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Öğe Design, fabrication and characterization of silane tailored surface of halloysite based polymer nanocomposites(Wiley, 2023) Uner, Gizem; Karakus, Gulderen; Can, Hatice KaplanIn recent years, polymeric drug conjugates, nanoparticles, nanocapsules, liposomes, micelles, dendrimers, and nanogels have been gained a great attention. Organically modified layered nanoclays have become an attractive hybrid biomaterial due to their wide range of uses, which can be designed with desired properties in a wide variety of applications from industry to medicine. Functional water-soluble poly(maleic anhydride-alt-acrylic acid) [poly(MA-alt-AA)], synthesized in our previous study, was chosen for the prepare of halloysite/polymer nanocomposite. Surface modification of halloysite nanotubes (HNTs) with 3-aminopropyltriethoxysilane (APTS) was performed to obtain organic functionalized halloysite and also for better compatibility of nanotubes (NTs) with monomers. Nanocomposite were obtained by in situ solution complex-radical copolymerization via charge transfer complex under conditions of copolymerization, using pristine and APTS functionalized HNTs, acrylic acid (AA), and maleic anhydride (MA) monomers. Optimization study using different clay ratios and recipe for organic-inorganic compatibility also were carried out. Characterization studies of halloysite, modified halloysite, copolymers and the formed copolymer-HNT nanotubes were enlighten by using spectroscopic analyzes such as, Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR), High resolution Raman (HR-Raman), X-Ray Diffraction Measurements (XRD) and X-Ray Photoelectron Spectroscopy (XPS). Thermal analysis and dynamic mechanical properties were performed with Thermogravimetric Analysis (TGA) and Dynamic Mechanical Analysis (DMA), respectively. Surface morphology was also carried out by Transmission Electron Microscopy (TEM). In the light of these detailed analysis results, it can be briefly concluded that surface modification of HNT, synthesis of copolymer/HNT nanocomposites, and structural characterization successfully achieved.Öğe Synthesis, characterization and in vitro antibacterial assessments of a novel modified poly[maleic anhydride-alt-acrylic acid]/acriflavine conjugate(SPRINGER, 2014) Can, Hatice Kaplan; Karakus, Gulderen; Tuzcu, NevinWater-soluble maleic anhydride-containing poly[maleic anhydride-alt-acrylic acid] (poly(MA-alt-AA) or MAAA) copolymer was synthesized by freer-adical chain polymerization reaction, in 1,4-dioxane in the presence of benzoyl peroxide, 0.1 %, as the radical initiator at 70 degrees C under a nitrogen atmosphere. The purified copolymer was then modified with an anti-external fungal and anti-cancer active agent, acriflavine (AF). The modification reaction was performed 48 h at 70 degrees C in dimethylformamide organic media, using triethylamine (TEA or Et3N) as the catalyst. The modified or conjugated copolymer/drug couple was named as MAAA/AF. Detailed structural characterization of the copolymer (MAAA) and modified product (MAAA/AF) was carried out by Fourier Transform Infrared (FTIR) and Nuclear Magnetic Resonance (H-1-NMR and C-13-NMR). The obtained FTIR, H-1-NMR, and C-13-NMR spectra confirmed that AF was successfully bound to the MAAA copolymer backbone by ring-opening reaction. Antimicrobial susceptibility of the MAAA, AF, and MAAA/AF was evaluated by Kirby Bauer Disc Diffusion method on Mueller-Hinton Agar using Enterecoccus faecium, Enterohaemorrhagic Escherichia coli (EHEC), Staphylococcus aureus and Listeria monocytogenes. Results obtained indicated that MAAA/AF had antibacterial activity on EHEC and S. aureus at 50, 40, and 30 mu g. A mechanism for MAAA and AF was then also suggested for the conjugation reaction.Öğe Synthesis, structural characterization, thermal behavior and cytotoxic/antiproliferative activity assessments of poly(maleic anhydride-alt-acrylic acid)/hydroxyurea polymer/drug conjugate(Elsevier, 2020) Karakus, Gulderen; Can, Hatice Kaplan; Yaglioglu, Ayse SahinAs drug carrier, poly(maleic anhydride-alt-acrylic acid) copolymer [poly(MA-alt-AA)], was prepared traditionally by radical initiated (benzoyl peroxide (BPO)), complex-radical polymerization technique via charge transfer complex (CTC) (50/50 in p-dioxane, at 70 degrees C under a nitrogen atmosphere). The pure alternating carrier was then conjugated as poly[MA-alt-AA]/HX (or MAAA/HX) copolymer/drug couple by ring opening reaction with an antineoplastic agent hydroxyurea (HX) for 48 h at 75 +/- 0.1 degrees C in dimethylformamide (DMF), presence of triethylamine (Et3N) catalytic base. Chemical structure of the copolymer, antineoplastic agent and conjugate was characterized by Fourier Transform Infrared (ATR-FTIR) and also Nuclear Magnetic Resonance (proton and carbon NMR). Physical characterizations were also carried out by Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). To verify the elemental composition and also conjugation reaction of conjugated product, quantitative elemental analysis was especially carried out. Cytotoxicity was determined with Lactate Dehydrogenase (LDH) leakage assay using LDH cytotoxicity detection kit provided by Roche Diagnostics GMBH (Mannheim, Germany) based on the protocol in the user's manual. Compared with 5-FU, toxicity values are as follows respectively: HX > MAAA > 5-FU. MAAA/HX. Furthermore, antiproliferative activity studies was examined on HeLa (human cervical cancer) and (C6) rat brain tumor cells using proliferation BrdU ELISA assay. Conjugated-drug was identified to have the higher antiproliferation than the copolymer and free-drug (Hydroxyurea) on all studied concentrations and cellular potency of inhibitions were found as MAAA/HX > HX > MAAA at the highest concentration, 100 mu g/mL. Toxic drug (HX) was modified as nontoxic MAAA/HX conjugate with good properties. (C) 2020 Elsevier B.V. All rights reserved.
