Photodynamic cytotoxic and antibacterial evaluation of Tecoma stans and Narcissus tazetta mediated silver nanoparticles

Nanobiotechnology is the intersection of nanotechnology and biology, where nano systems are applied to help study biological systems. There is a growing interest of researchers in the application of nanotechnology in improving the efficacy of photodynamic therapy. In this study, the antioxidant, photodynamic, anticancer, and antibacterial potential of plant extracts and silver nanoparticles (AgNPs) were investigated. In order to synthesize AgNPs, 10 g of dried powder of Tecoma stans and Narcissus tazetta was boiled in deionized water (100 ml) and mixed with aqueous solution of silver metals, resulting in the formation of AgNPs. The synthesized AgNPs were spherical having size in a range of 15–100 nm. The application of extract (50 µl) and AgNPs to rhabdomyosarcoma cell line showed a decreased cell viability (%). Photodynamic study revealed an improvement in photosensitizer efficacy on introducing AgNPs. Both plant extracts and AgNPs had significant effect against methicillin resistant Staphylococcus aureus (MRSA) as well as sensitive Staphylococcus aureus with minimum inhibitory concentration (MIC) values of AgNPs lower (32–256 µg/ml) than the plant extracts. According to the current findings, these AgNPs have an enhancing effect on the photodynamic cytotoxic potential of plant extracts. Because of biological efficacy, these AgNPs may play a crucial role in determining therapeutic potential of Tecoma stans and Narcissus tazetta.     

Ecofriendly synthesis of silver nanoparticles using Kei-apple (Dovyalis caffra) fruit and their efficacy against cancer cells and clinical pathogenic microorganisms

Green fabrication has become a safe approach for producing nanoparticles. Plant-based biogenic synthesis of silver nanoparticles (AgNPs) has emerged as a possible alternative to traditional chemical production. In this paper, we provide a low-cost, green synthesis of AgNPs utilizing using Kei-apple (Dovyalis caffra) fruit extract. Ultraviolet–visible (UV–Vis) spectroscopy, Fourier Transform Infrared (FTIR), Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD), Scanning-Electron Microscope (SEM), and Dynamic Light Scattering (DLS) analyses were used to characterize green produced AgNPs. The formation of AgNPs was shown to have a surface resonance peak of 415 nm in UV–visible spectra, and FTIR spectra verified the participation of biological molecules in Synthesis of AgNPs. The TEM revealed that the biosynthesized AgNPs were mostly spherical in form, with size range of 12–53 nm. XRD diffractogram was used to demonstrate the face cubic centre (fcc) character of AgNPs. Excellent anticancer activity of AgNPs was recorded where more than 80% of Prostate Cancer (PC-3) cell lines was inhibited by 100–150 µg/mL of AgNPs, while 38% only was recorded using AgNO₃ and 55.62% was recorded D. caffra fruit extract at 150 µg/mL. Destructions of PC-3 cell was observed as a result of exposed to AgNPs, followed by D. caffra fruit extract, while minor alterations were recorded as exposed to AgNO₃. The 2,2-Diphenyl-1-picrylhydrazyl (DPPH) scavenging using AgNPs was three fold using fruit extract at 100 µg/mL indicating good antioxidant activity. Excellent inhibitory activity of AgNPs was recorded against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Candida albicans and Aspergillus fumigatus with inhibition diameter zone 28.22 ± 0.25 mm, 23.21 ± 0.35 mm, 27.25 ± 0.03 mm, 28.40 ± 0.15 mm, 29.23 ± 0.44 mm, and 9.52 ± 0.5 mm, respectively compared with AgNO₃. D. caffra fruits considered a promising and safe source for fabrication of AgNPs with multi-biological functions.     

Antibacterial and antibiofilm activity of nanochelating based silver nanoparticles against several nosocomial pathogens

The emergence of multi‐drug resistant (MDR) bacteria and dynamic pattern of infectious diseases demand to develop alternative and more effective therapeutic strategies. Silver nanoparticles (AgNPs) are among the most widely commercialized engineered nanomaterials, because of their unique properties and increasing use for various applications in nanomedicine. This study for the first time aimed to evaluate the antibacterial and antibiofilm activities of newly synthesized nanochelating based AgNPs against several Gram‐positive and ‐negative nosocomial pathogens. Nanochelating technology was used to design and synthesize the AgNPs. The cytotoxicity was tested in human cell line using the MTT assay. AgNPs minimal inhibitory concentration (MIC) was determined by standard broth microdilution. Antibiofilm activity was assayed by a microtiter‐plate screening method. The two synthesized AgNPs including AgNPs (A) with the size of about 20‐25 nm, and AgNPs (B) with 30‐35 nm were tested against Staphylococcus aureus, Staphylococcus epidermidis, Acinetobacter baumannii, and Pseudomonas aeruginosa. AgNPs exhibited higher antibacterial activity against Gram‐positive strains. AgNPs were found to significantly inhibit the biofilm formation of tested strains in concentration 0.01 to 10 mg/mL. AgNPs (A) showed significant effective antibiofilm activity compared to AgNPs (B). In summary, our results showed the promising antibacterial and antibiofilm activity of our new nanochelating based synthesized AgNPs against several nosocomial pathogens.     

Novel bio compactable silver nanowires and nanocubes: An effective treatment against carbapenem and vancomycin resistant strains isolated from cancer patients

Blood stream infections in the cancer patients are a critical problem which leads to considerable rate of mortality and morbidity. In view of this herein, we account the response of Poly Vinyl Pyrrolidone (PVP) coated silver nanowires (Ag-NWs) and silver nano cubes (Ag-NCs) towards carbapenem (Escherichia coli) and vancomycin (Staphylococcus aureus) resistant strains as well as to human epithelial cells. The prepared PVP capped silver nanomaterials were in the range of 80 nm (Ag-NC) and 25 nm (Ag-NW) as observed from Transmission Electron Microscopy (TEM). Though the selected strains were resistant to carbapenem and vancomycin, PVP capped Ag-NWs and Ag-NCs could inhibit the growth of these strains. These nanomaterials could break the cell wall and damage the genetic material of these strains as observed by death rate assay and alkaline comet assay. Furthermore, we have shown that toxicity of Ag-NWs and Ag-NCs precisely follows the dose retort pattern. Even though the resistant strains were susceptible to a concentration of 10 µg ml^?1 of silver nanomaterials the epithelial cells were not affected by the same concentration. It is also confirmed with live dead staining assay and observed that metabolic activities of epithelial cells were not affected by a concentration of 10 µg ml^?1. Overall, this work suggests that these nanomaterials can be utilized to treat the multiple drug resistant strains from cancer patients.     

Application of micellar electrokinetic chromatography for detection of silver nanoparticles released from wound dressing

The recent emergence of nanotechnology has provided a new therapeutic modality in case of silver nanoparticles. Dressings containing silver form the basis for the treatment of burns and wounds, either acute or chronic ones. The aim of the study was to examine silver release from the different wound dressings: commercially available (Atrauman Ag, Aquacel Ag) and experimental (FKDP‐AgNPs) using MEKC. In order to characterize prepared keratin based wound dressing before and after its modification with AgNPs, a compositional analysis was conducted using energy dispersive X‐ray spectroscopy. Nanosilver toxicity was evaluated with the 3‐(4,5‐dimethylthiazol‐2‐yl)‐5‐(3‐carboxymethoxyphenyl)‐2‐(4 sulfophenyl)‐2H‐tetrazolium test. Silver release from wound dressings was assessed using MEKC. The best separation was observed for MEKC in 20 mM borate buffer at pH 9 with 20 mM SDS addition. In vitro studies showed silver at higher concentration than 10 ppm exerted a toxic effect on fibroblasts isolated from diabetic mice versus. NIH/3T3 and BJ cell lines (p < 0.05). We observed silver was released more gradually from experimental FKDP‐AgNPs wound dressing, in compare to commercially available wound dressings. The fast and low‐cost method utilizing MEKC can be used in clinical practice to detect silver release from the wound dressings.     

Synthesis of carrageenan coated silver nanoparticles by an easy green method and their characterization and antimicrobial activities

The aim of the present work was to synthesize carrageenan coated silver nanoparticles (CA–AgNPs) using carrageenan as reducing and stabilizing agent. For this purpose, 10 mL of 0.35% (w/v) carrageenan solution was mixed with 10 mL AgNO₃ solution at different concentrations (1, 5 and 10 mM), and the resulting mixture was stirred at 100 °C at high speed for 2 h. The formation of CA–AgNPs was proven with the surface plasmon peaks observed at approximately 420 nm. The sizes and zeta potentials of CA–AgNPs were determined by Zeta-Sizer. Negative zeta potentials of CA–AgNPs indicated that the obtained AgNPs were stable. With scanning electron microscope (SEM) and transmission electron microscope analysis, it was seen that CA–AgNPs have spherical structure. According to the energy dispersion spectrometer analysis based on SEM images, it was observed that the samples were elementally composed of carbon, oxygen, sulfur, potassium and silver. The chemical structures of CA–AgNPs were determined by Fourier transform infrared spectroscopy, and it was proved that the carbonyl and OH groups of carrageenan were involved in formation and stabilizing of AgNPs, respectively. According to thermal gravimetric analysis, it has been observed that CA–AgNPs were thermally more stable than pure carrageenan. Antibacterial activity of CA–AgNPs against gram-positive and gram-negative bacteria was investigated with agar well diffusion and liquid test. It has been observed that CA–AgNPs synthesized with 1 mM AgNO₃ did not have an antibacterial activity on Escherichia coli and Staphylococcus aureus. Inhibition zones of varying diameters were observed in the 5 mM and 10 mM S-AgNPs groups. The synthesized CA–AgNPs (5 and 10 mM) have the capacity to be used in wound dressing materials or topical agents applied to burns and wounds due to their antibacterial effects and stability.

     

Cytotoxicity,antifungal, antioxidant,antibacterial and photodegradation potential of silver nanoparticles mediated via Medicago sativa extract

The biosynthesis of metallic nanoparticles is on a sharp rise as they have growing applications in environmental and biomedical sciences. This study reports an eco-friendly and cost-effective methodology for synthesizing biogenic silver nanoparticles (AgNPs) using the extract of Medicago sativa (M. sativa) cultivated in South Khorasan. The parameters used in the synthesis process were optimized to obtain uniformly distributed AgNPs in suitable sizes. The morphological, structural, and bonding characteristics of M. sativa extract-based AgNPs (MSE-AgNPs) were explored using FTIR, FESEM, EDS, TEM, XRD, UV–Vis, and DLS techniques. UV–Vis spectroscopy confirmed the formation of MSE-AgNPs by observing the typical surface plasmon resonance (SPR) peak at 419 nm. XRD, FESEM, TEM, and DLS analyses confirmed the formation of face-centered cubic (fcc) crystalline structure, spherical/elliptical morphology, the average particle size of 15–35 nm, and highly stable MSE-AgNPs. Green synthesized MSE-AgNPs indicated a significant antioxidant activity (78%) compared to M. sativa extract (32%). As such, the synthesized MSE-AgNPs revealed a potential antioxidant activity towards the DPPH radicals. The biologically synthesized MSE-AgNPs exhibited highly potential antibacterial and antifungal activities against Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Staphylococcus epidermidis, Enterococcus faecalis, Staphylococcus aureus, and Candida albicans with the minimum inhibitory concentration (MIC) values of 62.5, 125, 125, 1000, 125, 1000, and 31.25 µg/mL, respectively. In vitro cytotoxicity of the MSE-AgNPs against human fibroblast (HF) cells indicated a dose–response activity (with IC50 value of 18 µg/mL). Moreover, the AgNPs revealed efficient photocatalytic degradation of thymol blue (TB) as an anionic dye and malachite green (MG) as a cationic dye under sunlight and UV irradiations. Up to 94.37% and 90.12% degradation rates were obtained for MG and TB within only 100 min of UV irradiation. These observations signify that synthesized MSE-AgNPs can have great potential for biological and environmental applications.     

Mussel-inspired anchoring for patterning cells using polydopamine

This Article introduces a simple method of cell patterning, inspired by the mussel anchoring protein. Polydopamine (PDA), artificial polymers made from self-polymerization of dopamine (a molecule that resembles mussel-adhesive proteins), has recently been studied for its ability to make modifications on surfaces in aqueous solutions. We explored the interfacial interaction between PDA and poly(ethylene glycol) (PEG) using microcontact printing (μCP). We patterned PDA on several substrates such as glass, polystyrene, and poly(dimethylsiloxane) and realized spatially defined anchoring of mammalian cells as well as bacteria. We applied our system in investigating the relationship between areas of mammalian nuclei and that of the cells. The combination of PDA and PEG enables us to make cell patterns on common laboratorial materials in a mild and convenient fashion.     

Mutagenicity of silver nanoparticles synthesized with curcumin (Cur-AgNPs)

IntroductionSilver nanoparticles (AgNPs) are of particular interest for their antibacterial properties and are produced by the action of reducing agents on silver ions. Curcumin from Curcuma longa (Zingiberaceae) has been used as a precursor for obtaining biogenic AgNPs, to act as a potential drug.ObjectivesThis study aimed to evaluate the toxicity of AgNPs synthesized with curcumin (Cur-AgNPs 0.081 mg/mL, ~130 nm) through the Salmonella/microsome (Ames test), one of the first required assays for evaluating toxicity.MethodsThe study design was experimental and in vitro. After defining the preliminary toxicity, the mutagenicity was assessed in a concentration range of 0.0010–0.0081 mg/plate Cur-AgNPs using histidine negative (His−) Salmonella Typhimurium strains TA97a, TA98, TA100, and TA102, with (+S9) and without metabolic activation (−S9), in triplicate. Assays were monitored by positive and negative controls. The results were statistically analyzed by Salanal software with p < 0.05 values considered significant.ResultsThe data obtained in the absence of metabolic activation showed that Cur-AgNPs is not mutagenic, but when exposed to the presence of S9, Cur-AgNPs became mutagenic to TA98 and TA100 strains, showing the significance of metabolizer enzymes to activate Cur-AgNPs on these bacteria, which recovered their abilities in synthesizing histidine (His+).ConclusionCur-AgNPs is mutagenic in the presence (+S9), but not in the absence (−S9) of metabolic activation, being able to act as indirect mutagens potentially to organisms that share the same genotype vulnerabilities found in TA98 and TA100 strains to cause a frameshift and base-pair substitution mutations, respectively.     

Measuring silver nanoparticle dissolution in complex biological and environmental matrices using UV-visible absorbance

Distinguishing the toxic effects of nanoparticles (NPs) themselves from the well-studied toxic effects of their ions is a critical but challenging measurement for nanotoxicity studies and regulation. This measurement is especially difficult for silver NPs (AgNPs) because in many relevant biological and environmental solutions, dissolved silver forms AgCl NPs or microparticles. Simulations predict that solid AgCl particles form at silver concentrations greater than 0.18 and 0.58 μg/mL in cell culture media and moderately hard reconstituted water (MHRW), respectively. The AgCl NPs are usually not easily separable from AgNPs. Therefore, common existing total silver techniques applied to measure AgNP dissolution, such as inductively coupled plasma mass spectrometry (ICP-MS) or atomic absorption, cannot accurately measure the amount of silver remaining in AgNP form, as they cannot distinguish Ag oxidation states. In this work, we introduce a simple localized surface plasmon resonance (LSPR) UV–visible absorbance measurement as a technique to measure the amount of silver remaining in AgNP form for AgNPs with constant agglomeration states. Unlike other existing methods, this absorbance method can be used to measure the amount of silver remaining in AgNP form even in biological and environmental solutions containing chloride because AgCl NPs do not have an associated LSPR absorbance. In addition, no separation step is required to measure the dissolution of the AgNPs. After using ICP-MS to show that the area under the absorbance curve is an accurate measure of silver in AgNP state for unagglomerating AgNPs in non-chloride-containing media, the absorbance is used to measure dissolution rates of AgNPs with different polymer coatings in biological and environmental solutions. We find that the dissolution rate decreases at high AgNP concentrations, 5 kDa polyethylene glycol thiol coatings increase the dissolution rate, and the rate is much higher in cell culture media than in MHRW.     

Glucosamine-functionalized silver glyconanoparticles: characterization and antibacterial activity

We report the analytical and in vitro antibacterial activity of glucosamine-functionalized silver glyconanoparticles. Morphological characterization ensured the surface topography and particle size distribution of both silver and glucosamine–silver nanoparticles. Surface plasmon resonance of both types of nanoparticle was determined from UV–visible spectroscopy using four different sample concentrations (10–40 μL). The resulting functionalized glyconanoparticles show maximum absorbance with a red shift of 30 ± 5 nm (390–400 nm) from their initial absorbance (425–430 nm). FT-Raman and ¹H-NMR spectroscopic measurement confirmed the surface functionalization of glucosamine on the silver surface through the carbonyl group of a secondary amide linkage (–NH–CO–), elucidated by the conjugation of N-hydroxysuccinimide (NHS)-terminated silver nanoparticles and the amino group of glucosamine. Antimicrobial experiments with well-characterized silver nanoparticles (AgNPs) and glucosamine-functionalized silver nanoparticles (GlcN-AgNPs) demonstrate that GlcN-AgNPs have similar and enhanced minimum inhibitory concentration (MIC) against eight gram-negative and eight gram-positive bacteria compared with AgNPs. MIC data shows that Klebsiella pneumoniae (ATCC 700603) and Bacillus cereus isolate express high levels of inhibition, with the quantity and magnitude of inhibition being higher in the presence of GlcN-AgNPs.     

Waste-grass-mediated green synthesis of silver nanoparticles and evaluation of their anticancer,antifungal and antibacterial activity

Grass waste was used for transform an inexpensive waste into health. Silver nanoparticles (AgNPs) have been synthesized using waste material (dried grass). The average size of silver nanoparticles observed in transmission electron images was estimated to be about 15?nm. The anticancer, antifungal and antibacterial effect of AgNPs were studied in vitro. The minimum inhibitory concentration of AgNPs against Pseudomonas aeruginosa and Acinetobacter baumannii was calculated about 3?µg/ml. The highest level of inhibitory effect of AgNPs against Fusarium solani was close to 90% at a concentration of 20?μg/ml of AgNPs. An inhibitory effect on the cancer cell growth is reach, by increasing the concentration of AgNPs to 5?µg/ml; the cancer cells’ survival decreases about 30%. Western results showed that the expression of Cyclin D1 protein of MCF-7 cell line decreased after treatment with the effective concentration of AgNPs.     

Biological synthesis of silver nanoparticles in Tribulus terrestris L. extract and evaluation of their photocatalyst,antibacterial, and cytotoxicity effects

In recent years, progress of biological synthesis of nanoparticles is inevitable due to its important applications. In this research, a new and simple method for the synthesis of AgNPs from plant extracts is presented. The extract from shoots of the plant Tribulus terrestris L. was mixed with AgNO₃ with the aim of biologically synthesizing AgNPs. The biomolecules existing in the extract were accountable for the fast reduction of silver ions (Ag⁺) to AgNPs. Characterization of biosynthesized AgNPs was performed by UV–Vis, TEM, DLS, and XRD. The AgNPs exhibit a strong peak at 434 nm, and sphere-shaped AgNPs were found to be ~?25 nm. The biosynthesized silver nanoparticles have demonstrated high antibacterial effect against pathogenic bacteria (i.e., Staphylococcus aureus, Escherichia coli, Bacillus subtilis and Pseudomonas aeruginosa). In addition, the in vitro cytotoxicity effect of biosynthesized silver nanoparticles was also investigated and was detected to be up to 15.62 μg/mL in the treated Neuro2A cells. The plant-mediated biosynthesis of AgNPs has comparatively rapid, eco-friendly, inexpensive and wide-ranging application in modern medicine and the food industry.

     

Synthesis of keratine,silver, and flavonols nanocomposites to inhibit oxidative stress in pancreatic beta-cell (INS-1) and reduce intracellular reactive oxygen species production

Flavonols (FLA) from Vaccinium macrocarpon (V. macrocarpon) were identified using high-performance liquid chromatography coupled with mass spectrometry detection. Nanoparticles were prepared using highly crosslinked keratin (KER) from human hair and silver and entrapped with flavonols [KER + FLA + AgNPs]. Nanocomposites were characterized using UV–Vis spectroscopy, transmission electron microscopy (TEM), X-ray diffraction, zeta potential, and dynamic light scattering, and release profiles. The interactions between the capping agent and the silver core have been investigated using FTIR spectroscopy·H₂O₂ is a source of Reactive Oxygen Species (ROS) and acts as an activator of oxidative stress affecting NS-1 cells, and the protective effect of the nanocomposites were evaluated against H₂O₂-induced pancreatic β-cell damage. LC-MS/MS and HPLC analyses revealed the presence of 12 flavonols in V. macrocarpon plant extract. The cell apoptosis and proliferation, were evaluated by Hoechst 33342 staining, flow cytometry and Cell Counting Kit-8 respectively. Preincubation of the NS-1 cells with 250 µg/mL of H₂O₂ induced oxidative stress conditions that show pancreatic β-cell dysfunction, including ROS, cell death, mitochondrial function, antioxidant enzymes, and lipid peroxidation. Nevertheless, pretreatment with FLA and [KER + FLA + AgNPs] prevented mitochondria disruption, maintained cellular ATP levels, inhibited LDH release, intracellular ROS production, decreased lipid peroxidation, increased expression of antioxidant enzymes (CAT, SOD, and GPx) and GSH levels. These results indicate that nanocomposites could protect rat INS-1 pancreatic β-cell from H₂O₂-induced oxidative damage, apoptosis and proliferation by reducing the production of intracellular reactive oxygen species.     

Controlling size and stabilization of silver nanoparticles for use in optimized chitosan-dialdehyde xylan wound dressings

The size of silver nanoparticles (AgNPs) is the key factor that governs their antibacterial activity. However, the size of AgNPs is difficult to control because agglomeration and uneven dispersion often occur during the processing of AgNP-based products, which has impeded their applications in different areas. In this work, an efficient strategy was developed to overcome this difficulty and to prepare an antibacterial hydrogel comprising AgNPs and chitosan (CS) with dialdehyde xylan (DAX) as the crosslinking agent. The size of AgNPs was controlled successfully to an extremely fine level (<?9 nm) by reducing AgNO₃ solution in a methanolic suspension of the metal organic framework (MOF) -UiO-66-NH₂, and forming an Ag@UiO-66-NH₂ core–shell structure which avoided the agglomeration of AgNPs. DAX played a dual role by forming a hydrogel structure with CS through crosslinking, but also by stabilizing the even dispersion of Ag@UiO-66-NH₂ in the hydrogel. Accordingly, the as-prepared hydrogels showed excellent antibacterial properties and low cytotoxicity. The survival ratio of NIH/3T3 cells cultured in the hydrogel extract was more than 90%, even when the concentration of the hydrogel extract was as high as 10 mg/mL. In addition, the hydrogel exhibited good abilities of water absorption (swelling ratio was up to 1100%) and self-healing (efficiency was up to 88% after 5 h). The hydrogels with size-well-controlled AgNPs prepared in this work are expected to find broad applications, especially in the area of antibacterial medical auxiliaries.

     

In vitro cytotoxicity against K562 tumor cell line,antibacterial, antioxidant,antifungal and catalytic activities of biosynthesized silver nanoparticles using Sophora pachycarpa extract

In the present study, we demonstrate the green synthesis of silver nanoparticles using Sophora pachycarpa extract (S. pachycarpa; SPE) as capping, reducing, and stabilizing agents. The biosynthesized silver nanoparticles (SPE-AgNPs) were tested for catalytic, antibacterial, antifungal, antioxidant, and anti-cancer activities. The affecting parameters (the concentration of silver nitrate, the temperature of the reaction, and time of reaction) on the synthesis process were optimized. The biosynthesized SPE-AgNPs were studied by X-Ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), dynamic light scattering (DLS), energy-dispersive X-ray spectroscopy (EDS) and Fourier-transform infrared spectroscopy (FT-IR). The FESEM and TEM results revealed spherical and oval-like morphology with sizes ranging from 30 to 40 nm. Photocatalytic performance experiments of SPE-AgNPs were determined by the rapid degradation of the eriochrome black T (EBT) and methylene blue (MB) under sunlight and UV irradiations. The results showed that SPE-AgNPs degraded more than 90% and 80% of both dyes under UV and sunlight irradiations, respectively. In addition, the SPE-AgNPs exhibited good antibacterial and antifungal properties against S. aureus, S. epidermidis, P. aeruginosa, E. coli, K. pneumoniae, E. faecalis, and C. albicans with MIC values of 6.25, 6.25, 0.78, 0.39, 0.78, 1.56 and 0.78 µg/ml. The green synthesized SPE-AgNPs were found to inhibit the activity of DPPH free radicals efficiently. Eventually, the SPE-AgNPs exhibited significant in vitro cytotoxicity against K562 tumor cell line (IC50 = 19.5 µg/ml). All these studies indicated that AgNPs synthesized using S. pachycarpa extract have applications in the environmental and biomedical fields.     

Assessment of antioxidant and cytotoxic potential of silver nanoparticles synthesized from root extract of Reynoutria japonica Houtt

Free radicals, mostly consist of reactive oxygen species, are generated in human body by several exogenous and endogenous systems. Overproduction of free radicals is known to cause several degenerative disorders including cancer. The aim of this study is to synthesize silver nanoparticles (AgNPs) using root extract of Reynoutria japonica and to investigate its antioxidant and cytotoxic potential. AgNPs were synthesized by green approach and subsequently characterized using UV–vis spectroscopy, SEM, TEM, FTIR, XRD, EDS and DLS. The antioxidant activity was investigated using DPPH, FRAP, H₂O₂, and ABT?⁺ radical scavenging assays while the cytotoxic effect was assessed using different human cancer cell lines including lung (A549), liver (Hep-G2) and breast (MDA-MB-231) by MTS assay. Moreover, the specificity of NPs was assessed against two normal human cell lines e.g. alveolar and renal primary epithelial cells (HPAEpiC and HRPTEpiC). The UV–vis spectra confirmed the synthesis of AgNPs by producing a characteristic peak at 410 nm. Further analysis confirmed that AgNPs were crystalline in nature, predominantly spherical in shape, with an average width and area of 17.34 nm and 164.46 nm², respectively. DLS analysis revealed that NPs possess a high negative zeta potential value (?28.5 mV), thus facilitating its electrostatic stabilization. AgNPs showed dose dependent antioxidant activity against DPPH, FRAP, H₂O₂ and ABTS with IC₅₀ values 19.25, 22.45, 24.20 and 18.88 µg/ml, respectively. The AgNPs depicted significant cytotoxic effects against A549, Hep-G2 and MDA-MB-231 cell lines with IC₅₀ values of 4.5, 5.1 and 3.46 µg/ml, respectively. Moreover, the NPs exhibited highest selectivity index (>2.0) for A549, Hep-G2 and MDA-MB-231, confirming its specificity towards cancer cell lines. In conclusion, AgNPs prepared from root extract of R. japonica possess strong antioxidant and cytotoxic potential which suggests that they should be investigated further in order to develop safe and effective antioxidant and/or cytotoxic formulations.     

Impact of polyvinylpyrrolidone and quantity of silver nitrate on silver nanoparticles sizing via solvothermal method for dye-sensitized solar cells

The multiple sizing of silver nanoparticles (AgNPs) were synthesized from the miscible compound of ethylene glycol (EG), polyvinylpyrrolidone (PVP) and silver nitrate (AgNO3) via the solvothermal method. During the synthesis, the PVP-AgNO3 was contemplated as a paramount parameter. Using the simple method of solvothermal, the sizing of AgNPs was easily controlled in accord with the augmentation of PVP-AgNO3 at secured and moderate temperature. In regards to the sizing of AgNPs, the presence of minimum agglomeration, the absorption capability and chemical structures were highlighted through a series of verification includes ultraviolet–visible (UV–Vis) spectroscopy, Fourier-transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM) analysis. The effectiveness of the synthesized AgNPs was further investigated and compared with the commercial AgNPs by incorporating the AgNPs into titanium dioxide (TiO2) semiconductor film-based dye-sensitized solar cells (DSSCs). Results signified that the spherical AgNPs with produced sizing within the range of 19.6 to 45.2 nm were greatly impacting by tunable quantities of PVP-AgNO3, which was validated in the forms of linear equations. A larger size promotes a slower nucleation rate that conduces agglomeration. In opposition to this, the smallest size of AgNPs develops a faster formation rate of Ag ions into AgNPs, inducing the deterrent of agglomeration in light of notable particle dispersion. The power conversion efficiency (PCE) contributed by the incorporation of synthesized AgNPs into TiO2 is also 41.2% higher than that of the commercial AgNPs-TiO2. This is because the synthesized AgNPs provides less agglomeration which led to a better surface plasmonic effect towards the nanoparticles.     

Sustainable green synthesis of silver nanoparticles using Sambucus ebulus phenolic extract (AgNPs@SEE): Optimization and assessment of photocatalytic degradation of methyl orange and their in vitro antibacterial and anticancer activity

The biogenic approach in the synthesis of nanoparticles provides an efficient alternative to the chemical synthesis system. Furthermore, the ecofriendly synthesis of metallic nanoparticles is developing rapidly due to its wide applications in sciences. In this research, metallic silver nanoparticles (AgNPs) were biosynthesized using Sambucus ebulus (S. ebulus; AgNPs@SEE) extract for the evaluation of efficient antibacterial, anticancer, and photocatalyst activities. The reaction parameters including temperatures, contact time, and AgNO₃ concentration were discussed and optimized. The optimized nanoparticles (AgNPs@SEE) showed cubic structure, spherical morphology with the average size of 35–50 nm. The photocatalytic performance of AgNPs was assessed by degradation of methyl orange at different concentrations of AgNPs@SEE (10 and 15 µl) under sun-light irradiation. About 95.89% of the pollutant was degraded (after 11 min), when 10 μl of nanocatalyst used. Also, the degradation of contaminant increased (about 95.47% after 7 min) by increasing the nanoparticle concentration to 20 μl. All in all, the results showed that the percentage of pollutant degradation increased with increasing the concentration of nanocatalyst. Furthermore, anticancer activity of AgNPs@SEE on human cancer cell lines (AGS and MCF-7), and antibacterial activity on both Gram-positive and Gram-negative microorganisms were studied. The synthesized AgNPs@SEE exhibited superior performance on cancer cell lines and effective antibacterial properties against Gram-positive microorganisms (like MIC value of 1.5 µg/ml for S. aureus) than Gram-negative microorganisms. All these investigations revealed that silver nanoparticles synthesized by natural extract have the potential to use as low-cost and efficient nanoparticles for environmental and biomedical applications.     

Nanocomposites based on cationic polyelectrolytes and silver nanoparticles: Synthesis,characterization, molybdate retention and antimicrobial activity

The objective of this work was to synthesize nanocomposites based on cationic polyelectrolytes and silver nanoparticles using poly(N-vinylbenzyl-N-triethylammonium chloride) as polymer phase. For that, a nanostructured crosslinker was synthesized from silver nanoparticles (AgNPs) and acrylic acid. Molybdate retention properties of nanocomposites were studied in function of pH and ionic strength. In addition, their antimicrobial properties were evaluated against E. coli and S. aureus. It was evidenced that AgNPs can be stabilized using acrylic acid and that this material can be incorporated to the polymer phase during polymerization by free radical of cationic monomers. The effect of pH on retention of molybdate, by the nanostructured polymer, was significant only to low ionic strength (the order seen was pH 5.0 > pH 7.0 > pH 9.0 for 0.0% NaCl). Results suggest that the main interaction influencing the molybdate retention is electrostatic in nature. Finally, antimicrobial activity was enhanced by incorporation of polymerizable nanostructured crosslinker based on AgNPs.