A review on plants extract mediated synthesis of silver nanoparticles for antimicrobial applications: A green expertise

Eco-Friendly Synthesis of Silver Nanoparticles Through Economical Methods and Assessment of Toxicity Through Oxidative Stress Analysis in the Labeo Rohita

The physicochemical and biological properties of metals change as the particles are reduced to nanoscale. This ability increases the application of nanoparticles in commercial and medical industry. Keeping in view this importance, Silver nanoparticles (Ag-NPs) were synthesized by reduction methods using formaldehyde as reducing agent in the chemical route and lemon extracts in the biological route. The scanning electron microscope (SEM) images of nanoparticles suggested that the particles were either agglomerated or spherical in shape with mean diameter of 16.59 nm in the chemical route and 42.93 nm in the biological route. The particles were between 5 and 80 nm with maximum frequency between 5 and 20 nm in the chemical route and between 5 and 100 nm with maximum frequency between 15 and 50 nm in the biological method. In the second phase of the study, the effect of Ag-NPs on the oxidative stress was studied. For this purpose, Labeo rohita (20 ± 2.5 g in weight and 12 ± 1.4 cm in length) were involved. Six treatments were applied in three replicates having five fishes in each replicate. The first treatment was used as control group, and the other five treatments were exposed to either 10 or 20 or 30 or 45 or 55 mg L^-1 of Ag-NPs for 28 days. The treatment of Ag-NPs caused oxidative stress in the liver and gill tissues, which induced alterations in the activities of antioxidant enzymes. The level of catalase (CAT) was decreased in response to Ag-NPs concentration in dose-dependent manner. Ag-NPs treatment stimulated the liver and gill tissues to significantly increase the level of superoxide dismutase (SOD), which might be due to synthesis of SOD and addition in the pre-existing SOD level. The level decreases again due to depletion of SOD level. There was a sharp decline in the activities of glutathione S-transferase (GST) in both gills and liver tissues even at lower concentration, and this decrease in the GST activity was significantly different at each treatment after 28 days of treatment except 20 mg L^-1. The malondialdehyde (MDA) levels of gills and liver tissues were increased with the increase in the concentration. The elevated levels of glutathione (GSH) showed that the liver started defensive mechanism against the oxyradicals. This study finds out the cheap eco-friendly and economical method of Ag-NP synthesis. It is further revealed that Ag-NPs caused oxidative stress in the aquatic animals if exposure occurs at high concentrations.

Antimicrobial, Antioxidant and Cytotoxic Activity of Silver Nanoparticles Synthesized by Leaf Extract of Erythrina suberosa (Roxb.)

In this experiment, biosynthesized silver nanoparticles (AgNPs) were synthesized using aqueous leaf extract of Erythrina suberosa (Roxb.). The biosynthesis of silver nanoparticle was continuously followed by UV-vis spectrophotometric analysis. The response of the phytoconstituents resides in E. suberusa during synthesis of stable AgNPs were analyzed by ATR- fourier-transform infrared spectroscopy. Further, the size, charge, and polydispersity nature of AgNPs were studied using dynamic light scattering spectroscopy. The morphology of the nanoparticles was determined by scanning electron microscopy. Current result shows core involvement of plant extracts containing glycosides, flavonoids, and phenolic compounds played a crucial role in the biosynthesis of AgNPs. The antimicrobial activities of silver nanoparticles were evaluated against different pathogenic bacterium and fungi. The antioxidant property was studied by radical scavenging (DPPH) assay and cytotoxic activity was evaluated against A-431 osteosarcoma cell line by MTT assay. The characteristics of the synthesized silver nanoparticles suggest their application as a potential antimicrobial and anticancer agent.

Cardamom fruits as a green resource for facile synthesis of gold and silver nanoparticles and their biological applications

Gold (FA-AuNps) and silver (FA-AgNps) nanoparticles were synthesized at room temperature by aqueous extract of dried fruits of Amomum villosum, also known as Fructus Amomi (cardamom), in order to confer antioxidant, catalytic, antimicrobial activities and treatment effect against breast cancer cells. Fruit extracts served as both reducing agents and stabilizers in lieu of chemical agents. Ultra-violet visible (UV-Vis) spectroscopy, field emission transmission electron microscopy (FE-TEM), energy-dispersive X-ray (EDX) spectroscopy, elemental mapping, X-ray powder diffraction (XRD), selected area electron diffraction (SAED), dynamic light scattering (DLS) and Fourier transform infrared (FTIR) spectroscopy were employed to characterize the biosynthesized nanoparticles. Both FA-AuNps and FA-AgNps exhibited free radical scavenging activity against 2,2-diphenyl-1-picrylhydrzyl (DPPH). Additionally, biosynthesized nanoparticles successfully reduced methylene blue, a well-known redox indicator. FA-AgNps showed zones of inhibition against pathogenic Staphylococcus aureus and Escherichia coli. Finally, the biological activities and cytotoxicity of nanoparticles were subsequently investigated in vitro. FA-AuNps demonstrated a potential cytotoxic agent against breast cancer cells as evaluated by MTT assay. The study highlights a rapid synthesis of FA-AuNps and FA-AgNps by dried Fructus Amomi aqueous extract and evaluates their potential biological applications on medical platforms.

KS. Antioxidant, antibacterial and cytotoxic potential of silver nanoparticles synthesized using terpenes rich extract of Lantana camara L. leaves

Several attempts have been made for green synthesis of silver nanoparticles (AgNPs) using different plant extracts. Present study revealed that, antioxidant, antibacterial and cytotoxic AgNPs were synthesized using terpenes-rich extract (TRE) of environmentally notorious Lantana camara L. leaves. AgNPs were characterized by advanced techniques like UV-Visible and Infra red spectroscopy; XRD, SEM techniques as terpenes coated sphere shaped NPs with average diameter 425 nm. Further, on evaluation, AgNPs were found to exhibit dose - dependent antioxidant potential, good to moderate antibacterial activity against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa; and toxicity on Brine shrimp (A. salinanauplii) with LD₅₀ value 514.50 µg/ml.

Biosynthesis of polyphenol-stabilised nanoparticles and assessment of anti-diabetic activity

Green synthesis of nanoparticles (NPs) is a major developing field. In this study, we utilised Whitania somnifera leaves as a green source to synthesise platinum (Pt) NPs. Synthesised Pt NPs resulted from controlled synthesis of 12nm spherical particles. The synthesised Pt NPs were subjected to anti-diabetic applications resulting in a significant decrease in plasma glucose levels after injecting the Pt NPs into streptozotocin-induced diabetic rats.

Colorimetric Detection Based on Localised Surface Plasmon Resonance Optical Characteristics for the Detection of Hydrogen Peroxide Using Acacia Gum-Stabilised Silver Nanoparticles

The use of nanoparticles in sensing is attracting the interest of many researchers. The aim of this work was to fabricate Acacia gum–stabilised silver nanoparticles (SNPs) using green chemistry to use them as a highly sensitive and cost-effective localised surface plasmon resonance (LSPR) colorimeter sensor for the determination of reactive oxygen species, such as hydrogen peroxide (H₂O₂). Silver nanoparticles were fabricated by the reduction of an inorganic precursor silver nitrate solution (AgNO₃) using white sugar as the reducing reagent and Acacia gum as the stabilising reagent and a sonication bath to form uniform silver nanoparticles. The fabricated nanoparticles were characterised by visual observation, ultraviolet-visible (UV-Vis) spectrophotometry, transmission electron microscopy (TEM) analysis, energy-dispersive X-ray spectroscopy (EDAX), thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FT-IR). The TEM micrographs of the synthesised nanoparticles showed the presence of spherical nanoparticles with sizes of approximately 10 nm. The EDAX spectrum result confirmed the presence of silver (58%), carbon (30%), and oxygen (12%). Plasmon colorimetric sensing of H₂O₂ solution was investigated by introducing H₂O₂ solution into Acacia gum–capped SNP dispersion, and the change in the LSPR band in the UV-Vis region of spectra was monitored. In this study, it was found that the yellow colour of Acacia gum–stabilised SNPs gradually changed to transparent, and moreover, a remarkable change in the LSPR absorbance strength was observed. The calibration curve was linear over 0.1–0.00001 M H₂O₂, with a correlation estimation (R²) of .953. This was due to the aggregation of SNPs following introduction of the H₂O₂ solution. Furthermore, the fabricated SNPs were successfully used to detect H₂O₂ solution in a liquid milk sample, thereby demonstrating the ability of the fabricated SNPs to detect H₂O₂ solution in liquid milk samples. This work showed that Acacia gum–stabilised SNPs may have the potential as a colour indicator in medical and environmental applications.

Toxicity evaluation of silver nanoparticles synthesized by chemical and green route in different experimental models

With the increased exposure of silver nanoparticles (AgNPs) to human beings, the risk and safety should be considered. In this study, nephro-toxicity of AgNPs prepared by chemical and green route (aqueous extract of Desmodium gangeticum root) in rat, proximal epithelial cell lines and renal mitochondria was evaluated. AgNPs (100 mg/kg) were administered orally to the wistar rats. After 15 d, we observed significant changes in the renal architecture of both AgNPs, supported by the urine and blood chemistry data. Further, exposure towards renal epithelial cells and renal mitochondria also confirm the toxic similarities between the AgNPs synthesized from two routes.

Biological activity of green-synthesized silver nanoparticles depends on the applied natural extracts: a comprehensive study

Due to obvious disadvantages of the classical chemical methods, green synthesis of metallic nanoparticles has attracted tremendous attention in recent years. Numerous environmentally benign synthesis methods have been developed yielding nanoparticles via low-cost, eco-friendly, and simple approaches. In this study, our aim was to determine the suitability of coffee and green tea extracts in green synthesis of silver nanoparticles as well as to compare the performance of the obtained materials in different biological systems. We successfully produced silver nanoparticles (C-AgNP and GT-AgNP) using coffee and green tea extracts; moreover, based on our comprehensive screening, we delineated major differences in the biological activity of C-AgNPs and GT-AgNPs. Our results indicate that although GT-AgNPs exhibited excellent antimicrobial activity against all the examined microbial pathogens, these particles were also highly toxic to mammalian cells, which limits their potential applications. On the contrary, C-AgNPs manifested substantial inhibitory action on the tested microbes but were nontoxic to human and mouse cells, indicating an outstanding capacity to discriminate between potential pathogens and mammalian cells. These results clearly show that the various green materials used for stabilization and for reduction of metal ions have a defining role in determining and fine-tuning the biological activity of the obtained nanoparticles.

A novel synthesis protocol for Co3O4 nanocatalysts and their catalytic applications

Green synthesis of Co₃O₄-NPs by a HPCM method using Azadirachta indica leaf extract is reported. HRTEM shows hollow sphere like NPs with polycrystalline nature and it is used in catalytic applications.

Synthesis and characterization of green tea (Camellia sinensis (L.) Kuntze) extract and its major components-based nanoflowers: a new strategy to enhance antimicrobial activity

In this study, for the first time, a novel organic–inorganic nanobio-antimicrobial agent called “nanoflowers” (Nfs) from Camellia sinensis (L.) Kuntze extracts and its main components were produced and the increase in the antimicrobial activity of Nfs was elucidated.

Biosynthesis of Ag/almond shell nanocomposite as a cost-effective and efficient catalyst for degradation of 4-nitrophenol and organic dyes

Silver nanoparticles have been immobilized on the surface of waste almond shell using Ruta graveolens sleeves extract as a reducing and stabilizing agent in the present work.

Synthesis of ZnO nanoparticles using leaf extract of Tectona grandis (L.) and their anti-bacterial, anti-arthritic, anti-oxidant and in vitro cytotoxicity activities

The novelty of this present work is the investigation of the anti-bacterial, anti-arthritic, anti-oxidant andin vitrocytotoxicity activities of green synthesized Zinc Oxide Nanoparticles (ZnO NPs) using leaf aqueous extract ofTectona grandis(L.).

Microwave-assisted biosynthesis of zinc nanoparticles and their cytotoxic and antioxidant activity

The present study was designed for microwave assisted synthesis of zinc nanoparticles (Zn NPs) using Lavandula vera leaf extract in the presence of ZnSO₄ (1mM). The biogenic Zn NPs were then characterized using scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray diffraction spectroscopy (XRD), UV-visible spectroscopy, and Fourier transform infrared spectroscopy (FTIR) techniques. Thereafter, the cytotoxic effect of ZnSO₄ and Zn NPs on different cell lines was investigated by MTT-based cytotoxicity assay and their antioxidant properties were assessed using DPPH scavenging activity and reducing power assay. The SEM micrograph showed that the Zn NPs had spherical shape with the size range of 30-80nm. For A549, MCF-7, HT-29, and Caco-2 cell lines treated with Zn NPs, the concentration necessary causing 50% cell death (IC₅₀) was found to be 22.3±1.1μgmL^-1, 86±3.7μgmL^-1, 10.9±0.5μgmL^-1, and 56.2±2.8μgmL^-1, respectively. In the case of ZnSO₄, the same results (IC₅₀) were observed at concentration of 81.6±1.3μgmL^-1 (A549), 121.0±2.4μgmL^-1 (MCF-7), 43.0±1.4μgmL^-1 (HT-29), and 85.7±2.3μgmL^-1 (Caco-2). The obtained results of antioxidant activity showed that the IC₅₀ values of butylated hydroxyanisole (BHA) and Zn NPs were 44μgmL^-1and 65.3μgmL^-1, respectively, while ZnSO₄ at concentration of 200μgmL^-1 exhibited only 10.9% DPPH radical scavenging effect. Moreover, the reducing power of Zn NPs and BHA were significantly higher than ZnSO₄ (p<0.05). To sum up, application of L. vera leaf extract combined with microwave heating energy led to simple and fast formation of Zn nanostructures exhibited higher antioxidant and cytotoxic activity compared to soluble Zn⁺² ions. However, identification of the related mechanisms merit further studies.

Biosynthesis of Silver Nanoparticles using Chlorella vulgaris and Evaluation of the Antibacterial Efficacy Against Staphylococcus aureus

BACKGROUND

It is well documented that Silver Nanoparticles (SNPs) are potent antimicrobial agents. However, little is known about antimicrobial effects of biologically synthesized SNPs at molecular level. In the present study, efficacy of the green microalgae Chlorella vulgaris in biosynthesis of silver nanoparticles and inhibitory effect of the biosynthesized SNPs on growth and virulence of Staphylococcus aureus (S. aureus) were investigated.

METHODS

Algal suspension was incubated in the presence of silver nitrate to induce formation of nanoparticles. The experiment was conducted under a pH range to evaluate pH effect on the shape and properties of nanoparticles. Characterization was performed by Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Energy Dispersive Spectrometry (EDS) and X-ray diffraction analysis (XRD). Moreover, concentration of biosynthesized SNPs was measured by high resolution ICP-OES spectrometer. Antibacterial effect of SNPs on growth of S. aureus was evaluated by broth micro-dilution method. Inhibitory effect of SNPs on alpha hemolysin, a well-known virulence factor of S. aureus was investigated through real time PCR assay.

RESULTS

Spherical SNPs were produced with characteristic monodispersity at low and neutral pHs; however, in alkaline condition, nanorod structures were formed. SNPs inhibited growth of S. aureus at concentration of 50 μg/ml. Alpha hemolysin expression was also effectively inhibited by SNPs treatment.

CONCLUSION

In general, results revealed formation of spherical silver nanoparticles with inhibitory effects on bacterial growth and antagonist activity on the expression of alpha hemolysin. Moreover, increase in pH to basic condition resulted in aggregation of nanoparticles and formation of rod-like nanostructures.

Phytogenic magnetic nanoparticles for wastewater treatment: a review

Presently, there is an emerging research trend in the fabrication of the noble Phytogenic Magnetic Nanoparticles (PMNPs) and their application in the water/wastewater treatment (WWT).

Bioformulation of silver nanoparticles as berberine carrier cum anticancer agent against breast cancer

The present work focuses on the bioformulation of AgNPs as a carrier for berberine and tests whether biogenic AgNPs elicit anticancer activity against breast cancer.

A review on biogenic synthesis of ZnO nanoparticles using plant extracts and microbes: A prospect towards green chemistry

Nanotechnology is emerging as an important area of research with its tremendous applications in all fields of science, engineering, medicine, pharmacy, etc. It involves the materials and their applications having one dimension in the range of 1-100nm. Generally, various techniques are used for syntheses of nanoparticles (NPs) viz. laser ablation, chemical reduction, milling, sputtering, etc. These conventional techniques e.g. chemical reduction method, in which various hazardous chemicals are used for the synthesis of NPs later become liable for innumerable health risks due to their toxicity and endangering serious concerns for environment, while other approaches are expensive, need high energy for the synthesis of NPs. However, biogenic synthesis method to produce NPs is eco-friendly and free of chemical contaminants for biological applications where purity is of concerns. In biological method, different biological entities such as extract, enzymes or proteins of a natural product are used to reduce and stabilised formation of NPs. The nature of these biological entities also influence the structure, shape, size and morphology of synthesized NPs. In this review, biogenic synthesis of zinc oxide (ZnO) NPs, procedures of syntheses, mechanism of formation and their various applications have been discussed. Various entities such as proteins, enzymes, phytochemicals, etc. available in the natural reductants are responsible for synthesis of ZnO NPs.

Green synthesis of silver nanoparticles via plant extracts: beginning a new era in cancer theranostics

With the development of the latest technologies, scientists are looking to design novel strategies for the treatment and diagnosis of cancer. Advances in medicinal plant research and nanotechnology have attracted many researchers to the green synthesis of metallic nanoparticles due to its several advantages over conventional synthesis (simple, fast, energy efficient, one pot processes, safer, economical and biocompatibility). Medicinally active plants have proven to be the best reservoirs of diverse phytochemicals for the synthesis of biogenic silver nanoparticles (AgNPs). In this review, we discuss mechanistic advances in the synthesis and optimization of AgNPs from plant extracts. Moreover, we have thoroughly discussed the recent developments and milestones achieved in the use of biogenic AgNPs as cancer theranostic agents and their proposed mechanism of action. Anticipating all of the challenges, we hope that biogenic AgNPs may become a potential cancer theranostic agent in the near future.

Antibacterial Potential of Jatropha curcas Synthesized Silver Nanoparticles against Food Borne Pathogens

The aqueous leaf extract of Jatropha curcas was used for the synthesis of silver nanoparticles (Jc-AgNps) which were further evaluated for its antibacterial potential against food borne pathogens. J. curcas leaf extract could synthesize stable silver nanoparticles (Zeta potential: -23.4 mV) with absorption band at 430 nm. Fourier transform infrared spectroscopy indicated various biological compounds responsible for capping and stabilizing Jc-AgNps in suspension, while the presence of silver was authenticated by scanning electron microscopy (SEM) equipped with energy-dispersive X-ray. Jc-AgNps were confirmed to be uniform in shape, size and behavior through dynamic light scattering, transmission electron microscopy (TEM), X-ray diffraction, SEM, and atomic force microscopy (AFM) analysis. To investigate the antibacterial activity, disk diffusion and microplate dilution assays were performed and zone of inhibition (ZOI) as well as minimum inhibitory/bactericidal concentrations (MIC/MBCs) were evaluated against selected bacterial strains. Overall results showed that Escherichia coli (ZOI: 23 mm, MBC: 0.010 mg/ml) was the most sensitive organism, whereas Staphylococcus aureus (ZOI: 14.66 mm, MBC: 0.041 mg/ml) and Salmonella enterica (ZOI: 16.66 mm, MBC: 0.041 mg/ml) were the least sensitive against Jc-AgNps. The detailed microscopic investigations using SEM, TEM, and AFM were performed to understand the antibacterial impacts of Jc-AgNps against Listeria monocytogenes. SEM and TEM analysis showed the clear deformation and disintegration of treated L. monocytogenes cells, whereas AFM established a decrease in the height and cell surface roughness (root mean square value) in the treated L. monocytogenes.

A review on green synthesis of silver nanoparticles and their applications

Development of reliable and eco-accommodating methods for the synthesis of nanoparticles is a vital step in the field of nanotechnology. Silver nanoparticles are important because of their exceptional chemical, physical, and biological properties, and hence applications. In the last decade, numerous efforts were made to develop green methods of synthesis to avoid the hazardous byproducts. This review describes the methods of green synthesis for Ag-NPs and their numerous applications. It also describes the comparison of efficient synthesis methods via green routes over physical and chemical methods, which provide strong evidence for the selection of suitable method for the synthesis of Ag-NPs.

Green synthesis of silver nanoparticles using extract of Parkia speciosa Hassk pods assisted by microwave irradiation

This paper reports an investigation of the microwave-assisted synthesis of silver nanoparticles (Ag NPs) using extract of stinky bean (Parkia speciosa Hassk) pods (BP). The formation of Ag NPs was identified by instrumental analysis consists of UV–vis spectrophotometry, Fourier-transform infrared (FTIR) spectrophotometry, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and particle size analysis. Furthermore, Ag NPs were used as antibacterial agents against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. The results indicate rapid formation of Ag NPs during microwave irradiation with similar properties to those obtained through the aging method. In general, the use of microwave irradiation yields larger particles, and it is affected by volume ratio of the extract to the AgNO₃ solution. The prepared materials demonstrated antibacterial activity.

Antimicrobial potential of green synthesized CeO2 nanoparticles from Olea europaea leaf extract

This article reports the green fabrication of cerium oxide nanoparticles (CeO2 NPs) using Olea europaea leaf extract and their applications as effective antimicrobial agents. O. europaea leaf extract functions as a chelating agent for reduction of cerium nitrate. The resulting CeO2 NPs exhibit pure single-face cubic structure, which is examined by X-ray diffraction, with a uniform spherical shape and a mean size 24 nm observed through scanning electron microscopy and transmission electron microscopy. Ultraviolet-visible spectroscopy confirms the characteristic absorption peak of CeO2 NPs at 315 nm. Fourier transform infrared spectroscopy reflects stretching frequencies at 459 cm-1, showing utilization of natural components for the production of NPs. Thermal gravimetric analysis predicts the successful capping of CeO2 NPs by bioactive molecules present in the plant extract. The antimicrobial studies show significant zone of inhibition against bacterial and fungal strains. The higher activities shown by the green synthesized NPs than the plant extract lead to the conclusion that they can be effectively used in biomedical application. Furthermore, reduction of cerium salt by plant extract will reduce environmental impact over chemical synthesis.

Biosynthesis of Silver Nanoparticles Using Taxus yunnanensis Callus and Their Antibacterial Activity and Cytotoxicity in Human Cancer Cells

Plant constituents could act as chelating/reducing or capping agents for synthesis of silver nanoparticles (AgNPs). The green synthesis of AgNPs has been considered as an environmental friendly and cost-effective alternative to other fabrication methods. The present work described the biosynthesis of AgNPs using callus extracts from Taxus yunnanensis and evaluated their antibacterial activities in vitro and potential cytotoxicity in cancer cells. Callus extracts were able to reduce silver nitrate at 1 mM in 10 min. Transmission electron microscope (TEM) indicated the synthesized AgNPs were spherical with the size range from 6.4 to 27.2 nm. X-ray diffraction (XRD) confirmed the AgNPs were in the form of nanocrystals. Fourier transform infrared spectroscopy (FTIR) suggested phytochemicals in callus extracts were possible reducing and capping agents. The AgNPs exhibited effective inhibitory activity against all tested human pathogen bacteria and the inhibition against Gram-positive bacteria was stronger than that of Gram-negative bacteria. Furthermore, they exhibited stronger cytotoxic activity against human hepatoma SMMC-7721 cells and induced noticeable apoptosis in SMMC-7721 cells, but showed lower cytotoxic against normal human liver cells (HL-7702). Our results suggested that biosynthesized AgNPs could be an alternative measure in the field of antibacterial and anticancer therapeutics.

Fungal Isolate Optimized for Biogenesis of Silver Nanoparticles with Enhanced Colloidal Stability

Understanding the synthesis and properties of nanomaterials is critical for reliable applications. Biological systems, such as fungi, have been described as a "green" alternative to synthesis, yet knowledge gaps exist in terms of production variability, comparison with commercial products, and identifying a clear biological advantage over other synthesis methods. In this study, we evaluated 12 fungal isolates of Fusarium oxysporum for Ag nanoparticle production and characterized the resultant biologically produced (biogenic) nanoparticles. We show evidence that isolate selection, temperature, and pH can influence the quantity, size, and shape of nanoparticles. All F. oxysporum isolates produced Ag nanoparticles, but in varied quantities. Increasing incubation temperature increased the quantity, yet nanoparticle diameter was inversely related to temperature. Variations in pH predominately influenced nanoparticle morphology. A direct comparison with commercial, chemically produced Ag nanoparticles yielded physical similarities; however, important differences in surface chemistry are observed. Biogenic nanoparticles show a greater degree of colloidal stability in high-ionic-strength solutions, pointing to a biological advantage associated with the fungal produced layer (corona) surrounding the nanoparticles. It is clear that understanding the organic layer and interfacial interactions will be beneficial in developing innovative applications, particularly in the field of biosensing.

A Study on Extracellular Synthesis of Silver Nanoparticles from Endophytic Fungi, Isolated from Ethanomedicinal Plants <i>Curcuma longa</i> and <i>Catharanthus roseus</i>

Biological method is considered as eco-friendly and reliable process for the synthesis of silver nanoparticles (AgNps) in the field of nanotechnology due to its tremendous applications in various fields. In this study we have isolated a total of twelve endophytic fungi from leaves of Curcuma longa (turmeric) and Catharanthusroseus out of which six endophytic fungi showed their ability to synthesized AgNps from silver nitrate (AgNO3) solution which splits into a positive silver ion (Ag+) and a negative nitrate ion (NO3-) in order to turn the silver ions into solid silver (Ago). Of the six positive endophytic fungi VRD2 showed good and encouraging results and was identified as Penicillium spinulosum VRD2. UV-Visible Spectroscopy confirms the AgNps showing maximum peak at 425nm implying the bioreduction of AgNO3. Transmission Electron Microscopy (TEM) revealed the particle are spherical and well dispersed without agglomeration size ranging from 25-30nm.

A Study on Extracellular Synthesis of Silver Nanoparticles from Endophytic Fungi, Isolated from Ethanomedicinal Plants <i>Curcuma longa</i> and <i>Catharanthus roseus</i>

Biological method is considered as eco-friendly and reliable process for the synthesis of silver nanoparticles (AgNps) in the field of nanotechnology due to its tremendous applications in various fields. In this study we have isolated a total of twelve endophytic fungi from leaves ofCurcumalonga(turmeric) andCatharanthusroseusout of which six endophytic fungi showed their ability to synthesized AgNps from silver nitrate (AgNO3)solution which splits into a positive silver ion (Ag+) and a negative nitrate ion (NO3-) in order to turn the silver ions into solid silver (Ago). Of the six positive endophytic fungi VRD2 showed good and encouraging results and was identified asPenicillium spinulosumVRD2. UV-Visible Spectroscopy confirms the AgNps showing maximum peak at 425nm implying the bioreduction of AgNO3. Transmission Electron Microscopy (TEM) revealed the particle are spherical and well dispersed without agglomeration size ranging from 25-30nm.

Photobiologic-mediated fabrication of silver nanoparticles with antibacterial activity

We present the simple, eco-friendly synthesis of silver nanoparticles (AgNPs) using sunlight or green, red, blue, or white LED light together with Dryopteris crassirhizoma rhizome extract (DCRE) as the reducing and capping agent. The preliminary indication of AgNP production was a color change from yellowish green to brown after light exposure in the presence of DCRE. Optimization of parameters such as pH, inoculum dose, and metal ion concentration played an important role in achieving nanoparticle production in 30min. The spectroscopic and morphological properties of AgNPs were characterized using UV-Vis spectroscopy through the presence of a characteristic surface plasmon resonance (SPR) band for AgNPs, Fourier transform infrared spectroscopy (FT-IR), high-resolution transmission electron microscopy (HR-TEM), and X-ray diffraction (XRD). The FT-IR results indicated that the phytochemical present in DCRE was the probable reducing/capping agent involved in the synthesis of AgNPs, and light radiation enhanced nanoparticle production. HR-TEM revealed that the AgNPs were almost spherical with an average size of 5-60nm under all light sources. XRD studies confirmed the face cubic center (fcc) unit cell structure of AgNPs. The synthesized AgNPs showed good antimicrobial activity against Bacillus cereus and Pseudomonas aeruginosa. This study will bring a new insight in ecofriendly production of metal nanoparticles.

Phyto-mediated biosynthesis of silver nanoparticles using the rind extract of watermelon (Citrullus lanatus) under photo-catalyzed condition and investigation of its antibacterial, anticandidal and antioxidant efficacy

The biological synthesis of nanoparticles has gained tremendous interest, and plants and plant extracts are preferred over other biological sources for this process because of their rich content of bioactive metabolites. In this study, silver nanoparticles (AgNPs) were produced utilizing the aqueous extract of watermelon rind (WRA), an agricultural waste material under photo exposed condition at room temperature, and tested for their antibacterial, anticandidal and antioxidant activities. The synthesized AgNPs showed surface plasmon resonance at 425nm with an average size of 109.97nm. The morphology and elemental composition was confirmed by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric and differential thermogravimetric analysis (TG/DTG) confirmed that the bioactive compounds from the WRA extract were involved in the synthesis and capping of AgNPs. X-ray diffraction (XRD) revealed the crystallite nature of the AgNPs. The AgNPs exhibited strong broad spectrum antibacterial activity against five different foodborne bacteria with zones of inhibition 9.12-14.54mm in diameter. When AgNPs were mixed with kanamycin and rifampicin the mixture exhibited strong antibacterial synergistic activity. The AgNPs also exerted strong synergistic anticandidal activity when they were combined with amphotericin b. The AgNPs had high antioxidant activity and reducing power. Overall, the results confirmed the bio-potentials of the synthesized AgNPs using WRA, which could have applications in the biomedical, cosmetic, pharmaceutical, food preservation and packaging industries.

Biosynthesis of gold nanoparticles: A green approach

Nanotechnology is an immensely developing field due to its extensive range of applications in different areas of technology and science. Different types of methods are employed for synthesis of nanoparticles due to their wide applications. The conventional chemical methods have certain limitations with them either in the form of chemical contaminations during their syntheses procedures or in later applications and use of higher energy. During the last decade research have been focussed on developing simple, clean, non-toxic, cost effective and eco-friendly protocols for synthesis of nanoparticles. In order to get this objective, biosynthesis methods have been developed in order to fill this gap. The biosynthesis of nanoparticles is simple, single step, eco-friendly and a green approach. The biochemical processes in biological agents reduce the dissolved metal ions into nano metals. The various biological agents like plant tissues, fungi, bacteria, etc. are used for biosynthesis for metal nanoparticles. In this review article, we summarised recent literature on biosynthesis of gold nanoparticles which have revolutionised technique of synthesis for their applications in different fields. Due to biocompatibility of gold nanoparticles, it has find its applications in biomedical applications. The protocol and mechanism of biosynthesis of gold nanoparticles along with various applications have also been discussed.