19 research outputs found

    Preparation of progressive antibacterial LDPE surface via active biomolecule deposition approach

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    The use of polymers in all aspects of daily life is increasing considerably, so there is high demand for polymers with specific properties. Polymers with antibacterial properties are highly needed in the food and medical industries. Low-density polyethylene (LDPE) is widely used in various industries, especially in food packaging, because it has suitable mechanical and safety properties. Nevertheless, the hydrophobicity of its surface makes it vulnerable to microbial attack and culturing. To enhance antimicrobial activity, a progressive surface modification of LDPE using the antimicrobial agent grafting process was applied. LDPE was first exposed to nonthermal radio-frequency (RF) plasma treatment to activate its surface. This led to the creation of reactive species on the LDPE surface, resulting in the ability to graft antibacterial agents, such as ascorbic acid (ASA), commonly known as vitamin C. ASA is a well-known antioxidant that is used as a food preservative, is essential to biological systems, and is found to be reactive against a number of microorganisms and bacteria. The antimicrobial effect of grafted LDPE with ASA was tested against two strong kinds of bacteria, namely, Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), with positive results. Surface analyses were performed thoroughly using contact angle measurements and peel tests to measure the wettability or surface free energy and adhesion properties after each modification step. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to analyze the surface morphology or topography changes of LDPE caused by plasma treatment and ASA grafting. Surface chemistry was studied by measuring the functional groups and elements introduced to the surface after plasma treatment and ASA grafting, using Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). These results showed wettability, adhesion, and roughness changes in the LDPE surface after plasma treatment, as well as after ASA grafting. This is a positive indicator of the ability of ASA to be grafted onto polymeric materials using plasma pretreatment, resulting in enhanced antibacterial activity. - 2019 by the authors.Funding: This publication was made possible by Award JSREP07-022-3-010 and NPRP10-0205-170349 from the Qatar National Research Fund (a member of The Qatar Foundation). The statements made herein are solely the responsibility of the authors

    Effect of humidity on the electrical properties of the silver polyaniline/polyvinyl alcohol nanocomposites

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    Polymer-metal nanocomposites with enhanced mechanical, optical, electrical, dielectric, and antimicrobial properties are currently in high demand for many industrial applications. Here, we study and present the effect of UV-reduced silver nanoparticles on the synthesis of polyaniline-polyvinyl alcohol-silver nanocomposites (PPVA-Ag) and utilize them to make a humidity sensor and antimicrobial agent. A thorough study of the surface morphology of the prepared films using SEM, AFM, and profilometry is performed; it is found that uniform film is formed in all these cases. These studies show that an increase in Ag concentration leads to an increase in the surface micro roughness of the PPVA-Ag film. XPS determines the chemical composition of the prepared PPVA-Ag nanocomposites. At different humidity conditions, the electrical resistivity of the PPVA-Ag nanocomposites is measured. The results show uniform changes in resistivity with an increase in humidity and good repeatability. These polymer-metal nanocomposites are found to have exhibited antimicrobial abilities making them useful for biomedical applications as well.Pioneer Hi-Bred, Qatar National Research Fund, Grantova Agentura ceska Republiky, Qatar National Research FundScopu

    Antimicrobial modification of PLA scaffolds with ascorbic and fumaric acids via plasma treatment

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    An optimal medical scaffold should be biocompatible and biodegradable and should have adequate mechanical properties and scaffold architecture porosity, a precise three-dimensional shape, and a reasonable manufacturing method. Polylactic acid (PLA) is a natural biodegradable thermoplastic aliphatic polyester that can be fabricated into nanofiber structures through many techniques, and electrospinning is one of the most widely used methods. Medical fiber mat scaffolds have been associated with inflammation and infection and, in some cases, have resulted in tissue degradation. Therefore, surface modification with antimicrobial agents represents a suitable solution if the mechanical properties of the fiber mats are not affected. In this study, the surfaces of electrospun PLA fiber mats were modified with naturally occurring L-ascorbic acid (ASA) or fumaric acid (FA) via a plasma treatment method. It was found that 30 s of radio-frequency (RF) plasma treatment was effective enough for the wettability enhancement and hydroperoxide formation needed for subsequent grafting reactions with antimicrobial agents upon their decomposition. This modification led to changes in the surface properties of the PLA fiber mats, which were analyzed by various spectroscopic and microscopic techniques. FTIR-ATR confirmed the chemical composition changes after the modification process and the surface morphology/topography changes were proven by SEM and AFM. Moreover, nanomechanical changes of prepared PLA fiber mats were investigated by AFM using amplitude modulation-frequency modulation (AM-FM) technique. A significant enhancement in antimicrobial activity of such modified PLA fiber mats against gram-positive Staphylococcus aureus and gram-negative Escherichia coli are demonstrated herein. 2020 The AuthorsThis publication was made possible by UREP grant # 22-076-1-011 from the Qatar National Research Fund (a member of The Qatar Foundation). This publication was supported by the Qatar University Collaborative Grant No. QUCG-CAM-20/21-3 . The findings achieved herein are solely the responsibility of the authors. Authors M. L. and P. H. would like to express their gratitude to the Czech Science Foundation (19-16861S) for partial financing of the research. SEM analysis was accomplished in the Central Laboratories unit, Qatar University.Scopu
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