Highly efficient multifunctional graphene/chitosan/magnetite nanocomposites for photocatalytic degradation of important dye molecules

Multifunctional chitosan/magnetite (CS/Fe3O4) and graphene/chitosan/magnetite (Gr/CS/Fe3O4) 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 Fe3O4 nanoparticles (NPs) were found to uniformly decorate CS and Gr surfaces. The synthesized Fe3O4 NPs, CS/Fe(3)O(4 )and Gr/CS/Fe3O4 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/Fe3O4 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 Fe3O4 NPs (100 min for Rh-B, 120 min for BTB, 160 min for MB and 180 min for MO) and CS/Fe3O4 NCs (90 min for Rh-B, 100 min for BTB, 140 min for MB and 150 min for MO). The photocatalytic irradiation efficiency of Fe3O4 NPs, CS/Fe3O4 and Gr/CS/Fe3O4 NCs, evaluated against visible light, was found to be significantly higher for Rh-B (100% within 40 min) compared to the other tested dyes.Comisión Nacional de Investigación Científica y Tecnológica (CONICYT) CONICYT FONDECYT 3180128 CONICYT/FONDEQUIP EQM130149 FONDEQUIP EQM15010

Extraction and partial purification of secondary metabolites from endophytic actinomycetes of marine green algae Caulerpa racemosa against multi drug resistant uropathogens

The aim of this study is to identify potential antibacterial compounds of endophytic actinomycetes (EA) from marine algae Caulerpa racemosa for inhibit the multi drug resistant (MDR) Gram negative bacteria (GNB) including Eschericia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa), Proteus mirabilis (P. mirabilis), Klebsiella pnumonia (K. pnumoniae) and Enterobacter sp., which were confirmed by UTI panel antibiotic discs. Among the 100 EA, five strains were showed better antogonistic activity against all the selected uropathogens. In the ethyl acetate extract, the NMS 5 strains of EA showed excellent anti-bacterial activity against all the MDR uropathogen. Further, the NMS 5 extract was partially purified from thin layar chramatogaraphy (TLC) and spot 3 of TLC crude compound showed 14, 12mm zone of inhibition against both the uropathogens. In addition, the minimum inhibition concentration (MIC) of crude exhibited the inhibition percentage was 87 and 84 at 120 μg/ mL concentration. The MIC was confirmed by minimum bactericidal concentration (MBC) and it was indicated same as MIC. The treated NMS 5 crude compound of P. aeruginosa and K. pneumonia cells were showed more dead cells, intracellular damage and morphological damage with disaggregated cells by confocal laser scanning electron microscope (CLSM) and scanning electron microscope (SEM). Hence, the present study was revealed that the algae derived EA have the potential anti-bacterial metabolites for inhibition of MDR bacteria and it can be applied for various other infections after further purification

Graphene/nickel oxide nanocomposites against isolated ESBL producing bacteria and A549 cancer cells

The synthesis of nickel oxide nanoparticles (NiO NPs)and graphene/nickel oxide nanocomposites (Gr/NiO NCs)was performed using a simple chemical reduction method. Powder X-ray diffraction (XRD)and thermogravimetric analysis (TGA)were used to examine the crystalline nature and thermal stability of the synthesized NiO NPs and Gr/NiO NCs, respectively. Scanning electron microscopy (SEM)and transmission electron microscopy (TEM)were utilized to observe the morphology of NiO NPs and Gr/NiO NCs and estimate their size range. TEM suggested that the NiO NPs were speared onto the surface of Gr nanosheet. The efficiency of NiO NPs and Gr/NiO NCs against extended spectrum β-lacamase (ESBL)producing bacteria, which was confirmed by specific HEXA disc Hexa G-minus 24 (HX-096)and MIC strip methods (CLSI); namely Escherichia coli (E. coli)and Pseudomonas aeruginosa (P. aeruginosa)was investigated using the minimal inhibitory concentration (MIC)and minimal bactericidal concentration (MBC)methods. MIC results suggested that the NiO NPs and Gr/NiO NCs possess maximum growth inhibition of 86%, 82% and 94%, 92% at 50 and 30 μg/mL concentrations, respectively. Similarly, both nanomaterials were found to inhibit the β-lacamase enzyme at concentrations of 60 μg/mL and 40 μg/mL, respectively. The cytotoxicity of NiO NPs and Gr/NiO NCs was quantified against A549 human lung cancer cells. Cell death percentage values of 52% at 50 μg/mL against NiO NPs and 54% at 20 μg/mL against Gr/NiO NCs were obtained, respectively. The NCs were found to reduce cell viability, increase the level of reactive oxygen species (ROS)and modify both the mitochondrial membrane permeability and cell cycle arrest

Biomarker response of climate change-induced ocean acidification and hypercapnia studies on brachyurian crab Portunus pelagicus

A laboratory level microcosm analysis of the impacts of ocean acidification on the environmental stress biomarkers in Portunus pelagicus (Linneaus 1758)exposed to a series of pH regimes expected in the year 2100 (pH 7.5 and 7.0) and leakage from a sub-seabed carbon dioxide storage site (pH 6.5 - 5.5) was carried out. Levels of the antioxidant enzyme catalase, the phase II detoxification enzyme, glutathione S. transferase, the lipid peroxidation biomarker, malondialdehyde, acetylcholinesterase, and reduced glutathione were estimated in the tissues of the exposed animals to validate theses enzymes as biomarkers of Hypercapnia. The integrated biomarkers indicated a stress full environment in all animals except those exposed to the control seawater (pH 8.1). The reducing pH was also observed to be highly lethal to the animals exposed to lower pH levels which were obvious from the rate of mortality in a short term of exposure. The present study substantiates the role of biomarkers as an early warning of ocean acidification at a sub-lethal level

Molecular identification and structural characterization of marine endophytic actinomycetes Nocardiopsis sp. GRG 2 (KT 235641) and its antibacterial efficacy against isolated ESBL producing bacteria

© 2018 Elsevier LtdThe present study was designed to identify the potential bioactive compound from endophytic actinomycetes (EA) Nocardiopsis sp. GRG 2 (KT 235641) against selected extended spectrum beta lactamase (ESBL) producing Pseudomonas aeruginosa (P. aeruginosa) and Klebsiella pneumoniae (K. pneumoniae). Initially, the multi drug resistance (MDR) effect of selected uropathogens was confirmed by respective UTI panel of Hexa antibiotics disc methods. The zone of inhibition ≤22 mm for ceftazidime, ≤ 27 mm for cefotaxime and ≤8 mm zone of MIC stripe against both the uropathogens of phenotypic methods confirmed, the selected strains were ESBL producer. Among the various EA extracts, GRG 2 extract showed excellent antibacterial activity against both ESBL producing P. aeruginosa and K. pneumonia by agar well diffution method. The molecular identification of selected GRG 2 strain was named as Nocardiopsis sp. GRG 2 (KT235641). The antibacterial metabolites present in the TLC elution w

Anti-ESBL investigation of chitosan/silver nanocomposites against carbapenem resistant Pseudomonas aeruginosa

In the present investigation functional chitosan/silver nanocomposites (CS/Ag NCs) were successfully synthesized and found to possess favorable antibacterial activity against extended spectrum beta-lactasame (ESBL) producing Pseudomonas aeruginosa. Powder X-ray diffraction showed that the obtained CS/Ag NCs are constituted of highly crystalline Ag nanoparticles (NPs) embedded in an amorphous CS matrix material. Transmission electron microscopy (TEM) analysis provided structural information about CS/Ag NCs, revealing the formation of spherical cluster structures constituted of Ag NPs with size ranging from 6 to 18 nm embedded in the amorphous CS matrix. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of Ag NPs and CS/Ag NCs were found to inhibit the ESBL producing P. aeruginosa at 80 μg/mL (76%) and 50 μg/mL (92%), respectively. Confocal laser scanning microscope (CLSM) and scanning electron microscopy (SEM) images revealed that P. aeruginosa experienced reduced cell viability and morphological cell membrane damage at desired MIC. The in-vivo toxicity effect of Ag NPs and CS/Ag NCs suggested an increased mortality rate when Artemia franciscana were exposed for 24 h to increasing concentrations of Ag NPs and CS/Ag NCs. Anti-ESBL activity and toxicity effect of CS/Ag NCs revealed that these NCs possess promising antibacterial properties to overcome numerous communicable bacterial strains

Chitosan/silver nanocomposites for colorimetric detection of glucose molecules

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

Graphene-zinc oxide nanocomposites (G-ZnO NCs): Synthesis, characterization and their photocatalytic degradation of dye molecules

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.National Natural Science Foundation of China 21641007 21471001 Natural Science Foundation of Anhui Province 1508085 Major Project of Education Department of Anhui Province KJ2016SD6