Biosynthesis Of AgNPs Research Articles

Biogenic synthesis of silver nanoparticles mediated by the consortium comprising the marine fungal filtrates of Penicillium oxalicum and Fusarium hainanense along with their antimicrobial, antioxidant, larvicidal and anticancer potency.

To biosynthesize silver nanoparticles (AgNPs) using fungal isolates [DS-2 (Penicillium oxalicum) and DW-8 (Fusarium hainanense)] as well as their mixed cell-free filtrate (CFF) acting as a consortium (DSW-28) and their bio-potentials. The fungi (DS-2 and DW-8) were harvested and CFF was prepared. CFF of each fungus and their mixture were reacted with silver nitrate solution under dark conditions for the synthesis of AgNPs. The UV-Visible spectra determined the surface plasmon resonance at 438, 441 and 437 nm for the AgNPs synthesized by DS-2, DW-8 and DSW-28, respectively. The band gap energy was found between 2.21 and 2.24 eV which depicted their ability to act as a semiconductor. The TEM imaging revealed the spherical shape and small size of AgNPs. The XRD pattern exhibited the crystalline structure corresponding to their peaks. The FTIR spectra indicate the presence of different functional groups present on the surface of AgNPs. The broad-spectrum antimicrobial activity was exhibited by AgNPs. The AgNPs also act as an effective antioxidant by depicting their radical scavenging activity against DPPH. Moreover, the AgNPs also inhibited the growth of fourth instar larvae of Aedes aegypti and Culex quinquefasciatus more efficiently in a dose-dependent method. The biosynthesized AgNPs from DSW-28 showed a significant anticancer activity against MCF-7 cells. The silver nanoparticles synthesized by the CFF of two different fungi act synergistically in a consortium leading towards the production of silver nanoparticles with smaller size and higher bioactivity. The impressive bioactivity of the silver nanoparticles synthesized by the mixture of CFF of various fungi acting as a consortium recommends their prospective use in agriculture as well as in biomedical as an antimicrobial, antioxidant, larvicidal and anticancer agents in future.

Biomedical and catalytic applications of agri-based biosynthesized silver nanoparticles

Nanotechnology has been recognized as the emerging field for the synthesis, designing, and manipulation of particle structure at the nanoscale. Its rapid development is also expected to revolutionize industries such as applied physics, mechanics, chemistry, and electronics engineering with suitably tailoring various nanomaterials. Inorganic nanoparticles such as silver nanoparticles (Ag-NPs) have garnered more interest with their diverse applications. In correspondence to green chemistry, researchers prioritize green synthetic techniques over conventional ones due to their eco-friendly and sustainable potential. Green-synthesized NPs have proven more beneficial than those synthesized by conventional methods because of capping by secondary metabolites. The present study reviews the various means being used by the researchers for the green synthesis of Ag-NPs. The morphological characteristics of these NPs as obtained from numerous characterization techniques have been explored. The potential applications of bio-synthesized Ag-NPs viz. Antimicrobial, antioxidant, catalytic, and water remediation along with the plausible mechanisms have been discussed. In addition, toxicity analysis and biomedical applications of these NPs have also been reviewed to provide a detailed overview. The study signifies that biosynthesized Ag-NPs can be efficiently used for various applications in the biomedical and industrial sectors as an environment-friendly and efficient tool.

The effect of AgNPS bio-functionalization on the cytotoxicity of the yeast Saccharomyces cerevisiae.

This work used Sedum praealtum leaf extract to synthesize silver nanoparticles (AgNPs) in a single step. The cytotoxicity of AgNPs was studied with the yeast Saccharomyces cerevisiae W303-1. In addition, the antioxidant activity of the DPPH radical was studied both in the extract of S. praealtum and in the AgNPs. UV-Vis spectroscopy determined the presence of AgNPs by the location of the surface plasmon resonance (SPR) band at 434nm. TEM and XRD analyzes show AgNPs with fcc structure and hemispherical morphology. Also, AgNPs range in size from 5 to 25nm and have an average size of 14nm. 1H NMR, FTIR, and UV-Vis spectroscopy techniques agreed that glycosidic compounds were the main phytochemical components responsible for the reduction and stabilization of AgNPs. In addition, AgNPs presented a maximum of 12% toxicity in yeast attributed to the generation of ROS. Consequently, there was low bioactivity because glycoside compounds cover the biosynthesized AgNPs from S. praealtum. These findings allow applications of AgNPs involving contact with mammals and higher organisms.

Synthesis and Biological Characterization of Phyto-Fabricated Silver Nanoparticles fromAzadirachta indica

Nanoparticles (NPs) have garnered a lot of interest in sectors like medicine, cosmetics, food, and pharmaceuticals for antibacterial catalytic properties, reduced toxicity, and easy production. Biological synthesis of silver nanoparticle (AgNPs) is considered as green, eco-friendly, and cost-effective approach; therefore,Azadirachta indicaextracts were utilized for a dual role of fabrication and functionalization of AgNPs. Optical and physical characterizations were achieved for confirming the biosynthesized AgNPs. SEM images detected quasi-spherical AgNPs of 44.04 to 66.50 nm. Some of potent phytochemicals like flavonoids and proteins fromAzadirachta indicaformed a strong coating or capping on the AgNPs without affecting their secondary structure by interacting with Ag+and NPs for the formation of AgNPs. AgNPs exhibited strong antibacterial activity (MIC 10μg/ml) against multidrug-resistant bacteriaEnterococcus faecalis; at different concentrations, no IC50 values were recorded for AgNPs as well asAzadirachta indicasignifying low cytotoxicity in the exposed concentration range. The DNA degradation activity of AgNPs through the TUNEL assay revealed no significant increase in the overall FITC mean fluorescence intensity as well as a DNA fragmentation index with 5.45% DNA damage (10μg/ml AgNPs). Drug uptake of AgNPs was also investigated through a permeability assay via Caco-2 cell lines at test concentrations where apparent permeability was detected as moderate.

Synergistic Antibacterial Activity of Green Synthesized Silver Nanomaterials with Colistin Antibiotic against Multidrug-Resistant Bacterial Pathogens

The high frequency of nosocomial bacterial infections caused by multidrug-resistant pathogens contributes to significant morbidity and mortality worldwide. As a result, finding effective antibacterial agents is of critical importance. Hence, the aim of the present study was to greenly synthesize silver nanoparticles (AgNPs) utilizing Salvia officinalis aqueous leaf extract. The biogenic AgNPs were characterized utilizing different physicochemical techniques such as energy-dispersive X-ray spectroscopy (EDX), ultraviolet-visible spectrophotometry (UV-Vis), X-ray diffraction analysis (XRD), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FT-IR) analysis. Additionally, the synergistic antimicrobial effectiveness of the biosynthesized AgNPs with colistin antibiotic against multidrug-resistant bacterial strains was evaluated utilizing the standard disk diffusion assay. The bioformulated AgNPs revealed significant physicochemical features, such as a small particle size of 17.615 ± 1.24 nm and net zeta potential value of −16.2 mV. The elemental mapping of AgNPs revealed that silver was the main element, recording a relative mass percent of 83.16%, followed by carbon (9.51%), oxygen (5.80%), silicon (0.87%), and chloride (0.67%). The disc diffusion assay revealed that AgNPs showed antibacterial potency against different tested bacterial pathogens, recording the highest efficiency against the Escherichia coli strain with an inhibitory zone diameter of 37.86 ± 0.21 mm at an AgNPs concentration of 100 µg/disk. In addition, the antibacterial activity of AgNPs was significantly higher than that of colistin (p ≤ 0.05) against the multidrug resistant bacterial strain namely, Acinetobacter baumannii. The biosynthesized AgNPs revealed synergistic antibacterial activity with colistin antibiotic, demonstrating the highest synergistic percent against the A. baumannii strain (85.57%) followed by Enterobacter cloacae (53.63%), E. coli (35.76%), Klebsiella pneumoniae (35.19%), Salmonella typhimurium (33.06%), and Pseudomonas aeruginosa (13.75%). In conclusion, the biogenic AgNPs revealed unique physicochemical characteristics and significant antibacterial activities against different multidrug-resistant bacterial pathogens. Consequently, the potent synergistic effect of the AgNPs–colistin combination highlights the potential of utilizing this combination for fabrication of highly effective antibacterial coatings in intensive care units for successful control of the spread of nosocomial bacterial infections.

Phytosynthesis, antimicrobial and catalytic activities of silver nanoparticles derived using leaf and stem extracts of Indigofera macrophylla

Background: The phytosynthesis of metal nanoparticles is a promising green alternative to traditional chemical approaches.Objective: The aim of this study was to synthesize silver nanoparticles (AgNPs) with antimicrobial and biocatalytic activities using aqueous leaf and stem extracts of Indigofera macrophylla.Methods: Critical reaction variables for the biosynthesis of AgNPs were optimized using UV-vis spectroscopy before the biosynthesised AgNPs were characterized using various spectroscopic and microscopic techniques. The biological activities of the biogenic nanoparticles were then investigated with particular focus on their antimicrobial activity and biocatalytic efficiency in the degradation of methylene blue.Results: The surface plasmon resonance of silver nanoparticles biosynthesized using aqueous extracts of leaf (LE-AgNPs) and stem (SE-AgNPs) of I. macrophylla occurred at 430 and 426 nm respectively. Scanning electron microscopy images of the nanoparticles showed highly aggregated polymorphs with mostly spherical shape. The particle sizes of LE-AgNPs and SE-AgNPs as determined by Transmission electron microscopy were 48.61±8.60 and 18.09±4.13 nm respectively with Energy dispersive X-ray analysis confirming characteristic absorption band at 3 KeV. In susceptibility assays, LE-AgNPs showed dose-dependent zones of inhibition against Escherichia coli (18 mm), Staphylococcus aureus (18 mm), Pseudomonas aeruginosa (20 mm) while SE-AgNP was only active against Staphylococcus aureus (10 mm). Both LE-AgNPs and SE-AgNPs showed good biocatalytic efficiency in the degradation of methylene blue with rate constants of 0.0204 and 0.0182 min-1 respectively.Conclusion: Silver nanoparticles with antimicrobial and catalytic activities have been biosynthesized using the aqueous extract of Indigofera macrophylla.

Biological Synthesis of Silver Nanoparticles and Prospects in Plant Disease Management.

Exploration of nanoparticles (NPs) for various biological and environmental applications has become one of the most important attributes of nanotechnology. Due to remarkable physicochemical properties, silver nanoparticles (AgNPs) are the most explored and used NPs in wide-ranging applications. Also, they have proven to be of high commercial use since they possess great chemical stability, conductivity, catalytic activity, and antimicrobial potential. Though several methods including chemical and physical methods have been devised, biological approaches using organisms such as bacteria, fungi, and plants have emerged as economical, safe, and effective alternatives for the biosynthesis of AgNPs. Recent studies highlight the potential of AgNPs in modern agricultural practices to control the growth and spread of infectious pathogenic microorganisms since the introduction of AgNPs effectively reduces plant diseases caused by a spectrum of bacteria and fungi. In this review, we highlight the biosynthesis of AgNPs and discuss their applications in plant disease management with recent examples. It is proposed that AgNPs are prospective NPs for the successful inhibition of pathogen growth and plant disease management. This review gives a better understanding of new biological approaches for AgNP synthesis and modes of their optimized applications that could contribute to sustainable agriculture.

Characterization of the biosynthesized intracellular and extracellular plasmonic silver nanoparticles using Bacillus cereus and their catalytic reduction of methylene blue

The biosynthesis of silver nanoparticles (Ag NPs) has been studied in detail using two different approaches. For the first time, Bacillus cereus is used for one-pot biosynthesis of capsulated Ag NPs, using both intracellular and extracellular approaches. To discriminate between the produced nanostructures by these two approaches, their structures, nanomorphologies, optical properties, hydrodynamic sizes and zeta potentials are studied using different techniques. Fourier-transform infrared spectroscopy was used to identify the bioactive components responsible for the reduction of Ag+ ions into Ag and the growth of stable Ag NPs. Scanning and transmission electron microscopy images displayed spherical and polygon nanomorphology for the intracellular and extracellular biosynthesized Ag NPs. For intracellular and extracellular biosynthesized Ag NPs, a face-centred cubic structure was observed, with average crystallite sizes of 45.4 and 90.8 nm, respectively. In comparison to the noncatalytic reduction test, the catalytic activities of intracellular and extracellular biosynthesized Ag NPs were explored for the reduction of highly concentrated MB dye solution. Extracellular Ag NPs achieved 100% MB reduction efficacy after around 80 min, compared to 50.6% and 24.1% in the presence and absence of intracellular Ag NPs, respectively. The rate of MB reduction was boosted by 22 times with the extracellular catalyst, and by 3 times with the intracellular catalyst. Therefore, the extracellular production process of Ag NPs utilizing Bacillus cereus bacteria might be applied in the industry as a cost-effective way for eliminating the toxic MB dye.

Antimicrobial, antibiofilm potential, and anti-quorum sensing activity of silver nanoparticles synthesized from Cyanobacteria Oscillatoria princeps.

Cyanobacteria are among the beneficial and environmentally friendly natural candidates used in the biosynthesis of nanoparticles, with their ability to accumulate heavy metals from their environment, thanks to their biologically active compounds. In the current study, an aqueous extract of Oscillatoria princeps fresh biomass was used for the green synthesis of AgNPs. UV-vis spectrum, Fourier transforms infrared, scanning electron microscopy, and energy-dispersive spectroscopy were used to validate and characterize biosynthesized of OSC-AgNPs. The biosynthesis of AgNPs was visually verified in terms of the change in the color of the AgNO3 solution from yellowish brown to brown colors from 72h onwards. An absorption peak of approximately 420nm was detected in the UV-vis spectrum, corresponding to the plasmon resonance of AgNPs. FT-IR analysis showed the presence of free amino groups in addition to sulfur-containing amino acid derivatives that act as stabilizing agents. SEM images detected the roughly spherical shape of OSC-AgNPs with an average size of 38nm. The pathogens tested were all susceptible to OSC-AgNPs showing varying antimicrobial effects on pathogenic microorganisms. E. coli and C. albicans displayed the maximum susceptibility, with zones of inhibition of 14.6 and 13.8mm at 3-mM concentration, respectively, while B. cereus had the lowest zone of inhibition (10.6mm) at 3-mM OSC-AgN03 concentration. In conclusion, AgNPs synthesized from Oscillatoria princeps inhibit biofilm formation, suggesting that AgNPs may be a promising candidate for the prevention and treatment of biofilm-associated infections caused by bacteria and yeasts.

Characterization and Biological Activities of Silver Nanoparticles Synthesized using Grewia tiliifolia Vahl Leaf Extract

Background: An eco-friendly approach for the synthesis of noble metal nanoparticles employing various plant extracts has become of great interest in the field of nanotechnology. In the present study, the efficacy of Grewia tiliifolia leaf extract in reducing 1mM silver nitrate to silver nanoparticles(AgNPs) has been reported for the first time and also we investigated the anticancer, antituberculosis and antioxidant activity. Methods: Characterization of biosynthesized AgNPs using G. tiliifolia leaf extract was evaluated by Uv-Vis, FTIR, XRD, DLS and TEM with SAED. Efficacy of biosynthesized AgNPs using G. tiliifolia leaf extract was tested for cytotoxicity against A549 Lung cancer cell lines by MTT Assay and also against the infectious agent Mycobacterium tuberculosis using MABA Assay. Further antioxidant activity was evaluated by DPPH radical scavaging assay. Results: The biosynthesis of AgNPs was evident by color change of reaction mixture from dark yellow to reddish-brown. Biofabricated AgNPs was further confirmed by characteristic surface plasmon absorption peak at 409nm by UV-vis analysis. FTIR data reveals the presence of phytochemicals involved in bioreduction and biocapping of AgNPs, XRD analysis depicted crystallographic nature of AgNPs. Further, size, charge, and polydispersity nature were studied using DLS (40.2nm with polydispersity index 0.361) and Zeta potential (-35.8mV). The morphology of AgNPs was determined by TEM analysis with size ranging from 11-34nm. The plant derived AgNPs exhibited a cytotoxic effect on the Lung cancer cell line with IC50 value of 23.45µg/ml and also found to be effective against M. tuberculosis with a MIC of 6.25µg/ml in comparison to the leaf extract (MIC 50µg/ml). Antioxidant activity observed by AgNPs was moderate with IC50 value 49.60 µg/ml. Conclusion: The findings indicate that the AgNPs synthesized from leaf extract of G. tiliifolia are eco-friendly, cost-effective, non-toxic and can be the effective natural anticancer, antituberculosis agents and antioxidant agent.

Bioprospects of Endophytic Bacteria in Plant Growth Promotion and Ag-Nanoparticle Biosynthesis.

In this study, five endophytic bacterial strains, namely Rhizobium pusense (MS-1), Bacillus cereus MS-2, Bacillus flexus (MS-3), Methylophilus flavus (MS-4), and Pseudomonas aeruginosa (MS-5), were used to investigate their potential role in the enhancement of growth yields of two types of tomato varieties, viz. hybrid and local, and in the biosynthesis of silver nanoparticles (AgNPs). The inoculation of bacterial strains enhanced the root and shoot length, biomass, and leaf chlorophyll contents. The fruit weight of the tomato (kg/plant) was also higher in the bacteria inoculated plants of both hybrid and local varieties than in the control (untreated). A significant increase was recorded in the fruit yield (g/plant) in all the treatments, whereas Methylophilus flavus (MS-4) inoculated plants yielded nearly 2.5 times more fruit weight compared to the control in the hybrid variety and two times higher in the local variety. The response to M. flavus as a microbial inoculant was greater than to the other strains. Biosynthesis of Ag nanoparticles was also carried out using all five endophytic bacterial strains. The weakest producers of AgNPs were Rhizobium pusense (MS-1) and Methylophilus flavus (MS-4), while Bacillus cereus MS-2, Bacillus flexus (MS-3), and Pseudomonas aeruginosa (MS-5) were strong producers of AgNPs. Nanoparticles were further characterized using high-resolution scanning electron microscopy (HR-SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), UV-Vis spectrophotometry, and X-ray diffraction (XRD) analysis, and revealed cuboidal shaped AgNPs in the Bacillus cereus MS-2 strain. In addition, the biosynthesized AgNPs showed antibacterial activity against various pathogenic and endophytic bacterial strains.

A methanogenic protein facilitates the biosynthesis of the silver nanoparticles

Silver nanoparticles (AgNPs) have recently attracted worldwide consideration because of their extensive applications. Within the clean production trends, eco-friendly approaches have been provided as an alternative which require less energy consumptions and polluting chemicals. Herein, a purified protein (methyl-coenzyme M reductase D subunit, McrD) from methanogen as bio-reducing agent was used for biosynthesis of AgNPs and the critical factor is mainly related to the characteristics of the protein itself. The obtained optimum condition for synthesis in the mixture was 15 mM silver nitrate and 150 μg mL−1 McrD protein at 30 °C and pH 11 for 24 h incubation. Readily proteins displayed a rapid reduction of silver ion to elementary silver, yielding the spherical AgNPs at a nano-scale of 20 nm. In addition, this eco-friendly synthesized AgNPs possessed a broad-spectrum antimicrobial activity against bacteria and fungi. This work also envisages the possibility of predicting the biological properties of a protein on synthesizing the metal nanoparticles. Overall, this green and facile method is expected to the trend of biosynthesis of synthesizing AgNPs.

Green synthesis of silver nanoparticles using Cinnamomum tamala (Tejpata) leaf and their potential application to control multidrug resistant Pseudomonas aeruginosa isolated from hospital drainage water

Green Synthesis of Metal Nanoparticles is becoming a more common method for producing nanoparticles with a diameter of 1–100 nm that may be employed in a variety of medical applications. The antibacterial efficacy of silver nanoparticles (AgNPs) derived from Cinnamomum tamala (Tejpata) leaf extract against antibiotic-resistant Pseudomonas aeruginosa is investigated in this study. Green AgNP synthesis is safe, cost-effective, and ecologically friendly. The biosynthesized AgNPs were studied using UV-Visible spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), Dynamic Light Scattering (DLS), X-ray Diffraction (XRD), and Transmission Electron Microscopy (TEM). The AgNPs were virtually spherical, with an average size of 25–30 nm, according to TEM observations. Biochemical and molecular identification were used to isolate multidrug-resistant P. aeruginosa from the hospital's drainage water. The antibacterial potential of AgNPs against P. aeruginosa is determined using the agar diffusion method. Silver nanoparticles produced from Cinnamomum tamala (Tejpata) leaf extract were shown to be effective in inhibiting four strains of P. aeruginosa. According to the agar disc diffusion method, AgNPs had the largest inhibition zone of 17.67 ± 0.577 mm, while aqueous extract had 5.67 ± 0.5777 mm, indicating that AgNPs had antibacterial activity. This study on AgNPs might assist with managing multidrug resistant pathogenic bacteria and be a possible source of medicinal application due to its potential antibacterial effect.

Characterization of Asafoetida Resin Silver Nanoparticles and Efficacy of Antioxidant, Antimicrobial Inhibition

Background: In recent years, biological precursor-based synthesis, particularly plant-based green synthesis, has piqued interest in the field of nanotechnology. The plant-based approach is a promising technique for the biosynthesis of nanoparticles. 
 Aim of the study: Biosynthesis nanoparticles (AgNPs) using the ethanolic extract of a resin exuded from Ferula asafoetida (resin) and evaluate its anti actinobacterial, and antioxidant properties. 
 Method: Ferula asafoetida resin was collected and processed for ethanolic extraction by soxhlet apparatus. Preliminary phytoconstituents were quantified by GC MS and NMR. Consequently, the biosynthesis of silver nanoparticles was carried out with ethanolic extract. Characterization studies of synthesized Asafoetida AgNPs were done by UV Vis spec, XRD and SEM. Bioactivity of As-AgNPs was evaluated for anti-actinobacterial activity against selected Streptomyces toxytricini D2, Streptomyces tritici D5 and antioxidants properties were proved by Antioxidant assays. 
 Result: Ferula asafoetida resin ethanolic extract can be successfully used for the biosynthesis of Ag NPs. It showed excellent antioxidant activity, including DPPH and hydroxyl radical scavenging abilities comparable to standard ascorbic acid antioxidants. Characterized silver nanoparticles have moderate antimicrobial properties.
 Conclusion: Currently, the biosynthesis of silver nanoparticles has fostered the development of a new generation of nanoproducts as well as increased scientific promise in the nanomaterial field. Asafoetida based AgNPs as novel materials can be utilized by antioxidant, antimicrobial inhibition

EFFECIENCY OF SILVER NANOPARTICALES AS ANTIBACTERIAL AGAINST AEROMONAS HYDROPHILA ISOLATED FROM INFECTED COMMON CARP

The present investigation was carried out to investigate the antibacterial efficiency of silver nanoparticles (AgNPs) in vitro against Aeromonas hydrophila using disc diffusion assay and minimum inhibitory concentration. The pathogenic A. hydrophila was isolated from infected common carp, usually diagnosed by chemical methods, and Avitek 2 compact device were used to confirm the diagnosis. The effectiveness of the prepared AgNPs was tested by chemical and biological (green synthesis using lemon extract) methods and were diagnosed by Fourier-transform infrared spectroscopy (FTIR), UV-Visible spectroscopy, Transmission electron microscopy (TEM), scanning electron microscope (SEM), which was spherical shape of the nanosilver and the size ranged between 30-50 nm. Results of disc diffusion assay showed that the chemical synthesized of AgNPs in 18hr recorded the highest inhibition zone followed by the bio-synthesized AgNPs and Oxytetracycline respectively. After 24 hr the highest inhibition zone was registered in Oxytetracycline, however after 5 days bio-synthesized AgNPs showed the higher inhibition zone which was significantly different(P≤0.05) in comparison to other products. Based on these results, both bio and chemical synthesized of AgNPs were effectively act as antibacterial against A.hydrophila. However, green synthesis using lemon extract is considered better antibacterial with low MIC than chemical AgNPs because lemon extract is regarded eco-friendly and also the low cost product compared to chemical AgNPs synthesis.

One Pot Green Synthesis and Structural Characterisation of Bio-Silver Nanoparticles Using Prunus Persica L.

The Plant mediated green synthesis of nanoparticles has attracted more attention among the researchers due to their physicochemical and biological properties and their immense applications in environmental, biomedical, agriculture, textile, and energy storage. The biosynthesis of nanoparticles using plants provides more advantages such as easy operation, eco-friendly, utilization of non-hazardous chemicals, less temperature or energy usage, etc. when compared to physical and chemical synthesis methods. In the present study, we propose aqueous extracts from the endemic-medicinal fruit Prunus persica L. as an efficient bioproduct for the green synthesis of silver - nanoparticles (AgNPs). The biosynthesized AgNPs were characterized using UV-Visible spectroscopy, Fourier transforms Infrared spectroscopy (FTIR) High-Resolution Transmission electron microscopy (HR-TEM), Scanning electron microscopy, Atomic Force Microscopy (AFM), and X-ray diffractometer (XRD). HR-TEM gives the formation of monodispersed spherical shape with a mean diameter of 12.6 ± 3.8 nm. The SAED pattern of the nanoparticles showed that the particles were highly crystalline in nature. The purity of the synthesized AgNPs samples was studied by EDS and confirmed the presence of Ag elements corresponding to TEM images. The 2D and 3D structure images of the nanoparticle were studied and the average particle size calculation has been performed using NOVA-TX software in AFM. X-ray diffraction analysis showed that the particles were crystalline in nature with face - centered cubic structure. The antimicrobial efficacy was evaluated using the resazurin assay against both Escherichia coli and Bacillus subtilis bacteria. The antimicrobial assay of the silver nanoparticles showed higher activity against Bacillus subtilis than Escherichia coli. Results confirmed this protocol as rapid, simple, eco-friendly and alternative to conventional physical, and chemical methods.

ANTIOXIDANT ACTIVITY AND CAPACITY OF SILVER NANOPARTICLES BIOSYNTHESIS OF COMMON FRUITS AQUEOUS EXTRACTS OF THE SUNDARBAN FOREST

Fruits provide numerous health-promoting polyphenols and antioxidants. The Sundarbans mangrove forest of Bangladesh produces various fruits, and off them ten to twelve are known to be consumed or used as an ingredient in food preparations. These fruits were used in this study to evaluate the total polyphenols (TPH) contents following the method of Folin-Ciocalteu’s; and the antioxidant activity by measuring 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radicals scavenging, reducing power and total antioxidant capacity. Additionally, capacity of silver nanoparticles (AgNPs) biosynthesis of the fruits was determined spectrophotometrically. Sonneratia apetala fruit showed the highest TPH content (45.7 mg of gallic acid equivalent (GAE)/g powder). The fruit also showed the largest antioxidant activity attributed to the DPPH free radicals scavenging, reducing power, and total antioxidant capacity. Additionally, S. apetala fruit showed the highest capacity in the AgNPs biosynthesis (OD, 0.41; 10 mg powder/mL). Avicennia officinalis, Ceriops decandra, Heritiera fomes, and S. apetala fruits showed scavenging of 50% DPPH free radicals at 81, 34.7, 61.2, and 33.5 µg powder/mL, respectively. Contents of total polyphenols in these fruits displayed strong positive correlations with reducing power (r2 = 0.97), total antioxidant capacity (r2 = 0.85) and scavenging DPPH free radicals (r2 = 0.85) whereas that for the AgNPs biosynthesis capacity was small (r2 = 0.32). Thus, the aqueous extract of S. apetala fruit is the most potential in antioxidant activity and biosynthesis of AgNPs.

Biosynthesis of silver nanoparticles using the extract of Alpinia galanga rhizome and Rhus semialata fruit and their antibacterial activity

Biosynthesis of silver nanoparticles (AgNPs) has been reported in this study using the Ethanol extract of Alpinia galanga rhizome and Rhus semialata fruit found in Nagaland, India. The black solid phase obtained after the termination of the reaction was collected as the synthesized AgNPs which were then characterized through FT-IR, UV–vis spectroscopy, XRD, SEM, TEM, SAED and EDX studies. XRD studies revealed the nanocrystalline phase and cubic structure of the synthesized AgNPs. The particle size of the synthesized AgNPs ranged from 10.732 nm to 34.927 nm with an average diameter of 17.625 nm for Alpinia galanga extract and 10.264 nm to 16.441 nm with an average diameter of 7.289 nm for Rhus semialata extract. The phytochemical screening and FT-IR spectra revealed the presence of carbohydrate, flavonoid, phenol, protein, and tannin. The antibacterial activity of the synthesized AgNPs was also investigated in vitro showing a comparable activity against Bacillus subtilis, Escherichia coli, Klebsiella pneumonia, and Staphylococcus aureus. Maximum inhibition was shown by AgNPs of Rhus semialata extract against Bacillus subtilis with an inhibition zone of 15 mm. The antibacterial study showed promising results for their possible application in the pharmaceutical and medical industries.

Efficacy of Calotropis gigantea L. flower extract and biosynthesized silver nanoparticles against fungal pathogens

Following the emergence of resistant fungal pathogens, plants mediated biosynthesized silver nanoparticles (AgNPs) have been recognized as promising tools to combat fungal pathogens. This study evaluated the potency of Calotropis gigantea L. in producing AgNPs followed by testing their antifungal effects against fungal pathogens. AgNPs were successfully produced utilizing the aqueous extract of C. gigantea flower extract. The biosynthesized AgNPs were characterized by UV-Vis spectroscopy, SEM, EDX and XRD analyzes. The visible brown color validated the synthesis of AgNPs and the UV-Vis spectrum revealed a maximum absorption at 438 nm. The SEM and EDX analyzes revealed that the AgNPs were rod shaped ranging from 10 nm to 150 nm in size along with the presence of elemental Ag. The X-ray diffraction further indicated that the biosynthesized AgNPs were crystalline in nature. The C. gigantea flower extract and biosynthesized AgNPs effectively mitigate the fungal growth viz.: Aspergillus aculeatus, Aspergillus flavus, Aspergillus fumigatus, Aspergillus niger, Cryptococcus neoformans, Phialophora verrucosa and Sporothrix schenckii. The maximum inhibition in growth by biosynthesized AgNPs was observed against P. verrucosa (13 mm) whereas the flower extract of C. gigantea was most effective against P. verrucosa (14.5 mm) and S. schenckii (13.5 mm). These findings may suggest C. gigantea flower extract as a green solution for biosynthesizing AgNPs with tremendous potentiality towards controlling human and plant pathogenic fungus.

Single-step biogenic synthesis of silver nanoparticles using honeybee-collected pollen

In this work, we describe a simplified and bottom-up synthesis of silver nanoparticles (AgNPs) using pollen collected by Andean honeybees as a natural reducing and capping agent for the first time. The biosynthesized AgNPs were characterized by their optical properties, electrochemical properties, average size, morphology, and purity by various analytical techniques. The synthesized AgNPs were spherical, having 10–35 nm size, showed λmax at 440 nm, well dispersed, and remained stable for up to 1 month under laboratory conditions without any sedimentation. Moreover, we also investigated the usability of synthesized AgNPs as antioxidants against 1, 1-diphenyl-2-picrylhydrazyl (DPPH). Thus, this protocol may be adapted for the large-scale production of nanoparticles without the use of chemical solvents and supports the importance of local resources in green chemistry.