Stable Nanosilver Research Articles

Cytotoxic effects of endophyte origin nanosilver and its computational studies

The present study aimed in the investigation of anticancer potential of silver nanoparticles (AgNPs) from endophytic bacterium Cupriavidus metallidurans (Cm-AgNPs) and Pantoea anthophila (Pa-AgNPs) of W. indica reported in our earlier studies, against human oral epidermoid carcinoma (KB 3–1) and COLON 26 cell lines. The cytotoxicity response was assessed by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT). Measurement of intracellular reactive oxygen species (ROS), mitochondrial membrane potential (ɅΨm) and apoptotic morphological changes were studied in KB 3–1 cell line. Both the endophytes were found to produce periplasmic nitrate reductase (PNR) that converts the ionic silver into stable nano silver. Hence the structure and function of PNR was determined by computationl tools and evolutionary relationships were constructed using Clustal Omega. The inhibitive properties of AgNP against selected cancer targets were analyzed by molecular docking tool Autodock 4.0. KB 3–1 cell line showed good anticancer response than COLON 26 cell lines. On comparison of AgNPs, Cm-AgNPs exhibited higher cytotoxicity with increased intracellular ROS levels, altered ɅΨm and apoptotic cell death than Pa-AgNPs. The three-dimensional structure of the PNR was modeled by Swiss model and validated using PROCHECK and PROVES. Docking study showed that the AgNP bound exactly in the inhibition site or in their close proximity that may enable the modulation of proteins. Thus the study provides an insight on the anticancer activity of AgNPs fabricated from endophytic extract.

A stable nanosilver decorated phosphorene nanozyme with phosphorus-doped porous carbon microsphere for intelligent sensing of 8-hydroxy-2′-deoxyguanosine

Nanozyme based on the silver nanoparticles (AgNPs) decorated highly water-oxygen stable phosphorene (BP) nanohybrid with phosphorus-doped porous carbon microspheres (P-PCMs) is applied as an intelligent sensing platform for the electrochemical detection of 8-hydroxy-2′-deoxyguanosine (8-OHdG) as a biomarker of oxidative DNA damage in human urine sample. The density functional theory (DFT) is use for investigating the effect of silver on the conductivity level of BP and discussing a possible mechanism for the electrocatalytic oxidation of 8-OHdG. The Ag+ is in-situ reduced as AgNPs that grows onto the BP surface for the controllable preparation of BP-AgNPs with effective surface passivation among different metal ions decorated BP. P-PCMs with 4.9-fold enhancement in specific surface area (1636.73 m2 g−1) are prepared by hydrothermal carbonization of α-cyclodextrin as carbon sources, then calcinate in the presence of phosphoric acid as an activator and dopant. P-PCMs-BP-AgNPs are prepared by the ultrasound-assisted liquid-phase exfoliation with the addition of Ag+, and both P-PCMs and black phosphorus crystals are sufficiently grinded. The P-PCMs-BP-AgNPs nanohybrid displays good long-term water-oxygen stability, extraordinary specific surface area, superior electrocatalytic capacity with 303-fold enhancement, enzyme-like characteristics with Imax of 100 μA and Km of 29 μM. The machine learning (ML) model with artificial neural network (ANN) algorithm is employed for the intelligent output of 8-OHdG in real sample with acceptable recovery in work range from 0.2 to 125 μM.

A highly sensitive enzyme catalytic SERS quantitative analysis method for ethanol with Victoria blue B molecular probe in the stable nanosilver sol substrate

Using AgNO3 as precursor, a stable silver nanosol with strong SERS activity was prepared rapidly by light-wave procedure. A highly sensitive SERS quantitative analysis method for ethanol was developed, coupled the alcohol oxidase catalytic reaction with the Fe2+ catalytic reaction that the produced hydroxyl radicals not only oxidized the silver atoms on the nanosilver surface to form more dispersed and small size nanosilvers with weak SERS effect, but also oxidized the molecular probe Vitoria blue B (VBB) to fade. With the increasing of ethanol concentration, the more nanosilver and probe molecules were oxidized, resulting in SERS intensity decreasing at 1615 cm−1. The decreased SERS intensity was linear to ethanol in the range of 0.008–0.40 mg/L, with a detection limit of 3 μg/L. This method was applied to determination of ethanol in beer and serum samples, with satisfactory results.

Synthesis of stable nanosilver particles (AgNPs) by the proteins of seagrass Syringodium isoetifolium and its biomedicinal properties.

A simple eco-friendly approach for the hasty synthesis of stable, potent and benign silver nanoparticles (AgNPs) using seagrass, Syringodium isoetifolium was proposed and described here. The UV-Vis, DLS, XRD, AFM, FESEM, EDX and HRTEM analysis highly characterized and confirmed the presence of polydispersed (2-50nm) spherical and stable AgNPs. FT-IR and phytochemical analysis suggested that the proteins act as reducing and also as capping agent. A hypothetical approach using bioinformatics tools revealed that the Phytochrome B protein of S. isoetifolium might be responsible for the biosynthesis of NPs. Furthermore, biosynthesized AgNPs showed magnificent antibacterial activity against thirteen clinical bacterial pathogens with maximum zone of inhibition of 14.3±0.12mm due to their smaller size and longer stability even at minimal nanomolar (nM) concentration. In addition, the MIC and MBC values also suggested the same. Moreover, the percentage of haemolysis (8.49±3.10 to 73.34±1.79%) and haemolytic index revealed the satisfactory biocompatibility of AgNPs that showed less/no haemolysis up to 3nM concentration. Further, the toxicity effect of biosynthesized AgNPs against the brine shrimp, Artemia salina exhibited significantly increasing mortality (13±4.7 to 100%) with LC50 value at 4nM concentration. Thus, the optical property, crystal structure, size, shape, stability, bactericidal activity, cytotoxicity, and biocompatibility apparently proved that the biologically synthesized AgNPs have typical properties of nanomaterials.

Surface-Enhanced Raman Scattering Determination of Trace Phenanthroline Using Aggregated-Nanosilver as Substrate

Using PEG10000 and sodium citrate as stabilizer, sodium borohydride as reducing agent, a stable nanosilver sol had been prepared. In pH 6.0 Na2HPO4- NaH2PO4buffer solution and in the presence of NaCl, a stable nanosilver aggregates were formed. Phenanthroline (Phen) adsorbed on the aggregated-nanosilver surfaces resulting in a surface-enhanced Raman scattering (SERS) peak at 1450 cm-1observed, and the SERS intensity was enhanced with the concentration of Phen was between 1.25×10-10mol/L and 2.5×10-9mol/L. Based on these, a new sensitive SERS method has been proposed for the determination of trace Phen in the synthesis of samples, with satisfactory results.

Nanosilver/hyperbranched polyester (HBPE): synthesis, characterization, and antibacterial activity

HBPE of different generations were synthesized using 4-hydroxybenzoic acid and 2,2′,2″-nitrilotriethanol via the A2 + B3 method. The reaction was carried out in a dry nitrogen atmosphere using p-toluene sulfonic acid (p-TSA) as an acid catalyst. The chosen molar ratios of 2,2′,2″-nitrilotriethanol to 4-hydroxybenzoic acid were 1:3, 1:6, and 1:21 for the G1, G2, and G5 generations, respectively. The G5 stage of HBPE was further coupled with acrylic acid to modify the terminal hydroxyl groups. The resulting products were analyzed using 1H NMR, 13C NMR, FTIR spectroscopy, and GPC. Silver nanoparticles were prepared by a reductive technique using HBPEs of the G5 generation as the matrix. XRD and TEM analysis indicated the formation of highly spherical and stable nanosilver in the HBPE. The antibacterial activity of the nanosilver/HBPE was evaluated against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) bacteria.

A Nanosilver Resonance Rayleigh Scattering Method for the Determination of Trace Cysteine

Using PEG-10000 and sodium citrate as stabilizer, and NaBH4 as reducer, a stable nanosilver (AgNPs) sol was prepared. In pH 6.6 phosphate buffer solution containing NaCl, the AgNPs were aggregated to large particles, which lead to resonance Rayleigh scattering (RRS) peak at 350 nm enhancement. Upon addition of cysteine, the peak decreased. The decreased value ΔI is linear to cysteine concentration in the range of 5.0×10-8-6.0×10-7 mol/L. Thus, a new RRS method was proposed for detection of cysteine.

A Surface-Enhanced Resonance Raman Scattering Method for Trace Cystine Using 4-Mercaptopyridine-Aggregated-Nanosilver as Probe

A stable nanosilver solution was prepared, using PEG10000 as stabilizer and NaBH4 as reducer. In pH 6.6 Na2HPO4-NaH2PO4 buffer solution containing PEG10000 and NaCl, nanosilvers were aggregated to form the stable aggregated-nanosilvers (ANS) that could conjugate with 4-mercaptopyridine (MP) to produce an ANS-MP surface-enhanced resonance Raman scattering (SERRS) probe, which exhibited a strong SERS peak at 1097 cm-1. When cystine (Cy) concentration increased, the SERS intensity at 1097 cm-1 decreased linearly. In the optimal condition, the decreased SERRS intensity was linear to Cy concentration in the range of 5.0×10-9-1.4×10-7 mol/L, with a detection limit of 2.0×10-9 mol/L Cy.

A stable and reproducible nanosilver-aggregation-4-mercaptopyridine surface-enhanced Raman scattering probe for rapid determination of trace Hg2+

A stable nanosilver solution was prepared, using PEG10000 as stabilizer and NaBH4 as reducer. In pH 6.6 Na2HPO4–NaH2PO4 buffer solution containing PEG10000 and NaCl, the nanosilvers (AgNPs) were aggregated to form the stable nanosilver-aggregation (AgNPA) that could conjugate with 4-mercaptopyridine (MPy) to obtain an AgNPA-MPy surface-enhanced Raman scattering (SERS) probe with a strong SERS peak at 1097cm−1. When Hg2+ concentration increased, the SERS intensity at 1097cm−1 decreased linearly as the stable complex of [Hg(MPy)2]2+ was formed and the AgNPA particles precipitate to the bottom. The decreased SERS intensity was linear to Hg2+ concentration in the range of 50–3000nmol/L. Based on this, a new sensitive SERS method has been proposed for the determination of trace Hg2+ in the water sample, with satisfactory results.

Preparation of Nano-Silver Artemisia Argyi and Anti-Bacterial Finishing to Silk Fabric

The hydroxyl in polysaccharide and flavones that extracted from Artemisia argyi can absorb onto the surface of silver nanoparticles and prevent aggregation from nanoparticles. The stable nano-silver solution was got. The preparation of Nano-silver Artemisia Argyi by Artemisia Argyi extract in alkaline and acidic environment was investigated, and the antibacterial property of fabric finished by the nano-silver Artemisia Argyi was analyzed. The experimental results show that the silver nanoparticles prepared in alkaline environment has small size with the minimum 12nm and uniform dispersion. The fabric finished by Nano-silver Artemisia Argyi exhibited strong antibacterial activity against E.coli and S.aureus, the sterilized rate was over 99.9%. The fabric has excellent antibacterial washability too.

Synthesis and characterization of polyacrylonitrile–silver nanocomposites by γ-irradiation

The nanocomposites of stable nanosilver particles embedded in polyacrylonitrile matrix were synthesized by γ-irradiation, in which the monomer acrylonitrile was polymerized and the silver ions were reduced simultaneously by γ-irradiation to form composites in situ. The strong interactions between silver ions with –CN groups of polyacrylonitrile are found, which were confirmed by X-ray powder diffraction, IR spectrum and absorption spectra.