Green synthesis of silver nanoparticles using Vernonia amygdalina plant extract and its antimicrobial activities

Plant-Derived Exosome-like Nanoparticles: A Comprehensive Overview of Their Composition, Biogenesis, Isolation, and Biological Applications

Plant-derived exosome-like nanoparticles (PELNs) are a type of membranous vesicle isolated from plant tissues. They contain proteins, lipids, nucleic acids, and other components. PELNs are involved in the defensive response to pathogen attacks by exerting anti-inflammatory, antiviral, antifibrotic, and antitumor effects through the substances they contain. Most PELNs are edible and can be used as carriers for delivering specific drugs without toxicity and side effects, making them a hot topic of research. Sources of PELNs are abundantly, and they can be produced in high yields, with a low risk of developing immunogenicity in vivo. This paper summarizes the formation, isolation, and purification methods; physical properties; and composition of PELNs through a comprehensive literature search. It also analyzes the biomedical applications of PELNs, as well as future research directions. This paper provides new ideas and methods for future research on PELNs.

Pharmaceutical effluent degradation using hydrogen peroxide-supported zerovalent iron nanoparticles catalyst

Pharmaceutical effluents generated during drugs production and application are often times released into the water systems with little or no treatment, which could pose potential danger to the ecosystem. Advanced oxidation processes for organic pollutants treatment have gained wide consideration due to their effectiveness. In this work, hydrogen peroxide (H2O2) and hydrogen peroxide-supported nano zerovalent iron (H2O2@nZVIs) were deployed to study pharmaceutical effluents (PE) degradation via batch experiments, under various reaction time, (H2O2) and (H2O2@nZVIs) concentrations, pH, PE concentration, and temperature. The nZVIs was prepared from the green synthesis of Vernonia amygdalina leaf extract and characterized using different analytical tools such as Fourier Transform-Infrared Spectroscopy (FT-IR), Gas Chromatography Mass Spectroscopy (GC-MS), Scanning Electron Microscopy (SEM), and X-Ray Diffraction Spectroscopy (XRD). The FT-IR results showed the presence of -C = O, -NH, -OH, -C = C and, -C-O functional groups, SEM report showed that the morphology of the nZVIs is round in shape, while GC-MS revealed the presence of several phytochemicals. When the concentration of the effluent was increased from 10 to 30 ml, the percentage decolourization decreased from 74.74 to 51.96% and from 80.36 to 54.38% for H2O2 and H2O2@nZVI respectively, whereas when the contact time was increased from 10 to 60 min, the percentage decolourization rose from 70.39 to 83.49% for H2O2 and from 85.19 to 89.73% when H2O2@nZVI was used. When the effect of pH was assessed, it was observed that on increasing the pH from 2 to 10, the percentage decolourization rose from 74.5 to 80.25% for H2O2, however, with H2O2@nZVI, the percentage decolourization decreased from 81.50 to 68%. Maximum percentage decolourization of 57.10% and 94.56% for H2O2 and H2O2@nZVI was achieved at catalyst volume of 25 ml. For all the parameters tested, the H2O2@nZVIs performed much better indicating that the nZVIs enhanced the decolourization ability of the H2O2. The kinetic results showed that the decolorization of pharmaceutical effluent by both catalysts fitted very well with the second-order model, while thermodynamic properties of enthalpy change were found to be 10.025 and 27.005 kJ/mol/K for H2O2 and H2O2@nZVIs respectively suggesting that the oxidation process is endothermic in nature. This technique employed in using hydrogen peroxide-supported zero valent iron, proved to be highly efficient not only for pharmaceutical effluent degradation but also in the elimination of lead from the effluent.

Biogenic Synthesis of Silver Nanoparticles Mediated by Aronia melanocarpa and Their Biological Evaluation

In the present study, two A. melanocarpa berry extracts were used for the synthesis of silver nanoparticles (AgNPs). After the optimization of synthesis, the AgNPs were characterized using UV-Vis, FTIR, EDX, DLS, and STEM analyses. The stability in different media, phytotoxicity, as well as antimicrobial and antioxidant activities were also evaluated. The ideal synthesis conditions were represented by a 3 mM AgNO3 concentration, 1:9 extract:AgNO3 volume ratio, alkaline medium, and stirring at 40 °C for 120 min. The synthesis was confirmed by the surface plasmon resonance (SPR) peak at 403 nm, and the strong signal at 3 keV from the EDX spectra. FTIR analysis indicated that polyphenols, polysaccharides, and amino acids could be the compounds responsible for synthesis. Stability tests and the negative zeta potential values showed that phytocompounds also play a role in the stabilization and capping of AgNPs. The preliminary phytotoxicity studies on T. aestivum showed that both the extracts and their corresponding AgNPs had an impact on the growth of roots and shoots as well as on the microscopic structure of leaves. The synthesized AgNPs presented antimicrobial activity against S. aureus, E. coli, and C. albicans. Moreover, considering the results obtained in the lipoxygenase inhibition, the DPPH and hydroxyl scavenging activities, and the ferrous ion chelating assay, AgNPs exhibit promising antioxidant activity.

Facile synthesis of silver nanoparticles using Calotropis procera leaves: unraveling biological and electrochemical potentials

HIGHLIGHTS

CPL-AgNPs exhibited improved biomimetic attributes. Antibiotic resistance against pathogens were challenged through use of CPL-AgNPs. Supercapacitor application of facile synthesized AgNPs for the first time demonstrated improved physical application.

Anti-Inflammatory and Antimicrobial Activity of Silver Nanoparticles Green-Synthesized Using Extracts of Different Plants

In this study, an easy, efficient, economical, and eco-friendly green bio-synthesis method was utilized to synthesize silver nanoparticles (AgNPs) using the extracts of four plants: Ginkgo biloba, Cichorium Intybus, Adiantum Capillus-Veneris, and Rosmarinus Officinalis. The synthesis of AgNPs was confirmed by using a uv-vis spectrometer, which showed distinct surface plasmon resonance (SPR) bands. The surface of AgNPs was characterized using scanning electron microscopy and Fourier-transform infrared spectroscopy. The anti-inflammatory activity of Tenoxicam/Meloxicam-loaded AgNPs has been studied using the inhibition of albumin denaturation method. Tenoxicam-loaded AgNPs showed higher % Inhibition, but Meloxicam-loaded AgNPs showed lower % Inhibition. Furthermore, the AgNPs showed excellent antimicrobial activity on both Gram-negative and Gram-positive bacteria.

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.

Isolation, characterization and anti-inflammatory activity of compounds from the Vernonia amygdalina

The need to explore the abundance of natural products cannot be overemphasized particularly in the management of various disease conditions. In traditional medical practice, Vernonia amygdalina has been widely adopted in the management of various inflammatory disorders. The objective of this investigation was to isolate the bioactive principles from the stem-bark and root of V. amygdalina and assess the anti-inflammatory (in vitro) activity of both the crude extracts and the isolated compounds. Following extraction with the methanol, the extract was subjected to gravity column chromatography and the resultant fractions was further purified to obtained pure compounds. The structural elucidation of the compounds were based on data obtained from 1H to 13C nuclear magnetic resonance (NMR) spectroscopies as well as fourier transform infrared (FT-IR). Using diclofenac as a control drug, the albumin denaturation assay was used to determine the in vitro anti-inflammatory activity of the extracts and isolates. Three distinct compounds characterized are vernoamyoside D, luteolin-7-α-o-glucuronide, and vernotolaside, a new glycoside. When compared to diclofenac, which has an IC50 of 167.8 μg/mL, luteolin-7-α-o-glucuronide, vernoamyoside D, and vernotolaside all showed significant inhibitions with respective IC50 values 549.8, 379.5, and 201.7 μg/mL. Vernotolaside is reported for the first time from the root. The assertion that the plant is used in traditional medicine for the management of inflammatory disorder is somewhat validated by the confirmation of the existence of the compounds with the biochemical actions. Further validation of the isolated compounds would be required in animal studies.

Plasmon-based colorimetric assay using green synthesized gold nanoparticles for the detection of bisphenol A

Herein, we report a green synthesized gold nanoparticle (AuNPs) based colorimetric detection of bisphenol A (BPA). The AuNPs were synthesized using khat leaf extract as a reducing agent by optimizing factors affecting the AuNPs synthesis, including gold precursor concentration (1 mM), and reaction temperature (60 °C). The AuNPs characterization was carried out using ultraviolet-visible spectrophotometry and transmission electron microscopy, and it was found spherical with an average particle size of 17.3 ± 3.7 nm. A colorimetric nanosensor was developed by conjugation of bio-inspired AuNPs with BPA-specific aptamer for a quick and easy detection of BPA in plastic bottled water. The colorimetric assay relies on the strong affinity of BPA for aptamer, which causes detachment of the aptamer from the AuNPs surface in the presence of BPA inducing AuNPs aggregation. To achieve the colorimetric detection of BPA, the concentrations of NaCl and aptamer were optimized. The detection of BPA was monitored visually using a naked eye, as well as quantitatively using an ultraviolet-visible spectrophotometer. The method visual limit of detection (LOD) was determined to be 0.1 ng/mL and reached 0.09 ng/mL using ultraviolet-visible spectrophotometer. The method demonstrated very good linearity (R2 = 0.9986) in the range of 0.1-100 ng/mL. The proposed method showed high sensitivity to BPA detection in plastic bottled water with 86.7-98.0%, recovery. Therefore, the proposed colorimetric nanosensor can be used for determination of BPA in plastic bottled waters with reliable performance at lower concentrations.

Antimicrobial Activity of Citrate-Coated Cerium Oxide Nanoparticles

The purpose of this study was to investigate the antimicrobial activity of citrate-stabilized sols of cerium oxide nanoparticles at different concentrations via different microbiological methods and to compare the effect with the peroxidase activity of nanoceria for the subsequent development of a regeneration-stimulating medical and/or veterinary wound-healing product providing new types of antimicrobial action. The object of this study was cerium oxide nanoparticles synthesized from aqueous solutions of cerium (III) nitrate hexahydrate and citric acid (the size of the nanoparticles was 3-5 nm, and their aggregates were 60-130 nm). Nanoceria oxide sols with a wide range of concentrations (10-1-10-6 M) as well as powder (the dry substance) were used. Both bacterial and fungal strains (Bacillus subtilis, Bacillus cereus, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Proteus vulgaris, Candida albicans, Aspergillus brasielensis) were used for the microbiological studies. The antimicrobial activity of nanoceria was investigated across a wide range of concentrations using three methods sequentially; the antimicrobial activity was studied by examining diffusion into agar, the serial dilution method was used to detect the minimum inhibitory and bactericidal concentrations, and, finally, gas chromatography with mass-selective detection was performed to study the inhibition of E. coli's growth. To study the redox activity of different concentrations of nanocerium, we studied the intensity of chemiluminescence in the oxidation reaction of luminol in the presence of hydrogen peroxide. As a result of this study's use of the agar diffusion and serial dilution methods followed by sowing, no significant evidence of antimicrobial activity was found. At the same time, in the current study of antimicrobial activity against E. coli strains using gas chromatography with mass spectrometry, the ability of nanoceria to significantly inhibit the growth and reproduction of microorganisms after 24 h and, in particular, after 48 h of incubation at a wide range of concentrations, 10-2-10-5 M (48-95% reduction in the number of microbes with a significant dose-dependent effect) was determined as the optimum concentration. A reliable redox activity of nanoceria coated with citrate was established, increasing in proportion to the concentration, confirming the oxidative mechanism of the action of nanoceria. Thus, nanoceria have a dose-dependent bacteriostatic effect, which is most pronounced at concentrations of 10-2-10-3 M. Unlike the effects of classical antiseptics, the effect was manifested from 2 days and increased during the observation. To study the antimicrobial activity of nanomaterials, it is advisable not to use classical qualitative and semi-quantitative methods; rather, the employment of more accurate quantitative methods is advised, in particular, gas chromatography-mass spectrometry, during several days of incubation.

Synthesis of iron oxide nanoparticles using orange fruit peel extract for efficient remediation of dye pollutant in wastewater

The removal of color-causing compounds from wastewater is a significant challenge that industries encounter due to their toxic, carcinogenic, and harmful properties. Despite the extensive research and development of various techniques with the objective of effectively degrading color pollutants, the challenge still persists. This paper introduces a simple technique for producing iron oxide nanoparticles (Fe2O3 NPs) using orange fruit peel for sustainable dye degradation in aqueous environment. The observation of color change and the measurement of UV-visible absorbance at 240 nm provided a confirmation for the development of Fe2O3 NPs. Transmission electron microscopy examination demonstrated that the Fe2O3 NPs have an agglomerated distribution and forming spherical structures with size ranging from 25-80 nm. Energy-dispersive X-ray spectroscopy analysis supported the existence of Fe and O. Fourier transform infrared spectroscopy conducted to investigate the involvement of orange peel extract in the reduction, capping, and synthesis of Fe2O3 NPs from the precursor salt. Fe2O3 NPs showed a photocatalytic remediation of 97%, for methylene blue under visible light irradiation. Additionally, prepared NPs exhibited concentration depended biofilm inhibition action against E. coli and S. aureus. In conclusion, Fe2O3 NPs can efficiently purify water and suppress pathogens due to their strong degrading activity, reusability, and biofilm inhibition property.