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    Coating of silver nanoparticles on polyurethane film surface by green chemistry approach and investigation of antibacterial activity against S. epidermidis
    (2022) Kara, Filiz; Aksoy, Eda Ayse; Aksoy, Serpil; Hasirci, Nesrin; 0000-0002-5017-0783; AAC-5455-2020
    Silver nanoparticles with potential antibacterial properties are included in biomaterials for the production of medical devices, which are used for diagnoses or treatment purposes. The aim of the current study was coating the polyurethane (PU) films with silver nanoparticles (AgNPs) due to their antibacterial efficacy. PU films were first modified by chitosan (CH), treated with AgNO3 to let CH chelate with silver ions, and then treated with vitamin-C (vit C) or glucose (Glu) to reduce the adsorbed ions to atomic silver to form AgNPs. The surfaces of the films were examined by ATR-FTIR, XPS, XRD, and SEM. Chemical bond formation between CH and Ag ions and AgNPs were determined by ATR-FTIR. Meanwhile, XPS and SEM analyses proved the presence of reduced metallic silver and nanoparticles on the film surfaces, respectively. According to the SEM analyses, a homogeneous distribution of AgNPs, with sizes 99-214 nm and 37-54 nm, on the film surfaces were obtained depending on Glu or vit C reduction, respectively. The films presented excellent antibacterial performance against Gram positive Staphylococcus epidermidis (S. epidermidis). These results suggested that the mentioned green technology can be easily applied to obtain AgNP coated polymeric surfaces with very high antibacterial efficacy. Although there are some studies dealing with AgNP formation on PU sponges or fibers, to the best of our knowledge, this is the first study showing AgNP formation on the CH conjugated PU films.
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    The Effects of Polymer Coating of Gold Nanoparticles on Oxidative Stress and DNA Damage
    (2020) Sen, Gamze Tilbe; Ozkemahli, Gizem; Shahbazi, Reza; Erkekoglu, Pinar; Ulubayram, Kezban; Kocer-Gumusel, Belma; 0000-0002-9421-6069; 32483993
    Gold nanoparticles (AuNPs) have been widely used in many biological and biomedical applications. In this regard, their surface modification is of paramount importance in order to increase their cellular uptake, delivery capability, and optimize their distribution inside the body. The aim of this study was to examine the effects of AuNPs on cytotoxicity, oxidant/antioxidant parameters, and DNA damage in HepG2 cells and investigate the potential toxic effects of different surface modifications such as polyethylene glycol (PEG) and polyethyleneimine (PEI; molecular weights of 2,000 (low molecular weight [LMW]) and 25,000 (high molecular weight [HMW]). The study groups were determined as AuNPs, PEG-coated AuNPs (AuNPs/PEG), low-molecular weight polyethyleneimine-coated gold nanoparticles (AuNPs/PEI LMW), and high-molecular weight polyethyleneimine-coated gold nanoparticles (AuNPs/PEI HMW). After incubating HepG2 cells with different concentrations of nanoparticles for 24 hours, half maximal inhibitory concentrations (the concentration that kills 50% of the cells) were determined as 166.77, 257.73, and 198.44 mu g/mL for AuNPs, AuNPs/PEG, and AuNPs/PEI LMW groups, respectively. Later, inhibitory concentration 30 (IC30, the concentration that kills 30% of the cells) doses were calculated, and further experiments were performed on cells that were exposed to IC30 doses. Although intracellular reactive oxygen species levels significantly increased in all nanoparticles, AuNPs as well as AuNPs/PEG did not cause any changes in oxidant/antioxidant parameters. However, AuNPs/PEI HMW particularly induced oxidative stress as evidence of alterations in lipid peroxidation and protein oxidation. These results suggest that at IC30 doses, AuNPs do not affect oxidative stress and DNA damage significantly. Polyethylene glycol coating does not have an impact on toxicity, however PEI coating (particularly HMW) can induce oxidative stress.
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    In vitro and in vivo bacterial antifouling properties of phosphite plasma-Treated silicone
    (2018) Akdogan, E.; Demirbilek, M.; Sen, Y.; Onur, M.A.; Azap, O.K.; Sonmez, E.; Sirin, H.T.; Mutlu, M.; 0000-0002-3171-8926; 0000-0002-5693-3542; AAK-4089-2021; AAI-8820-2021
    In order to improve their bacterial antifouling property, silicone surfaces were functionalized through the plasma polymerization (PP) technique using diethyl phosphite as the precursor. The functionalized surfaces were characterized using contact angle measurements, contact angle titration, Fourier transform infrared-Attenuated total reflection spectroscopy and in vitro cytotoxicity assay. The amount of non-specific protein adsorption and the conformational changes of surface-Adsorbed proteins were investigated. Antifouling properties of the surfaces were evaluated in vitro and in vivo. PP functionalization generated a hydrophilic and amphoteric surface with a very good protein and bacterial antifouling property and caused less conformational changes on the secondary structure of surface-Adsorbed proteins. In in vivo conditions, no slime layer was formed around bacteria that adhered on the PP-functionalized surface. It is concluded that the amphoteric nature of the PP-functionalized surface is the reason for the good antifouling property. © 2019 ICE Publishing: All rights reserved.