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Öğe 2-Isopropenyl-2-oxazoline: A versatile monomer for functionalization of polymers obtained via RAFT(2012) Weber, Christine; Neuwirth, Toni; Kempe, Kristian; Özkahraman, Bengi; Tamahkar Irmak, Emel; Mert Balaban, Hümeyra; Becer, C. Remzi; Schubert, Ulrich S.2-Isopropenyl-2-oxazoline (iPOx) was polymerized for the first time via a controlled radical polymerization technique. Reversible addition-fragmentation chain transfer (RAFT) polymerization utilizing a dithiobenzoate-based chain transfer agent was employed to form a backbone that is highly reactive toward thiols and acids. Moreover, the statistical copolymerization of iPOx with methyl methacrylate (MMA) and N-iso-propylacrylamide (NiPAm) was investigated resulting in two copolymer series with iPOx content varying from 100% to 13% (PDI = 1.37 to 1.21). The P(iPOx-stat-NiPAm) copolymers displayed thermoresponsive behavior in water as well as phosphate buffered saline at higher temperatures in comparison to homopolymers of NiPAm due to the hydrophilicity of the introduced iPOx moieties (T cp = 25 to 75 °C). Futhermore, iPOx-based (co)polymers were functionalized by polymer analogous addition reactions with thiophenol, benzoic acid and 4-azidobenzoic acid in high conversions (74-100%). The latter adduct represented a suitable building block for the synthesis of a graft copolymer consisting of a PMMA backbone and poly(2-ethyl-2-oxazoline) (PEtOx) side chains via copper-catalyzed azide-alkyne cycloaddition (CuAAC) of PEtOx with alkyne terminus. © 2011 American Chemical Society.Öğe Affinity binding of proteins to the modified bacterial cellulose nanofibers(Elsevier B.V., 2017) Bakhshpour, Monireh; Tamahkar Irmak, Emel; Andaç, Müge; Denizli, AdilThe potential of the modified bacterial cellulose (BC) nanofibers was determined bearing metal ion coordination interactions to enhance the protein adsorption and binding capacity. Thus, a household synthesized metal chelating monomer, namely N-methacryloyl-L-histidine methylester (MAH), and a commercial metal chelating monomer, namely 4-vinylimidazole (VIm), were used to complex with metal ions Cu(II) and Ni(II) respectively for the synthesis of the modified BC nanofibers. The modified nanofibers were characterized by FT-IR, SEM and EDX measurements. The protein adsorption tests were carried out using hemoglobin as a model protein and it was determined that the maximum adsorption capacity of hemoglobin onto the modified BC nanofibers was found as 47.40 mg/g. The novel strategy for the preparation of metal chelated nanofibers was developed. © 2017 Elsevier B.V.Öğe Bacterial cellulose nanofibers for efficient removal of Hg2+ from aqueous solutions(Wiley Blackwell, 2018) Tamahkar Irmak, Emel; Türkmen, Deniz; Akgönüllü, Semra; Qureshi, Tahira; Denizli, Adil; Mishra, Ajay Kumar; Hussain, Chaudhery MustansarThe removal of mercury from wastewater is gaining much attention because of being one of the common heavy metal pollutants found in water source affecting human health and environment. Dye affinity chromatography is a general method for heavy metal removal having high reactivity, stability, easiness, and cost effectiveness. In this study, modified bacterial cellulose nanofibers (BC) were prepared using a dye namely Cibacron Blue F3GA (CB). The covalently attached Cibacron Blue F3GA (17.8 × 104 nmol/g) to the bacterial cellulose nanofibers was successfully applied to remove Hg2+ from aqueous solutions. Cibacron Blue F3GA attachment onto the bacterial cellulose nanofibers significantly increased the Hg2+ adsorption (928.0 mg/g), while the adsorption of Hg2+ onto the unmodified bacterial cellulose nanofibers was obtained very low (0.62 mg/g polymer). The competitive adsorption of heavy metals on BC-CB nanofibers was performed to examine the efficiency of BC-CB nanofibers for Hg2+ in comparison with other divalent metal ions. The adsorption capacities were observed as 322.4 mg/g for Hg2+; 48.5 mg/g for Cd2+; and 41.9 mg/g for Pb2+ indicating higher specificity for Hg2+ adsorption onto BC-CB nanofibers for the mercury ions comparing to other ions. The successive adsorption experiments and elution process demonstrated the efficient repeated workability of modified BC nanofibers. The results show that the preparation of cheap, effective, and eco-friendly nanofibers for mercury removal was performed successfully indicating the potential of BC-CB nanofibers for metal ion removal applications. © 2018 Scrivener Publishing LLC. All rights reserved.Öğe Carbon nanotube based polyvinylalcohol-polyvinylpyrolidone nanocomposite hydrogels for controlled drug delivery applications(Eskişehir Teknik Üniversitesi, 2017) Özkahraman, Bengi; Tamahkar Irmak, EmelControlled drug release systems present a significant alternative to the conventional drug dosages providing drug release for prolonged time periods. Nanocomposite hydrogels offer an important potential for drug release with enhanced physicochemical properties. In this study, the preparation of carbon nanotube (CNT)-based Polyvinylalcohol-Polyvinylpyrolidone (PVA/PVP) nanocomposite hydrogels namely, CNT-25, CNT-50 and CNT-100 were succeedded via the freeze/thawing method with the addition of different amounts of CNT. The nanocomposite hydrogels were characterized by swelling tests, SEM, FTIR, DSC and BET measurements. It was determined that CNT-50 was the most suitable hydrogel for drug release studies having better morphological properties with homogenous distribution of CNT throughout the polymeric nanocomposite matrix. The release of 5-fluororacil (5-FU) as a model drug was investigated in-vitro. The release of 5-FU from CNT-based PVA/PVP nanocomposite hydrogels was exhibited controlled release for one week at pH 7.4. The amount of released 5-FU was effectively increased with the addition of CNT into the hydrogel matrix. Korsmeyer-Peppas model was well fitted for determining the release mechanism of 5-FU from CNT-based PVA/PVP nanocomposite hydrogels corresponding the combination of diffusion of the drug and the dissolution of polymer chains.Öğe Ion imprinted cryogels for selective removal of Ni(II) ions from aqueous solutions(Elsevier B.V., 2017) Tamahkar Irmak, Emel; Bakhshpour, Monireh; Andaç, Müge; Denizli, AdilIn this article, ion imprinted poly(hydroxyethyl methacrylate) (PHEMA) based supermacroporous cryogels were synthesized in the presence of a functional monomer, namely N-methacryloyl-histidine methyl ester (MAH), to be complexed with Ni(II) ions. Two types of cryogels (MIP1 and MIP2) were synthesized according to functional monomer/template [MAH/Ni(II)] complexing molar ratios. These cryogels were then characterized by swelling tests, FT-IR and SEM measurements and used for selective binding of Ni(II) ions from aqueous solutions and a certified material. The maximum adsorption capacities of MIP1 and MIP2 cryogels were found as 1.89 and 5.54 mg/g, respectively. Ni(II) imprinted cryogels exhibited excellent selectivity toward competitive metal ions [Fe(III), Cu(II) and Zn(II)] indicating important potential for selective removal of Ni(II) ions from aqueous solutions. In addition, Ni(II) imprinted cryogels were used repeatedly without a decrement in the binding capacity. © 2016 Elsevier B.V.Öğe Molecularly imprinted composite bacterial cellulose nanofibers for antibiotic release(Taylor and Francis Inc., 2019) Tamahkar Irmak, Emel; Bakhshpour, Monireh; Denizli, AdilThe aim of this work is to develop drug carrier system with high loading capacity and controlled drug release profile for antibiotic release. For this purpose, composite molecularly imprinted nanofibers were prepared via in-situ graft polymerization of methacrylic acid as a monomer, N,N’-methylene bisacrylamide as a crosslinker and gentamicin sulfate as a template molecule onto surface-modified bacterial cellulose nanofibers. Gentamicin imprinted microparticles were fabricated onto bacterial cellulose nanofibers resulting in the formation of composite BC nanofibers. Thus, the composite nanofibers incorporated with gentamicin imprinted microparticles were achieved to fabricated. The in-vitro drug release tests were performed to evaluate the release performance of the resultant composite nanofibers at 37 °C. Also, kinetic models were applied to the drug release data. It was determined that the drug release from the composite molecularly imprinted nanofibers fit well in the Korsmeyer-Peppas model. © 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group.Öğe Protein depletion with bacterial cellulose nanofibers(Elsevier B.V., 2018) Göktürk, İlgim; Tamahkar Irmak, Emel; Yılmaz, Fatma; Denizli, AdilIn this study, we have reported a novel fabrication technique for human serum albumin (HSA) imprinted composite bacterial cellulose nanofibers (MIP-cBCNFs) used for the depletion of HSA selectively from artificial blood plasma for proteomic applications. Molecular imprinting was achieved by using metal ion coordination interactions of N?methacryloyl?(L)?histidinemethylester (MAH) monomer and Cu(II) ions. MAH-Cu(II)-HSA complex was polymerized with bacterial cellulose nanofibers (BCNFs) under constant stirring at room temperature. The characterization of the MIP-cBCNFs was carried out by FTIR-ATR, SEM, contact angle measurements and surface area measurements. The adsorption experiments of HSA onto the MIP-BCNFs and NIP-BCNFs from aqueous HSA solutions were investigated in a batch system. The selectivity of the MIP-cBCNFs was investigated by using non-template human transferrin (HTR), and myoglobin (Myo). The relative selectivity coefficients of the MIP-cBCNFs were calculated as 4.73 and 3.02 for HSA/HTR and HSA/Myo molecules, respectively. In addition, the depletion of HSA from artificial human plasma was confirmed by SDS-PAGE and 2-D gel electrophoresis. As a result, it has been shown that metal ion coordination interactions contribute to specific binding of template when preparing MIP-cBCNFs for the depletion of HSA with a high adsorption capacity, significant selectivity and reusability. © 2018Öğe Recognition of lysozyme using surface imprinted bacterial cellulose nanofibers(Taylor and Francis Inc., 2017) Saylan, Yeşeren; Tamahkar Irmak, Emel; Denizli, AdilHere, we developed the lysozyme imprinted bacterial cellulose (Lyz-MIP/BC) nanofibers via the surface imprinting strategy that was designed to recognize lysozyme. This study includes the molecular imprinting method onto the surface of bacterial cellulose nanofibers in the presence of lysozyme by metal ion coordination, as well as further characterizations methods FTIR, SEM and contact angle measurements. The maximum lysozyme adsorption capacity of Lyz-MIP/BC nanofibers was found to be 71 mg/g. The Lyz-MIP/BC nanofibers showed high selectivity for lysozyme towards bovine serum albumin and cytochrome c. Overall, the Lyz-MIP/BC nanofibers hold great potential for lysozyme recognition due to the high binding capacity, significant selectivity and excellent reusability. © 2017 Informa UK Limited, trading as Taylor & Francis Group.Öğe Surface imprinted bacterial cellulose nanofibers for hemoglobin purification(Elsevier B.V., 2017) Bakhshpour, Monireh; Tamahkar Irmak, Emel; Andaç, Müge; Denizli, AdilThere is a significant need for the development of the novel adsorbents in the field of protein purification. In this study, thin hemoglobin imprinted film (MIP) was fabricated onto the bacterial cellulose nanofibers’ (BCNFs) by surface imprinting method using metal ion coordination interactions with N-methacryloyl–(L)-histidinemethylester (MAH) and copper ions. The hemoglobin surface imprinted bacterial cellulose nanofibers (MIP-BCNFs) was applied to selective recognition of hemoglobin and purification from hemolysate. The characterization of the MIP-BCNFs was carried out by the Fourier Transformed Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), micro-Computerized Tomography (?CT), atomic force microscopy (AFM) and surface area measurements. The adsorption experiments of hemoglobin onto the MIP-BCNFs and NIP-BCNFs from aqueous hemoglobin solutions were investigated in a batch system. The results showed that MIP-BCNFs are promising materials for purification of hemoglobin with high adsorption capacity, significant selectivity and reusability. © 2017 Elsevier B.V.Öğe Synthesis of chitosan-based hydrogels as a novel drug release device for wound healing(Hitit University, 2017) Tamahkar Irmak, Emel; Özkahraman, BengiThe development of the porous, biocompatible and biodegradable hydrogels has been gaining much attention for wound dressing applications. The hydrogels prepared using freeze-thawing method present important properties of high biocompatibility and nontoxicity. The hydrogels that are able to release drugs for prolonged time are widely used biomaterials for wound healing. In this study chitosan (CS)-based poly-?-caprolactone (PCL) hydrogels were prepared using poly vinyl alcohol (PVA), poly ethylene glycol (PEG) and poly vinyl pyrrolidone (PVP). PVA-CS-PCL hydrogels only could remain stable at room temperature after synthesis. The properties of the hydrogels were determined with SEM, FTIR, swelling tests and degradation tests. The drugs of ceftazidime (CZ) as an antibiotic and ketoprofen (KP) as an analgesic were loaded onto the hydrogels and the loaded hydrogels were used for the drug release studies at pH 5.5 and pH 7.4. All these results suggest that the developed PVA-CS-PCL hydrogels offer significant potential as a wound dressing material.Öğe Toward a universal method for preparing molecularly imprinted polymer nanoparticles with antibody-like affinity for proteins(American Chemical Society, 2016) Xu, Jingjing; Ambrosini, Serena; Tamahkar Irmak, Emel; Rossi, Claire; Haupt, Karsten; Bui, Bernadette Tse SumWe describe a potentially universal, simple and cheap method to prepare water-compatible molecularly imprinted polymer nanoparticles (MIP-NPs) as synthetic antibodies against proteins. The strategy is based on a solid phase synthesis approach where glass beads (GBs) are functionalized with a metal chelate, acting as a general affinity ligand to attract surface-bound histidines present on proteins. This configuration enables an oriented immobilization of the proteins, upon which thermoresponsive MIP-NPs are synthesized. The GBs play the role of both a reactor and a separation column since, after synthesis, the MIP-NPs are released from the support by a simple temperature change, resulting in protein-free polymers. The resulting MIP-NPs are endowed with improved binding site homogeneity, since the binding sites have the same orientation. Moreover, they are stable (no aggregation) in a buffer solution for prolonged storage time and exhibit apparent dissociation constants in the nanomolar range, with little or no cross-reactivity toward other proteins. © 2015 American Chemical Society.
