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- Al-Hinai, Muna H., et al.
(author)
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Antimicrobial Activity Enhancement of Poly(ether sulfone) Membranes by in Situ Growth of ZnO Nanorods
- 2017
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In: ACS Omega. - : AMER CHEMICAL SOC. - 2470-1343. ; 2:7, s. 3157-3167
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Journal article (peer-reviewed)abstract
- Composite poly(ether sulfone) membranes integrated with ZnO nanostructures either directly blended or grown in situ have enhanced antibacterial activity with improved functionality in reducing the biofouling in water treatment applications. The pore structure and surface properties of the composite were studied to investigate the effect of the addition of ZnO nanostructures. The hydrophilicity of the blended membranes increased with a higher content of ZnO nanoparticles in the membrane (2-6%), which could be further controlled by varying the growth conditions of ZnO nanorods on the polymer surface. Improved water flux, bovine serum albumin rejection, and inhibition of Escherichia coli bacterial growth under visible light irradiation was observed for the membranes decorated with ZnO nanorods compared to those in the membranes simply blended with ZnO nanoparticles. No regrowth of E. coli was recorded even 2 days after the incubation.
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| 5. |
- Al-Naamani, Laila, et al.
(author)
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Chitosan-zinc oxide nanocomposite coatings for the prevention of marine biofouling
- 2017
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In: Chemosphere. - : Elsevier. - 0045-6535 .- 1879-1298. ; 168, s. 408-417
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Journal article (peer-reviewed)abstract
- Marine biofouling is a worldwide problem affecting maritime industries. Global concerns about the high toxicity of antifouling paints have highlighted the need to develop less toxic antifouling coatings. Chitosan is a natural polymer with antimicrobial, antifungal and antialgal properties that is obtained from partial deacetylation of crustacean waste. In the present study, nanocomposite chitosan-zinc oxide (chitosan-ZnO) nanoparticle hybrid coatings were developed and their antifouling activity was tested. Chitosan-ZnO nanoparticle coatings showed anti-diatom activity against Navicula sp. and antibacterial activity against the marine bacterium Pseudoalteromonas nigrifaciens. Additional antifouling properties of the coatings were investigated in a mesocosm study using tanks containing natural sea water under controlled laboratory conditions. Each week for four weeks, biofilm was removed and analysed by flow cytometry to estimate total bacterial densities on the coated substrates. Chitosan-ZnO hybrid coatings led to better inhibition of bacterial growth in comparison to chitosan coatings alone, as determined by flow cytometry. This study demonstrates the antifouling potential of chitosan-ZnO nanocomposite hybrid coatings, which can be used for the prevention of biofouling. (C) 2016 Elsevier Ltd. All rights reserved.
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| 6. |
- Al-Naamani, Laila, et al.
(author)
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Chitosan-zinc oxide nanoparticle composite coating for active food packaging applications
- 2016
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In: Innovative Food Science & Emerging Technologies. - : Elsevier. - 1466-8564 .- 1878-5522. ; 38, s. 231-237
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Journal article (peer-reviewed)abstract
- In this study antimicrobial properties of chitosan and chitosan-zinc oxide (ZnO) nanocomposite coatings on PE films were studied. Oxygen plasma pretreatment of PE films led to increased adhesion by 2% of chitosan and the nanocomposite coating solutions to the packaging films. Scanning Electron Microscopy (SEM) revealed uniform coatings on PE surfaces. Incorporation of ZnO nanoparticles into the chitosan matrix resulted in 42% increase in solubility; swelling decreased by 80% while the water contact angle (WCA) increased from 60 to 95 compared to chitosan coating. PE coated with chitosan-ZnO nanocomposite films completely inactivated and prevented the growth of food pathogens, while chitosan-coated films showed only 10-fold decline in the viable cell counts of Salmonella enterica, Escherichia coli and Staphylococcus aureus after 24-h incubation compared to the control. Industrial relevance: One of the greatest challenges of food industry is microbial contamination. The present study suggests that PE coating with chitosan-ZnO nanocomposite is a promising technique to enhance antimicrobial properties of the films. Chitosan-ZnO nanocomposite coatings improved antibacterial properties of PE by inactivating about 99.9% of viable pathogenic bacteria. Hence, our results show the effectiveness of the nanocomposite coating in the development of active food packaging in order to prolong the shelf life of food products.
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| 7. |
- Al-Naamani, Laila, et al.
(author)
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Nanocomposite Zinc Oxide-Chitosan Coatings on Polyethylene Films for Extending Storage Life of Okra (Abelmoschus esculentus)
- 2018
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In: Nanomaterials. - : MDPI. - 2079-4991. ; 8:7
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Journal article (peer-reviewed)abstract
- Efficiency of nanocomposite zinc oxide-chitosan antimicrobial polyethylene packaging films for the preservation of quality of vegetables was studied using okra Abelmoschus esculentus. Low density polyethylene films (LDPE) coated with chitosan-ZnO nanocomposites were used for packaging of okra samples stored at room temperature (25 degrees C). Compared to the control sample (no coating), the total bacterial concentrations in the case of chitosan and nanocomposite coatings were reduced by 53% and 63%, respectively. The nanocomposite coating showed a 2-fold reduction in total fungal concentrations in comparison to the chitosan treated samples. Results demonstrate the effectiveness of the nanocomposite coatings for the reduction of fungal and bacterial growth in the okra samples after 12 storage days. The nanocomposite coatings did not affect the quality attributes of the okra, such as pH, total soluble solids, moisture content, and weight loss. This work demonstrates that the chitosan-ZnO nanocomposite coatings not only maintains the quality of the packed okra but also retards microbial and fungal growth. Thus, chitosan-ZnO nanocomposite coating can be used as a potential coating material for active food packaging applications.
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| 8. |
- Bora, Tanujjal, et al.
(author)
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Defect engineered visible light active ZnO nanorods for photocatalytic treatment of water
- 2017
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In: Catalysis Today. - : ELSEVIER SCIENCE BV. - 0920-5861 .- 1873-4308. ; 284, s. 11-18
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Journal article (peer-reviewed)abstract
- Photocatalytic degradation of organic wastes and microbes in water using solar light is a green technology that requires the design of visible light active photocatalysts. Here we report the fabrication of visible light active zinc oxide nanorods (ZnO NRs), wherein the visible light absorption is enhanced by modulating the surface defects on the NRs. Oxygen vacancies in the NRs as characterized by photoluminescence and X-ray photoelectron spectroscopy are controlled by annealing at different temperatures in the ambient. The role of surface defects on the visible light photocatalytic degradation of an organic dye, industrial waste, bacterial culture and inland brackish water is studied. Results presented here provide a simple strategy to make the wide bandgap ZnO NRs visible light active, enabling their use for the photocatalytic decontamination of water.
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| 9. |
- Falfushynska, Halina I., et al.
(author)
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The effects of ZnO nanostructures of different morphology on bioenergetics and stress response biomarkers of the blue mussels Mytilus edulis
- 2019
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In: Science of the Total Environment. - : ELSEVIER. - 0048-9697 .- 1879-1026. ; 694
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Journal article (peer-reviewed)abstract
- Biofouling causes massive economical losses in the maritime sector creating an urgent need for effective and ecologically non-harmful antifouling materials. Zinc oxide (ZnO) nanorod coatings show promise as an antifouling material; however, the toxicity of ZnO nanorods to marine organisms is not known. We compared the toxicity of suspended ZnO nanorods (NR) with that of ZnO nanoparticles (NP) and ionic Zn2+ in amarine bivalve Mytilus edulis exposed for two weeks to 10 or 100 mu g Zn L-1 of ZnO NPs, NRs or Zn2+, or to immobilized NRs. The multi-biomarker assessment included bioenergetics markers (tissue energy reserves, activity ofmitochondrial electron transport system and autophagic enzymes), expression of apoptotic and inflammatory genes, and general stress biomarkers (oxidative lesions, lysosomalmembrane stability and metallothionein expression). Exposure to ZnO NPs, NRs and Zn2+ caused accumulation of oxidative lesions in proteins and lipids, stimulated autophagy, and led to lysosomal membrane destabilization indicating toxicity. However, these responses were not specific for the form of Zn (NPs, NR or Zn2+) and showed no monotonous increase with increasing Zn concentrations in the experimental exposures. No major disturbance of the energy status was found in the mussels exposed to ZnO NPs, NRs, or Zn2+. Exposure to ZnO NPs and NRs led to a strong induction of apoptosis- and inflammation-related genes, which was not seen in Zn2+ exposures. Based on the integrated biomarker response, the overall toxicity as well as the pro-apoptotic and pro-inflammatory action was stronger in ZnO NPs compared with the NRs. Given the stability of ZnO NR coatings and the relatively low toxicity of suspended ZnO NR, ZnO NR coating might be considered a promising low-toxicity material for antifouling paints.
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| 10. |
- Kumar, Santosh, et al.
(author)
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Chitosan Nanocomposite Coatings Containing Chemically Resistant ZnO-SnOx Core-shell Nanoparticles for Photocatalytic Antifouling
- 2021
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In: International Journal of Molecular Sciences. - : MDPI. - 1661-6596 .- 1422-0067. ; 22:9
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Journal article (peer-reviewed)abstract
- Functional nanocomposites with biopolymers and zinc oxide (ZnO) nanoparticles is an emerging application of photocatalysis in antifouling coatings. The reduced chemical stability of ZnO in the acidic media in which chitosan is soluble affects the performance of chitosan nanocomposites in antifouling applications. In this study, a thin shell of amorphous tin dioxide (SnOx) was grown on the surface of ZnO to form ZnO-SnOx core-shell nanoparticles that improved the chemical stability of the photocatalyst nanoparticles, as examined at pH 3 and 6. The photocatalytic activity of ZnO-SnOx in the degradation of methylene blue (MB) dye under visible light showed a higher efficiency than that of ZnO nanoparticles due to the passivation of electronic defects. Chitosan-based antifouling coatings with varying percentages of ZnO or ZnO-SnOx nanoparticles, with or without the glutaraldehyde (GA) crosslinking of chitosan, were developed and studied. The incorporation of photocatalysts into the chitosan matrix enhanced the thermal stability of the coatings. Through a mesocosm study using running natural seawater, it was found that chitosan/ZnO-SnOx/GA coatings enabled better inhibition of bacterial growth compared to chitosan coatings alone. This study demonstrates the antifouling potential of chitosan nanocomposite coatings containing core-shell nanoparticles as an effective solution for the prevention of biofouling.
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