanoparticles via Camellia sinensis Leaves and their Insecticidal Effects towards the Storage Pest, Sitophilus oryzae. (L.)


 
 
 Existing agricultural practices are not enough to satisfy the growing demand for food. Therefore, high-yielding varieties, fertilizers, and pesticides must be used to increase productivity with limited arable land. As the crop yield increases, the incidence of pest attack within field and storage ecosystems rise which leads to increased demand for insecticides. Plant-mediated biosynthesis of nanomaterials has attracted much researcher interest in recent years due to many advantages over chemically synthesized conventional insecticides. This study was carried out to evaluate the effectiveness of silver nanoparticles (AgNPs) synthesized using the leaf extract of Sri Lankan tea from Camellia sinensis to control a major stored-grain insect pest, the Sitophilus oryzae adults (Coleoptera: Curculionidae). The biosynthesized AgNPs were characterized by UV-Vis spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The bio-transformed AgNPs were applied at the rates of 1.5, 1.0, 0.5, 0.25, 0.125 and 0.0625 g/kg on pesticide-free rice grains, wherein the mortality percentage was assessed after every 24 hours for seven days continuously. The appearance of the signature brown color of the solution indicated the formation of silver nanoparticles. UV-Vis spectroscopy results showed a peak of absorbance in the range of 400-460 nm, which is in good agreement with previous records for silver nanoparticles synthesized by green techniques. The average crystallite size determined by subjecting XRD results into Debye-Scherrer equation was found to be 61.9 nm, which was further characterized by the electronmicrography results obtained by SEM, whereby particles were confirmed to be within the nano-range. Results of the toxicity bioassay showed that mortality of S. oryzae adults increased with increasing dosages and time exposed to each dosage, producing 100% mortality at 1.5 g/kg dosage. Hence, it can be concluded that the green synthesized silver nanoparticles can be applied effectively and successfully in a stored grain integrated pest management programs.
 Keywords: Green-synthesized silver nanoparticles, Camellia sinensis, Insecticidal, Sitophilus oryzae
 
 

Silver Nanoparticles Biosynthesis Using White Nest-Swiftlet Extract: A Sustainable Pathway for Nanomedicine Applications

Demand of antibacterial-based metal nanoparticles biomaterials against broad ranges of pathogenic microorganisms show unique functionality in a wide range of applications. Silver nanoparticles (AgNPs) play a major role especially in nanomedicine field; thus, there are urge to find more economic and eco-friendly synthesis method without harming the consumers and/or patients. In this study, an aqueous of white nest-swiftlet (Aerodramus fuciphagus) extract was used as bio-reductant and stabilizing agent to synthesis the AgNPs. The changes colour from colourless to reddish brown within 15 minutes under heat condition, 50 mM AgNO3 concentration and 3, 4, and 5 % (w/v) edible bird nest (EBN) dose indicated the successful of AgNPs biosynthesis by using visual indication. Further characterization of AgNPs was carried out by UV-visible spectroscopy through presence of plasmon resonance band between 410 nm to 430 nm. Infrared spectroscopy technique was used to analyse the involvement of biomolecules in EBN reduced the AgNPs. Their morphology and particle size analysed by field emission scanning electron microscopy (FESEM) showed nearly spherical in size with average diameter of 35 nm. Energy dispersive X-ray (EDX) attached with FESEM evaluate the composition of silver in the solutions. The content of silver increasing with the concentration of EBN extract. On the basis of results and facts, the green approach on AgNPs synthesis through EBN can be proposed as ecologically and economically feasible approach to become antibacterial wound dressing.

Biosynthesis of silver nanoparticles by banana pulp extract: Characterizations, antibacterial activity, and bioelectricity generation

Here, green banana pulp extract (PE) has been used as a bio-reducing agent for the reduction of silver ions to silver nanoparticles (AgNPs). Bio-synthesized AgNPs were characterized by using UV, XRD, FEEM, TEM, and FTIR analysis. The face-centered cubic structures of AgNPs were formed with an average crystallite size of 31.26 nm and an average particle size of 42.97 nm. In this report, the electrical activities of green synthesized AgNPs have been evaluated along with the antibacterial activities. The antibacterial activities of AgNPs were evaluated against two pathogenic bacteria: Escherichia coli (gram-negative) and Staphylococcus epidermidis (gram-positive). AgNPs were added to the electrochemical cell and results demonstrated the improvement of power of the electrochemical cell. Green synthesized AgNPs showed excellent antibacterial activities against both gram-positive and negative bacteria and most importantly the NPs played an important role as an effective catalyst to enhance the electrical performance of bio-electrochemical cells. These significant findings may help in the advancement of nanotechnology in biomedical applications as well as in the creation of cheap and eco-friendly power generation devices.

Stimulating effect of biogenic nanoparticles on the germination of basil (Ocimum basilicum L.) seeds

Metal nanoparticles synthesized using various biosources are the subject of focus in many research areas thanks to their improved biological effects and increased bioavailability. Silver (Ag), zinc oxide (ZnO) and magnetite (Fe3O4) nanoparticles (NPs) were obtained by using low-cost, low-energy, environmentally friendly, non-toxic chemicals and easily accessible thyme leaves and lavender flowers. The effects of various concentrations of biosynthesized NPs on the germination and germination index of basil seeds were defined comparatively. Phytochemicals in lavender flower extract acted as reducing and capping agents in the biosynthesis of Ag-NPs, and phytochemicals in thyme leaves extract acted for the biosynthesis of ZnO-NPs ve Fe3O4-NPs. Relative root length was detected at 25 mg/L ZnO-NP, stem length at 50 mg/L ZnO-NP, and relative seed germination 100 mg/L Fe3O4-NP with the maximum value. However, germination percentage, germination index, germination vigor index and root length were found to be maximum compared to other NP applications at Ag-NPs at 200 mg/L. This research showed that the germination promoting effects of NPs, which may be essential microelements, are related to their size, surface area, morphology and concentration. Thus, it promoted early and rapid germination by breaking the NP's seed dormancy.