Eco-Friendly Synthesis of Silver Nanoparticles from Trans-Himalayan Herbs

The present study was aimed to synthesize nanoparticles using a facile environmentally benevolent green synthetic route. They were synthesized by reducing the silver ions present in the solution of silver nitrate (0.001M) with aqueous seed extract of Sorghum bicolor. The aqueous extract was subjected for preliminary phytochemical analysis according to standard methods. Characterization of silver nanoparticles was done by using UV, FTIR, SEM and TEM analysis. Further synthesized silver nano particles were screened for antibacterial activity at 50, 100, 150, 200^g/ml concentrations against two Gram positive bacteria (Staphylococcus aureus, Bacillus subtilis) and one Gram negative bacteria (Escherichia coli). The synthesized nanoparticles had shown highest antibacterial activity against Staphylococcus aureus and moderate anti-bacterial activity against Bacillus subtilis and Escherichia coli. Thus this study can be applied for rapid, cost effective and eco-friendly green synthesis of silver nanoparticles using seeds of Sorghum bicolor.

Photocatalytic activity of biogenic silver nanoparticles synthesized using Coleus Vettiveroids

Background: Green synthesized nanoparticles are perceived as an inexpensive, safe & ecologically beneficent approach to control pathogenic oral microbes compared to conventional methods. In the current study, silver nano particles (AgNPs) were effectively synthesised using clove and cardamom plant extracts. Methods: In the present study, aqueous silver nitrate was reacted with the clove, cardamom extracts and characterization was analyzed using UV-vis spectrophotometer and TEM analysis. Clove and cardamom reinforced silver nanoparticles were examined at 25 µL, 50 µL and 100 µL concentrations for their antibacterial activity against Staphylococcus aureus, Streptococcus mutans, Lactobacillus species and Candida albicans. Cytotoxicity was assessed using brine shrimp assays. Results: The formation of AgNPs was observed as shifting in color from orange-red color to dark brown at the end of the day three. Reducing silver ions to AgNPs, as shown by UV-vis spectroscopy, has produced an emission peak at 462 nm. TEM imaging showed that the particles were spherical and varied in size from 5-20 nm. Antimicrobial activity of the AgNPs at 100 µL was superior to that of antibiotics against Streptococcus mutans. Excellent antibacterial activity was shown by a zone of inhibition that was closer to that of antibiotics when examined against Lactobacillus. Staphylococcus aureus and Candida albicans were also moderately impacted. There was no evidence of cytotoxicity. Conclusion: Silver nanoparticles reinforced with clove and cardamom exhibited no cytotoxicity and showed promise as a potent antibacterial agent against oral pathogensKey words: silver nanoparticles.

The increasing resistance of bacteria to conventional antibiotics necessitates the exploration of alternative antimicrobial strategies. This study presents a green, eco-friendly synthesis of silver nanoparticles (AgNPs) using methanolic leaf extract of Eugenia roxburghii DC., a medicinal plant known for its rich phytochemical content. The synthesized AgNPs were characterized by UV–Visible spectroscopy, X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), and zeta potential analysis. A distinct surface plasmon resonance peak at 417 nm confirmed nanoparticle formation, while XRD and HR-TEM analyses revealed a crystalline, predominantly spherical morphology with an average particle size of 24–35 nm. The AgNPs exhibited strong antibacterial activity, particularly against Staphylococcus aureus, as demonstrated by disc diffusion and minimum inhibitory concentration (MIC) assays. Furthermore, the nanoparticles significantly inhibited biofilm formation, as observed on Congo Red Agar plates. These findings underscore the potential of E. roxburghii-mediated AgNPs as a sustainable and biocompatible alternative for combating pathogenic bacteria and biofilm-related infections. Future in vivo and toxicological studies are warranted to evaluate clinical applicability.

Objective(s): Nanoparticles are at the leading edge of the rapidly developing field of nanotechnology. Silver nanoparticles (Ag-NPs) have received considerable attention due to their attractive physical, chemical, antimicrobial, anti-inflammatory and wound healing properties. This paper reports simple, cost effective and eco-friendly method for the preparation of Ag-NPs from leaf extracts of Clerodendrum viscosum using silver nitrate solution as the metal precursor. Methods: The synthesis of nanoparticles was done by using the aqueous solution of Clerodendrum viscosum leaf extract and AgNO3. The formation of nanoparticles was confirmed by the change of colour to dark brown due to the phenomenon of surface plasmon resonance. The synthesized nanoparticles were characterized by UV-Vis spectrophotometer, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), Dynamic Light Scattering (DLS) and Fourier Transform Infra-red Spectroscopy (FTIR) techniques. In addition, the antibacterial activity was tested by agar disc diffusion method against some bacteria.Results: The formation of silver nanoparticles was confirmed by the presence of an absorption peak at 422 nm. The images of the electron microscope showed that the nanoparticles were spherical and had an average size about 56 nm at 25oC and 53 nm at 60oC. The X-ray diffraction was clearly proven that the nanoparticles were crystalline nature. The results of microbial test also indicated that the synthesized nanoparticles had significant antibacterial activity.Conclusions: This experiment showed that leaf extracts of Clerodendrum viscosum can be used for eco-friendly synthesis of nanoparticles, which also have potential antibacterial effect.

Eco-friendly synthesis of silver nanoparticles from peel and juice C. limon and their antiviral efficacy against HSV-1 and SARS-CoV-2

The present study reports an eco-friendlier, cost efficient, rapid and easy method for synthesis of silver nanoparticles using Carica papaya plant leaf extract which act as reducing and capping agent. In this study different factor which affects the silver reduction were investigated. The optimum conditions obtained were for synthesis process were silver nitrate (1mM), plant extract (10ml), pH (4) and incubation time (72 h). Plant extract reduces silver ions into silver nanoparticles within 5 min after heating the reaction mixture (30-80°C) as indicated by the developed reddish brown colour. The UV-vis spectrum of silver nanoparticles revealed a characteristic surface plasmon resonance (SPR) peak at 400-450 nm. Fourier transform infrared spectroscopy affirmed the role of plant extract as a reducing and capping agent of silver ions. Scanning electron microscope and field emission scanning electron microscope showed roughly spherical shaped nanoparticles. The average size of nanoparticles was found to be 80 nm as determined by dynamic light scattering. Energy dispersive X-ray spectroscopy analysis showed the peak in silver region confirming presence of elemental silver. Silver nanoparticles showed effective antibacterial activity against representative pathogens of bacteria. The minimum inhibitory concentration and minimum bactericidal concentration were determined.

Nanotechnology is a rapidly advancing field that involves the manipulation of materials at the nanoscale. In recent years, "green" synthesis methods have gained popularity for nanoparticle production due to their eco-friendly and sustainable nature. This study presents a green synthesis approach for the production of silver nanoparticles (AgNPs) using the leaf extract of Rivea ornata choisy, widely used as a medicinal plant. The objective of this study was to explore the antimicrobial potential of AgNPs synthesized from the leaves of Rivea ornate choisy. The formation of AgNPs was indicated by a noticeable color change in the silver nitrate solution upon addition of the plant extract. This change was further confirmed through UV-Visible spectroscopy, showing characteristic surface plasmon resonance (SPR) peaks in the range of 425–475 nm. The nanoparticles were then separated via centrifugation and subjected to further characterization. X-ray diffraction (XRD) analysis revealed distinct diffraction peaks corresponding to the (111), (200), (220), (222), and (311) planes, confirming the crystalline nature of the synthesized AgNPs. (24 nm) The antimicrobial activity of the biosynthesized AgNPs was evaluated by using the standard disc diffusion method. Antibacterial activity was tested against two Gram-positive bacteria (Bacillus sp. and Staphylococcus sp.) and three Gram-negative bacteria (Escherichia coli, Pseudomonas sp., and Proteus sp.). Antifungal activity was assessed against Rhizopus sp., Aspergillus sp., Mucor sp., Fusarium sp., and Penicillium sp. Statistical analysis revealed that the synthesized silver nanoparticles exhibited significantly higher degree of antifungal and antibacterial activity against all tested fungi and bacteria. The biosynthesized silver nanoparticles using Rivea ornata choisy leaf extract proved excellent antimicrobial activity. These findings highlighted the potential of Rivea ornata-mediated AgNPs as effective antimicrobial agents, paving the way for future applications in biomedicine and sustainable nanotechnology.

In the present communication potential of Aegle Marmelos extract is demonstrated as reducing and stabilizing agent for the eco-friendly synthesis of silver nanoparticles (SNPs) and gold nanoparticles (GNPs). The characteristic surface plasmon resonance peak for SNPs was observed at 425 nm, and that of GNPs was observed at 552 nm. TEM micrographs indicated spherical morphology of synthesized nanoparticles for both the cases with some deviations in GNPs. Spherical shape SNPs lie in between 10 and 30 nm and GNPs are in the range of 15-40 nm. Surface enhanced Raman scattering (SERS) activity of synthesized NPs was investigated using Rhodamine 6 G (R6G). When compared to standard R6G Raman spectrum, significant Raman enhancement was observed in R6G- nanoparticles conjugate. When applied for the SERS detection of DNA, well resolved Raman peaks were observed in SERS spectrum of DNA with the synthesized nanoparticles which favors the application of biosynthesized nanoparticles as SERS substrate.

Tuber extract of Arisaema flavum eco-benignly and effectively synthesize silver nanoparticles: Photocatalytic and antibacterial response against multidrug resistant engineered E. coli QH4

The present study aimed to estimate the antiviral activities of Ginkgo biloba (GB) leaves extract and eco-friendly free silver nanoparticles (Ag NPs) against the MERS-CoV (Middle East respiratory syndrome-coronavirus) and HCoV-229E (human coronavirus 229E), as well as isolation and identification of phytochemicals from GB. Different solvents and high-performance liquid chromatography (HPLC) were used to extract and identify flavonoids and phenolic compounds from GB leaves. The green, silver nanoparticle synthesis was synthesized from GB leaves aqueous extract and investigated for their possible effects as anti-coronaviruses MERS-CoV and HCoV-229E using MTT assay protocol. To verify the synthesis of Ag NPs, several techniques were employed, including X-ray diffraction (XRD), scan, transmission electron microscopy, FT-IR, and UV-visible spectroscopy. The highest contents of flavonoids and phenolic compounds were recorded for acetone, methanol, and ethanol as mixtures with water, in addition to pure water. HPLC flavonoids were detected as apegenin, luteolin, myricetin, and catechin, while HPLC phenolic compounds were pyrogallol, caffeic acid, gallic acid, and ellagic acid. In addition, our results revealed that Ag NPs were produced through the shift from yellow to dark brown. TEM examination of Ag NPs revealed spherical nanoparticles with mean sizes ranging from 5.46 to 19.40 nm and an average particle diameter of 11.81 nm. A UV-visible spectrophotometric investigation revealed an absorption peak at λ max of 441.56 nm. MTT protocol signified the use of GB leaves extract as an anti-coronavirus to be best from Ag NPs because GB extract had moderate anti-MERS-CoV with SI = 8.94, while had promising anti-HCov-229E, with an SI of 21.71. On the other hand, Ag NPs had a mild anti-MERS-CoV with SI = 4.23, and a moderate anti-HCoV-229E, with an SI of 7.51.

The Ginger (Zingiber Officinale) extract contain a lot of constituents and elements. Ginger extract can effort as a good bio-reductant to produce silver nanoparticles (AgNPs). The AgNPs Green synthesis was achieved by using the Ginger plant extract with AgNO3. The green synthesis of AgNPs is the best developing procedure for preparation, since this process is easier than other procedures, eco-friendly and fewer times consuming. The produced AgNPs were characterizing via UV-Vis, FTIR, AFM, SEM, Zeta potential and EDX. The optimal conditions for the synthesis AgNPs which was confirmed through UV–Vis spectrophotometer. Also, the AgNPs has been characterized by AFM with average size of 53.45 nm, SEM with average size of 21.91 to 33.79 nm. Antioxidant and free radical scavenge activity are examined through TLC and DPPH test, the results shows that the Ginger have a high activity, moreover, this activity increased with characterized AgNPs.

In this study, silver nanoparticles (Ag-NPs) were prepared using an aqueous extract of Ziziphus Spina-Christi Seeds (ZSCS) powder as an eco-friendly material, reducing agent and capping ligand. The synthesized Ag-NP was characterized using UV-visible absorption spectroscopy (UV-Vis), Fourier transform infrared (FTIR), transmission electron microscopy (TEM) and dynamic light scattering (DLS). From The UV-Vis spectra, the surface plasmon resonance (SPR) absorption band at 443 nm confirmed the formation of Ag-NPs. The TEM results demonstrated that the synthesized Ag-NPs have mostly spherical shapes with a particle size of 21.54 nm. In addition, the particle size and the specific surface area (SSA) of Ag-NPs decreased with increasing ZSCS powder extract volume and AgNO3 concentration. The basic medium was found to be better than the acidic medium to prepare Ag-NPs. At a pH value equal to 9.5, within 30 minutes, the color of the solution was changed from colorless to brownish-orange. SPR absorption band of Ag-NPs demonstrated that the synthesized Ag-NPs have high stability over a period of 8 months. From FTIR results, the stretching of C-O group at 1223 and 1031 cm-1 disappeared after bioreduction of AgNO3, these results may be due to that Ag reduction was carried out by some hydroxyl groups that get oxidized at the expense of Ag+ because Ag+ is reduced to Ag-NPs.

Green synthesis methods for producing silver nanoparticles (AgNPs) have garnered significant attention for their potential in medical applications. Despite the known potential of Lantana camara in AgNP synthesis, there is a lack of studies investigating its application when grown in extreme geothermal environments, which may influence the properties and efficacy of the synthesized nanoparticles. This research aimed to fabricate AgNPs utilizing aqueous extract from L. camara, a plant growing in an extreme geothermal manifestation area. Another aim of this study is to evaluate their antimicrobial activity. Qualitative and quantitative phytochemical analyses of the plant's leaves were also conducted. Reaction optimization was performed using response surface methodology (RSM), employing a central composite design (CCD) approach. The characterization of AgNPs involved UV–vis spectroscopy, FTIR, SEM-EDX, and PSA. The antimicrobial testing was conducted against Gram-positive bacterium (S. aureus), Gram-negative bacterium (E. coli), and the fungus (C. albicans). The phytochemicals analysis revealed that the L. camara leaf extract contains flavonoids, phenolics, saponins, tannins, and steroids, lacking alkaloids and terpenoids, with total phenolic and flavonoid contents of 11.94 mg (GAE/g) and 6.70 mg (QE/g), respectively. The AgNPs exhibited a spherical shape with a surface plasmon resonance (SPR) peak at a wavelength of 417 nm, and the smallest particle size measured was 44 nm. Based on FTIR analysis, AgNPs have functional groups such as OH, NH, CC, and CH that were identified as groups involved in the reduction of Ag+ to Ag0 during the green synthesis of AgNPs. The AgNPs demonstrated the lowest antifungal activity against C. albicans. In summary, the aqueous leaf extract of L. camara from geothermal manifestation areas can serve as a bioreductant for AgNPs, exhibiting higher antibacterial activity against Gram-positive bacteria compared to Gram-negative ones.

The extensive application of silver compounds especially in nanomedicine, has increased the need to develop environmental friendly and cost effective route to synthesizing silver nanoparticles (AgNPs). Water, diethyl ether, and ethanol were used in the extraction of Waltheria americana root. Silver nanoparticles (AgNPs) were synthesized by reacting 0.001 M AgNO3 solution with the different crude extracts of W. americana root in the ratio of 10:1. The synthesized AgNPs were analyzed using UV–visible spectrophotometer, X–ray diffraction (XRD), scanning electron microscope (SEM), and FTIR techniques. The different crude extracts and their synthesized colloidal AgNPs were tested against Proteus species, Streptococcus species, Klebsiella species, Staphylococcus aureus, and ciprofloxacin (control). UV–vis results showed surface plasmon resonance (SPR) at 415, 435, and 425 nm for synthesized colloidal AgNPs from water, diethyl ether, and ethanol extracts, respectively. When screened against all test organisms, the synthesized colloidal AgNPs from diethyl ether extract of W. americana root (WARDEEP) showed more improved antimicrobial efficacy than other crude extracts and their synthesized AgNPs. The strongest antimicrobial activity of WARDEEP against all test organisms were at 400, 100, and 200 mg/mL concentrations for Proteus species and Staphylococcus aureus, Klebsiella species, and Streptococcus species, respectively. From minimum inhibitory concentration (MIC) results, it was observed that WARDEEP exhibited a strong antibiotic activity against Proteus and Streptococcus species at a least value of 12.5 mg/mL concentration. Minimum bactericidal concentration (MBC) results showed that WARDEEP exhibited a minimum antibiotic activity at 25 mg/mL concentration against Proteus and Streptococcus species. Therefore, silver nanoparticles were sucessfully synthesized from all the crude extracts. The synthesized silver nanoparticles could comparatively provide better alternative treatment to both gram–positive and gram–negative bacteria than the crude plant extracts.