Green Phytosynthesis of Silver Nanoparticles Using Echinochloa stagnina Extract with Reference to Their Antibacterial, Cytotoxic, and Larvicidal Activities

Biogenic Ag2O nanoparticles with "Hoja Santa" (Piper auritum) extract: characterization and biological capabilities

The 'sacred leaf' or "Hoja Santa" (Piper auritum Kunth) has a great value for Mexican culture and has gained popularity worldwide for its excellent properties from culinary to remedies. To contribute to its heritage, in this project we proposed the green synthesis of silver oxide nanoparticles (Ag2O NPs) using an extract of "Hoja Santa" (Piper auritum) as a reducing and stabilizing agent. The synthesized Ag2O NPs were characterized by UV-Visible spectroscopy (plasmon located at 405 nm), X-ray diffraction (XRD) (particle size diameter of 10 nm), scanning electron microscopy (SEM) (particle size diameter of 13.62 ± 4.61 nm), and Fourier-transform infrared spectroscopy (FTIR) (functional groups from "Hoja Santa" attached to nanoparticles). Antioxidant capacity was evaluated using DPPH, ABTS and FRAP methods. Furthermore, the antimicrobial activity of NPs against a panel of clinically relevant bacterial strains, including both Gram-positive (Staphylococcus aureus) and Gram-negative bacteria (Salmonella Enteritidis and Escherichia coli O157:H7), was over 90% at concentrations of 200 µg/mL. Additionally, we assessed the antibiofilm activity of the NPs against Pseudomonas aeruginosa (reaching 98% of biofilm destruction at 800 µg/mL), as biofilm formation plays a crucial role in bacterial resistance and chronic infections. Moreover, we investigated the impact of Ag2O NPs on immune cell viability, respiratory burst, and phagocytic activity to understand their effects on the immune system.

An Investigation into the Larvicidal Activity of Biologically Synthesized Silver and Copper Oxide Nanoparticles Against Mosquito Larvae

This study is primarily focused on the synthesis of silver and copper oxide nanoparticles utilizing the extract of Ipomoea staphylina plant and their larvicidal activity against specific larvae. Notably, Anopheles stephensi and Aedes aegypti are significant disease vectors responsible for transmitting diseases such as malaria, dengue fever, Zika virus, and chikungunya (Anopheles stephensi), and dengue and Zika (Aedes aegypti). These mosquitoes have a substantial impact on urban areas, influencing disease transmission dynamics. In an effort to control these larvae, we have pursued the synthesis of a herbal-based nanomedicine derived from I. staphylina, a valuable herb in traditional medicine. Our successful synthesis of silver and CuO nanoparticles followed environmentally sustainable green chemistry methodologies. The I. staphylina plant extract played a dual role as a reducing agent and dopant, aligning with principles of sustainability. We employed X-ray diffraction (XRD) analysis to validate the nanoparticle structure and size, while field-emission scanning electron microscopy (FE-SEM) revealed well-defined nanostructures. Elemental composition was determined through energy-dispersive X-ray (EDX) analysis, and UV-visible spectroscopy provided insights into the bandgap energy (3.15 eV for silver, 1.2 eV for CuO nanoparticles). These nanoparticles exhibited robust larvicidal activity, with CuO nanoparticles surpassing silver nanoparticles in terms of LC50 and LC90 values. Moreover, the developmental toxicity of CuO and Ag NPs was evaluated in zebrafish embryos as part of non-target eco-toxicological studies conducted in a standard laboratory environment. These findings underscore the potential utility of these nanoparticles as highly effective and environmentally friendly natural pesticides, offering cost-effectiveness and ecological benefits.

Biosynthesis of Bt-Ag2O nanoparticles using Bacillus thuringiensis and their pesticidal and antimicrobial activities

Nanosilver oxide exhibits strong antibacterial and photocatalytic properties and has shown great application potential in food packaging, biochemical fields, and other fields involving diseases and pest control. In this study, Ag2O nanoparticles were synthesized using Bacillus thuringiensis (Bt-Ag2O NPs). The physicochemical characteristics of the Bt-Ag2O NPs were analyzed by UV‒vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM), inductively coupled plasma emission spectrometry (ICP), high-resolution transmission electron microscopy (HR-TEM), and zeta potential. The phis-chemical characterization revealed that the Bt-Ag2O NPs are in spherical shape with the small particle size (18.24 nm), high crystallinity, well dispersity, and stability. The biopesticidal and antifungal effects of Bt-Ag2O NPs were tested against Tribolium castaneum, Aspergillus flavus, and Penicillium chrysogenum. The survival, growth, and reproduction of tested pests and molds were significantly inhibited by Bt-Ag2O NPs in a dose-dependent manner. Bt-Ag2O NPs showed higher pesticidal activities against T. castaneum than Bt and commercial Ag2O NPs. The LC50 values of Bt, Ag2O NPs, and Bt-Ag2O NPs were 0.139%, 0.072%, and 0.06% on day 14, respectively. The Bt-Ag2O NPs also showed well antifungal activities against A. flavus and P. chrysogenum, while it resulted a small inhibition zone than commercial Ag2O NPs did. In addition, A. flavus showed much more sensitive to Bt-Ag2O NP treatments, compared to P. chrysogenum. Our results revealed that Bt-Ag2O NPs synthesized using B. thuringiensis could act as pesticides and antifungal agents in stored-product fields. KEY POINTS: • Bt-Ag2O NPs could be synthesized using Bacillus thuringiensis (Bt). • The NPs showed a high degree of crystallinity, spherical shape, and small particle size. • The NPs also showed excellent insecticidal and antifungal activity.

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.

Surf Redfish-Based ZnO-NPs and Their Biological Activity with Reference to Their Non-Target Toxicity

The marine environment is a rich source of bioactive compounds. Therefore, the sea cucumber was isolated from the Red Sea at the Al-Ain Al-Sokhna coast and it was identified as surf redfish (Actinopyga mauritiana). The aqueous extract of the surf redfish was utilized as an ecofriendly, novel and sustainable approach to fabricate zinc oxide nanoparticles (ZnO-NPs). The biosynthesized ZnO-NPs were physico-chemically characterized and evaluated for their possible antibacterial and insecticidal activities. Additionally, their safety in the non-target organism model (Nile tilapia fish) was also investigated. ZnO-NPs were spherical with an average size of 24.69 ± 11.61 nm and had a peak at 350 nm as shown by TEM and UV-Vis, respectively. XRD analysis indicated a crystalline phase of ZnO-NPs with an average size of 21.7 nm. The FTIR pattern showed biological residues from the surf redfish extract, highlighting their potential role in the biosynthesis process. DLS indicated a negative zeta potential (-19.2 mV) of the ZnO-NPs which is a good preliminary indicator for their stability. ZnO-NPs showed larvicidal activity against mosquito Culex pipiens (LC50 = 15.412 ppm and LC90 = 52.745 ppm) and a potent adulticidal effect to the housefly Musca domestica (LD50 = 21.132 ppm and LD90 = 84.930 ppm). Tested concentrations of ZnO-NPs showed strong activity against the 3rd larval instar. Topical assays revealed dose-dependent adulticidal activity against M. domestica after 24 h of treatment with ZnO-NPs. ZnO-NPs presented a wide antibacterial activity against two fish-pathogen bacteria, Pseudomonas aeruginosa and Aeromonas hydrophila. Histopathological and hematological investigations of the non-target organism, Nile tilapia fish exposed to 75-600 ppm ZnO-NPs provide dose-dependent impacts. Overall, data highlighted the potential applications of surf redfish-mediated ZnO-NPs as an effective and safe way to control mosquitoes, houseflies and fish pathogenic bacteria.

Antimicrobial and Antiproliferative Activity of Green Synthesized Silver Nanoparticles Using Bee Bread Extracts

Bee bread (BB) is a fermented mixture of bee pollen, is rich in proteins, amino acids, fatty acids, polyphenols, flavonoids, as well as other bioactive compounds, and is considered functional food for humans. In this study, we explored an innovative green synthesis of colloidal silver nanoparticles, using BB extracts as reducing and stabilizing agents. A preliminary chemical characterization of the BB extracts was conducted. The plasmonic response of the as-synthesized silver nanoparticles (BB-AgNPs) was evaluated by UV-Vis spectroscopy, while their hydrodynamic diameter and zeta potential were investigated by dynamic light spectroscopy (DLS). Transmission electron microscopy (TEM) analysis pointed out polydisperse NPs with quasi-spherical shapes. The newly synthesized nanoparticles showed good antioxidant activity against the tested free radicals, DPPH, ABTS^•+, and FRAP, the best results being obtained in the case of ABTS^•+. BB-AgNPs exhibited good antibacterial activity on the tested Gram-positive and Gram-negative bacterial strains: herein S. aureus, B. cereus, E. faecalis, E. coli, P. aeruginosa, S. enteritidis, and on yeast C. albicans, respectively. The inhibition diameters varied between 7.67 ± 0.59 and 22.21 ± 1.06 mm, while the values obtained for minimum inhibitory concentration varied between 0.39 and 6.25 µg/mL. In vitro antiproliferative activity was tested on colon adenocarcinoma, ATCC HTB-37 cell line, and the results have shown that the green synthetized BB-AgNPs induced a substantial decrease in tumor cell viability in a dose-dependent manner with an IC50 ranging from 24.58 to 67.91 µg/mL. Consequently, more investigation is required to comprehend the processes of the cytotoxicity of AgNPs and develop strategies to mitigate their potentially harmful effects while harnessing their antimicrobial properties.

Comparative analysis of phyto-fabricated chitosan, copper oxide, and chitosan-based CuO nanoparticles: antibacterial potential against Acinetobacter baumannii isolates and anticancer activity against HepG2 cell lines

The aim of this study was to provide a comparative analysis of chitosan (CH), copper oxide (CuO), and chitosan-based copper oxide (CH-CuO) nanoparticles for their application in the healthcare sector. The nanoparticles were synthesized by a green approach using the extract of Trianthema portulacastrum. The synthesized nanoparticles were characterized using different techniques, such as the synthesis of the particles, which was confirmed by UV-visible spectrometry that showed absorbance at 300 nm, 255 nm, and 275 nm for the CH, CuO, and CH-CuO nanoparticles, respectively. The spherical morphology of the nanoparticles and the presence of active functional groups was validated by SEM, TEM, and FTIR analysis. The crystalline nature of the particles was verified by XRD spectrum, and the average crystallite sizes of 33.54 nm, 20.13 nm, and 24.14 nm were obtained, respectively. The characterized nanoparticles were evaluated for their in vitro antibacterial and antibiofilm potential against Acinetobacter baumannii isolates, where potent activities were exhibited by the nanoparticles. The bioassay for antioxidant activity also confirmed DPPH scavenging activity for all the nanoparticles. This study also evaluated anticancer activities of the CH, CuO, and CH-CuO nanoparticles against HepG2 cell lines, where maximum inhibitions of 54, 75, and 84% were recorded, respectively. The anticancer activity was also confirmed by phase contrast microscopy, where the treated cells exhibited deformed morphologies. This study demonstrates the potential of the CH-CuO nanoparticle as an effective antibacterial agent, having with its antibiofilm activity, and in cancer treatment.

Biosynthesized ZnO-NPs Using Sea Cucumber (Holothuria impatiens): Antimicrobial Potential, Insecticidal Activity and In Vivo Toxicity in Nile Tilapia Fish, Oreochromis niloticus

In this study, a sustainable and eco-friendly method was used to prepare zinc oxide nanoparticles (ZnO-NPs) using a sea cucumber aqueous extract. Then, ZnO-NPs were characterized by instrumental analysis (UV-vis, HR-TEM, XRD, FT-IR, and DLS) and evaluated for their possible antibacterial, antifungal, and insecticidal activities. Additionally, the toxicity of ZnO-NPs was evaluated in vivo against Nile Tilapia (Oreochromis niloticus). The sea cucumber was collected from the Gulf of Suez (Red Sea) at Al-Ain Al-Sokhna coast in Egypt and identified as Holothuria impatiens. The prepared Hi-ZnO-NPs peaked at 350 nm in UV–Vis spectral analysis. They showed quasi-spherical shaped particles with sizes ranging from 13 nm to 47 nm and a predominate size of 26 nm as indicated by HR-TEM. The XRD pattern of Hi-ZnO-NPs revealed a crystalline phase with an average size of 17.2 nm as calculated by Debye–Scherrer equation. FTIR analysis revealed the possible role of H. impatiens biological molecules in the biosynthesis process of ZnO-NPs. Hi-ZnO-NPs showed a negative zeta potential of −19.6 mV, demonstrating moderate stability. Biosynthesized Hi-ZnO-NPs revealed broad antimicrobial activity against Gram-positive bacteria (S. aureus ATCC 25923 and E. feacalis), Gram-negative bacteria (S. typhi, K. pneumonia and E. coli), and filamentous fungi (Aspergillus niger). Hi-ZnO-NPs demonstrated larvicidal activity against the mosquito, Culex pipiens (LC50 = 2.756 ppm and LC90 = 9.294 ppm), and adulticidal action against the housefly, Musca domestica (LD50 = 4.285 ppm and LD90 = 22.847 ppm). Interestingly, Hi-ZnO-NPs did not show mortality effects against Nile tilapia fish (Oreochromis niloticus), highlighting the potential safety of Hi-ZnO-NPs to highly exposed, non-target organisms. However, histopathological and hematological investigations provided dose-dependent impacts of Hi-ZnO-NPs to Nile tilapia. Overall, data provide an eco-friendly approach for synthesizing novel Hi-ZnO-NPs with multiple biomedical properties and potentially low toxicity to Nile tilapia fish.

TA-AgNPs/Alginate Hydrogel and Its Potential Application as a Promising Antibiofilm Material against Polymicrobial Wound Biofilms Using a Unique Biofilm Flow Model

The presence of biofilm within a chronic wound may delay the healing process. Thus, control of biofilm formation and providing bactericidal effect are crucial factors for wound healing management. Alginate-based nanocomposite hydrogels have been suggested as dressing materials for wound treatment, which are employed as a biocompatible matrix. Therefore, in this study, we aimed to develop a biocompatible antimicrobial wound dressing containing AgNPs and demonstrate its efficacy against polymicrobial wound biofilms by using a biofilm flow device to simulate a chronic infected, exuding wound and specific wound environment. The results from agar well diffusion, the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) assays showed that TA-AgNPs exhibited antibacterial activity against wound pathogens. Additionally, the Minimum Biofilm Eradication Concentration assay (MBEC) demonstrated it could impair biofilm formation. Importantly, our TA-AgNPs/Alginate hydrogel clearly showed antibacterial activities against Streptococcus pyogenes, Staphylococcus aureus and Pseudomonas aeruginosa. Furthermore, we used the biofilm flow device to test the topical antimicrobial hydrogel against a three-species biofilm. We found that TA-AgNPs/Alginate hydrogel significantly showed a 3-4 log reduction in bacterial numbers when applied with multiple doses at 24 h intervals, and was especially effective against the chronic wound pathogen P. aeruginosa. This work highlighted that the TA-AgNPs/Alginate hydrogel is a promising material for treating complex wound biofilms.

Mosquitocidal Activity of the Methanolic Extract of Annickiachlorantha and Its Isolated Compounds against Culex pipiens, and Their Impact on the Non-Target Organism Zebrafish, Danio rerio

In this study, the crude extract and its isolated compounds from the stem bark of Annickia chlorantha were tested for their larvicidal, developmental, and repellent activity against the mosquito vector, Culex pipiens, besides their toxicity to the non-target aquatic organism, the zebrafish (Danio rerio). The acute larvicidal activity of isolated compounds; namely, palmatine, jatrorrhizine, columbamine, β-sitosterol, and Annickia chlorantha methanolic extract (AC), was observed. Developmentally, the larval duration was significantly prolonged when palmatine and β-sitosterol were applied, whereas the pupal duration was significantly prolonged for almost all treatments except palmatine and jatrorrhizine, where it shortened from those in the control. Acetylcholinesterase (AChE) enzyme showed different activity patterns, where it significantly increased in columbamine and β-sitosterol, and decreased in (AC), palmatine, and jatrorrhizine treatments, whereas glutathione S-transferase (GST) enzyme was significantly increased when AC methanolic extract/isolated compounds were applied, compared to the control. The adult emergence percentages were significantly decreased in all treatments, whereas tested compounds revealed non-significant (p > 0.05) changes in the sex ratio percentages, with a slight female-to-male preference presented in the AC-treated group. Additionally, the tested materials revealed repellence action; interestingly, palmatine and jatrorrhizine recorded higher levels of protection, followed by AC, columbamine, and β-sitosterol for 7 consecutive hours compared to the negative and positive control groups. The non-target assay confirms that the tested materials have very low toxic activity compared to the reported toxicity against mosquito larvae. A docking simulation was employed to better understand the interaction of the isolated compounds with the enzymes, AChE and GST. Additionally, DFT calculations revealed that the reported larvicidal activity may be due to the differing electron distributions among tested compounds. Overall, this study highlights the potential of A. chlorantha extract and its isolated compounds as effective mosquitocidal agents with a very low toxic effect on non-target organisms.

Biosynthesis of Silver Nanoparticles Using Bersama engleriana Fruits Extracts and Their Potential Inhibitory Effect on Resistant Bacteria

The absence of novel, safe, and effective bactericide is an urgent concern worldwide and remains a challenge in scientific communities. The unique proprieties of silver nanoparticles (SNPs) synthesized from plant extracts make them a suitable candidate to overcome these limitations. Herein, we synthesized SNPs from Bersama engleriana fruit (BEfr) extracts and determined their potential antibacterial activity and mode of action. SNPs were synthesized from BEfr methanolic fruit extracts at 25 and 70 °C, and the antibacterial effectiveness of SNPs against bacterial strains was investigated. The surface plasmon resonance peaked at 430.18 and 434.08 nm, respectively, for SNPs synthesized at 25 and 70 °C, confirming SNPs synthesis. BEfr-SNPs had minimum inhibitory concentrations (MIC) range of 0.234 to >50 µg/mL, which was 30-fold greater than extract alone (MIC of 500 µg/mL). BEfr-SNPs-25 °C was potent against six bacterial strains (S. aureus, S. enterica, MRS. aureus, K. pneumonia, and S. pyogenes), with MIC range of 0.339 to 6.25 µg/mL. The mode of action of BEfr-SNPs-25 °C was achieved by an MRSA bacteria strain outer membrane and DNA nucleotide linkage. These results suggest that our synthesized SNPs, especially BEfr-SNPs-25 °C, demonstrated an enhanced antibacterial effect and could be potential candidates for bacterial infection treatment.

Anticancer Effects of Vitis vinifera L. Mediated Biosynthesized Silver Nanoparticles and Cotreatment with 5 Fluorouracil on HT-29 Cell Line

The aim of this study was to evaluate the anticancer effects of biosynthesized silver nanoparticles (Vv-AgNPs) from grape (Vitis vinifera L.) seed aqueous extract, alone or in combination with 5-Fluorouracil (5-FU) on HT-29 cell line. Vv-AgNPs were characterized by techniques such as UV-vis spectrophotometer (surface plasmon peak 454 nm), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). HT-29 cells were treated with different concentrations (0-80 μg/mL for MTT) and (0-20 μg/mL for BrdU) of Vv-AgNPs alone and combined with (200 μg/mL) 5-FU for 72 h. The cytotoxic effects were analyzed by [3-(4,5-dimethylthiazol-2- yl)-2,5-diphenyl tetrazolium bromide] (MTT) assay (IC₅₀ values 13.74 and 5.35 μg/mL, respectively). Antiproliferative effects were examined 5-bromo-2'-deoxyuridine (BrdU) assay (IC₅₀ values 9.65 and 5.00 μg/mL, respectively). Activation of caspase-3 and protein expression levels of p53 were determined by Western blotting analysis. It was observed that Vv-AgNPs significantly increased the cleavage of the proapoptotic proteins caspase 3 and obviously enhanced the expression of p53 in a dose-dependent manner. The increased amount of total oxidant status (TOS) in the 10 μg/mL Vv-AgNPs + 5-FU treatment group, despite the increasing amount of total antioxidant status (TAS), caused an increase in Oxidative Stress Index (OSI) compared to the control. In this study, it has been shown in vitro that the use of successfully biosynthesized Vv-AgNPs in combination with 5-FU exhibits synergistic cytotoxic, antiproliferative, apoptotic, and oxidative effects against HT-29 cell line.

Synergistic Antifungal Efficiency of Biogenic Silver Nanoparticles with Itraconazole against Multidrug-Resistant Candidal Strains

Fungal infections caused by multidrug-resistant strains are considered one of the leading causes of morbidity and mortality worldwide. Moreover, antifungal medications used in conventional antifungal treatment revealed poor therapeutic effectiveness and possible side effects such as hepatotoxicity, nephrotoxicity, and myelotoxicity. Therefore, the current study was developed to determine the antifungal effectiveness of green synthesized silver nanoparticles (AgNPs) and their synergistic efficiency with antifungal drugs against multidrug-resistant candidal strains. The AgNPs were greenly synthesized using the aqueous peel extract of Punica granatum. In addition, AgNPs were characterized using ultraviolet-visible spectrophotometry (UV/Vis), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction analysis (XRD), and zeta potential analysis. In this regard, UV-vis analysis indicated SPR of AgNPs at 396 nm, while the particle size distribution revealed that the average particle size was 18.567 ± 1.46 nm. The surface charge of AgNPs was found to be −15.6 mV, indicating their stability in aqueous solutions. The biofabricated AgNPs indicated antifungal activity against Candida tropicalis, C. albicans, and C. glabrata strains showing inhibitory zone diameters of 23.78 ± 0.63, 21.38 ± 0.58, and 16.53 ± 0.21 mm, respectively while their minimum inhibitory concentration (MIC) was found to be 2.5 µg/mL against C. tropicalis strain. AgNPs and itraconazole revealed the highest synergistic activity against the multidrug-resistant strain, C. glabrata, recording a synergism percentage of 74.32%. In conclusion, the biogenic AgNPs in combination with itraconazole drug exhibited potential synergistic activity against different candidal strains indicating their potential usage in the bioformulation of highly effective antifungal agents.

Multifunctional Silver Nanoparticles Based on Chitosan: Antibacterial, Antibiofilm, Antifungal, Antioxidant, and Wound-Healing Activities

The purpose of this study is to create chitosan-stabilized silver nanoparticles (Chi/Ag-NPs) and determine whether they were cytotoxic and also to determine their characteristic antibacterial, antibiofilm, and wound healing activities. Recently, the development of an efficient and environmentally friendly method for synthesizing metal nanoparticles based on polysaccharides has attracted a lot of interest in the field of nanotechnology. Colloidal Chi/Ag-NPs are prepared by chemical reduction of silver ions in the presence of Chi, giving Chi/Ag-NPs. Physiochemical properties are determined by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic light scattering (DLS), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) analyses. TEM pictures indicate that the generated Chi/Ag-NPs are nearly spherical in shape with a thin chitosan covering around the Ag core and had sizes in the range of 9–65 nm. In vitro antibacterial activity was evaluated against Staphylococcus aureus and Pseudomonas aeruginosa by a resazurin-mediated microtiter plate assay. The highest activity was observed with the lowest concentration of Chi/Ag-NPs, which was 12.5 µg/mL for both bacterial strains. Additionally, Chi/Ag-NPs showed promising antifungal features against Candida albicans, Aspergillus fumigatus, Aspergillus terreus, and Aspergillus niger, where inhibition zones were 22, 29, 20, and 17 mm, respectively. Likewise, Chi/Ag-NPs revealed potential antioxidant activity is 92, 90, and 75% at concentrations of 4000, 2000, and 1000 µg/mL, where the IC₅₀ of Chi/Ag-NPs was 261 µg/mL. Wound healing results illustrated that fibroblasts advanced toward the opening to close the scratch wound by roughly 50.5% after a 24-h exposure to Chi/Ag-NPs, greatly accelerating the wound healing process. In conclusion, a nanocomposite based on AgNPs and chitosan was successfully prepared and exhibited antibacterial, antibiofilm, antifungal, antioxidant, and wound healing activities that can be used in the medical field.

Synthesis of Chitosan-Based Gold Nanoparticles: Antimicrobial and Wound-Healing Activities

The global spread of multidrug-resistant bacteria has become a significant hazard to public health, and more effective antibacterial agents are required. Therefore, this study describes the preparation, characterization, and evaluation of gold nanoparticles modified with chitosan (Chi/AuNPs) as a reducing and stabilizing agent with efficient antimicrobial effects. In recent years, the development of an efficient and ecofriendly method for synthesizing metal nanoparticles has attracted a lot of interest in the field of nanotechnology. Colloidal gold nanoparticles (AuNPs) were prepared by the chemical reduction of gold ions in the presence of chitosan (Chi), giving Chi/AuNPs. The characterization of Chi/AuNPs was carried out by transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR), and X-ray diffraction (XRD). Chi/AuNPs appeared spherical and monodispersed, with a diameter ranging between 20 to 120 nm. The synergistic effects of AuNPs and Chi led to the disruption of bacterial membranes. The maximum inhibitory impact was seen against P. aeruginosa at 500 µg/mL, with a zone of inhibition diameter of 26 ± 1.8 mm, whereas the least inhibitory effect was reported for S. aureus, with a zone of inhibition diameter of 16 ± 2.1 mm at the highest dose tested. Moreover, Chi/AuNPs exhibited antifungal activity toward Candida albicans when the MIC was 62.5 µg/mL. Cell viability and proliferation of the developed nanocomposite were evaluated using a sulphorhodamine B (SRB) assay with a half inhibitory concentration (IC50) of 111.1 µg/mL. Moreover, the in vitro wound-healing model revealed that the Chi/AuNP dressing provides a relatively rapid and efficacious wound-healing ability, making the obtained nanocomposite a promising candidate for the development of improved bandage materials.

Investigation of the Oxidative Stress Response of a Green Synthesis Nanoparticle (RP-Ag/ACNPs) in Zebrafish

Silver nanoparticles (AgNPs) are prominent nanomaterials that are efficiently used in different industries including medical products, water treatment, and cosmetics. However, AgNPs are known to cause adverse effects on the ecosystem and human health. In this study, aqueous extract of Rumex patientia (RP) was used as a reducing and stabilizing agent in AgNP biosynthesis. The obtained activated carbon (AC) from Chenopodium album (CA) plant was combined with RP-AgNPs to synthesize RP-Ag/AC NPs. Next, the effects of these green synthesis RP-Ag/AC NPs on zebrafish (Danio rerio) embryos and larvae were investigated. First, we characterized the RP-Ag/AC NPs by using X-ray diffraction (XRD) and transmission electron microscopy (TEM) and determined LC50 value as 217.23 mg/L at 96 h. Next, the alterations in survival rate, hatching rate, and morphology of the larvae at 96 h were monitored. The survival rates decreased in a dose-dependent manner. Morphological defects such as yolk sac edema, pericardial edema, spinal curvature, and tail malformation in the NP-treated larvae were observed. RP-Ag/AC NPs stimulated the production of neuronal NOS (nNOS) and 8-OHdG in zebrafish brain tissues in a dose-dependent manner and enhanced neutrophil degeneration and necrosis at concentrations of 50 and 100 mg/L. Thus, the obtained data suggest that the green synthesis process is not sufficient to reduce the effect of oxidative stress caused by AgNPs on oxidative signaling.

Green synthesis and characterization of nanosilver derived from extracellular metabolites of potent Bacillus subtilis for antifungal and eco-friendly action against phytopathogen

The potent antagonist Bacillus isolated from the soil rhizosphere elucidated the highest antagonism against the phytopathogen Fusarium oxysporum f. sp. cumini and was identified as Bacillus subtilis strain JSD-RSCu-8D based on molecular recognition by 16S rRNA sequencing (NCBI Accession No. KT894724). Live Bacillus may not work as effectively against phytopathogen under unfavorable environmental conditions like temperature, humidity, or other abiotic stresses. The extracellular metabolites, obtained from culturing potent B. subtilis, were exploited for the creation of green nanosilver for proficient actions in a changing climate. The synthesized green nanosilver was illustrated for shape (spherical with 65.21 ± 3.71 nm under SEM), size (70.9 nm in PSA), purity (2.69 keV peak corresponded to the binding energy of silver under EDAX), and stability (44.2 mV as ZETA). The formation of green Ag-NPs from extracellular metabolites was confirmed by a comparative appraisal of the electromagnetic peak of the metabolite's functional groups, silver nitrate, and green nanoparticles in Fourier transform infrared spectroscopy. The novel mode of action of pathogen mycelium degradation was elucidated by the minimum inhibitory concentration (MIC) of green nanosilver as 40 µg Ag ml^-1 to diminish F. oxysporum (SEM morphology). The green nanosilver at 2 DAI renowned the leakage of sugars from mycelia of the cell membrane and defeated the activity of respiratory chain dehydrogenases, followed by lipid peroxidation and the highest leakage of proteins at 3 DAI on MIC. The in-vivo study might allow for novel insight to utilize green nanosilver at MIC (40 µg Ag ml^-1) as an eco-friendly and fungicide alternate way for antifungal action to demolish Fusarium wilt infection under harsh conditions.

Synergistic actions of phytonutrient capped nanosilver as a novel broad-spectrum antimicrobial agent: unveiling the antibacterial effectiveness and bactericidal mechanism

Bactericidal action of cogon grass extract mediated AgNPs and LDI-MS analysis revealed the putative phytochemicals capped on the AgNP surface.

Ecofriendly preparation of silver nanoparticles-based nanocomposite stabilized by polysaccharides with antibacterial, antifungal and antiviral activities

In the present work, sustainable and green method was used to prepare silver nanoparticles (Ag-NPs), followed with incorporation into tertiary nanocomposite consisted of starch, oxidized cellulose and ethyl cellulose. The prepared tertiary silver-nanocomposite (Ag-NC) was fully characterized via instrumental analysis (UV-vis, FT-IR, XRD, SEM, EDX and TEM) and evaluated for antibacterial, antifungal, and antiviral activities. Ag-NC significantly suppressed growth of tested bacterial strains (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus subtilis)  as compared with controls. Antifungal activity revealed that the prepared tertiary Ag-NC has a promising antifungal activity towards unicellular (Candida albicans) and multicellular fungi  ( Aspergillus niger, A. terreus, A. flavus and A. fumigatus). In same line, both Ag-NC and free Ag-NPs have shown a dose-dependent reduction in Vero cell line with maximum non-toxic dose at 6.25 and 12.5 μg/mL, respectively. Both Ag-NPs and Ag-NC exhibited antiviral effects against Herpes simplex virus, Adenovirus and Coxsackie B virus in a dose-dependent manner. Combined treatment of Ag-NPs incorporated into tertiary nanocomposite based on starch, oxidized cellulose and ethyl cellulose opens new possibilities to be more efficient nanomaterials for preventing microbial growth. In conclusion, the prepared tertiary Ag-NC has a promising antibacterial, antifungal as well as antiviral activities.