Search

Multifunctional chitosan/magnetite (CS/Fe 3 O 4) and graphene/chitosan/magnetite (Gr/CS/Fe 3 O 4) nanocomposites (NCs) were synthesized using a simple hydrothermal method. The NCs were subsequently evaluated as magnetic photocatalysts towards the photodegradation of dye molecules that are detrimental to the environment. In the present study, sphere shaped Fe 3 O 4 nanoparticles (NPs) were found to uniformly decorate CS and Gr surfaces. The synthesized Fe 3 O 4 NPs, CS/Fe 3 O 4 and Gr/CS/Fe 3 O 4 NCs were characterized by powder X-ray diffraction, Fourier-transform infrared and Raman spectroscopy, thermogravimetric analysis, UV–visible diffuse reflectance and photoluminescence spectroscopy, and field emission scanning electron microscopy coupled with energy dispersive X-ray spectroscopy. The Gr/CS/Fe 3 O 4 NCs showed 100% photocatalytic efficiency against rhodamine B (40 min), bromothymol blue (60 min), methylene blue (80 min) and methyl orange (100 min) compared to Fe 3 O 4 NPs (100 min for Rh-B, 120 min for BTB, 160 min for MB and 180 min for MO) and CS/Fe 3 O 4 NCs (90 min for Rh-B, 100 min for BTB, 140 min for MB and 150 min for MO). The photocatalytic irradiation efficiency of Fe 3 O 4 NPs, CS/Fe 3 O 4 and Gr/CS/Fe 3 O 4 NCs, evaluated against visible light, was found to be significantly higher for Rh-B (100% within 40 min) compared to the other tested dyes. • Fe3O4 NPs, CS/Fe3O4 and Gr/CS/Fe3O4 NCs were synthesized via a hydrothermal method. • The obtained NPs and NCs were characterized by XRD, FTIR, FE-SEM and EDX. • The photodegradation efficiency rate of NCs follows the order Rh-B > BTB > MB > MO. • Gr/CS/Fe3O4 NCs possess higher degradation ability than Fe3O4 NPs and CS/Fe3O4 NCs. [ABSTRACT FROM AUTHOR]

Multi-walled carbon nanotubes (MWCNTs), widely used in several industrial fields, are not readily degradable thus, persist in environmental matrices, serving as a source of environmental toxicity to organisms. However, the effects of environmental weathering on nanomaterial toxicity remain unclear. Herein, we prepared aged-MWCNTs (a-CNTs) by incubating commercial pristine-MWCNTs (p-CNTs) for two years and compared their changes in physicochemical properties and toxic effects on zebrafish. The characterization of a-CNTs by transmission electron microscopy, X-ray photoelectron spectra, Raman spectroscopy, and Fourier-transform infrared spectroscopy showed an increased surface area, pore size, structural defects, and surface oxidation than those of p-CNTs. Zebrafish were exposed to 100 mg/L p-CNT and a-CNT for four days. Subsequently, the mRNA expression of antioxidant enzymes, including cat, gst , and sod , in a-CNT group increased by 1.5- to 1.7-fold, consistent with increased expression of genes associated with inflammation (interleukin-8) and apoptosis (p53) compared to control. The higher toxicity of a-CNTs to zebrafish than p-CNT might be due to the increased oxidative potential by altered physicochemical properties. These findings provide new insights into the risk assessment and environmental management of MWCNTs in the aquatic environment. However, further testing at environmentally relevant doses, different exposure durations, and diverse weathering parameters is warranted. [Display omitted] • MWCNTs were incubated in water for two years to mimic environmental aging. • Aging in water altered the surface physicochemical properties of MWCNTs. • Pristine- and aged-MWCNTs induced a ROS production in zebrafish. • Aged-MWCNTs differed from pristine-MWCNTs in the expression patterns of ROS-related genes. [ABSTRACT FROM AUTHOR]

Abstract The aim of the current study is to identify bioactive compound from marine endophytic actinomycetes (MEA) isolated from Gulf of Mannar region, Southeast coast of India. Among the isolated actinomycetes, strain GRG 4 exhibited excellent ability to inhibit isolated colistin resistant (CR) Pseudomonas aeruginosa (P. aeruginosa) and Klebsiella pneumoniae (K. pneumoniae), which is a emerging threat to the world. The strain was identified as Streptomyces coeruleorubidus GRG 4 (KY457708), based on morphological, biochemical, phenotypic and genotypic characters. The bioactive metabolites present in the methanolic extract were partially purified by TLC and preparative HPLC. The active HPLC fraction 2 showed 15, 20 mm zone of inhibition against both CR P. aeruginosa and K. pneumoniae respectively. Analytical HPLC and FT-IR results of fraction 2 showed with carbonyl group. Both GC-MS and LC-MS results confirmed that the fraction 2 contained chemical constituents of Bis (2-Ethylhexyl) Phthalate (BEP). The compromised structure with loosely integrated and ruptured cell wall of BEP treated CR bacteria were observed by confocal laser scanning microscope (CLSM) and scanning electron microscope (SEM) at 75 μg/mL of minimum inhibitory concentration (MIC) dose. Further, cytotoxic effect of BEP against A549 human lung cancer cells revealed complete inhibition by cell proliferation and apoptosis was observed at 100 μg/mL in 24 h treatment. In addition, irreversible ROS dependent oxidative damage was clearly observed at the IC 50 concentration of BEP. The toxicity of BEP was also studied against Vibrio fischeri (V. fischeri) and found to be highly toxic after 15 and 30 min of treatment. Based on the results it could be concluded that the identified compound BEP is a potent inhibitor for CR bacteria and A549 lung cancer cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • SnO 2 NPs and CS/SnO 2 NCs were synthesized by a chemical precipitation method. • TEM revealed that the nanosized SnO 2 NPs were homogeneously distributed within the CS matrix. • CS/SnO 2 NCs demonstrated enhanced photodegradation efficiency against CR and Rh-B. Tin oxide (SnO 2) nanoparticles (NPs) as well as SnO 2 /chitosan(CS) nanocomposites (NCs) were successfully synthesized by a simple chemical precipitation technique and their photocatalytic degradation ability against congo red (CR) and Rhodamine-B (Rh-B) were subsequently evaluated. The crystallinity and surface morphology of the materials were evaluated using X-ray diffraction analysis and transmission electron microscopy (TEM), respectively. The TEM images revealed that nanosized SnO 2 NPs were successfully obtained and were homogeneously distributed within the CS matrix. The CS/SnO 2 NCs were exposed to Rh-B dye molecules, resulting in 95% degradation within 60 min, which was significantly higher than for SnO 2 NPs. On the other hand, CS/SnO 2 NCs were found to degrade 98% of CR dye molecules within 40 min of visible light irradiation, which was also significantly shorter than for SnO 2 NPs. The CR dye molecules experienced significantly better levels of photodegradation parameters than Rh-B. The present study demonstrates the potential of CS/SnO 2 NCs in the area of environmental remediation of organic dye-based water pollutants. [ABSTRACT FROM AUTHOR]

Hexagonal ZnO nanodisks (hZnO Nds) were synthesized via chemical precipitation and characterized by powder X-ray diffraction (XRD), photoluminescence (PL) spectroscopy, Fourier transform infrared spectroscopy (FTIR), UV-diffuse reflectance spectroscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). Results of SEM, EDX and XRD showed that synthesized hZnO Nds has a length of ∼300 nm, porous with pore size of ∼50 nm along with areas that possessed relatively smooth surface, highly pure and crystalline nature. The catalytic reduction performance of hZnO Nds against p-nitrophenol was quantified by UV–visible spectrophotometry in aqueous medium in the presence of sodium borohydride (NaBH 4). The complete hZnO Nds based catalytic reduction of p-nitrophenol (100%) occurred within 45 min. The hZnO Nds based catalytic reduction of p-nitrophenol exhibited a significant response, suggesting low reduction limit and good selectivity. [Display omitted] • Hexagonal ZnO nanodisks (hZnO Nds) were synthesized by chemical precipitation method. • The structure and morphology of hZnO Nds were confirmed by XRD and SEM imaging. • HZnO Nds possessed nanopores onto their surface as revealed by SEM imaging. • HZnO Nds were excellent catalysts of p-nitrophenol to p-aminophenol within 45 min. [ABSTRACT FROM AUTHOR]

[Display omitted] • NiO NRs and Grn/NiO NCs were synthesized by a chemical reduction approach. • The obtained NiO NRs decorated the surface of graphene sheets. • Grn/NiO NCs showed 100% degradation against MB and MO. • Large specific surface area of the Grn could aid in the adsorption efficiency of dye molecules. Simplified synthesis of nickel oxide nanorods (NiO NRs) and graphene/NiO nanocomposites (Grn/NiO NCs) was achieved using a chemical reduction approach of Grn and nickel chloride precursors. The crystalline nature of the prepared NiO NRs and Grn/NiO NCs was investigated using X-ray diffraction analysis, and the surface morphology was examined using transmission electron microscope. We examined the phtocatalytic efficiency of Grn/NiO NCs against anionic and cationic dye molecules. The Grn/NiO NCs showed 100% photocatalytic activity for methylene blue (MB) and methyl orange (MO) dye molecules within 90 and 120 min, respectively. The presence of Grn sheets has enhance the photocatalytic activity of NCs under visible light irradiation by reducing the recombination of excited electrons in the conduction band (CB) with holes in the valence band (VB) when Grn/NiO NCs reacted with dyes. We have developed efficient visible light functionalized Grn/NiO NCs photocatalysts for practical environmental applications using simple and cost-effective approach for large-scale manufacturing. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fe 3 O 4 and Cts/Fe 3 O 4 Nsps were synthesized by a one-pot hydrothermal method. • Cts decorated heterogeneously the surface of Fe 3 O 4 nanospheres. • Cts/Fe 3 O 4 Nsps showed excellent photocatalytic activity against CR (98% in 60 min). Fe 3 O 4 nanospheres (Nsps) and chitosan (Cts)/Fe 3 O 4 Nsps were prepared using a one-pot hydrothermal method and subsequently used as photocatalysts against the degradation of Congo red (CR) dye molecules. The sphere-shaped Fe 3 O 4 nanoparticles were heterogeneously decorated by the Cts matrix, which was confirmed by powder X-ray diffraction, scanning and transmission electron microscopies. The Cts/Fe 3 O 4 Nsps demonstrated 98% efficient photocatalytic activity against CR dye molecules upon 60 min exposure to visible light compared to Fe 3 O 4 Nsps (77% for 60 min). When compared to Fe 3 O 4 Nsps, the visible light photocatalytic efficiency of Cts/Fe 3 O 4 Nsps against CR dye molecules was significantly improved. [ABSTRACT FROM AUTHOR]

Abstract Copper oxide nanoparticles (CuO NPs) were synthesized biologically using leaf extract of Camilla japonica. The typical UV–visible spectral peak of CuO NPs was observed at a wavelength of ∼290 nm, which confirmed their successful synthesis. From scanning electron microscope (SEM) and transmission electron microscope (TEM) analyses, the synthesized CuO NPs were found to possess spherical shape. Energy dispersive X-ray analyzer (EDX) results revealed that the CuO NPs are almost pure with atomic percentages of 50.92 for Cu and 49.08 for O. Fourier transform infrared (FTIR) confirmed the presence of an absorption peak located at a wavenumber position of ∼480 cm−1 typical for highly pure CuO NPs. TEM images displayed that the particles are relatively uniform in size ∼15–25 nm. The P. aeruginosa and K. pneumonia showed complete resistance against Hexa 077 antibiotic discs. The result of ≤22 ceftazidime and ≤27 cefotaxime confirmed that both the uropathogens were ESBL producers. The ≥8 mm of the MIC stripe further confirmed that both the uropathogens were ESBL producers. Furthermore, the antibacterial activity of CuO NPs against selected ESBL producing P. aeruginosa and K. pneumoniae at minimum inhibition concentration (MIC) of 100 μg/mL. The decreased cell viability and damaged membrane construction of both the uropathogens were observed by confocal laser scanning microscope (CLSM) using AO/EB stains at desired MIC dose. The morphological damage of the bacterial cells was demonstrated by SEM analysis. Hence, based on the above in vitro findings, the results suggested that the CuO NPs are efficient antibacterial compounds against ESBL producing bacteria, and that the plant leaf mediated CuO NPs can be considered as novel and promising material to act against various infectious bacteria. Graphical abstract Image 1 Highlights • CuO NPs was synthesized using biological route of Camilla japonica plant leaf extract. • Screening of ciprofloxacin resistance gram negative bacteria by Hexa Disc method. • Confirmation of ESBLs producing bacteria using MIC strip methods. • Antibacterial effect of CuO NPs against P. aeroginosa and K. pneumoniae. • Cell viability, cell membrane disruption and morphological damage of ESBLs producers by CLSM and SEM. [ABSTRACT FROM AUTHOR]

Abstract This study was about the simple method for the rapid colorimetric and visual detection of glucose molecules in water medium. Silver nanoparticles were spread on the chitosan surface (CS/Ag NCs) and it was characterized by UV–visible spectroscopy, fourier transform infrared spectroscopy (FTIR), X-ray diffraction spectroscopy (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The CS/Ag NCs displayed a strong surface plasmon resonance band at 429 nm which disappears in the addition of accelerative concentrations of glucose molecules and it was attended by color alteration from yellow to colorless. The interaction of glucose molecules on the CS/Ag NCs was displayed through TEM technique. Glucose molecules was detected not only by naked eyes (from yellow to purple grey) but also by UV–vis spectrophotometer in the concentration range between 0 and 100 μM, with limit detection of 5 μM and a good linear relationship of R2 value = 0.99. The proposed paper was used for the application of the detection of glucose molecules in water sample with adequate outcome. This CS/Ag NCs was very simple and low cost system without using any other enzymatic catalyst and organic chromogenic agents for glucose molecules detection. Highlights • Synthesis of CS/Ag NCs using simple method of heating at 90 °C for 6 h • Synthesized CS/Ag NCs were characterized using FTIR, XRD, SEM and TEM. • Addition of glucose molecules on the surface of CS/Ag NCs was imaged using TEM analysis. • To develop a colorimetric detection of glucose molecules between 5 and 100 μM concentration using CS/Ag NCs [ABSTRACT FROM AUTHOR]

The accelerative outgrowth of extended spectrum β-lactamases (ESBLs) producing Escherichia coli ( E. coli ) and Proteus mirabilis ( P. mirabilis ) was mainly due to incessant relentless influence of antibiotics thereby increasing incidence and death rate which was obvious from the survey of ESBLs producing bacteria related health problem. In the present paper, we synthesized and characterized zinc oxide nanoparticles (ZnO NPs) employing using Camellia japonica leaf extract, bactericidal action of these NPs against extended spectrum β lactamases (ESBLs) positive E. coli and P. mirabilis clinical strains owing the minimal inhibitory concentration (MIC) percentage 83, 81% at 100 μg/mL concentration and minimum bactericidal concentration (MBC) final inhibiting concentration at 150 μg/mL. Moreover, confocal laser scanning microscopy (CLSM) and scanning electron microscope (SEM) results evident for loss of viability, cell shrinkage, disarrangement of cell membrane, and cell wall lysis activity of ZnO NPs against ESBLs positive E. coli BDUMS3 (KY617770) and P. mirabilis BDUMS1 (KY617768) strains. From the results, it was observed that the biologically synthesized ZnO NPs has stronger antibacterial effect against ESBLs producing bacterial strains. Nevertheless, current date there is no reports of antibacterial activity of metal oxide (ZnO) NPs against ESBL producing gram negative bacteria. Consequently, this finding is the first report in this respect and it shows band gap energy and ROS accumulation to damage the cell wall and inhibit the growth of ESBL producing gram negative strains. [ABSTRACT FROM AUTHOR]

Activity of zinc oxide nanosheets (ZnO NS) synthesized using actinomycetes of Nocardiopsis sp. GRG1 (KT235640) was analyzed for anti-biofilm activity against multidrug resistant (MDR) strains of Proteus mirabilis BDUMS1 ( KY617768 ) and Escherichia coli BDUMS3 ( KY617770 ) uropathogens. Characterization of synthesized ZnO NSs was done using scanning electron microscopy (SEM), UV–vis absorption spectrum, fourier transform infrared (FTIR), X-ray diffraction (XRD) pattern, raman spectrum, and energy-dispersive X-ray spectroscopy (EDS). Biofilm formation was evaluated by tissue culture plate method (TCP) and congo red agar assay (CRA). It was observed that the synthesized ZnO NSs showed significant antibacterial activity against the selected MDR strains. Further, these synthesized ZnO NSs holds the capability to deliver antibiofilm activity against MDR strains such as P. mirabilis BDUMS1 ( KY617768 ) and E. coli BDUMS3 ( KY617770 ). [ABSTRACT FROM AUTHOR]

• Developed a high-frequency regeneration protocol via Polyethylene glycol (PEG)–induced somatic embryogenesis. • 3-day old cotyledonary explants used for the development of early-stage- somatic embryos. • Incorporation of ABA and proline was effective in the maturation of somatic embryos. • Regenerated plants are phenotypically identical to the mother plants. • Genetic fidelity analysis of in vitro regenerated Vigna radiata plants was reported newly. The results show that the in vitro regenerated plants are true-to-type with no somaclonal variation. • This protocol could be useful for genetic transformation studies as well as large-scale production strategies of true-to-type plants without any somoclonal variation. An efficient plantlet regeneration protocol of green gram [ Vigna radiata (L.) Wilczek] via somatic embryogenesis (SE) using Polyethylene glycol (PEG) is reported in this study. Embryogenic calli were induced using 3-day-old cotyledonary explants on MS medium supplemented with picloram (5 µM). Early-stage somatic embryos were generated by treating these 3-day-old cotyledonary explants or calli derived from those explants with osmolytes such as, sorbitol, mannitol and PEG, among which PEG was found to be the ideal. Early-stage embryoids were subsequently developed into torpedo and cotyledonary stage embryoids in liquid cultures supplemented with abscisic acid (5 μM), proline (130 μM). Furthermore, plantlet conversion was achieved in MS medium with 6-Benzylaminopurine (BAP) 1 μM + gibberellic acid (GA 3) 12 μM with a ca. 35% regeneration frequency. Plantlets were established under field conditions after the confirmation of their survival. The survival rate of plantlets post-transplantation was ca. 99%. The field-grown plants were confirmed to be phenotypically identical to the mother plant. According to RAPD profiles, in vitro regenerated plants were monomorphic and similar to the control/mother plants. The regeneration protocol developed in this study could be efficiently utilized for genetic transformation studies and large-scale production strategies of true-to-type plants without any somaclonal variation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fe 3 O 4 NPs as well as Cs/Fe 3 O 4 and Gr/CS/Fe 3 O 4 NCs were synthesized by a simple hydrothermal method. • The obtained Fe 3 O 4 NPs uniformly decorated the surface of CS and graphene sheets. • Gr/CS/Fe 3 O 4 NCs possess significantly higher antimicrobial activity than Fe 3 O 4 NPs and CS/Fe 3 O 4 NCs. • MIC values of Gr/CS/Fe 3 O 4 NCs were found to be 60 and 70 μg/mL against P. aeruginosa and K. pneumoniae, respectively. In the present study, chitosan-containing nanocomposites were investigated as new antibacterial agents. Magnetite (Fe 3 O 4) nanoparticles (NPs) as well as chitosan (CS)/Fe 3 O 4 nanocomposites (NCs) and graphene(Gr)/CS/Fe 3 O 4 NCs were synthesized by simple hydrothermal method. Their composition, structure and morphology were studied, followed by the evaluation of their antibacterial activity against ESBL-producing and gram-negative P. aeruginosa and K. pneumoniae bacterial strains. The Gr/CS/Fe 3 O 4 NCs showed significantly higher antibacterial activity compared to Fe 3 O 4 NPs and CS/Fe 3 O 4 NCs (105 and 69 % higher against P. aeruginosa as well as 91 and 77 % higher against K. pneumoniae , respectively). The minimum inhibitory concentration (MIC) of Gr/CS/Fe 3 O 4 NCs against P. aeruginosa and K. pneumoniae were 60 and 70 μg/mL, respectively. The synergistic antibacterial activity and facile synthesis of Gr/CS/Fe 3 O 4 NCs suggests their applicability as novel highly efficient antibacterial agents with potential for a wide range of biomedical applications, where antibacterial properties are needed. [ABSTRACT FROM AUTHOR]

• ZnO NPs and G-ZnO NCs synthesized using simple chemical precipitation method. • The obtained G-ZnO NCs were uniformly dispersed on the surface of graphene sheets. • G-ZnO NCs have higher degradation ability than ZnO NPs for Rh-B, MB, and MO. Highly pure zinc oxide nanoparticles (ZnO NPs) and graphene-zinc oxide nanocomposites (G-ZnO NCs) were synthesized via chemical precipitation method. The structure, morphology, and composition of the synthesized ZnO NPs and G-ZnO NCs were characterized by using fourier transfer infrared spectroscopy, X-ray diffraction spectroscopy, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy (TEM). The TEM images revealed that the diameter of ZnO NPs is 8–12 nm and homogeneously dispersed onto the surface of graphene sheets. The photocatalytic degradation efficiency of the synthesized G-ZnO NCs against rhodamine-B (Rh-B), methylene blue (MB) and methyl orange (MO) was quantified under visible light irradiation. The irradiation time required for complete removal of the dyes are dependent on dye molecules (MB, MO and Rh-B) and their interaction with the prepared ZnO NPs and G-ZnO NCs. The synthesized NCs were highly efficient for the removal of Rh-B compared to other tested dyes. Hence, the synthesized G-ZnO NCs could be used for environmental dye remediation. [ABSTRACT FROM AUTHOR]

• Ag NPs were synthesized using Nocardiopsis sp. as biological agent. • Identification and detection of biofilm producing MR-CoNS by various Hexa discs and CRA assays. • Detection of antibacterial and anti-biofilm efficiency of Ag NPs (5–60 µg/mL) against MR-CoNS strain. • Ag NPs treated MR-CoNS showed bacterial cell viability and cell damage as revealed by CLSM and SEM. The ability of a natural stabilizing and reducing agent on the synthesis of silver nanoparticles (Ag NPs) was explored using a rapid and single-pot biological reduction method using Nocardiopsis sp. GRG1 (KT235640) biomass. The UV–visible spectral analysis of Ag NPs was found to show a maximum absorption peak located at a wavelength position of ∼422 nm for initial conformation. The major peaks in the XRD pattern were found to be in excellent agreement with the standard values of metallic Ag NPs. No other peaks of impurity phases were observed. The morphology of Ag NPs was confirmed through TEM observation, demonstrating that the particle size distribution of Ag NPs entrenched in spherical particles is in a range between 20 and 50 nm. AFM analysis further supported the nanosized morphology of the synthesized Ag NPs and allowed quantifying the Ag NPs surface roughness. The synthesized Ag NPs showed significant antibacterial and antibiofilm activity against biofilm positive methicillin-resistant coagulase negative Staphylococci (MR-CoNS), which were isolated from urinary tract infection as determined by spectroscopic methods in the concentration range of 5–60 µg/ml. The inhibition of biofilm formation with coloring stain was morphologically imaged by confocal laser scanning microscopy (CLSM). Morphological alteration of treated bacteria was observed by SEM analysis. The results clearly indicate that these biologically synthesized Ag NPs could provide a safer alternative to conventional antibiofilm agents against uropathogen of MR-CoNS. [ABSTRACT FROM AUTHOR]

The article presents chemical reactions for Iodine catalyzed One-Pot synthesis of N-Methyl Pyrroles via [3 + 2] Annulation and their in vitro evaluation as antibacterial agents.