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

Surfactants can be used as nanoparticle stabilizing agents. However, since synthetic surfactants are not economically viable and environmentally friendly, biosurfactants are emerging as a green alternative for the synthesis and stabilization of nanoparticles. Nanoparticles have been applied in several areas of industry, such as the production of biomedical and therapeutic components, packaging coating, solar energy generation and transmission and distribution of electrical energy, among others. The aim of this study was to synthesize, in a simple and green way, silver nanoparticles (AgNPs) using the biosurfactant produced by Candida lipolytica UCP 0899 as a stabilizer. AgNPs were examined and morphologically characterized using the techniques of ultraviolet–visible spectroscopy (UV–visible), scanning electron microscopy (SEM), zeta potential and energy dispersive X-ray spectroscopy (EDS). Newly formed silver nanoparticles showed a maximum UV–visible absorption peak at 400 nm, while a shift to 410 nm was observed in those stored for 120 days. SEM micrograph confirmed the formation of nanoparticles with an average size of 20 nm and with a predominant spherical structure, while a zeta potential of −60 mV suggested that the use of the biosurfactant promoted their stability. Stabilized nanoparticles were tested for their antimicrobial activity against bacterial isolates of Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli and Enterobacter sp., as well as fungal isolates of Candida albicans and Aspergillus niger. At a concentration of 16.50 µg/mL, AgNPs inhibited the growth of all target microorganisms according to the following decreasing order: E. coli (95%), S. aureus, C. albicans (90%), A. niger (85%), Enterobacter sp. (75%) and P. aeruginosa (71%). These results suggest the potential use of the biosurfactant as a stabilizer of silver nanoparticles as an antimicrobial agent in different industrial sectors. Furthermore, the in vivo toxicity potential of biosurfactants was evaluated using the Tenebrio molitor model. The larvae were treated with concentrations in the range of 2.5, 5.0 and 10 g/L, and no mortality was observed within the 24 to 72 h period, demonstrating non-toxicity within the tested concentration range. These findings support the safety, efficacy and non-toxicity of biosurfactant-stabilized nanoparticles. [ABSTRACT FROM AUTHOR]

The green synthesis of silver nanoparticles (AgNPs) and their applications have gathered great attention as these nanoparticles can be used effectively in targeting microorganisms due to their antimicrobial properties. In this study, the reducing and capping potential of polyphenols extracted from energy cane bagasse was investigated in the green synthesis of AgNPs without the external addition of reducing agents. The reddish color formation and peak appearance at 430 nm were indications of the successful synthesis of the AgNPs. The synthesized nanoparticles and reducing biomolecules were further characterized by microscopy (SEM, TEM) and spectroscopy (FTIR-ATR, EDS, XRD) techniques indicating nanoparticles of spherical shape, with particle sizes averaging ~ 15 nm and surface charge of −24.8 mV. The antimicrobial activity of the synthesized nanoparticles was evaluated against several microbial species, Listeria monocytogenes ATCC 19115, Staphylococcus aureus ATCC 12600, Salmonella enterica ATCC 13312, Pseudomonas syringae ATCC BAA 871, Escherichia coli ATCC 35218, and two strains isolated from sugarcane crusher juice, Leuconostoc mesenteroides (A17) and Leuconostoc pseudomesenteroides (A25). The synthesized nanoparticles showed biocidal activity against the bacteria which was further confirmed by microscopy techniques. The cell and nanoparticles are interacting with the cell surface of microorganisms, penetrating the cell, and causing the disruption of intracellular organelles. These nanoparticles also prevented the growth of microbial biofilms. A biofilm is a complex and functional community of microbes encased in a primarily polysaccharide matrix, which acts as a barrier to protect microbes against most antimicrobials. [ABSTRACT FROM AUTHOR]

Abstract Silver nanoparticles (AgNPs) have gained much attention due to their unique physical, and chemical properties. Integration of phytochemicals in nanoformulation might have higher applicability in healthcare. Current work demonstrates the synthesis of green AgNPs with O. gratissimum (gr-AgNPs) O. tenuiflorum (te-AgNPs) and O. americanum (am-AgNPs) followed by an evaluation of their antimicrobial and anticancer properties. SEM analysis revealed spherical-shaped particles with average particle sizes of 69.0 ± 5 nm for te-AgNPs, 46.9 ± 9 nm for gr-AgNPs, and 58.5 ± 18.7 nm for am-AgNPs with a polydispersity index below 0.4. The synthesized am-AgNPs effectively inhibited Klebsiella pneumonia , Escherichia coli , Staphylococcus aureus, Aspergillus niger, and Candida albicans with 23 ± 1.58 mm, 20 ± 1.68 mm, 22 ± 1.80 mm, 26 ± 1.85 mm, and 22 ± 1.40 nm of zone of inhibition respectively. Synthesized AgNPs also induced apoptotic cell death in MCF-7 in concentration-dependent manner. IC50 values for am-AgNPs, te-AgNPs, and gr-AgNPs were 14.78 ± 0.89 µg, 18.04 ± 0.63 and 15.41 ± 0.37 µg respectively which suggested that am-AgNPs were the most effective against cancer. At higher dose size (20 µg) AgNPs were equally effective to commercial standard Doxorubicin (DOX). In comparison to te-AgNPs and gr-AgNPs, am-AgNPs have higher in vitro anticancer and antimicrobial effects. The work reported Ocimum americanum for its anticancer properties with chemical profile (GCMS) and compared it with earlier reported species. The activity against microbial pathogens and selected cancer cells clearly depicted that these species have distinct variations in activity. The results have also emphasized on higher potential of biogenic silver nanoparticles in healthcare but before formulation of commercial products, detailed analysis is required with human and animal models.

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. [ABSTRACT FROM AUTHOR]

Background and Aim: The use of bioengineered nanocomposites as antimicrobials has increased in recent years, but very few investigations have been conducted to test their effectiveness against Pseudomonas aeruginosa, a pathogen presenting public health risks that can impact both humans and animals. The aim of this study was to assess the antimicrobial potential of phytofabricated silver nanoparticles synthesized using lemongrass extract against clinical isolates of P. aeruginosa. Materials and Methods: The extraction of active compounds from the leaves of Cymbopogon citratus was performed using ethanol (80%) as a solvent, high-performance liquid chromatography-mass spectrometry was used to analyze the chemical composition of the extract, the synthesis of silver nanoparticles (AgNPs) was done using silver nitrate (AgNO3) as a precursor, and the antimicrobial and antibiofilm activity of the extract and the AgNPs phytofabricated was assessed against 10 clinical strains of P. aeruginosa. Results: Lemongrass extract was found to consist of the following main compounds: Caffeic acid (445.21 ± 32.77 μg/g), p-coumaric acid (393.32 ± 39.56 μg/g), chlorogenic acid (377.65 ± 4.26 μg/g), quinic acid (161.52 ± 17.62 μg/g), and quercetin-3-glucoside (151.35 ± 11.34 μg/g). AgNPs were successfully phytofabricated using 2.5 mM AgNO3. The ultraviolet (UV)-visible absorption spectra of the AgNPs showed a localized surface plasmon resonance at 464 nm with an absorbance of 0.32 A. The 50x hydrodynamic diameter was 50.29 nm with a surface area value of 120.10 m2/ cm3, and the volume mean diameter and Sauter mean diameter were 50.63 nm and 49.96 nm, respectively. Despite the compound found in lemongrass extract, no antimicrobial activity was observed with the extract, while AgNPs exhibited noteworthy dose-dependent antimicrobial activity with inhibition diameters up to 24 mm and minimum inhibitory concentration (MIC) and minimum bactericidal concentration ranging from 2 to 16 and 4–64 µg/mL, respectively. AgNPs also demonstrated significant antibiofilm activity by inhibiting biofilms up to 99% between MIC/2 and 2MIC. Conclusion: The present study suggests that lemongrass is a good candidate for the synthesis of AgNPs with good physicochemical characteristics and having a strong anti-pseudomonas activity. Further research is needed to assess the stability and safety of these AgNPs.

The present work aims to study the possibilities of developing silver nanoparticles using natural extracts of grape pomace wastes originating from the native variety of Fetească Neagră 6 Șt. This study focused on investigating the influence of grape pomace extract obtained by two different extraction methods (classical temperature extraction and microwave-assisted extraction) in the phytosynthesis process of metal nanoparticles. The total phenolic content of the extracts was assessed using the spectrophotometric method with the Folin–Ciocâlteu reagent, while the identification and quantification of specific components were conducted through high-performance liquid chromatography with a diode array detector (HPLC-DAD). The obtained nanoparticles were characterized by UV–Vis absorption spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM), along with assessing their antioxidant and antimicrobial properties against Gram-positive bacteria. The data collected from the experiments indicated that the nanoparticles were formed in a relatively short period of time (96 h) and, for the experimental variant involving the use of a 1:1 ratio (v/v, grape pomace extract: silver nitrate) for the nanoparticle phytosynthesis, the smallest crystallite sizes (from X-ray diffraction—4.58 nm and 5.14 nm) as well as spherical or semispherical nanoparticles with the lowest average diameters were obtained (19.99–23 nm, from TEM analysis). The phytosynthesis process was shown to enhance the antioxidant properties (determined using the DPPH assay) and the antimicrobial potential (tested against Gram-positive strains) of the nanoparticles, as evidenced by comparing their properties with those of the parent extracts; at the same time, the nanoparticles exhibited a selectivity in action, being active against the Staphylococcus aureus strain while presenting no antimicrobial potential against the Enterococcus faecalis strain. [ABSTRACT FROM AUTHOR]

The green synthesized silver nanoparticles (AgNPs) with the aqueous extract of the leaves of household vegetable, Trigonella foenumgraecum were characterized and tested for their anti-oxidant and anti-bacterial efficacy with sixteen human clinical isolates. The Formation of AgNPs was confirmed with the surface plasmon spectra of the dark brown solution centered at 448 nm. The Particle size calculated with XRD data was 41.23 nm and the SEM size ranged between 52.56 nm and 80.51 nm. The presence of -NH and -OH groups that effectively react and reduce Ag+ ions to Ag0 was evident from the FT-IR spectra. The particles are predominantly spherical in shape and varied from 5 to 80 nm in size. As Suggested from the analysis by SEM and TEM, majority of them fall between 5 nm and 20 nm. A composite solution of AgNPs with polyvinyl alcohol (PVA) was electrospun into films and tested on 8 human clinical isolates including methicillin-resistant Staphylococcus aureus (MRSA). The PVA-AgNP films showed enormous activity against the MRSA prompting further study as wound dressings in the Wistar albino rat model. Although the animal study was abruptly terminated owing to the pandemic-induced lock down, the preliminary study results for 9 days suggest the potential clinical applications of these wound dressings. The synthesized AgNPs with and without PVA demonstrated good anti-oxidant activity and highly significant (P = 0.001) zones of inhibition with eighteen clinical isolates were tested. [ABSTRACT FROM AUTHOR]

Biosynthesized nanoparticles are receiving attention because of naturally existing secondary metabolites from plants that support green synthesis and their biological applications. Hence, the Objective of this paper as to biosynthesize and characterize silver nano-composites of Enantia chlorantha extracts using appropriate standard techniques. The results of the FTIR research revealed significant heterogeneity in chemical shifts among the functional groups, indicating changes in chemical surroundings. Furthermore, the GC-MS analysis showed that the extract and Ec-AgNPs had different numbers of compound peaks: the extract had 28 peaks, while Ec-AgNPs had 32 peaks. Ec-AgNPs showed more antibacterial activity than the extract, although having equal phytochemical contents, suggesting their potential for medicinal uses. The importance of using plant extracts in green synthesis techniques to produce nanoparticles and their potential biological uses is highlighted by this study. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (AgNPs) are widely recognized as a prominent antimicrobial agent and have found applications in the field of medicine. This study focuses on the synthesis of AgNPs utilizing the natural reducing agent of Ceylon olive (Elaeocarpus serratus), presenting an economically viable and ecologically friendly approach. For the first time, this research demonstrated the synthesis of AgNPs using phytochemicals extracted from Ceylon olive, serving as both natural reducing and stabilizing agents. The synthesized AgNPs were characterized with UV–visible spectroscopy, a particle size analyzer (PSA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) coupled with an energy dispersive X-ray spectrometer (EDX). The UV–visible spectra primarily indicated the formation of the AgNPs by the surface plasmon resonance band around 434 nm. SEM analysis confirmed the presence of silver nanoparticles within a size range of 50–110 nm, with an average size of approximately 70 nm. FTIR determined that proteins, phenols, and flavonoids may have acted as reducing and capping agents. Experimental parameters were optimized to improve the yield and size of the AgNPs and eventually evaluate their antibacterial properties. The well diffusion method exhibits a significantly larger zone of inhibition for Gram-negative bacterial strains (18.4 ± 0.55 mm for Pseudomonas aeruginosa and 14.4 ± 0.55 mm for Escherichia coli) compared to Gram-positive bacterial strains (11.6 ± 0.55 mm for Staphylococcus aureus and 10.4 ± 0.55 mm for Staphylococcus epidermidis) for 50 µg/mL AgNPs. These findings demonstrate that AgNPs synthesized with Ceylon olive have the potential to develop into novel materials for bacterial-mediated diseases. [ABSTRACT FROM AUTHOR]

In the present study, silver nanoparticles were synthesized using aqueous root and leaf extracts of Rhus chinensis Mill. This study aimed to undertake the green synthesis of silver nanoparticles utilizing plant extracts in an eco-friendly, cost-effective, and more efficient manner with its antibacterial application. The prepared silver nanoparticles (AgNPs) were characterized by using different techniques. Such as ultraviolet–visible spectroscopy (UV–Vis), Fourier transform infrared spectroscopy (FT-IR), x-ray diffraction spectroscopy (XRD), field emission-scanning electron microscopy (FE-SEM), and energy dispersive X-ray (EDX). The color changes from yellowish to reddish brown can be visualized and it indicates the formation of silver nanoparticles. The UV–Vis absorption peak shown by the synthesized AgNPs assisted by root and leaf extract was at 443 nm and 440 nm respectively. The functional group present in plants' secondary metabolites may act as capping and stabilizing agents, indicated by the shifting and disappearing of the peak in the plant extracts and the extracts-assisted synthetic nanoparticles. The crystallite size of synthesized AgNPs assisted by the root and leaf extracts of Rhus cinensis was found to be 11.01 nm and 13.39 nm respectively, while with the help of FE-SEM image the shape and particle size of synthesized AgNPs root and leaf extract was found spherical with particle diameter of 54.40 nm and 30.89 nm respectively. The presence of an intense silver component was confirmed by EDX analysis which showed an intense peak at around 3 Kev and other elements like Cl, O, C, and N were also reported in synthesized AgNPs. Both the plant extracts assisted synthesized AgNPs showed higher zones of inhibition (ZOI) against both the Gram-positive and Gram-negative bacteria. The results of the study indicate the potential benefit of synthesized silver nanoparticles using Rhus chinensis root and leaf extracts for biomedical purposes.

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

Surfactants can be used as nanoparticle stabilizing agents. However, since synthetic surfactants are not economically viable and environmentally friendly, biosurfactants are emerging as a green alternative for the synthesis and stabilization of nanoparticles. Nanoparticles have been applied in several areas of industry, such as the production of biomedical and therapeutic components, packaging coating, solar energy generation and transmission and distribution of electrical energy, among others. The aim of this study was to synthesize, in a simple and green way, silver nanoparticles (AgNPs) using the biosurfactant produced by Candida lipolytica UCP 0899 as a stabilizer. AgNPs were examined and morphologically characterized using the techniques of ultraviolet–visible spectroscopy (UV–visible), scanning electron microscopy (SEM), zeta potential and energy dispersive X-ray spectroscopy (EDS). Newly formed silver nanoparticles showed a maximum UV–visible absorption peak at 400 nm, while a shift to 410 nm was observed in those stored for 120 days. SEM micrograph confirmed the formation of nanoparticles with an average size of 20 nm and with a predominant spherical structure, while a zeta potential of −60 mV suggested that the use of the biosurfactant promoted their stability. Stabilized nanoparticles were tested for their antimicrobial activity against bacterial isolates of Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli and Enterobacter sp., as well as fungal isolates of Candida albicans and Aspergillus niger. At a concentration of 16.50 µg/mL, AgNPs inhibited the growth of all target microorganisms according to the following decreasing order: E. coli (95%), S. aureus, C. albicans (90%), A. niger (85%), Enterobacter sp. (75%) and P. aeruginosa (71%). These results suggest the potential use of the biosurfactant as a stabilizer of silver nanoparticles as an antimicrobial agent in different industrial sectors. Furthermore, the in vivo toxicity potential of biosurfactants was evaluated using the Tenebrio molitor model. The larvae were treated with concentrations in the range of 2.5, 5.0 and 10 g/L, and no mortality was observed within the 24 to 72 h period, demonstrating non-toxicity within the tested concentration range. These findings support the safety, efficacy and non-toxicity of biosurfactant-stabilized nanoparticles.

Background and Aim: The use of bioengineered nanocomposites as antimicrobials has increased in recent years, but very few investigations have been conducted to test their effectiveness against Pseudomonas aeruginosa, a pathogen presenting public health risks that can impact both humans and animals. The aim of this study was to assess the antimicrobial potential of phytofabricated silver nanoparticles synthesized using lemongrass extract against clinical isolates of P. aeruginosa. Materials and Methods: The extraction of active compounds from the leaves of Cymbopogon citratus was performed using ethanol (80%) as a solvent, high-performance liquid chromatography-mass spectrometry was used to analyze the chemical composition of the extract, the synthesis of silver nanoparticles (AgNPs) was done using silver nitrate (AgNO3) as a precursor, and the antimicrobial and antibiofilm activity of the extract and the AgNPs phytofabricated was assessed against 10 clinical strains of P. aeruginosa. Results: Lemongrass extract was found to consist of the following main compounds: Caffeic acid (445.21 ± 32.77 µg/g), p-coumaric acid (393.32 ± 39.56 µg/g), chlorogenic acid (377.65 ± 4.26 µg/g), quinic acid (161.52 ± 17.62 µg/g), and quercetin-3-glucoside (151.35 ± 11.34 µg/g). AgNPs were successfully phytofabricated using 2.5 mM AgNO3. The ultraviolet (UV)-visible absorption spectra of the AgNPs showed a localized surface plasmon resonance at 464 nm with an absorbance of 0.32 A. The 50× hydrodynamic diameter was 50.29 nm with a surface area value of 120.10 m2/cm3, and the volume mean diameter and Sauter mean diameter were 50.63 nm and 49.96 nm, respectively. Despite the compound found in lemongrass extract, no antimicrobial activity was observed with the extract, while AgNPs exhibited noteworthy dose-dependent antimicrobial activity with inhibition diameters up to 24 mm and minimum inhibitory concentration (MIC) and minimum bactericidal concentration ranging from 2 to 16 and 4-64 µg/mL, respectively. AgNPs also demonstrated significant antibiofilm activity by inhibiting biofilms up to 99% between MIC/2 and 2MIC. Conclusion: The present study suggests that lemongrass is a good candidate for the synthesis of AgNPs with good physicochemical characteristics and having a strong anti-pseudomonas activity. Further research is needed to assess the stability and safety of these AgNPs. [ABSTRACT FROM AUTHOR]

Nanoparticles are synthesized by using various chemical methods in higher yields but they are not very environmentally friendly and have hazardous effects on living cells. This can be attributed to the overuse of hazardous chemicals involved in the process. The green approach of nanoparticle synthesis is widely gaining attention worldwide as it is considered as nontoxic, harmless and ecofriendly. Apart from this they also have multiple applications in various fields of science and technology. Nanoparticles synthesized by using various phytochemicals are also effective against a variety of microbial populations. The objective of this study is to synthesize silver nanoparticles (AgNPs) from the fruit extracts of Wrightia tinctoria and evaluating its antimicrobial capacities against gram-positive and negative bacterial strains. Silver nanoparticles were synthesized using different solvent extracts of Wrightia tinctoria pods. The formation of silver nanoparticles was noted by detecting the change in color of the solution. The presence of nanoparticles was detected by performing UV visible spectroscopy and monitoring the spectrum from 400 nm to 800 nm. A small peak at 425 nm suggested the presence of silver nanoparticles. In a later part of the study, the inhibitory effect of green synthesized silver nanoparticles on the growth of E. coli and S. aureus was monitored. The appearance of a zone of inhibition further confirmed the antimicrobial effect of the synthesized nanoparticles. [ABSTRACT FROM AUTHOR]

In the current study, using Cleistocalyx operculatus bud extracts to synthesize silver nanoparticles is considered a novel, eco-friendly, and low-priced process that advances chemical and physical methods. C. operculatus bud extracts played a dual part in reducing and stabilizing silver nanoparticles. The formation of silver nanoparticles was recognized on UV–Vis spectra at an absorption maximum of 432 nm. Transmission electron microscopy images detected the quasi-spherical nanoparticle shape with an average size of 26.2 nm corresponding with water extract and 27.5 nm synthesized by ethanol–water extract. The obtained silver nanoparticles had moderate stability with zeta potential ranging from − 15.4 to − 38.4 mV. The phase purity of the bio-synthesized materials was confirmed by an X-ray diffraction pattern. The Fourier transform infrared analysis demonstrated hydroxyl groups acting as stabilizing agents in the extract. Silver nanoparticles synthesized from ethanol–water extract exhibited higher antibacterial and anticancer activity than nanomaterials prepared with water extract. Positive-gram bacteria (Bacillus subtilis, Lactobacillus fermentum, and Staphylococcus aureus, negative-gram bacteria (Escherichia coli, Pseudomonas aeruginosa, and Salmonella enterica), and cancer cell lines (lung cancer A549, hepatic cancer Hep-G2, epidermal carcinoma KB, and breast cancer MCF-7) were both inhibited by the nanoparticles synthesized with ethanol–water extract. [ABSTRACT FROM AUTHOR]

Objectives: Disinfection of alginate impression materials is a mandatory step to prevent cross-infection in dental clinics. However, alginate disinfection methods are time-consuming and exert a negative impact on accuracy and mechanical properties. Thus, this study aimed to prepare disinfecting agents (CHX and AgNO3) and silver nanoparticles reduced by a natural plant extract to produce a self-disinfecting dental alginate. Methods: Conventional alginate impression material was used in this study. Silver nitrate (0.2% AgNO3 group) and chlorohexidine (0.2% CHX group) solutions were prepared using distilled water, and these solutions were later employed for alginate preparation. Moreover, a 90% aqueous plant extract was prepared from Boswellia sacra (BS) oleoresin and used to reduce silver nitrate to form silver nanoparticles that were incorporated in the dental alginate preparation (BS+AgNPs group). The plant extract was characterized by gas chromatography/mass spectrometry (GC/MS) analysis while green-synthesized silver nanoparticles (AgNPs) were characterized by UV-visible (UV–vis) spectroscopy and scanning electron microscopy (SEM). An agar disc diffusion assay was used to test the antimicrobial activity against Candida albicans, Streptococcus mutans, Escherichia coli, methicillin-resistant and susceptible Staphylococcus aureus strains, and Micrococcus luteus. Agar plates were incubated at 37 ± 1 °C for 24 h to allow microbial growth. Diameters of the circular inhibition zones formed around each specimen were measured digitally by using ImageJ software. Results: Chemical analysis of the plant extract revealed the presence of 41 volatile and semi-volatile active compounds. UV–Vis spectrophotometry, SEM, and EDX confirmed the formation of spherical silver nanoparticles using the BS extract. CHX, AgNO3, and the BS+AgNPs modified groups showed significantly larger inhibition zones than the control group against all tested strains. BS+AgNPs and CHX groups showed comparable efficacy against all tested strains except for Staphylococcus aureus, where the CHX-modified alginate had a significantly higher effect. Conclusions and clinical relevance: CHX, silver nitrate, and biosynthesized silver nanoparticles could be promising inexpensive potential candidates for the preparation of a self-disinfecting alginate impression material without affecting its performance. Green synthesis of metal nanoparticles using Boswellia sacra extract could be a very safe, efficient, and nontoxic way with the additional advantage of a synergistic action between metal ions and the phytotherapeutic agents of the plant extract. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (AgNPs), widely recognized for their nanoscale geometric size and unique properties, such as large specific surface area, high permeability, and high safety, were synthesized using the endophytic fungus Penicillium polonicum PG21 through a green approach. Four key synthesis factors—48 h, 45 °C, pH 9.0, and 80 mM AgNPs concentration—were optimized. Characterization via ultraviolet–visible spectroscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, and X-ray diffraction revealed the AgNPs as approximately 3–25 nm spherical particles with numerous functional groups ensuring stability. AgNPs were tested against various fungal and bacterial plant pathogens, including Botrytis cinerea (EB-1), Alternaria alternata (EB-2, EB-3), Fusarium solani (RG-1), Williamsia serinedens (SL-1), Sphingopyxis macrogoltabida (SL-2), Bacillus velezensis (SL-3), and Pseudomonas mediterranea (SL-4), causing agricultural challenges. PG21-synthesized AgNPs exhibited inhibition rates against all tested fungi, with 60 μg/mL AgNPs demonstrating optimal inhibition rates. Notably, EB-1 experienced a significant growth inhibition, reaching an inhibition rate reached of 74.22 ± 1.54%. Conversely, RG-1 exhibited the smallest inhibitory effect at 48.13 ± 0.92%. The effect of AgNPs on safflower seed germination and growth revealed notable increases in shoot length, fresh weight, stem length, and number of lateral roots—1.4, 1.4, 1.33, and 10.67 times higher than the control, respectively, at an AgNPs concentration of 80 μg/mL. In conclusion, green-synthesized AgNPs demonstrate pathogen toxicity, showcasing potential applications in disease management for industrial crops and promoting plant growth.

Biosynthesized nanoparticles are receiving attention because of naturally existing secondary metabolites from plants that support green synthesis and their biological applications. Hence, the Objective of this paper as to biosynthesize and characterize silver nano-composites of Enantia chlorantha extracts using appropriate standard techniques. The results of the FTIR research revealed significant heterogeneity in chemical shifts among the functional groups, indicating changes in chemical surroundings. Furthermore, the GC-MS analysis showed that the extract and Ec-AgNPs had different numbers of compound peaks: the extract had 28 peaks, while Ec-AgNPs had 32 peaks. Ec-AgNPs showed more antibacterial activity than the extract, although having equal phytochemical contents, suggesting their potential for medicinal uses. The importance of using plant extracts in green synthesis techniques to produce nanoparticles and their potential biological uses is highlighted by this study.

Herbal medicinal plants have been used for centuries in traditional medicine, and it is interesting to see how modern research has identified the active compounds responsible for their therapeutic effects. The green synthesis of silver nanoparticles using herbal medicinal plants, such as Swertia chirata, is particularly noteworthy due to its antimicrobial properties. In the current study, the Swertia chirata plant was collected for the first time from the region of Murree, Punjab, Pakistan. After collection, extracts were prepared in different solvents (ethanol, methanol, chloroform, and distilled water), and silver nanoparticles were synthesized by reducing silver nitrate (AgNO3). The UV–visible spectrophotometer, SEM, and EDX were used to characterize the synthesized nanoparticles in terms of their size and shape. The phytochemical analysis of crude extract was performed to determine the presence of different kinds of phytochemicals. The antibacterial activity of plant extracts and the silver nanoparticles were then assessed using the agar well diffusion method against various pathogenic bacteria. The results showed that the plant contains several phytochemicals with remarkable antioxidant potential. The antibacterial analysis revealed that silver nanoparticles and the plant extracts exhibited a significant zone of inhibition against human pathogenic bacteria (Escherichia coli, S. capitis, B. subtilis, and Pseudomonas aeruginosa) as compared to the cefixime and norfloxacin. This implies that the nanoparticles have the potential to be used in nano-medicine applications, such as drug delivery systems, as well as for their antibacterial, antifungal, and antiviral activities. Additionally, the development and application of materials and technologies at the nanometer scale opens possibilities for the creation of novel drugs and therapies. Overall, the study highlights the promising potential of herbal medicinal plants found in Murree, Punjab, Pakistan, and green-synthesized silver nanoparticles in various fields of medicine and nanotechnology.

Nanoparticles are synthesized by using various chemical methods in higher yields but they are not very environmentally friendly and have hazardous effects on living cells. This can be attributed to the overuse of hazardous chemicals involved in the process. The green approach of nanoparticle synthesis is widely gaining attention worldwide as it is considered as nontoxic, harmless and ecofriendly. Apart from this they also have multiple applications in various fields of science and technology. Nanoparticles synthesized by using various phytochemicals are also effective against a variety of microbial populations. The objective of this study is to synthesize silver nanoparticles (AgNPs) from the fruit extracts of Wrightia tinctoria and evaluating its antimicrobial capacities against gram-positive and negative bacterial strains. Silver nanoparticles were synthesized using different solvent extracts of Wrightia tinctoria pods. The formation of silver nanoparticles was noted by detecting the change in color of the solution. The presence of nanoparticles was detected by performing UV visible spectroscopy and monitoring the spectrum from 400 nm to 800 nm. A small peak at 425 nm suggested the presence of silver nanoparticles. In a later part of the study, the inhibitory effect of green synthesized silver nanoparticles on the growth of E. coli and S. aureus was monitored. The appearance of a zone of inhibition further confirmed the antimicrobial effect of the synthesized nanoparticles.

The global spread of multi-resistant pathogenic microorganisms has significantly complicated the treatment of chronic wounds. The development of novel drugs requires a substantial time investment. Hybrid materials such as nanoparticles stabilized by plant extracts are considered the best for creating efficient antiseptic substances. This paper is the first to discuss quantitative and qualitative analyses of the phytochemical constituents of the medicinal plant Artemisia terrae-albae, collected in Kazakhstan. The antimicrobial activity of the extracts, as well as of silver nanoparticles (AgNPs) stabilized by Artemisia terrae-albae extract, were evaluated. AgNPs were characterized by an average size of 82 nm or larger with a negative surface charge. TEM analysis of the obtained suspension showed a nonuniform structure of particles synthesized at a low concentration of ethyl acetate solvent in water. The SPR peak of AgNPs@Art aq. extract was detected at 420 nm, while any clear SPR peak was observed for AgNPs@Art ethylacetate extract. Diluted Artemisia terrae-albae extracts did not exhibit pronounced antimicrobial activity due to the poor solubility of compounds in water. Nevertheless, the AgNPs@Art aq. and AgNPs@Art EtAc. extracts possessed antimicrobial activity against the Pseudomonas aeruginosa ATCC 9027, Staphylococcus aureus ATCC 6538, Escherichia coli (ATCC 8739), and Candida albicans ATCC 10231 strains. [ABSTRACT FROM AUTHOR]

The aim of this study is to investigate the antimicrobial activity and in vitro toxicity of caffeine/AgNPs–triton X-100 and characterize the produced nanoparticle. In the present investigation, the green biosynthesis of caffeine/AgNPs with triton X-100 has been carried out, and Ultraviolet–Visible Spectroscopy (UV–Vis) analysis was done which revealed an intense surface plasmon resonance (SPR) band at 420 nm, thus confirming the formation of triton X-100. Transmission electron microscopy (TEM) study showed that the nanoparticles were spherical in shape with an average size of 16–24 nm diameter. Using the MTT assay, biosynthesized AgNPs effectively inhibited Hep-G2 cancer cells with a 60.53% reduction.. The antibacterial activity of synthesized AgNPs against a diverse range of Gram-positive pathogens was determined using disk diffusion method and the results showed that caffeine–AgNP–Triton X-100 effectively inhibited E. coli and S. aureus. [ABSTRACT FROM AUTHOR]

Nanoparticles, nowadays, are being used in multiple applications such as therapeutics, industries, healthcare, cosmetics, and wound healing. Nanoparticles are entirely distinct from bulk particles as they have a giant surface area to volume ratio, therefore, showing various mechanical, electrical, physical, chemical, and optical properties, and thus, being used in different properties. As there are so many applications of metallic nanoparticles, there is a requirement for an efficient method for nanoparticle synthesis because the conventional chemical methods used to synthesize nanoparticles have limitations such as high cost and negative environmental impact. To overcome these drawbacks, green methods for nanoparticle synthesis have emerged as an eco-friendly and cost-efficient alternative. The green method for nanoparticle amalgam is cost-efficient and eco-friendly, unlike the chemical technique for nanoparticle synthesis. A variety of dimensions of nanoparticles can be synthesized by a substitute of the plant's extract. Moreover, there is no requirement for external stabilizing agents and the involvement of harmful chemicals. This review aims to investigate how plant compounds can be used to synthesize silver nanoparticles and to evaluate the potential of plant extracts as reducing and stabilizing agents in the green synthesis of metallic nanoparticles. This review seeks to investigate the green production of metallic nanoparticles using plant-derived chemicals and to assess the potential of plant extracts as reducing and stabilizing agents. The study investigates the function of numerous plant substances in the synthesis process, such as flavonoids, alkaloids, terpenoids, saponins, and phenols. The paper also examines various methods for figuring out the morphology of nanoparticles created from various plant parts and their prospective uses as antibacterial agents, wastewater treatment, and reactive oxygen species modulators. This review offers insightful information about the possible uses of metallic nanoparticles by highlighting the advantages of environmentally friendly processes for the manufacture of silver nanoparticles. [ABSTRACT FROM AUTHOR]

In the present work, we report a simple, cost-efficient, and eco-friendly green method to synthesize silver nanoparticles with antimicrobial activity. An ethanolic extract from Moringa oleifera seed residue was used as a reducing and stabilizing agent in an aqueous solution of silver nitrate. The synthesized silver nanoparticles' hydrodynamic radius, polydispersity index, and zeta-potential were evaluated by Dynamic Light Scattering. Scanning Electron Microscopy was employed to confirm the size and morphology of the nanoparticles. Synthesis of spherical particles with 127 ± 24 nm was confirmed. After sintering, the product of the synthesis was analyzed by X-ray diffraction. The X-ray diffraction pattern attributed to reflections of the (111), (200), (220), and (311) planes, which are characteristic of silver nanoparticles, confirms the successful synthesis of crystalline face-centered cubic nanoparticles. The antimicrobial activity of the bionanoparticles was tested against Escherichia coli BL21(DE3) cells and compared with the effect of a Moringa oleifera seed cake extract. Herein, we show that the growth of Escherichia coli is significantly affected by the addition of the synthesized bionanoparticles. Addition of the bionanoparticles inhibited the growth and lengthened the lag phase of the bacterial culture. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Nanoparticles are nano-sized materials that can be widely used in fields such as medicine, pharmacology, and industry. The use of natural and easily available materials in nanoparticle synthesis is preferable for economic reasons. Plants are extremely suitable for the synthesis of nanoparticles due to their wide availability and the large number of components they contain with various properties. For this purpose, silver nanoparticles and zinc nanoparticles (AgNPs and ZnNPs), two different nanoparticles were synthesized from an edible plant, watercress (Nasturtium officinale). Scanning electron microscopy, scanning electron microscopy-energy dispersive X-ray, UV-VIS spectroscopy, X-ray diffraction (XRD), and fourier transform infrared spectrophotometer (FTIR) analyses of these nanoparticles were performed. In addition, the antimicrobial effects of these synthesized nanoparticles were determined using the disk diffusion method. The nanoparticles obtained from Nasturtium officinale were effective on Gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa), Gram-positive bacteria (Staphylococcus aureus, Streptococcus pyogenes), and fungi (Candida albicans). In particular, AgNPs with broad-spectrum antimicrobial activity were obtained from the watercress. While ZnNPs showed inhibition effects of 49% on K. pneumoniae, 51% on S. aureus, and 62% on C. albicans, AgNPs showed inhibition effects of 93% on P. aeruginosa, 87% on S. aureus, 81% on E. coli, 80% on C. albicans, 72% on K. pneumoniae, and 56% on S. pyogenes. The results show that Nasturtium officinale can be used effectively in the production of new biotechnological products, particularly ones with antimicrobial properties. [ABSTRACT FROM AUTHOR]

Green synthesis is a promising strategy for producing eco-friendly, non-toxic, and less expensive metallic nanoparticles from plants and microorganisms. This research synthesized silver nanoparticles (AgNPs) from fermented leaf extract of bush tea (Athrixia phylicoides DC). The physicochemical characterization of AgNPs was conducted by UV-vis spectroscopy, Fourier Transform Infrared Spectrometry (FTIR), and Differential Scanning Calorimetry (DSC). In addition, the total phenolic and flavonoid contents, antioxidant and antimicrobial activities of AgNPs were evaluated. The results indicated the successful formation of AgNPs by a visual change of color in fermented bush tea leaf extract from black to brown and in unfermented bush tea leaf crude extract from dark brown to light brown. The UV-vis spectrum of the reaction of the mixture of synthesized AgNPs with unfermented and fermented bush tea showed maximum absorbance at 457 nm and 450 nm, which confirmed the formation of AgNPs. FTIR revealed the functional groups of a leaf extract from bush tea that contributed to the reduction and capping process. The thermal properties suggest that low thermal stable compounds contributed to the reduction of Ag+ to Ag° in the phyto compounds found in the extract. The total phenolic content was higher in fermented AgNPs (290.44 mg/g GAE) compared to unfermented AgNPs (171.34 mg/g GAE). On the other hand, the total flavonoid content was higher in unfermented AgNPs (17.87 mg/g CE) than in fermented AgNPs (9.98 mg/g CE). Regarding antioxidant activity values, unfermented AgNPs had the highest FRAP (535.30 TE/mL) and 47.58% for DPPH. Fermented AgNPs had more antimicrobial activity than unfermented AgNPs. The results show that bush tea leaf extract can be used in different industries such as food, cosmetics, and biomedical. [ABSTRACT FROM AUTHOR]

"Green chemistry" is a simple and easily reproductible method that provides nanoparticles characterized by better stability and good dispersion in an aqueous solution. Nanoparticles can be synthesized by algae, bacteria, fungi, and plant extracts. Ganoderma lucidum is a commonly used medicinal mushroom with distinctive biological properties, such as antibacterial, antifungal, antioxidant, anti-inflammatory, anticancer, etc. In this study, aqueous mycelial extracts of Ganoderma lucidum were used to reduce AgNO3 to form silver nanoparticles (AgNPs). The biosynthesized nanoparticles were characterized by UV-visible spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) analysis. The maximum UV absorption was obtained at 420 nm, which represents the specific surface plasmon resonance band for biosynthesized silver nanoparticles. SEM images showed particles as predominantly spherical, while FTIR spectroscopic studies illustrated the presence of functional groups that can support the reducing of ion Ag+ to Ag(0). XRD peaks ratified the presence of AgNPs. The antimicrobial effectiveness of synthesized nanoparticles was tested against Gram-positive and Gram-negative bacterial and yeasts strains. The silver nanoparticles were effective against pathogens, inhibiting their proliferation, and thus reducing the risk to the environment and to public health. [ABSTRACT FROM AUTHOR]

Antimicrobial resistance is an ever-growing global concern to public health with no clear or immediate solution. Silver nanoparticles (AgNPs) have long been proposed as efficient agents to fight the growing number of antibiotic-resistant strains. However, the synthesis of these particles is often linked to high costs and the use of toxic, hazardous chemicals, with environmental and health impact. In this study, we successfully produced AgNPs by green synthesis with the aid of the extract of two brown algae—Cystoseira baccata (CB) and Cystoseira tamariscifolia (CT)—and characterized their physico-chemical properties. The NPs produced in both cases (Ag@CB and Ag@CT) present similar sizes, with mean diameters of around 22 nm. The antioxidant activity of the extracts and the NPs was evaluated, with the extracts showing important antioxidant activity. The bacteriostatic and bactericidal properties of both Ag@CB and Ag@CT were tested and compared with gold NPs produced in the same algae extracts as previously reported. AgNPs demonstrated the strongest bacteriostatic and bactericidal properties, at concentrations as low as 2.16 µg/mL against Pseudomonas aeruginosa and Escherichia coli. Finally, the capacity of these samples to prevent the formation of biofilms characteristic of infections with a poorer outcome was assessed, obtaining similar results. This work points towards an alternative for the treatment of bacterial infections, even biofilm-inducing, with the possibility of minimizing the risk of drug resistance, albeit the necessary caution implied using metallic NPs. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (AgNPs) synthesized from green synthesis using medicinal plants are presented as an option for the development of new antimicrobial agents. In this context, this study aims to evaluate the antimicrobial activity of silver nanoparticles synthesized from the aqueous extract of Schinus terebinthifolius Raddi leaves, popularly known as "aroeira." A 23 factorial design was used to assess the statistical significance of the studied factors, and Box–Behnken design was used to define the optimal conditions for the green synthesis of AgNPs. The studied factors were significant for the synthesis of nanoparticles, and the optimal conditions were pH 9.5, reaction time of 180 min, and 10 g of S. terebinthifolius Raddi leaves. The samples were characterized using UV–Vis spectroscopy, Fourier transform infrared spectroscopy, X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, and dynamic light scattering. Antimicrobial activity was evaluated using the broth microdilution method and through the minimum microbicidal concentration. AgNPs showed greater antimicrobial efficacy compared to the extract, both for bacteria and fungi: bacteriostatic activity against all tested bacteria and bactericidal against Pseudomonas aeruginosa, besides fungistatic action against Candida albicans and Candida glabrata. Finally, the aqueous extract of "aroeira" leaves was effective in the synthesis of AgNPs, with greater antimicrobial potential than the extract. [ABSTRACT FROM AUTHOR]

UV-initiated green synthesis of metal nanoparticles by using plant extracts as photoreducing agents is of particular interest since it is an environmentally friendly, easy-to-maintain, and cost-effective method. Plant molecules that act as reducing agents are assembled in a highly controlled way which makes them suitable for metal nanoparticle synthesis. Depending on the plant species, their application for green synthesis of metal nanoparticles for diverse applications may contribute to the mediation/reduction in organic waste amounts, thus enabling the implementation of the circular economy concept. In this work, UV-initiated green synthesis of Ag nanoparticles in hydrogels and hydrogel's thin films containing gelatin (matrix), red onion peel extract of different concentrations, water, and a small amount of 1 M AgNO3 have been investigated and characterized using UV-Vis spectroscopy, SEM and EDS analysis, XRD technique, performing swelling experiments and antimicrobial tests using bacteria (Staphylococcus aureus, Acinetobacter baumannii, Pseudomonas aeruginosa), yeasts (Candida parapsilosis, Candida albicans) and microscopic fungi (Aspergillus flavus, Aspergillus fumigatus). It was found that the antimicrobial effectiveness of the silver-enriched red onion peel extract–gelatin films was higher at lower AgNO3 concentrations as compared to those usually used in the commercially available antimicrobial products. The enhancement of the antimicrobial effectiveness was analyzed and discussed, assuming the synergy between photoreducing agent (red onion peel extract) and silver nitrate (AgNO3) in the initial gel solutions leading to the intensification of Ag nanoparticles production. [ABSTRACT FROM AUTHOR]

The citrus canker pathogen Xanthomonas axonopodis has caused severe damage to citrus crops worldwide, resulting in significant economic losses for the citrus industry. To address this, a green synthesis method was used to develop silver nanoparticles with the leaf extract of Phyllanthus niruri (GS-AgNP-LEPN). This method replaces the need for toxic reagents, as the LEPN acts as a reducing and capping agent. To further enhance their effectiveness, the GS-AgNP-LEPN were encapsulated in extracellular vesicles (EVs), nanovesicles with a diameter of approximately 30–1000 nm naturally released from different sources, including plant and mammalian cells, and found in the apoplastic fluid (APF) of leaves. When compared to a regular antibiotic (ampicillin), the delivery of APF-EV-GS-AgNP-LEPN and GS-AgNP-LEPN to X. axonopodis pv. was shown to have more significant antimicrobial activity. Our analysis showed the presence of phyllanthin and nirurinetin in the LEPN and found evidence that both could be responsible for antimicrobial activity against X. axonopodis pv. Ferredoxin-NADP+ reductase (FAD-FNR) and the effector protein XopAI play a crucial role in the survival and virulence of X. axonopodis pv. Our molecular docking studies showed that nirurinetin could bind to FAD-FNR and XopAI with high binding energies (−10.32 kcal/mol and −6.13 kcal/mol, respectively) as compared to phyllanthin (−6.42 kcal/mol and −2.93 kcal/mol, respectively), which was also supported by the western blot experiment. We conclude that (a) the hybrid of APF-EV and GS-NP could be an effective treatment for citrus canker, and (b) it works via the nirurinetin-dependent inhibition of FAD-FNR and XopAI in X. axonopodis pv. [ABSTRACT FROM AUTHOR]

The Vitrus vinifera fruit extract was used to make silver nanoparticles (AgNPs) utilizing a green chemical technique. The biosynthesized Tween-20/Vitrus vinifera-AgNPs were observed by UV–Vis spectrophotometry. Fourier transform infrared spectroscopy, scanning transmission electron microscopy, selected area electron diffraction, and energy-dispersive X-ray spectroscopy were used to characterize the physiochemical properties. The spherical form of AgNPs was confirmed by transmission electron microscopy. The peaks in the Tween-20/Vitrus vinifera-AgNPs have an average crystallite size that is found to be 46 nm according to powder X-ray diffraction examination. Biosynthesized AgNPs had a significant effect on bone osteosarcoma MG63 cells with 55% inhibition, respectively, using MTT assay. The effective dangerous concentration of Tween-20/Vitrus vinifera with AgNP nanoparticles was less harmful to MG63 cells. The results of antibacterial activity showed that Tween-20/Vitrus vinifera-AgNPs effectively inhibited Eggerthella lenta and Staphylococcus epidermis bacteria. [ABSTRACT FROM AUTHOR]

This study investigates an efficient and sustainable route of preparing Ag nanoparticles (NPs) using 1-5 mmol/L aqueous silver nitrate with leaf extracts of five plants--Musa balbisiana (banana), Azadiracta indica (neem), Ricinus communis (castor-oil plant), Tridax procumbens (tridax), and Cardiospermum halicacabum (balloon vine) for their wide availability. These synthesized nanoparticles were characterized with the help of ultraviolet (UV)-visible (Vis) spectrophotometer. The peaks were observed in 418-493 nm. For M. balbisiana, A. indica, R. communis, and C. halicacabum, the average size of nanoparticles was in the range of 90-100 nm. For T. procumbens, it was 39-60 nm as determined by dynamic light scattering. Energy dispersive X-ray spectroscopy analysis showed the peak in silver region confirming presence of elemental silver. Field emission scanning electron microscopy showed that the particles were of a spherical shape in M. balbisiana sample with an average size of 33.87 nm as well as in T. procumbents sample with an average size of 28.512 nm. Ag NPs showed effective antibacterial and antifungal activity against representative pathogens of bacteria and fungi. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity of Ag NPs was found to be in the range of 8.9%-78.86%. H2O2 radical scavenging activity was recorded in the range of 6.036%-57.342%. The nanogel was prepared from synthesized Ag NPs, and its properties like viscosity and stability were evaluated. The results confirmed that this protocol is a simple, rapid, one-step, eco-friendly, nontoxic, and alternative conventional physical/chemical method. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (AgNPs) are obtained herein by green synthesis using plant extracts instead of chemical reagents. However, the AgNPs fabricated via green synthesis are prone to aggregation, and their reproducible formations are difficult owing to the lack of capping ability in the extract. Although such aggregations of AgNPs are also observed in chemical synthesis, the phenomenon is more severe in green synthesis. In this study, we used Pinus koraiensis pinecone extract as a new green-synthetic agent along with 1 mM AgNO 3 and diatomite (DE) as the biosilica surface to prepare AgNPs stably. Scanning electron microscopy with energy-dispersive X-ray spectroscopy analysis confirmed that the AgNPs were formed on DE by green synthesis with a size of 27 nm; they were non-aggregated and well-dispersed on the DE surface. The AgNP-coated DE composite (AgNPs/DE) showed antibacterial activity that could kill > 99% of E. coli and S. aureus within one hour. Further, the AgNPs/DE with antimicrobial activity can be used up to five times repeatedly. The use of DE in the green synthesis of nanoparticles can thus provide advantages such as adequate dispersion and enhanced ability of the AgNPs. The results obtained herein support the environmentally friendly strategy of preparation and application of AgNPs. [Display omitted] • Green synthesis of silica nanoparticle (AgNPs) by pinecone extract was done on diatomite (DE) to yield DE/AgNPs. • In AgNPs/DE composite, the formed AgNPs are well dispersed on diatomite surface. • AgNPs/DE composite showed good antibacterial activity for gram-positive and gram–negative bacteria. • Antibacterial activity of AgNP can be re-used via AgNPs/DE composite. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (AgNPs) are widely recognized as a prominent antimicrobial agent and have found applications in the field of medicine. This study focuses on the synthesis of AgNPs utilizing the natural reducing agent of Ceylon olive (Elaeocarpus serratus), presenting an economically viable and ecologically friendly approach. For the first time, this research demonstrated the synthesis of AgNPs using phytochemicals extracted from Ceylon olive, serving as both natural reducing and stabilizing agents. The synthesized AgNPs were characterized with UV–visible spectroscopy, a particle size analyzer (PSA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) coupled with an energy dispersive X-ray spectrometer (EDX). The UV–visible spectra primarily indicated the formation of the AgNPs by the surface plasmon resonance band around 434 nm. SEM analysis confirmed the presence of silver nanoparticles within a size range of 50–110 nm, with an average size of approximately 70 nm. FTIR determined that proteins, phenols, and flavonoids may have acted as reducing and capping agents. Experimental parameters were optimized to improve the yield and size of the AgNPs and eventually evaluate their antibacterial properties. The well diffusion method exhibits a significantly larger zone of inhibition for Gram-negative bacterial strains (18.4 ± 0.55 mm for Pseudomonas aeruginosa and 14.4 ± 0.55 mm for Escherichia coli) compared to Gram-positive bacterial strains (11.6 ± 0.55 mm for Staphylococcus aureus and 10.4 ± 0.55 mm for Staphylococcus epidermidis) for 50 µg/mL AgNPs. These findings demonstrate that AgNPs synthesized with Ceylon olive have the potential to develop into novel materials for bacterial-mediated diseases.

In the advanced progress of the synthesis of metal nanoparticles, the use of a bio-mimicking approach has been extensively studied and recognised as a non-toxic method. The use of Ag-NPs synthesised from inorganic compounds using plant extracts as surfactants are quite novel. Therefore, this study was carried out by synthesising and characterising Ag-NPs using a composite leave and bark extract solution of Croton macrostachyus as a capping agent. A 1:3 composite solution exhibited small nanoparticles with a rod-like shape that were active against bacteria. In addition, Ag-NPs were observed from leaf and bark extracts of a 1:1 components, as well as sand mall NPs from leaf extract, showing that leaf extract solution contained more reducing biomolecules. Furthermore, we studied the antibacterial activity of the synthesised NPs following the disc diffusion method (by preparing gram-negative and gram-positive bacteria). Thus, the synthesised NPs were active on Streptococcus pyogen compared with Pseudomonas aeruginosa bacteria. [ABSTRACT FROM AUTHOR]

Green synthesis of metal nanoparticles (NP) has emerged as a recent trend in green chemistry. However, their potential in the field of agriculture is yet underexplored. In this study, silver nanoparticles (Ag NPs) were synthesized by using the fruit juice and peel extract of Citrus maxima (Burm.) Merr.as a reducing and capping agent. The nano-primed seeds of Zea mays, Glycine max, and Cicerarietinumshowed enhanced germination rate up to 90% as compared to the respective control (30-60%) and also enhanced plant growth. The HRTEM images of fruit-mediated Ag NPs showed well-dispersed particles. The XRD diffraction pattern confirmed the crystalline nature of Ag NPs with fcc lattice points of 101, 111, 200, 220, and 311 with an average crystal size of 19.1275±1.73 nm. On the other hand, the peelmediated Ag NPs exhibited a size range of 10-20 nm with average crystal size of 19.09±1.71 nm. The FTIR spectra confirmed the presence of ʋC=C-H, ʋCH2, ʋC=O (stretch), ʋC=C (stretch), ʋC-H (bend), ʋC-O (bend) in the Ag NPs synthesized by the fruit and peel extract. The Ag NPs also showed potential antimicrobial effects against both Gram-positive (Staphylococcus aureus) and negative bacteria (Klebsiella pneumonia). [ABSTRACT FROM AUTHOR]

Silver nanoparticles (AgNPs) have broad biocidal activities, and are widely employed as an active ingredient in antiseptic, anti-viral, and anti-inflammatory preparations. Green-synthesizing AgNPs would be a rapid, cheap, and environmentally friendly method of synthesis. The methanolic extract of the leaves of Bellevalia flexuosa Boiss. (Asparagaceae) was used for the green synthesis of the AgNPs. The effects of the pH and the concentration of silver nitrate (AgNO3) on the synthesis of the AgNPs were investigated. The AgNPs produced above pH 10, and 1 mM of AgNO3 resulted in lower hydrodynamic diameters. Ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy, and X-ray diffraction proved the formation of the AgNPs, with a face-centered, cubed geometry. Scanning electron microscopy images showed colloidal and well-dispersed nanoparticles. In addition, the antibacterial activities of the prepared AgNPs were assessed by optical densities (ODs) against Gram-positive bacteria (Enterococcus faecalis and Staphylococcus epidermidis) and Gram-negative bacteria (Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, and Salmonella enterica). The broths of Gram-negative and Gram-positive bacteria that contained AgNPs, showed lower OD values compared to the controls. In conclusion, AgNPs were prepared using B. flexuosa methanolic extract, and showed antibacterial activity against the tested bacterial strains. [ABSTRACT FROM AUTHOR]

Plant fractions have a diversity of biomolecules that can be used to make complicated reactions for the bioactive fabrication of metal nanoparticles (NPs), in addition to being beneficial as antioxidant medications or dietary supplements. The current study shows that Urtica dioica (UD) and biologically synthesized silver nanoparticles (AgNPs) of UD have antibacterial and antioxidant properties against bacteria (Escherichia coli and Pseudomonas putida) and Drosophila melanogaster (Oregon R+). According to their ability to scavenge free radicals, DPPH, ABTS, TFC, and TPC initially estimated the antioxidant potential of UD and UD AgNPs. The fabricated AgNPs were analyzed (UV–Vis, FTIR, EDS, and SEM) to determine the functional groups (alcohol, carboxylic acids, phenol, proteins, and aldehydes) and to observe the shape (agglomerated crystalline and rod-shaped structure). The disc diffusion method was used to test the antimicrobial properties of synthesized Ag-NPs against E. coli and P. putida. For 24 to 120 h, newly enclosed flies and third instar larvae of Drosophila were treated with UD and UD AgNPs. After exposure, tests for biochemical effects (acetylcholinesterase inhibition and protein estimation assays), cytotoxicity (dye exclusion), and behavioral effects (jumping and climbing assays) were conducted. The results showed that nanoparticles were found to have potent antimicrobial activity against all microbial strains tested at various concentrations. In this regard, ethno-medicinal characteristics exhibit a similar impact in D. melanogaster, showing (p < 0.05) significantly decreased cellular toxicity (trypan blue dye), enhanced biochemical markers (AChE efficacy and proteotoxicity), and improved behavioral patterns in the organism treated with UD AgNPs, especially in comparison to UD extract. The results of this study may help in the utilization of specific plants as reliable sources of natural antioxidants that may have been beneficial in the synthesis of metallic NPs, which aids in the production of nanomedicine and other therapeutic applications. [ABSTRACT FROM AUTHOR]

This study emphasizes the production of eco-friendly silver nanoparticles from a medicinal plant extract of Morinda lucida (M. lucida) and investigated its antioxidant and antimicrobial activity. Phytochemical screening of M. lucida (ML) leave extract was carried out and observed to contain some fundamental phyto-reducing agents such as reducing sugar, proteins, and alkaloids. The green synthesized AgNPs (ML-AgNPs) were characterized by UV–vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), transmission emission microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Energy dispersive X-ray analysis (EDX). Thermo gravimetric analysis (TGA) was performed on the synthesized ML-capped AgNPs to determine the thermal stability and the formation of the green synthesized AgNPs. The formation of AgNPs was confirmed by the UV–vis absorption spectra, which showed an absorption band at 420 nm. The morphology of ML extract-mediated AgNPs was mostly spherical and rough-edged crystallite nanostructures, with an average particle size of 11 nm. The FTIR analyses revealed distinctive functional groups which were directly involved in the synthesis and stability of AgNPs. The crystallite size was 8.79 nm, with four intense peaks at 2θ angles of 38°, 44°, 64°, and 77°. At an energy level of 3.4 keV, a significant signal was observed indicating the production of thermally stable and pure crystallite AgNPs. The antioxidant property of green synthesized ML-AgNPs was determined to be 40% higher than that of crude M. lucida leaf extract. The ability of green synthesized ML-AgNPs to scavenge free radicals also increased in the order of OH− < NO < H2O2. The ML-AgNPs have strong activities with a maximum against P. vulgaris and a minimum with E. faecalis. [ABSTRACT FROM AUTHOR]

Bacterial resistance to antibiotics is on the rise and hinders the fight against bacterial infections, which are expected to cause millions of deaths by 2050. New antibiotics are difficult to find, so alternatives are needed. One could be metal-based drugs, such as silver nanoparticles (AgNPs). In general, chemical methods for AgNPs' production are potentially toxic, and the physical ones expensive, while green approaches are not. In this paper, we present the green synthesis of AgNPs using two Pseudomonas alloputida B003 UAM culture broths, sampled from their exponential and stationary growth phases. AgNPs were physicochemically characterized by transmission electron microscopy (TEM), total reflection X-ray fluorescence (TXRF), infrared spectroscopy (FTIR), dynamic light scattering (DLS), and X-ray diffraction (XRD), showing differential characteristics depending on the synthesis method used. Antibacterial activity was tested in three assays, and we compared the growth and biofilm-formation inhibition of six test bacteria: Bacillus subtilis, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, and Staphylococcus epidermidis. We also monitored nanoparticles' synergic behavior through the growth inhibition of E. coli and S. aureus by three classical antibiotics: ampicillin, nalidixic acid, and streptomycin. The results indicate that very good AgNP activity was obtained with particularly low MICs for the three tested strains of P. aeruginosa. A good synergistic effect on streptomycin activity was observed for all the nanoparticles. For ampicillin, a synergic effect was detected only against S. aureus. ROS production was found to be related to the AgNPs' antibacterial activity. [ABSTRACT FROM AUTHOR]

Skin lesions are caused by the interruption of their functions, causing several possibilities of injury, and affecting the patient's quality of life. Thus, an effective alternative to this problem is the application of metallic nanoparticles with considerable antimicrobial activity, such as silver nanoparticles (AgNPs). In this context, the present study aims to synthesize and characterize AgNPs from l -ascorbic acid (AA) for a possible cutaneous tissue engineering, evaluating the in vitro safety profile (VERO cells line), antimicrobial activity (Staphylococcus aureus , Escherichia coli , Klebsiella pneumoniae, and Pseudomonas aeruginosa strains), genotoxicity effect and phytotoxicity (Lactuca sativa and Beta vulgaris L. seeds). The novelty of the present study consists of applying green silver nanoparticles for potential application in skin lesions, followed by the study of toxicity in seeds (phytotoxicity), cells (cytotoxicity and genotoxicity with the in vitro safety profile), and antimicrobial activity. X-ray diffraction (XRD), N 2 porosimetry, Field Emission Gun – Scanning Electron Microscope (FEG-SEM), zeta potential (ZP), Scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX), and Fourier-transform infrared spectroscopy (FT-IR) were used to evaluate the morphological, structural, and textural properties of the AgNPs. XRD diffractogram showed characteristic peaks of a face-centered cubic crystal structure at 38.06° (111); 44.26° (200); 64.45° (220); 77.37° (311) and 81.34° (200). FEG-SEM micrography indicated a predominantly spherical morphology and uniformly distributed structure with an average size of 58.4 ± 19 nm. Moreover, AgNPs demonstrated functional groups characteristics of the reducing agent and the metallic precursor, such as the –OH, –CH, –CO, - C C, and Ag–O stretchings. AgNPs showed S BET = 0.3 ± 0.0085 m2 g−1, Dp = 16.2 ± 10.2 nm, Vp = 0.0008 ± 0.0002 cm³ g−1 and ZP = −27.6 ± 1.9 mV with hysteresis type H1 and mesoporous characteristics. EDX analysis indicated the presence of AgNPs (72.34 wt% and 10.46 wt% silver and oxygen respectively) indicating the effectiveness of the biosynthesis process. For the in vitro safety profile, AgNPs did not show cytotoxicity on VERO cells ranging from 0.5 to 150 μg mL−1 with a good gemoprotection. The minimum inhibitory concentration (MIC) showed that AgNPs have an inhibition of 312 μg mL−1 and 156 μg mL−1 on Gram-positive and Gram-negative strains, respectively. The phytotoxicity showed that only high concentrations (50 and 100 μg mL−1) of AgNPs interfered with seed growth. Therefore, AgNPs biosynthesized from l -ascorbic acid (AA) have potential applications as antimicrobial dressings and are biocompatible for application in skin lesions. [Display omitted] • Silver nanoparticles were biosynthesized from ascorbic acid (Vitamin C). • AgNPs were characterized by XRD, FT-IR, FEG-SEM, SEM-EDX, ZP and N 2 porosimetry. • The safety profile and antimicrobial activity of the AgNPs were evaluated. • AgNPs did not show cell death in Vero cells (0.5–150 μg mL−1). • AgNPs showed antibacterial activity against Gram-positive and Gram-negative strains. [ABSTRACT FROM AUTHOR]

To form silver nanoparticles by reduction from metal ions in the presence of a reducing agent, D-glucose, a water-soluble derivative of chitosan, succinyl-chitosan, was used as a polymer matrix at room temperature. The synthesis of silver nanoparticles can also be carried out without a reducing agent by thermal activation of the system using an alkali (NaOH) as an accelerator. The presence of silver nanoparticles in the obtained colloidal solutions was judged by the appearance of an absorption band in the electron plasmon resonance spectra (ƛmax = 417 nm). It has been shown that the use of an additional component, polyethylene oxide, in a macromolecular system makes it possible to obtain small silver nanoparticles (1–3 nm). The results of in vitro studies of the antimicrobial activity of the obtained colloidal solutions containing silver nanoparticles confirm that a decrease in the size of silver nanoparticles leads to an expansion of the spectrum of antibacterial activity of strains of gram-positive and gram-negative bacteria (B. subtilis ATCC 6633, S. aureus 209P, E. coli ATCC 25922) and to the manifestation of a pronounced antifungal action in relation to A. niger INA 00760. [ABSTRACT FROM AUTHOR]

Nowadays, the increase in bacteria resistant to multiple antibiotics has become a real threat to the human health, forcing researchers to develop new strategies. Silver nanoparticles (AgNPs) may be a viable solution to this problem. The green synthesis of AgNPs is considered a green, ecological and low-priced process that provides small and biocompatible nanostructures with antimicrobial activity with a potential application in medicine. In this work, pecan nut shell extracts were analyzed in order to determine their viability for the production of AgNPs. These NPs were synthesized using an extract rich in bioactive molecules, varying the reaction time and silver nitrate (AgNO3) concentration. AgNPs production was confirmed by FT-IR, UV-Vis and EDX spectroscopy, while their morphology and size were determined by transmission electron microscopy (TEM) and dynamic light scattering (DLS). The antibacterial activity of AgNPs was evaluated by the agar diffusion method against Salmonella typhi, Staphylococcus aureus and Proteus mirabilis. The results showed that it is possible to obtain nanoparticles from an extract rich in antioxidant molecules with a size between 39.9 and 98.3 nm with a semi-spherical morphology. In addition, it was shown that the reaction time and the concentration of the precursor influence the final nanoparticles size. Antimicrobial tests showed that there is greater antimicrobial inhibition against Gram-negative than Gram-positive microorganisms, obtaining inhibition zone from 0.67 to 5.67 mm. [ABSTRACT FROM AUTHOR]

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.

“Green chemistry” is a simple and easily reproductible method that provides nanoparticles characterized by better stability and good dispersion in an aqueous solution. Nanoparticles can be synthesized by algae, bacteria, fungi, and plant extracts. Ganoderma lucidum is a commonly used medicinal mushroom with distinctive biological properties, such as antibacterial, antifungal, antioxidant, anti-inflammatory, anticancer, etc. In this study, aqueous mycelial extracts of Ganoderma lucidum were used to reduce AgNO3 to form silver nanoparticles (AgNPs). The biosynthesized nanoparticles were characterized by UV-visible spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) analysis. The maximum UV absorption was obtained at 420 nm, which represents the specific surface plasmon resonance band for biosynthesized silver nanoparticles. SEM images showed particles as predominantly spherical, while FTIR spectroscopic studies illustrated the presence of functional groups that can support the reducing of ion Ag+ to Ag(0). XRD peaks ratified the presence of AgNPs. The antimicrobial effectiveness of synthesized nanoparticles was tested against Gram-positive and Gram-negative bacterial and yeasts strains. The silver nanoparticles were effective against pathogens, inhibiting their proliferation, and thus reducing the risk to the environment and to public health.

The problem of water pollution by persistent substances and microorganisms requires solutions that materials such as silver-modified titanium dioxide can provide due to their excellent photocatalytic and antimicrobial properties. However, the synthesis methods conventionally used to obtain these materials involve toxic chemical reagents such as sodium borohydride (NaBH4). The search for alternative synthesis methods that use environmentally friendly substances, such as the biosynthesis method, was evaluated. Silver-titanium dioxide (Ag-TiO2) was synthesized by a Eucalyptus globulus L. extract as a reductive agent through sol-gel and microwave-assisted sol-gel processes. Four different solvents were tested to extract secondary metabolites to determine their roles in reducing silver nanoparticles. Titanium dioxide nanoparticles with sizes from 11 to 14 nm were obtained in the anatase phase, and no narrowing of the bandgap was observed (3.1–3.2 eV) for the Ag-TiO2 materials compared with the pure TiO2. Interestingly, the bacterial inhibition values were close to 100%, suggesting an effective antimicrobial mechanism related to the properties of silver. Finally, by the physicochemical characterization of the materials and their antimicrobial properties, it was possible to obtain a suitable biosynthesized Ag-TiO2 material as a green option for water disinfection that may be compared to the conventional methods. [ABSTRACT FROM AUTHOR]