Green Synthesis of Silver Nanoparticles with Antibacterial Activity Using Various Medicinal Plant Extracts: Morphology and Antibacterial Efficacy

Combining the Pharmaceutical and Toxicological Properties of Selected Essential Oils with their Chemical Components by GC-MS Analysis

In the current investigation, a comprehensive analysis was carried out on essential oils (EOs) extracted from six aromatic plant species, namely Rosmarinus officinalis, Pelargonium graveolens, Thymus vulgaris, Origanum vulgare, Laurus nobilis, and Aloysia citrodora. An exploration was conducted into the chemical composition using Gas Chromatography-Mass Spectrometry (GC/MS), antioxidant properties assessed through DPPH, ABTS, CUPRAC, FRAP, MCA, and PBD assays, ecotoxicological impacts evaluated via allelopathy and the Daphnia magna heartbeat test, as well as bio-pharmacological effects including anticancer activity and gene expression analysis. Results revealed strong antioxidant activity in all essential oils, with T. vulgaris EO (2748.00 mg TE/g) and O. vulgare EO (2609.29 mg TE/g) leading in CUPRAC assay. R. officinalis EO showed the highest α-amylase inhibition at 1.58 mmol ACAE/g, while O. vulgare EO excelled in α-glucosidase inhibition at 1.57 mmol ACAE/g. Additionally, cytotoxic effects were evaluated on human colorectal cancer (HCT116) cells. A. citrodora, O. vulgare, and R. officinalis EOs were found the most potent anticancer, as also witnessed by their higher modulatory effects on the gene expression of BAX and Bcl-2. Collectively, the present data highlight the importance to implement the knowledge and to valorize the supply chain of aromatic plants.

Pharmacological Potential of Three Berberine-Containing Plant Extracts Obtained from Berberis vulgaris L., Mahonia aquifolium (Pursh) Nutt., and Phellodendron amurense Rupr

Three berberine-containing plant extracts were investigated for their pharmacological properties. The stems and leaves of Berberis vulgaris, Mahonia aquifolium, and Phellodendron amurense were characterized through scanning electron microscopy. The plant extracts obtained from fresh stem barks were further analyzed through high-performance liquid chromatography, revealing berberine concentrations, among berbamine and palmatine. The plant extracts were further tested for their anticancer potential against 2D and 3D human skin melanoma (A375) and lung adenocarcinoma (A549) cell lines. The concentrations at which 50% of the cells are affected was determined by the viability assay and it was shown that B. vulgaris, the plant extract with the highest berberine concentration, is the most efficient inhibitor (0.4% extract concentration for the 2D model and 3.8% for the 3D model). The membrane integrity and nitrate/nitrite concentration assays were consistent with the viability results and showed effective anticancer potential. For further investigations, the B. vulgaris extract was used to obtain silver nanoparticles, which were characterized through transmission electron microscopy, energy dispersive spectroscopy, and X-ray diffraction. The formed nanoparticles have a uniform size distribution and are suited for future investigations in the field of biomedical applications, together with the B. vulgaris plant extract.

Comparative Study of Callistemon citrinus (Bottlebrush) and Punica granatum (Pomegranate) Extracts for Sustainable Synthesis of Silver Nanoparticles and Their Oral Antimicrobial Efficacy

A comparative study was applied to investigate the potential of Callistemon citrinus (bottlebrush) flower extract (BBE) and Punica granatum (pomegranate) peel extracts (PPE) for the sustainable synthesis of the silver nanoparticles, Ag-BBE and Ag-PPE, respectively. The synthesis process of Ag NPs using the selected extracts was applied under optimized conditions. Hence, the effect of the selected plant's type on the different characteristics of the synthesized green Ag NPs was investigated. The UV-Vis spectroscopy revealed the presence of the characteristic silver peaks at 419 and 433 nm of the Ag-BBE and Ag-PPE, respectively. The XRD spectra reported the fcc phase formation of Ag NPs. The TEM results highlighted the morphological features of the synthesized Ag NPs. with a size range of 20-70 nm, and with 10-30 nm for Ag-BBE and Ag-PPE, correspondingly. The Raman spectra revealed characteristic silver bands in the Ag-PPE and reflected some bands related to the natural extract in the Ag-BBE sample. The antimicrobial activity and statistical analysis investigation were conducted against four selected oral pathogens (Staphylococcus aureus (SA), Candida albicans (CA), Staphylococcus epidermidis (S. epi), and Enterococcus faecalis (EF)). Both tested extracts, BBE, and PPE, revealed potential effectivity as reducing and capping agents for Ag NP green synthesis. However, the synthesized NPs demonstrated different features, depending on the used extract, reflecting the influence of the plant's biomolecules on the nanoparticles' properties.

Biosynthesis, characterization and study of the application of silver nanoparticle for 4-nitrophenol reduction, and antimicrobial activities

Silver nanoparticles (AgNPs) were synthesized from Vigna unguiculata (L) Walp extracted leaves, and characterized. The UV-Visible spectrum showed a peak between 411 and 415 nm at the Plasmon absorbance of the AgNPs. TEM showed that the size of AgNPs ranged from 5 to 13 nm. It was spherical with an average size of 11.08 nm. The size of AgNPs was 7 ± 6 nm and disperse in water. The AgNPs effectively reduced 4-Nitrophenol (4-NP) to 4-aminophenol (4-AP) in the presence of NaBH4. The AgNPs exhibited a strong antioxidant and antibacterial activity against Gram-negative bacteria: Escherichia coli (E. coli) and Klebsiella pneumonia and Gram-positive: Bacillus pumilus and Staphylococcus aureus. The average zones of inhibition of AgNPs were: 29 mm for Staphylococcus aureus, 23 mm for Bacillus pumilus, 17 mm for Klebsiella pneumonia and 15 mm for Escherichia coli (E. coli). Thus, AgNPs has exhibted good antibacterial activity compared to antibiotics drug and 4-NP reduction.

Facile green synthesis of silver nanoparticles derived from the medicinal plant Clerodendrum serratum and its biological activity against Mycobacterium species

The emergence of multidrug-resistant mycobacterial strains is a significant crisis that has led to higher treatment failure rates and more toxic and expensive medications for tuberculosis (TB). The urgent need to develop novel therapeutics has galvanized research interest towards developing alternative antimicrobials such as silver nanoparticles (AgNPs). The current study focused on the anti-mycobacterial activity of green-synthesized AgNPs and its polyethylene glycol encapsulated derivative (PEG-AgNPs) with improved stability using the leaves extract of Clerodendrum serratum. Different characterization methods were used to analyze them. DLS analysis revealed a lower polydispersity index of PEG-AgNPs, suggesting a more uniform size distribution than that of AgNPs. The HR-TEM results revealed that the AgNPs and PEG-AgNPs have predominantly spherical shapes in the size range of 9-35 nm and 15-60 nm, respectively, while positive values of Zeta potential indicate their stability. FTIR-ATR analysis confirmed the presence of functional groups responsible for reducing and capping the bio-reduced AgNPs, whereas the XRD data established its crystalline nature. Impressively, the PEG-AgNPs exhibited maximum inhibitory activity against different Tubercular and Non-Tuberculous Mycobacterium species i.e., Mycobacterium smegmatis, Mycobacterium fortuitum and Mycobacterium marinum, relative to those of AgNPs and Linezolid. The flow cytometry assay showed that the anti-mycobacterial action was mediated by an increase in cell wall permeability. Notably, the results of AFM confirm their ability to inhibit mycobacterial biofilm significantly. We demonstrated the nontoxic nature of these AgNPs, explicated by the absence of hemolytic activity against human RBCs. Overall, the results suggest that PEG-AgNPs could offer a novel therapeutic approach with potential anti-mycobacterial activity and can overcome the limitations of existing TB therapies.

Silver nanoparticle biosynthesis utilizing Ocimum kilimandscharicum leaf extract and assessment of its antibacterial activity against certain chosen bacteria

The use of plants in the biological production of silver nanoparticles for antibacterial applications is a growing field of research. In the current work, we formulated Ocimum kilimandscharicum extracts using silver nanoparticles, and evaluated its potential antibacterial activity. Aqueous and methanol plant extracts were used to reduce silver nitrate at different time intervals (30 to 150 minutes) and pH (2 to 11). The UV-visible absorption spectrum recorded for methanol and aqueous extracts revealed a successful synthesis of AgNPs for methanol and aqueous extracts. The antimicrobial activity of the AgNPs was evaluated against Escherichia coli ATCC 25922, Salmonella choleraesuius ATCC 10708, and Staphylococcus aureus ATCC 25923 The best inhibition zone for the methanol and aqueous-mediated AgNPs, ranging from 12 ± 1 to 16 ± 1mm. Additionally, the methanol and aqueous extract silver nanoparticles had the same Minimum Inhibitory Concentration (6.25 ± 0.00 mg/ml), whereas the Minimum Bactericidal Concentrations were 12.5 ± 0.00 and 25 ± 0.00 mg/ml, respectively. The highest inhibition zone of 16 ± 1 mm was observed against Salmonella choleraesuius with 50 ± 0.00 mg/ml aqueous silver nanoparticles. The results show that the silver nanoparticles made with Ocimum kilimandscharicum have antibacterial action against those microorganisms.

Green synthesis of silver doped zinc oxide/magnesium oxide nanocomposite for waste water treatment and examination of their cytotoxicity properties

This research attempted to prepare silver-doped zinc oxide/magnesium oxide nanocomposite (Ag-doped ZnO/MgO-NCP) using Mentha pulegium plant extract. The synthesized NCP was investigated by X-ray diffraction analysis (XRD), Fourier Transform Infrared (FT-IR), Field Emission Scanning Electron Microscope (FESEM), Energy dispersive X-ray spectroscopy (EDX), Mapping, and UV-Visible analyses. The XRD data displayed cubic crystal structures for silver & magnesium oxide and a hexagonal framework for zinc oxide. Also, FESEM and PSA images of NCP pointed out, that the average size of the spherical morphology is about 10-16 nm, while the analysis of EDX confirmed the attendance of Zn, Mg, Ag, and O elements. Under UVA light, we tested the photocatalytic activity of NCP to the degradation of Methylene blue (MB) and Rhodamine B (RhB) dyes in various temperatures (400, 500, and 600 °C). The results of the photocatalytic test displayed that the degradation percentage of MB dye in pH = 9, nanocomposite amount ∼30 mg, and dye concentration ∼1 × 10 -5 M was about 98 %. We also evaluated the cytotoxicity of nanocomposite on cancer CT-26 cell line through the MTT method and obtained an IC50 value of 250 μg/mL.

Green Synthesis and Characterization of Silver Nanoparticles Using Moringa Peregrina and Their Toxicity on MCF-7 and Caco-2 Human Cancer Cells

Introduction

The synthesis of nanoparticles using naturally occurring reagents such as vitamins, sugars, plant extracts, biodegradable polymers and microorganisms as reductants and capping agents could be considered attractive for nanotechnology. These syntheses have led to the fabrication of limited number of inorganic nanoparticles. Among the reagents mentioned above, plant-based materials seem to be the best candidates, and they are suitable for large-scale biosynthesis of nanoparticles.

Methods

The aqueous extract of Moringa peregrina leaves was used to synthesize silver nanoparticles. The synthesized nanoparticles were characterized by various spectral studies including FT-IR, SEM, HR-TEM and XRD. In addition, the antioxidant activity of the silver nanoparticles was studied viz. DPPH, ABTS, hydroxyl radical scavenging, superoxide radical scavenging, nitric oxide scavenging potential and reducing power with varied concentrations. The anticancer potential of the nanoparticles was also studied against MCF-7 and Caco-2 cancer cell lines.

Results

The results showed that silver nanoparticles displayed strong antioxidant activity compared with gallic acid. Furthermore, the anticancer potential of the nanoparticles against MCF-7 and Caco-2 in comparison with the standard Doxorubicin revealed that the silver nanoparticles produced significant toxic effects against the studied cancer cell lines with the IC50 values of 41.59 (Caco-2) and 26.93 (MCF-7) µg/mL.

Conclusion

In conclusion, the biosynthesized nanoparticles using M. peregrina leaf aqueous extract as a reducing agent showed good antioxidant and anticancer potential on human cancer cells and can be used in biological applications.

Antibacterial Potential of Biosynthesized Silver Nanoparticles Using Berberine Extract Against Multidrug-resistant Acinetobacter baumannii and Pseudomonas aeruginosa

The emergence of multidrug resistance in bacterial infections has limited the use of antibiotics. Helping the action of antibiotics is one of the needs of the day. Today, the biosynthesis of nanoparticles (NPs) is considered due to its safety and cost-effectiveness. In this study, we investigated the effect of biosynthesized silver nanoparticles (AgNPs) by Berberine plant extract against standard strains of multidrug-resistant (MDR) Acinetobacter baumannii and Pseudomonas aeruginosa. Utilized UV-Vis, FTIR, FESEM/EDX, XRD, DLS, and Zeta potential techniques to confirm the biosynthesis of NPs. Then, disk diffusion agar (DDA) and minimum inhibitory concentration (MIC) tests were performed using common classes of standard antibiotics and AgNPs on the mentioned bacteria. The synergistic action between AgNPs and antibiotics was evaluated by the checkerboard method. First, we obtained the confirmation results of the biosynthesis of AgNPs. According to the DDA test, both standard bacterial strains were sensitive to NPs and had an inhibition zone. Also, the MIC values showed that AgNPs inhibit the growth of bacteria at lower concentrations than antibiotics. On the other hand, the results obtained from checkerboard monitoring showed that AgNPs, in combination with conventional antibiotics, have a synergistic effect. The advantage of this study was comparing the antibacterial effect of AgNPs alone and mixed with antibiotics. The antibacterial sensitivity tests indicated that the desired bacterial strains could not grow even in low concentrations of AgNPs. This property can be applied in future programs to solve the drug resistance of microorganisms in bacterial diseases.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12088-023-01136-y.

Valorization of plant by-products in the biosynthesis of silver nanoparticles with antimicrobial and catalytic properties

Biosynthesis based on natural compounds has emerged as a sustainable approach for the production of metallic nanoparticles (MNP). The main objective of this study was to biosynthesize stable and multifunctional silver nanoparticles (AgNP) using different plant by-products as reducers and capping agents. Extracts obtained from Eucalyptus globulus, Pinus pinaster, Citrus sinensis, Cedrus atlantica and Camellia sinensis by-products, were evaluated. From all plant by-products tested, aqueous extract of eucalyptus leaves (EL), green tea (GT) and black tea (BT) were selected due to their higher antioxidant phenolic content and were individually employed as reducers and capping agents to biosynthesize AgNP. The green AgNP showed zeta potential values of -31.8 to -36.3 mV, with a wide range of particle sizes (40.6 to 86.4 nm), depending on the plant extract used. Green AgNP exhibited an inhibitory effect against various pathogenic bacteria, including Gram-negative (P. putida, E. coli, Vibrio spp.) and Gram-positive (B. megaterium, S. aureus, S. equisimilis) bacteria with EL-AgNP being the nanostructure with the greatest antimicrobial action. EL-AgNP showed an excellent photodegradation of indigo carmine (IC) dye under direct sunlight, with a removal percentage of up to 100% after 75 min. A complete cost analysis revealed a competitive total cost range of 8.0-9.0 €/g for the biosynthesis of AgNP.

Biosynthesis and characterization of silver nanoparticles synthesized using extracts of Agrimonia eupatoria L. and in vitro and in vivo studies of potential medicinal applications

This research explores the synthesis, characterization, and biological activities of silver nanoparticles (AgNPs) derived from acetone (AgNPs-acetone) and aqueous (AgNPs-H2O) extracts of Agrimonia eupatoria. The nanoparticles exhibit isometric morphology and uniform size distribution, as elucidated through Transmission Electron Microscopy (TEM) and high-resolution TEM (HRTEM) analyses. The utilization of Scanning Transmission Microscopy (STEM) with High-Angle Annular Dark-Field (HAADF) imaging and energy dispersive spectrometry (EDS) confirms the crystalline nature of AgNPs. Fourier Transform Infrared (FTIR) analysis reveals identical functional groups in the plant extracts and their corresponding AgNPs, suggesting the involvement of phytochemicals in the reduction of silver ions. Spectrophotometric monitoring of the synthesis process, influenced by various parameters, provides insights into the kinetics and optimal conditions for AgNP formation. The antioxidant activities of the plant extracts and synthesized AgNPs are evaluated through DPPH and ABTS methods, highlighting AgNPs-acetone as a potent antioxidant. Third-instar larvae exposed to the extracts have differential effects on DNA damage, with the acetone extract demonstrating antigenotoxic properties. Similarly, biosynthesized AgNPs-acetone displays antigenotoxic effects against EMS-induced DNA damage. The genotoxic effect of water extract and AgNPs-acetone was dose-dependent. Hemolytic potential is assessed on rat erythrocytes, revealing that low concentrations of AgNPs-acetone and AgNPs-H2O had a nontoxic effect on erythrocytes. Cytotoxicity assays demonstrate time-dependent and dose-dependent effects, with AgNPs-acetone exhibiting superior cytotoxicity. Proapoptotic activity is confirmed through apoptosis induction, emphasizing the potential therapeutic applications of AgNPs. The antimicrobial activity of AgNPs reveals concentration-dependent effects. AgNPs-H2O display better antibacterial activity, while antifungal activities are comparable between the two nanoparticle types.

Application of Lavandula angustifolia Mill. Extracts for the Phytosynthesis of Silver Nanoparticles: Characterization and Biomedical Potential

Nanotechnology can offer a series of new "green" and eco-friendly methods for developing different types of nanoparticles, among which the development of nanomaterials using plant extracts (phytosynthesis) represents one of the most promising areas of research. This present study details the use of lavender flowers (Lavandula angustifolia Mill., well-known for their use in homeopathic applications) for the biosynthesis of silver nanoparticles with enhanced antioxidant and antibacterial properties. Several qualitative and quantitative assays were carried out in order to offer an image of the extracts' composition (the recorded total phenolics content varied between 21.0 to 40.9 mg GAE (gallic acid equivalents)/g dry weight (d.w.), while the total flavonoids content ranged between 3.57 and 16.8 mg CE (catechin equivalents)/g d.w.), alongside modern analytical methods (such as gas chromatography-mass spectrometry-GC-MS, quantifying 12 phytoconstituents present in the extracts). The formation of silver nanoparticles (AgNPs) using lavender extract was studied by UV-Vis spectroscopy, Fourier-transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and dynamic light scattering (DLS)/zeta potential, with the selected nanoparticles having crystallite sizes of approx. 14.55 nm (AgNP-L2) and 4.61 nm, respectively (for AgNP-L4), and hydrodynamic diameters of 392.4 nm (for AgNP-L2) and 391.6 nm (for AgNP-L4), determined by DLS. A zeta potential of around -6.4 mV was displayed for both samples while presenting as large aggregates, in which nanoparticle clusters with dimensions of around 130-200 nm can be observed. The biomedical applications of the extracts and the corresponding phytosynthesized nanoparticles were evaluated using antioxidant and antimicrobial assays. The obtained results confirmed the phytosynthesis of the silver nanoparticles using Lavandula angustifolia Mill. extracts, as well as their antioxidant and antimicrobial potential.

Diffused sunlight assisted green synthesis of silver nanoparticles using Cotoneaster nummularia polar extract for antimicrobial and wound healing applications

The current study reports the synthesis of silver nanoparticles (Ag NPs) using a polar extract of Cotoneaster nummularia leaves. Various analytical techniques, like UV-Vis spectrophotometry, FT-IR spectroscopy, XRD, SEM, and EDX were employed for characterisation. These techniques confirmed the stability of Ag NPs in solution and endorsed the interaction between different groups and Ag, crystal phase, surface morphology, and size of Ag NPs. UV-Vis spectrophotometer displayed SPR absorption bands ranging from 380 to 470 nm, characteristic of Ag NPs, within 1.0 h exposure to sunlight. XRD and SEM discovered the face-centered cubic crystals of Ag NPs with a 122.8 ± 1.1 nm average diameter. The bands at 525 cm-1 in FT-IR spectrum supported the development of Ag NPs. The Ag NPs showed antimicrobial potential against three pathogenic bacterial strains and two fungal strains. The wound healing results, as studied by tissue re-development and wound closure in rabbits were comparable to standard Sufre tulle® dressing.

Optimization of the biosynthesis of silver nanoparticles using bacterial extracts and their antimicrobial potential

In the present study, silver nanoparticles (AgNPs) were biosynthesized using the supernatant and the intracellular extract of Cupriavidus necator, Bacillus megaterium, and Bacillus subtilis. The characterization of the AgNPs was carried out using UV-Vis spectroscopy, FTIR, DLS and TEM. Resazurin microtiter-plate assay was used to determine the antimicrobial action of AgNPs against Escherichia coli. UV-Visible spectra showed peaks between 414 and 460 nm. TEM analysis revealed that the synthesized AgNPs showed mostly spherical shapes. DLS results determined sizes from 20.8 to 118.4 nm. The highest antimicrobial activity was obtained with the AgNPs synthesized with supernatant rather than those using the intracellular extract. Therefore, it was determined that the bacterial species, temperature, pH, and type of extract (supernatant or intracellular) influence the biosynthesis. This synthesis thus offers a simple, environmentally friendly, and low-cost method for the production of AgNPs, which can be used as antibacterial agents.

The Characterization and Study of Antibacterial, Free Radical Scavenging, and Anticancer Potential of Livistona chinensis-Mediated Silver Nanoparticles

In the present research, Livistona chinensis leaf extracts were utilized as reductants to bio-fabricate silver nanoparticles (LC-AgNPs) and this was followed by the evaluation of their antioxidant, antibacterial, and anticancer potential. Multiple parameters were optimized for the formation and fidelity of LC-AgNPs. The color shift of the reaction mixture from yellow to dark brown confirmed the LC-AgNPs formation. UV/VIS spectroscopy exhibited a surface plasmon resonance (SPR) band at 436 nm. The Fourier transform infrared (FTIR) spectroscopy spectrum depicted phytochemicals in the plant extract acting as bio-reducers for LC-AgNPs synthesis. The XRD pattern confirmed the presence of LC-AgNPs by showing peaks corresponding to 2θ angle at 8.24° (111), 38.16° (200), 44.20° (220), and 64.72° (311). Zetasizer analysis exhibited size distribution by intensity of LC-AgNPs with a mean value of 255.7 d. nm. Moreover, the zeta potential indicated that the AgNPs synthesized were stable. The irregular shape of LC-AgNPs with a mean average of 38.46 ± 0.26 nm was found by scanning electron microscopy. Furthermore, the antioxidant potential of LC-AgNPs was examined using a DPPH assay and was calculated to be higher in LC-AgNPs than in leaf extracts. The calculated IC50 values of the LC-AgNPs and plant extract are 85.01 ± 0.17 and 209.44 ± 0.24, respectively. The antibacterial activity of LC-AgNPs was investigated against Escherichia coli, Pseudomonas aeruginosa, and Bacillus subtilis as well as Staphylococcus aureus, and maximum potential was observed after 24 h against P. aeruginosa. Moreover, LC-AgNPs exhibited maximum anticancer potential against TPC1 cell lines compared to the plant extract. The findings suggested that LC-AgNPs could be used as antioxidant, antibacterial, and anticancer agents for the cure of free-radical-oriented bacterial and oncogenic diseases.

Green Synthesis of Silver Nanoparticles Using Jacobaea maritima and the Evaluation of Their Antibacterial and Anticancer Activities

Much attention has been gained on green silver nanoparticles (green-AgNPs) in the medical field due to their remarkable effects against multi-drug resistant (MDR) microorganisms and targeted cancer treatment. In the current study, we demonstrated a simple and environment-friendly (i.e., green) AgNP synthesis utilizing Jacobaea maritima aqueous leaf extract. This leaf is well-known for its medicinal properties and acts as a reducing and stabilizing agent. Nanoparticle preparation with the desired size and shape was controlled by distinct parameters; for instance, temperature, extract concentration of salt, and pH. The characterization of biosynthesized AgNPs was performed by the UV-spectroscopy technique, dynamic light scattering, scanning electron microscopy, X-ray diffraction, and Fourier-transform infrared. The successful formation of AgNPs was confirmed by a surface plasmon resonance at 422 nm using UV-visible spectroscopy and color change observation with a particle size of 37± 10 nm and a zeta potential of -10.9 ± 2.3 mV. SEM further confirmed the spherical size and shape of AgNPs with a size varying from 28 to 52 nm. Antibacterial activity of the AgNPs was confirmed against all Gram-negative and Gram-positive bacterial reference and MDR strains that were used in different inhibitory rates, and the highest effect was on the E-coli reference strain (MIC = 25 μg/mL). The anticancer study of AgNPs exhibited an IC50 of 1.37 μg/mL and 1.98 μg/mL against MCF-7 (breast cancer cells) and A549 (lung cancer cells), respectively. Therefore, this green synthesis of AgNPs could have a potential clinical application, and further in vivo study is required to assess their safety and efficacy.

Biosynthesis of copper oxide nanoparticles using Caesalpinia sappan extract: In vitro evaluation of antifungal and antibiofilm activities against Candida albicans

Synthesis of nanoparticles using natural organic substances has attracted more attention due to avoiding inorganic toxicity. This work aimed to synthesize copper oxide nanoparticles (CuONPs) using Caesalpinia sappan heartwood extract as a reducing agent. The effects of pH of synthesis reaction were investigated. The obtained CuONPs were characterized using UV-visible spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy. Their particle size, size distribution, and zeta potential were determined using photon correlation spectrophotometry. Candida albicans is a major cause of chronic fungal infections due to its biofilms leading to severe drug resistance problems. In this study, in vitro antifungal and antibiofilm activities as well as killing kinetics of the synthesized CuONPs against C. albicans were investigated. Additionally, fungal biofilm was observed by using confocal laser scanning microscopy. The results showed that the pH of the synthesis reaction played an important role in the physicochemical properties and antifungal activities of the obtained CuONPs. CuONPs synthesized at pH 10 and 12 showed the relatively small and narrow size distribution with high negative zeta potential and time-dependent killing kinetics. Confocal laser scanning microscopy confirms obvious fungal biofilm reduction and increased fungal cell death after exposure to CuONPs. These findings suggest the optimal pH of CuONPs synthesis using C. sappan extract as a reducing agent. The results on antifungal and antibiofilm activities indicate that the obtained CuONPs can be a promising agent for treating fungal infection.

Antibacterial Efficacy of Green Synthesized Silver Nanoparticles Using Salvia nubicola Extract against Ralstonia solanacearum, the Causal Agent of Vascular Wilt of Tomato

Ralstonia solanacearum is a phytopathogen causing bacterial wilt diseases of tomato and affecting its productivity, which leads to prominent economic losses annually. As an alternative to conventional pesticides, green synthesized nanoparticles are believed to possess strong antibacterial activities besides being cheap and ecofriendly. Here, we present the synthesis of silver nanoparticles (Sn-AgNPs) from medicinally important aqueous plant extracts of Salvia nubicola. Characterization of biologically synthesized nanoparticles was performed through UV-vis spectrophotometry, Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), and thermogravimetric analysis. The antibacterial activity of the biosynthesized silver nanoparticles was tested against the phytopathogen R. solanacearum through in vitro experiments. Preliminary phytochemical analysis of the plant extracts revealed the presence of substantial amounts of flavonoids (57.08 mg GAE/g), phenolics (42.30 mg GAE/g), tannins, and terpenoids. The HPLC phenolic profile indicated the presence of 25 possible bioactive compounds. Results regarding green synthesized silver nanoparticles revealed the conformation of different functional groups through FTIR analysis, which could be responsible for the bioreduction and capping of Ag ions into silver NPs. TEM results revealed the spherical, crystalline shape of nanoparticles with the size in the range of 23-63 nm, which validates SEM results. Different concentrations of Sn-AgNPs (T1 (500 μg/mL) to T7 (78.1 μg/mL)) with a combination of plant extracts (PE-Sn-AgNPs) and plant extracts alone exhibited an efficient inhibition of R. solanacearum. These findings could be used as an effective alternative preparation against the bacterial wilt of tomato.

Novel extracellular synthesized silver nanoparticles using thermophilic Anoxybacillus flavithermus and Geobacillus stearothermophilus and their evaluation as nanodrugs

In this investigation, two new thermophilic bacteria were isolated. The new isolates were characterized by 16S rRNA, biochemical, morphological, and physiological analyzes and the isolates were identified as Geobacillus stearothermophilus strain Gecek20 and thermophilic Anoxybacillus flavithermus strain Gecek19. Various biological activities of extracellular Ag-NPs synthesized from thermophilic G. stearothermophilus strain Gecek20 and thermophilic A. flavithermus strain Gecek19 were evaluated. The produced NPs were analyzed by SEM, SEM-EDX, and XRD analyses. The antioxidant abilities of new synthesized Ag-NPs from thermophilic G. stearothermophilus strain Gecek20 (T1-Ag-NPs) and new synthesized Ag-NPs from thermophilic A. flavithermus strain Gecek19 (T2-Ag-NPs) were studied by DPPH inhibition and metal chelating ability. The highest DPPH and metal chelating abilities of T1-Ag-NPs and T2-Ag-NPs at 200 mg/L concentration were 93.17 and 90.85%, and 75.80 and 83.64%, respectively. The extracellular green synthesized T1-Ag-NPs and T2-AgN-Ps showed DNA nuclease activity at all tested concentrations. Moreover, both new synthesized Ag-NPs had antimicrobial activity against the strains studied, especially on Gram positive bacteria. T1-Ag-NPs and T2-AgNPs also showed powerful Escherichia coli growth inhibition. The highest biofilm inhibition percentages of T1-Ag-NPs and T2-Ag-NPs against Pseudomonas aeruginosa and Staphylococcus aureus were 100.0%, respectively, at 500 mg/L.

Pendant Modification of Poly(methyl methacrylate) to Enhance Its Stability against Photoirradiation

Photostabilization of functional polymeric materials is important for protection against aging and ultraviolet (UV) irradiation. There is, therefore, the impetus to modify polymers to increase their resistance to photodegradation and photooxidation on extended exposure to UV light in harsh conditions. Various polymeric additives have been designed and synthesized in recent years, and their potential as photostabilizers has been explored. Reported here is the effect of pendant functionalization of poly(methyl methacrylate) (PMMA) through organometallic moiety incorporation into the polymer's backbone. The reaction of PMMA with ethylenediamine leads to the formation of an amino residue that can react with salicylaldehyde to produce the corresponding Schiff base. Adding metal chlorides (zinc, copper, nickel, and cobalt) led to the formation of organometallic residues on the polymeric chains. Thin films of modified and unmodified PMMA were produced and irradiated with UV light to determine the effect of pendant modification on photostability. The photostabilization of PMMA was assessed using a range of methods, including infrared spectroscopy, weight loss, decomposition rate constant, and surface morphology. The modified PMMA incorporating organic Schiff base metal complexes showed less photodecomposition than the unmodified polymer or one containing the Schiff base only. Thus, the metals significantly reduced the photodegradation of polymeric materials. The polymer containing the Schiff base-cobalt unit showed the least damage in the PMMA surface due to photoirradiation, followed by those containing nickel, zinc, and copper, in that order.

Phytochemical-Mediated Biosynthesis of Silver Nanoparticles from Strobilanthes glutinosus: Exploring Biological Applications

The application of green synthesis for silver nanoparticles in nanomedicine has experienced significant growth. Strobilanthes glutinosus, a plant primarily located in the Himalayas, remains largely unexplored. Considering the biomedical value of S. glutinosus, phytochemicals from this plant were used for the biosynthesis of silver nanoparticles. Silver nanoparticles were synthesized from aqueous extract of root and leaves of Strobilanthes glutinosus. The synthesized silver nanoparticles were characterized using UV-Vis spectrophotometry, Fourier-transform infrared spectroscopy, transmission electron microscopy, and X-ray diffraction. Total phenolic and flavonoid contents of plants were determined and compared with nanoparticles. The biomedical efficacy of plant extracts and silver nanoparticles was assessed using antioxidant and antibacterial assays. The UV-Vis spectra of leaf- and root-extract-mediated AgNPs showed characteristic peaks at 428 nm and 429 nm, respectively. TEM images revealed the polycrystalline and spherical shapes of leaf- and root-extract-mediated AgNPs with size ranges of 15-60 nm and 20-52 nm, respectively. FTIR findings shown the involvement of phytochemicals of root and leaf extracts in the reduction of silver ions into silver nanoparticles. The crystalline face-centered cubic structure of nanoparticles is depicted by the XRD spectra of leaf and root AgNPs. The plant has an ample amount of total phenolic content (TPC) and total flavonoid content (TFC), which enhance the scavenging activity of plant samples and their respective AgNPs. Leaf and root AgNPs have also shown good antibacterial activity, which may enhance the medicinal value of AgNPs.

Editorial for the Special Issue "Biological and Toxicological Studies of Nanoparticles"

Nanoparticles have attracted a great deal of attention over the past two decades or more due to their unique size-dependent physical and chemical properties [...].

Use of Euphorbia balsamifera Extract in Precursor Fabrication of Silver Nanoparticles for Efficient Removal of Bromocresol Green and Bromophenol Blue Toxic Dyes

Silver nanoparticles (Ag-NPs) are attracting great attention for their use in various applications, along with methods for their green and facile production. In this study, we present a new eco-friendly approach based on the use of Euphorbia balsamifera extract (EBE) in the green synthesis of silver nanoparticles (Ag-NPs), which are then applied as a reducing and stabilizing agent for the efficient removal of water-based reactive dyes such as bromocresol green (BCG) and bromophenol blue (BPB). The as-prepared Ag-NPs are quasi-spherical in shape, with an average diameter of 20-34 nm. Diverse characterization methods, including X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Brunauer-Emmett-Teller (BET) analysis, were used to analyze these Ag-NPs. The results reveal that water-soluble biomolecules in the Euphorbia balsamifera extract play an important role in the formation of the Ag-NPs. The removal of toxic dyes was studied under varied operational parameters such as Ag-NP dosage, initial dye concentration, pH, stirring time, and temperature. Under the optimum investigated conditions, nearly 99.12% and 97.25% of the bromocresol green and bromophenol blue dyes, respectively, were removed. Both BCG and BPB adsorption were found to adhere to pseudo-second-order kinetics (r₂² = 1 and 0.995) and fit the Langmuir isotherm models well (R₁² = 0.998 and 0.994), with maximal monolayer adsorption capacities of 20.40 and 41.03 mg/g, respectively. Their adsorption processes were observed to be intrinsically endothermic. The results confirm the potential of the Euphorbia balsamifera extract as a low-cost, nontoxic, and eco-friendly natural resource for the synthesis of Ag-NPs that may be useful in the remediation of hazardous dye-contaminated water sources.

Effect of Size, Shape and Surface Functionalization on the Antibacterial Activity of Silver Nanoparticles

Silver nanoparticles (AgNPs) are the most investigated antibacterial agents against multidrug resistant (MDR) pathogens. They can lead to cellular death by means of different mechanisms, damaging several cell compartments, from the external membrane, to enzymes, DNA and proteins; this simultaneous attack amplifies the toxic effect on bacteria with respect to traditional antibiotics. The effectiveness of AgNPs against MDR bacteria is strongly correlated with their chemical and morphological properties, which influence the pathways involved in cellular damage. In this review, AgNPs' size, shape and modification by functional groups or other materials are reported, both to investigate the different synthetic pathways correlated with nanoparticles' modifications and to evaluate the related effect on their antibacterial activity. Indeed, understanding the synthetic conditions for obtaining performing antibacterial AgNPs could help to tailor new and improved silver-based agents to combat multidrug resistance.

Comparative assessment of the biological activity of the green synthesized silver nanoparticles and aqueous leaf extract of Perilla frutescens (L.)

Green synthesized nanoparticles (GSNPs) display fascinating properties compared to physical and chemical synthesized ones. GSNPs are currently used in numerous applications such as food packaging, surface coating agents, environmental remediation, antimicrobial, and medicine. In the present study, the aqueous leaf extract of Perilla frutescens L. having suitable capping, reducing, and stabilizing compounds was used for green synthesis of silver nanoparticles (Pf-AgNPs). The bioreductant capacity of aqueous leaf extract of P. frutescens for Pf-AgNPs was determined by different confirmatory techniques including UV-Visible spectroscopy, XRD, FESEM, EDX, zeta potential, DLS, SERS, and FTIR analysis. The results exhibited that Pf-AgNPs had optimal size (< 61 nm), shape (spherical), and stability (- 18.1 mV). The antioxidant activity of Pf-AgNPs with both DPPH and FRAP assays was significantly higher compared to P. frutescens extract. Furthermore, Pf-AgNPs had high antimicrobial activity against Escherichia coli and Staphylococcus aureus (MIC = 0.78 mg/mL), and Candida albicans (MIC = 8 mg/mL) while the plant extract showed low antimicrobial activity against both bacterial strains and the fungus tested. Pf-AgNPs and P. frutescens extract also exhibited moderate toxicity on MCF-7 cancer cells with IC₅₀ values of 346.2 and 467.4 µg/mL, respectively. The results provide insights into using the biosynthesized Pf-AgNPs as an eco-friendly material for a wide range of biomedical applications.

Bactericidal activity of Ag nanoparticles biosynthesized from Capsicum annuum pericarps against phytopathogenic Clavibacter michiganensis

Metallic nanoparticles of different compositions have already found numerous applications in various branches of industry, agriculture, and medicine. Given the well-known antibacterial activity of Ag, silver nanoparticles (AgNPs) are constantly being investigated for their promising ability to fight antibiotic-resistant pathogens. A promising candidate for AgNPs biosynthesis is chili pepper Capsicum annuum, cultivated worldwide and known for accumulating significant amounts of active substances. Phytochemical screening of aqueous extract of C. annuum pericarps demonstrated accumulation of 4.38 mg/g DW of total capsaicinoids, 14.56 mg GAE/g DW of total phenolic compounds, 1.67 mg QE/g DW of total flavonoids, and 1.03 mg CAE/g DW of total phenolic acids. All determined aromatic compounds carry various active functional groups, which effectively participate in the biosynthesis of AgNPs and are characterized by high antioxidant potential. Therefore, the present research focused on the facile, quick, and effective procedure for the biosynthesis of AgNPs, which were analyzed for their morphology such as shape and size through UV-visible, Fourier-transform infrared spectroscopy (FTIR) assays, and scanning electron microscopy. We found that the AgNPs biosynthesis resulted in changes in FTIR spectra, depicting the rearrangement of numerous functional groups, while the nanoparticles themselves were shown to be stable, spherical, 10-17 nm in size. Also we investigated the antibacterial properties of biosynthesized AgNPs, obtained with C. annuum fruit extracts, against a common phytopathogen Clavibacter michiganensis subsp. michiganensis. As was shown by zone inhibition assay, AgNPs showed dose-dependent 5.13-6.44 cm antibacterial activity, greatly exceeding the 4.98 cm inhibition area, produced by the precursor salt, AgNO₃.

Metal Oxide Nanoparticles Containing Clotrimazole to Suppress Photodegradation of Poly(Vinyl Chloride) Thin Films

Pol(vinyl chloride) or PVC has functional properties that enable its use in many industrial applications. It suffers from aging, however, in harsh conditions (e.g., elevated temperature or high humidity levels) if oxygen is present. One way to enhance the photostability of PVC is to blend it with additives. Thus, thin films were made by mixing PVC with clotrimazole, and five metal oxide (titanium, copper, cobalt, chromium, and nickel oxides) additives. The metal oxides and clotrimazole were added at concentrations of 0.1 and 0.5% by weight, respectively. The effect of the metal oxide nanoparticles accompanied by clotrimazole on the photodegradation of PVC was then assessed. The results indicated that the additives have a stabilizing effect and protect PVC against photodegradation significantly. The formation of polymeric fragments of small molecular weight containing carbon-carbon double bonds and carbonyl groups was lower in the blends containing metal oxide nanoparticles and clotrimazole than in unblended PVC. Similarly, the decrease in weight was much less for the films blended with additives. Additionally, surface analysis of the irradiated polymeric films showed significantly lower damage in the materials containing additives. The most effective additive in the stabilization of PVC was nickel oxide nanoparticles. The metal oxides are highly alkaline and act as scavengers for the hydrogen chloride produced during the photodegradation of PVC. They additionally act as peroxide decomposers. In contrast, clotrimazole can absorb harmful radiation and act as an ultraviolet absorber due to its heteroatom and aromatic content. Thus, the use of a combination of metal oxide nanoparticles and clotrimazole led to significant improvement in the resistance of PVC toward photodegradation.

Green Synthesis, Characterization, Antioxidant, Antibacterial and Enzyme Inhibition Effects of Chestnut (Castanea sativa) Honey-Mediated Silver Nanoparticles

In this study, chestnut honey-based silver nanoparticles (CH-AgNPs) were synthesized at different temperatures (30, 60 and 90 °C) and these nanoparticles were characterized by different techniques such as UV-vis spectrophotometer, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX). The DPPH free radical scavenging assay was used to determine the antioxidant activity of the obtained nanoparticles. The inhibition effects of these nanoparticles for some clinically important enzymes such as myeloperoxidase and collagenase were investigated. In addition, the disk diffusion method (DDM), agar well diffusion (AWD), and minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) techniques were used to determine the antibacterial activity of CH-AgNPs. In honey-based silver nanoparticle production processes using green synthesis, it was determined that the nanoparticle sizes decreased from 55 to 27 nm with an increase in temperature. In addition, it was determined that the rate of inhibition of myeloperoxidase (36.4% to 34.0%) and collagenase enzymes (74.2% to 68.7%) increased with a decrease in particle size. As a result of the antibacterial activity tests, it was observed that CH-AgNPs have antibacterial activity against all target pathogens including Gram-positive and Gram-negative bacteria. The obtained results show that CH-AgNPs produced using chestnut honey have the potential to be used in fields such as medicine, pharmacy and cosmetic technology.

Blending Approach Preparation of PVA-g-PMA Films with Embedded "Green" Synthesized Silver Nanoparticles for Acetone Optical Detection

The blending approach (also known as the ex-situ approach) was used for the deposition of thin composite films comprising poly(vinyl alcohol-graft-methyl acrylate) (PVA-g-PMA) and silver nanoparticles (AgNPs). Firstly, the copolymer aqueous dispersion was synthesized through the redox polymerization of methyl acrylate (MA) on poly(vinyl alcohol) (PVA) using ammonium cerium (IV) nitrate as the initiator. Then, AgNPs were synthesized through a "green" method using the water extract of lavender based on by-products of the essential oil industry, and then they were blended with the polymer. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) were used to determine nanoparticle size, along with their stability over time in suspension, during the 30-day period. Thin films of the PVA-g-PMA copolymer, with different AgNP volume fractions varying between 0.008 and 0.260%, were deposited via the spin-coating method on Si substrates, and their optical properties were explored. UV-VIS-NIR spectroscopy and non-linear curve fitting were used for the determination of the refractive index, extinction coefficient, and thickness of the films, while photoluminescence measurements at room temperature were conducted for studying the emission of the films. The concentration dependence of film thickness was observed and showed that thickness increased linearly from 31 nm to 75 nm when the nanoparticles' weight content increased from 0.3 wt% to 2.3 wt%. The sensing properties toward acetone vapors were tested in a controlled atmosphere by measuring reflectance spectra before and during exposure to the analyte molecules in the same film spot; the swelling degree of films was calculated and compared to the corresponding undoped samples. It was shown that the concentration of AgNPs of 1.2 wt% in the films is optimal for the enhancement of the sensing response toward acetone. The influence of AgNPs on the films' properties was revealed and discussed.

In Situ Gel with Silver Nanoparticles Prepared Using Agrimonia eupatoria L. Shows Antibacterial Activity

Silver nanoparticles (Ag NPs) with antibacterial activity can be prepared in different ways. In our case, we used ecological green synthesis with Agrimonia eupatoria L. The plant extract was used with Ag NPs for the first time to prepare termosensitive in situ gels (ISGs). Such gels are used to heal human or animal skin and mucous membranes, as they can change from a liquid to solid state after application. Ag NPs were characterized with various techniques (FTIR, TEM, size distribution, zeta potential) and their antibacterial activity was tested against Staphylococcus aureus and Escherichia coli. In accordance with the TEM data, we prepared monodispersed spherical Ag NPs with an average size of about 20 nm. Organic active compounds from Agrimonia eupatoria L. were found on their surfaces using FTIR spectroscopy. Surprisingly, only the in situ gel with Ag NPs showed antibacterial activity against Escherichia coli, while Ag NPs alone did not. Ag NPs prepared via green synthesis using plants with medicinal properties and incorporated into ISGs have great potential for wound healing due to the antibacterial activity of Ag NPs and the dermatological activity of organic substances from plants.

Environmentally benign silver bio-nanomaterials as potent antioxidant, antibacterial, and antidiabetic agents: Green synthesis using Salacia oblonga root extract

Introduction: The use of plant extracts in the green synthesis of metallic nanoparticles is one of the simplest, most practical, economical, and ecologically friendly methods for avoiding the use of toxic chemicals. Method: Silver nanoparticles (AgNPs) were synthesized, employing a high-efficiency, non- toxic, cost-effective, green, and simple technique that included the use of Salacia oblonga root extract (SOR) as a capping agent compared to synthetic nanoparticles. The use of S. oblonga can be seen in traditional medicines for treating diabetes, obesity, rheumatism, gonorrhea, asthma, and hyperglycemia. The objectives of the current study were to green synthesize S. oblonga root extract silver nanoparticles (SOR-AgNPs), characterize them, and study their antioxidant, antibacterial, and antidiabetic activities. Result: The shape of SOR-AgNPs was spherical, at less than 99.8 nm in size, and exhibited a crystalline peak at XRD. The green synthesized SOR-AgNPs showed significant antioxidant properties like DPPH (80.64 μg/mL), reducing power capacity (81.09 ± SEM μg/mL), nitric oxide (96.58 μg/mL), and hydroxyl (58.38 μg/mL) radical scavenging activities. The MIC of SOR-AgNPs was lower in gram-positive bacteria. The SOR-AgNPs have displayed efficient inhibitory activity against α-amylase, with an EC50 of 58.38 μg/mL. Analysis of capping protein around the SOR-AgNPs showed a molecular weight of 30 kDa. Discussion: These SOR-AgNPs could be used as antibacterial and antidiabetic drugs in the future as it is cheap, non-toxic, and environmentally friendly. Bio-fabricated AgNPs had a significant impact on bacterial strains and could be used as a starting point for future antibacterial drug development.

Silver Nanoparticles: Bactericidal and Mechanistic Approach against Drug Resistant Pathogens

This review highlights the different modes of synthesizing silver nanoparticles (AgNPs) from their elemental state to particle format and their mechanism of action against multidrug-resistant and biofilm-forming bacterial pathogens. Various studies have demonstrated that the AgNPs cause oxidative stress, protein dysfunction, membrane disruption, and DNA damage in bacteria, ultimately leading to bacterial death. AgNPs have also been found to alter the adhesion of bacterial cells to prevent biofilm formation. The benefits of using AgNPs in medicine are, to some extent, counter-weighted by their toxic effect on humans and the environment. In this review, we have compiled recent studies demonstrating the antibacterial activity of AgNPs, and we are discussing the known mechanisms of action of AgNPs against bacterial pathogens. Ongoing clinical trials involving AgNPs are briefly presented. A particular focus is placed on the mechanism of interaction of AgNPs with bacterial biofilms, which are a significant pathogenicity determinant. A brief overview of the use of AgNPs in other medical applications (e.g., diagnostics, promotion of wound healing) and the non-medical sectors is presented. Finally, current drawbacks and limitations of AgNPs use in medicine are discussed, and perspectives for the improved future use of functionalized AgNPs in medical applications are presented.

Chitosan coated - biogenic silver nanoparticles from wheat residues as green antifungal and nanoprimig in wheat seeds

In this study, chitosan-coated biogenic silver nanoparticles (AgNP-CH) were obtained through green chemistry by recycling wheat crop leaf residues. The nanoparticles were characterized by UV-VIS spectroscopy, and total reflectance-Fourier transform infrared spectroscopy confirmed the nanoparticle formation, and the incorporation of chitosan surrounding silver nanoparticles. The size and morphology of nanoparticles were evaluated by microscopy techniques, showing a size range of 2-10 nm, with spherical shape and narrow distribution. The antifungal assay indicated a higher antimicrobial activity showing values of minimum inhibitory concentrations of 41.7 μg/mL against Fusarium oxysporum, and 208.37 μg/mL for Aspergillus niger, A. versicolor and A. brasiliensis. Finally, non-phytotoxic effects were observed in germination assays at early plant stage of development, and an increase in chlorophyll levels were observed at the doses tested with AgNP-CH. Thus, the use of AgNP-CH could be a potential alternative for the prevention of fungal infections in cereals in the early stages of wheat crop development.

Synergistic Antibacterial Potential of Greenly Synthesized Silver Nanoparticles with Fosfomycin Against Some Nosocomial Bacterial Pathogens

Introduction

A considerable number of morbidities and fatalities occur worldwide as a result of the multidrug resistant microorganisms that cause a high prevalence of nosocomial bacterial infections. Hence, the current investigation was conducted to evaluate the antibacterial potency of green fabricated silver nanoparticles (AgNPs) against four different nosocomial pathogens.

Methods

The flower extract of Hibiscus sabdariffa mediated green fabrication of AgNPs and their physicochemical features were scrutinized using different techniques. Antimicrobial activity of the biogenic AgNPs and their synergistic patterns with fosfomycin antibiotic were evaluated using disk diffusion assay.

Results and Discussion

UV spectral analysis affirmed the successful formation of AgNPs through the detection of broad absorption band at 395 and 524 nm, indicating the surface plasmon resonance of the biofabricated AgNPs. In this setting, the biofabricated AgNPs demonstrated average particle size of 58.682 nm according to transmission electron microscope (TEM) micrographs. The detected hydrodynamic diameter was higher than that noticed by TEM analysis, recording 72.30 nm in diameter and this could be attributed to the action of capping agents, which was confirmed by Fourier Transform Infrared (FT-IR) analysis. Disk diffusion assay indicated the antibacterial potency of biogenic AgNPs (50 μg/disk) against Enterobacter cloacae, Methicillin-resistant Staphylococcus aureus, Klebsiella pneumoniae and Escherichia coli strains with relative inhibition zone diameters of 12.82 ± 0.36 mm, 14.54 ± 0.15 mm, 18.35 ± 0.24 mm and 21.69 ± 0.12 mm, respectively. In addition, E. coli was found to be the most susceptible strain to the biogenic AgNPs. However, the highest synergistic pattern of AgNPs-fosfomycin combination was detected against K. pneumonia strain recording relative synergistic percentage of 64.22%. In conclusion, the detected synergistic efficiency of AgNPs and the antibiotic fosfomycin highlight the potential for utilizing this combination in the biofabrication of effective antibacterial agents against nosocomial pathogens.

Green Synthesis of Antibacterial Silver Nanocolloids with Agroindustrial Waste Extracts, Assisted by LED Light

Herein, the green synthesis of silver nanoparticles (AgNPs), assisted by LED light, using the aqueous extracts of agroindustrial waste products, such as avocado seeds (ASs), cocoa pod husks (CPHs), and orange peels (OPs), is presented. Surface plasmon resonance analysis showed faster and complete NP formation when irradiated with blue LED light. Green and red light irradiation showed non- and limited nanoparticle formation. TEM analyses confirmed the semispherical morphology of the synthesized AgNPs, with the exception of OP–AgNPs, which showed agglomeration during the light irradiation. For AS–AgNPs and CPH–AgNPs, the average particle diameter was about 15 nm. Interestingly, the CPH extract demonstrated faster nanoparticle formation as compared to the AS extract (100 min vs. 250 min irradiation time, respectively). FTIR spectroscopy assessed the involvement of diverse functional groups of the bioactive phytochemicals present in the plant extracts during nanoparticle photobiosynthesis. The antioxidant activity, as determined by ferric reducing antioxidant power (FRAP) assay, varied from 1323.72 µmol TE/mL in the AS aqueous extract to 836.50 µmol TE/mL in the CPH aqueous extract. The total polyphenol content was determined according to the Folin–Ciocalteu procedure; the AS aqueous extract exhibited a higher polyphenol content (1.54 mg GAE/g) than did the CPH aqueous extract (0.948 mg GAE/g). In vitro antibacterial assays revealed that the AS–AgNPs exhibited promising antibacterial properties against pathogenic bacteria (E. Coli), whereas the CPH–AgNPs showed antibacterial activity against S. aureus and E. coli. The green synthesis of AgNPs using AS, CPH, and OP aqueous extracts reported in this work is environmentally friendly and cost-effective, and it paves the way for future studies related to agroindustrial waste valorization for the production of advanced nanomaterials, such as antibacterial AgNPs, for potential biomedical, industrial, and environmental applications.

Functional silver nanoparticles synthesis from sustainable point of view: 2000 to 2023 ‒ A review on game changing materials

The green and facile synthesis of metallic silver nanoparticles (AgNPs) is getting tremendous attention for exploring superior applications because of their small dimensions and shape. AgNPs are already proven materials for superior coloration, biocidal, thermal, UV-protection, and mechanical performance. Originally, some conventional chemical-based reducing agents were used to synthesize AgNPs, but these posed potential risks, especially for enhanced toxicity. This became a driving force to innovate plant-based sustainable and green metallic nanoparticles (NPs). Moreover, the synthesized NPs using plant-based derivatives could be tuned and regulated to achieve the required shape and size of the AgNPs. AgNPs synthesized from naturally derived materials are safe, economical, eco-friendly, facile, and convenient, which is also motivating researchers to find greener routes and viable options, utilizing various parts of plants like flowers, stems, heartwood, leaves and carbohydrates like chitosan to meet the demands. This article intends to provide a comprehensive review of all aspects of AgNP materials, including green synthesis methodology and mechanism, incorporation of advanced technologies, morphological and elemental study, functional properties (coloration, UV-protection, biocidal, thermal, and mechanical properties), marketing value, future prospects and application, especially for the last 20 years or more. The article also includes a SWOT (Strengths, weaknesses, opportunities, and threats) analysis regarding the use of AgNPs. This report would facilitate the industries and consumers associated with AgNP synthesis and application through fulfilling the demand for sustainable, feasible, and low-cost product manufacturing protocols and their future prospects.

Bioinspired Green Synthesis of Silver Nanoparticles Using Three Plant Extracts and Their Antibacterial Activity against Rice Bacterial Leaf Blight Pathogen Xanthomonas oryzae pv. oryzae

Rice bacterial leaf blight caused by Xanthomonas oryzae pv. oryzae (Xoo) is responsible for a significant reduction in rice production. Due to the small impact on the environment, biogenic nanomaterials are regarded as a new type of antibacterial agent. In this research, three colloids of silver nanoparticles (AgNPs) were synthesized with different biological materials such as Arctium lappa fruit, Solanum melongena leaves, and Taraxacum mongolicum leaves, and called Al-AgNPs, Sm-AgNPs and Tm-AgNPs, respectively. The appearance of brown colloids and the UV-Visible spectroscopy analysis proved the successful synthesis of the three colloids of AgNPs. Moreover, FTIR and XRD analysis revealed the formation of AgNPs structure. The SEM and TEM analysis indicated that the average diameters of the three synthesized spherical AgNPs were 20.18 nm, 21.00 nm, and 40.08 nm, respectively. The three botanical AgNPs had the strongest bacteriostatic against Xoo strain C2 at 20 μg/mL with the inhibition zone of 16.5 mm, 14.5 mm, and 12.4 mm, while bacterial numbers in a liquid broth (measured by OD600) decreased by 72.10%, 68.19%, and 65.60%, respectively. Results showed that the three AgNPs could inhibit biofilm formation and swarming motility of Xoo. The ultrastructural observation showed that Al-AgNPs adhered to the surface of bacteria and broke the bacteria. Overall, the three synthetic AgNPs could be used to inhibit the pathogen Xoo of rice bacterial leaf blight.

Green synthesis of silver nanoparticles from Mahonia fortunei extracts and characterization of its inhibitory effect on Chinese cabbage soft rot pathogen

The pathogenic bacterium Pectobacterium carotovorum causes soft rot in cabbage and significantly reduces plant yield. In this study, we employed Mhonia fortunei extracts to synthesis silver nanoparticles (Mf-AgNPs) and investigated their functions against P. carotovorum. The results showed that the surface plasmon resonance (SPR) peak of AgNP was 412 nm under optimal synthesis conditions. Furthermore, the results of Scanning electron microscope-Energy dispersive spectrometer (SEM-EDS) and High-resolution transmission electron microscopy (HR-TEM) revealed that the Mf-AgNPs had a spherical structure with an average diameter of 13.19 nm and the content of Ag0 ions accounted for 82.68% of the total elemental content. The X-Ray diffraction (XRD) results confirmed that AgNPs had a face-centered cubic (FCC) crystal structure, while Fourier transform infrared spectroscopy (FTIR) results indicated the presence of various biomolecules as reducing and stabilizing agents on the AgNP surface. Antibacterial activity was first evaluated by an inhibitory zone test, which revealed that 500 μg ml⁻¹ of AgNPs had antibacterial activity against P. carotovorum and four model bacteria including Staphylococcus aureus, Escherichia coli, Bacillus subtilis, and Pseudomonas aeruginosa, respectively with an antibacterial function comparable to 1 mM AgNO₃ solution. The Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values for P. carotovorum were 8 μg ml⁻¹, respectively. Furthermore, AgNPs at 8 μg ml⁻¹ completely inhibited the growth of P. carotovorum, decreased their tolerance to 0.25 mM H₂O₂ as well as considerably reduced colony formation after 1 h of treatment and thereafter. Treatment with Mf-AgNPs resulted in bacterial cell membrane destruction and biofilm formation inhibition, respectively. With an FIC (fractional inhibitory concentration) index of 0.174, AgNP and zhongshengmycin showed a significant synergistic effect. The infection of P. carotovorum to cabbage explants was significantly inhibited in vitro by a combination of 2 μg ml⁻¹ Mf-AgNP and 5 μg ml⁻¹ zhongshengmycin. In conclusion, the synthesized Mf-AgNP exhibited significant antibacterial activity against P. carotovorum.

Chemical Compositions of Essential Oil from Aerial Parts of Cyclospermum leptophyllum and Its Application as Antibacterial Activity against Some Food Spoilage Bacteria

Cyclospermum leptophyllum is plant species known for its medicinal value and pleasant aroma. The aerial part and plant seeds are traditionally used as food additives as a spice. This study aims to isolate the chemical constituents of essential oil of the aerial part of the plant and study their potential antibacterial activities against some food contaminating bacteria. The essential oil of C. leptophyllum (CSEO) was isolated from aerial parts of the plant species and studied using GC-MS and FTIR techniques. The first four major chemical constituents determined from GC-MS analysis of CSEO (for peak area % ≥ 1.15%) were 2,5-dimethoxy-p-cymene (87.09%), 2-methoxy-1-methyl-4-(1-methylethyl) benzene (3.09%), 2-methoxy-4-methyl-1-(1-methylethyl) benzene (1.71%), and humulene (1.15%). 60%, 30%, 15%, 7.5%, and 3.75% of CSEO solutions were prepared and evaluated for their potential antibacterial activities against six food spoilage pathogenic bacterial strains. Three Gram-positive strains: Staphylococcus aureus (ATCC 25923), Staphylococcus epidermidis (ATCC 12228), Streptococcus agalactiae (ATCC 12386) and three Gram-negative strains: Escherichia coli (ATCC 25922), Proteus mirabilis (ATCC 35659), and Pseudomonas aeruginosa (ATCC 27853) were used as test microorganisms. Compared to ciprofloxacin, a positive control, the promising antibacterial activity was observed for CSEO against S. aureus at minimum and maximum test solutions as the values of the zone of inhibition diameter (ZID, mm) were recorded as 14.33 ± 0.58 for 3.75% CSEO solution and 30.67 ± 0.58 for 60% CSEO solution. Tests of CSEO solutions generally showed stronger antibacterial activities against Gram-positive than Gram-negative strains. Therefore, CSEO contains potent chemical constituents that might be applicable in treating pathogenic bacterial species.

Green Biosynthesis of Silver Nanoparticles from Moringa oleifera Leaves and Its Antimicrobial and Cytotoxicity Activities

The plant occupied the largest area in the biosynthesis of silver nanoparticles, especially the medicinal plants, and it has shown great potential in biotechnology applications. In this study, green synthesis of silver nanoparticles from Moringa oleifera leaves extract and its antifungal and antitumor activities were investigated. The formation of silver nanoparticles was observed after 1 hour of preparation color changing. The ultraviolet and visible spectrum, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy techniques were used to characterize synthesis particles. Ultraviolet and visible spectroscopy showed a silver surface plasmon resonance band at 434 nm. Fourier transform infrared analysis shows the possible interactions between silver and bioactive molecules in Moringa oleifera leaves extracts, which may be responsible for the synthesis and stabilization of silver nanoparticles. X-ray diffraction showed that the particles were a semicubic crystal structure and with a size of 38.495 nm. Scanning electron microscopy imaging shows that the atoms are spherical in shape and the average size is 17 nm. The transmission electron microscopy image demonstrated that AgNPs were spherical and semispherical particles with an average of (50–60) nm. The nanoparticles also showed potent antimicrobial activity against pathogenic bacteria and fungi using the well diffusion method. Candida glabrata found that the concentration of 1000 μg/mL exhibited the highest inhibition. As for bacteria, the concentration of 1000 μg/mL appeared to be the inhibition against Staphylococcus aureus. Moringa oleifera AgNPs inhibited human melanoma cells A375 line significant concentration-dependent cytotoxic effects. The powerful bioactivity of the green synthesized silver nanoparticles from medical plants recommends their biomedical use as antimicrobial as well as cytotoxic agents.

Optimized Green Synthesis and Anticancer Potential of Silver Nanoparticles Using Juniperus procera Extract Against Lung Cancer Cells

Silver nanoparticles (AgNPs) have been considered promising candidates for medical practices in various fields. This study proposed an efficient, economical, uncomplicated, and reliable method to synthesize AgNPs utilizing leaf and fruit extracts of Juniperus procera (J. procera) as capping, reducing, and stabilizing agents. The study includes optimizing the green synthesis conditions to produce stable AgNPs with high yields, acceptable particle size, and shape, hence, AgNPs may be used for different medical purposes through the improvement of their properties. Several spectroscopic and other analyses performed characterization of the fabricated AgNPs, and the results show stable and spherical AgNPs between 14 and 18 nm in size. The study also evaluated the anticancer activities of the biosynthesized AgNPs using J. procera fruit and leaf extracts against in vitro lung cancer A549 and H1975 cells. The results demonstrate the high toxicity of the biosynthesized AgNPs against in vitro lung cancer cells, supporting therapeutic and biomedical applications of AgNPs.

Green Synthesis of Silver Nanoparticles for Preparation of Gelatin Films with Antimicrobial Activity

Silver nanoparticles were successfully synthesized using Thuja orientalis aqueous extract and AgNO₃ as a precursor. UV–Vis showed a distinct absorption peak at 424 nm attributed to silver nanoparticles due to their surface plasmon resonance. Atomic absorption analysis reflected an increase in the concentration of nanoparticles in relation to the progress of the synthesis, obtaining a peak concentration value of 15.7 mg/L at 50 min. The FTIR spectra revealed the characteristic functional groups of phytomolecules involved in the silver–ion binding process, such as R–O–H (3335 cm⁻¹⁾ O=C–OH (2314 cm⁻¹) and C—C=C (1450 cm⁻¹). At 50 min, zeta potential showed the stability of the nanoparticles with the value of −21.73 mV. TEM micrographs revealed the formation of spherical nanoparticles with an average size of about 85.77 nm. Furthermore, films incorporated with nanoparticles exhibited a Tg from 66.42 °C to 73.71 °C and Tm at 103.31 °C. Films from the G22 formulation presented excellent antibacterial properties inhibiting the growth of Staphylococcus aureus. Thuja orientalis aqueous extract could be a low-cost, eco-friendly, and efficient reducing and capping agent for the synthesis of nanometric-sized Ag particles. Gelatin films with nanoparticles are expected to have high potential as an active food packaging system.