Person: OSMAN, BİLGEN
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OSMAN
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BİLGEN
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Publication Adsorption of cinnabarinic acid from culture fluid with magnetic microbeads(Wiley, 2016-02-01) Sarıkaya, Aslı Göçenoğlu; Osman, Bilgen; Kara, Ali; Pazarlıoğlu, Nurdan; Besirli, Necati; GÖÇENOĞLU SARIKAYA, ASLI; OSMAN, BİLGEN; KARA, ALİ; Besirli, Necati; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Kimya Bölümü,; 0000-0002-7161-7003; 0000-0001-8406-149X; 0000-0003-2457-6314; AAC-6901-2020; ABF-4791-2020; JXW-6168-2024; AAG-6271-2019In this study, antimicrobial pigment cinnabarinic acid (CA) was produced from Pycnoporus cinnabarinus in laboratory-scale batch cultures. Magnetic poly(ethylene glycol dimethacrylate-N-methacryloyl-l-tryptophan methyl ester) [m-poly(EGDMA-MATrp)] beads (average diameter = 53-103 mu m) were synthesized by copolymerizing of N-methacryloyl-l-tryptophan methyl ester (MATrp) with ethylene glycol dimethacrylate (EGDMA) in the presence of magnetite (Fe3O4) and used for the adsorption of CA. The m-poly(EGDMA-MATrp) beads were characterized by N-2 adsorption/desorption isotherms (Brunauer Emmet Teller), X-ray photoelecron spectroscopy, scanning electron microscopy, infrared spectroscopy, thermal gravimetric analysis, electron spin resonance and swelling studies. The efficiency of m-poly(EGDMA-MATrp) beads for separation of CA from culture fluid was evaluated. The effects of pH, initial concentration, contact time and temperature on adsorption were analyzed. The maximum CA adsorption capacity of the m-poly(EGDMA-MATrp) beads was 272.9mgg(-1) at pH7.0, 25 degrees C. All the isotherm data can be fitted with the Langmuir, Freundlich and Dubinin-Radushkevich isotherm models. The adsorption process obeyed pseudo-second-order kinetic model. Thermodynamic parameters H = 5.056kJmol(-1), S = 52.44JK(-1)mol(-1) and G = -9.424kJmol-(1) to -11.27kJmol-(1) with the rise in temperature from 4 to 40 degrees C indicated that the adsorption process was endothermic and spontaneous.Publication L-(+)-tryptophan methyl ester derived polymeric microbeads as an efffiicient heterogeneous catalyst for green synthesis of 2-amino-4-(nitromethyl)-4h-chromene-3-carbonitriles(Tubitak Scientific & Technological Research Council Turkey, 2022-01-01) Poslu, Ayse Haliç; Kaya, Yunus; Koz, Ömer; Koz, Gamze; Osman, Bilgen; OSMAN, BİLGEN; Bursa Uludağ Üniversitesi/Fen Edebiyat Fakültesi/Kimya Bölümü.; 0000-0001-8406-149X; ABF-4791-2020The cross-linked microbeads with average diameter of 106-300 mu m, [poly(EGDMA-MATrp)], were obtained by copolymerization reaction of N-methacryloyl-L-(+)-tryptophan methyl ester (MATrp) with ethylene glycol dimethacrylate (EGDMA) and successfully applied as a heterogeneous catalyst in conjugate addition reaction of nitromethane to substituted 2-iminochromenes in aqueous media. A variety of 2-amino-4-(nitromethyl)-4H-chromene-3-carbonitriles has been synthesized in good yields. Polymeric microbeads were very durable and reused 5 times without a significant loss of activity. DFT calculations and experimental results revealed the significant role of Tr-Tr interactions as well as hydrogen bonding in the reaction mechanism.Publication A new design to enhance the enzyme activities: Investigation of L-asparaginase catalytic performance by IMAC effect on g-C₃N₄ nanolayers(Springer, 2023-07-08) Sert, Buse; Acet, Ömür; Noma, Samir Abbas Ali; Osman, Bilgen; Odabaşı, Mehmet; Ocakoğlu, Kasim; NOMA, Samir Abbas Ali; OSMAN, BİLGEN; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Kimya Bölümü.; 0000-0001-8406-149X ; ABH-1773-2021; ABF-4791-2020Recently, graphite carbon nitride (g-C3N4) has come to the fore as a new material with its carbon-based two-dimensional structure, simple preparation procedure, and excellent physicochemical stability properties. This study aims to investigate the activity and kinetic studies of the L-asparaginase enzyme via immobilized metal ion affinity chromatography (IMAC) process of g-C3N4 nanolayers. Firstly, g-C3N4 nanolayers were synthetized and Ni2+ ions were binded their surfaces. The synthesized samples were investigated by SEM, ICP-MS, XRD, and FTIR. The highest L-ASNase adsorption on Ni2+-g-C3N4 nanostructures was 444.1 mg/g, at 3 mg/mL L-ASNase concentration. Optimal medium conditions for L-ASNase adsorption occurred at pH 8.0 and 25 degrees C. The immobilized enzyme showed improved stability relating to the soluble enzyme in extreme situations. On the other hand, the storage stability and reusability of the immobilized enzyme were found to be approximately 64 and 53% of the original activity after 29 days at room temperature and 10 cycles, respectively. From the Michaelis-Menten constants Km and Vmax, both of them decreased after immobilization compare to the free one. The obtained outcomes showed that the g-C3N4 is a suitable matrix for L-asparaginase immobilization with ideal catalytic efficiency and improved stability.[GRAPHICS].Publication Dummy molecularly imprinted polymer-based solid-phase extraction method for the determination of some phthalate monoesters in urine by gas chromatography-mass spectrometry analysis(Elsevier, 2023-11-24) Küçük, Melike; Osman, Bilgen; Özer, Elif Tumay; KÜÇÜK, MELİKE; OSMAN, BİLGEN; TÜMAY ÖZER, ELİF; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Kimya Bölümü.; 0000-0001-8406-149X; V-1616-2019; JCP-4547-2023; JME-2199-2023A dummy molecularly imprinted polymer-based solid-phase extraction (SPE) sorbent was used for the selective extraction of some phthalate monoesters, monoethyl phthalate (MEP), monobutyl phthalate (MnBP) and mono-(2-ethylhexyl) phthalate (MEHP) in urine prior to gas-chromatography-mass spectrometry (GC-MS) analysis. Diethyl phthalate (DEP), a phthalate ester, was successfully used as a dummy template to prepare selective sorbent for MEP, MnBP, and MEHP extraction. DEP-imprinted poly(ethylene glycol dimethacrylate N-meth-acryloyl-L-tryptophan methyl ester) (DPEMT) microbeads were synthesized by suspension polymerization and characterized by Fourier Transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and Brunauer Emmet Teller (BET) analysis. The critical parameters (i.e., pH, sorbent amount, ionic strength, sample volume, elution solvent) affecting the extraction performance of the DPEMT-SPE sorbent were optimized. Under optimum conditions, good linearities were obtained in the concentration range of 4 to 60 ng/mL with deter-mination coefficients (R2) of greater than 0.9959. The developed SPE method provided low limits of detection (LOD) of 0.05-1.20 ng/mL and limits of quantification (LOQ) of 0.18-4.01 ng/mL with relative standard de-viations (RSDs) of less than 8.95 % for intra-and inter-day analyses. The proposed SPE method was used to analyze phthalate monoesters in spiked urine samples, and recoveries of 97.45-109.26 % were obtained. DPEMT-SPE sorbent was reused for 15 times without any losses of performance. Consequently, a highly selective and sensitive SPE method based on a dummy molecularly imprinted polymer combined with GC-MS was suc-cessfully developed to monitor human phthalate exposure via urine samples.Publication Molecularly imprinted solid-phase extraction sorbent for selective determination of melatonin(Elsevier, 2021-07-30) Esen, Elif; Osman, Bilgen; Demir, M. Nalan; OSMAN, BİLGEN; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Kimya Bölümü; 0000-0001-8406-149X; ABF-4791-2020In this study, melatonin (MLT)-imprinted poly (ethylene glycol dimethacrylate-N-methacryloyl-L-tryptophan methyl ester) [MLT-PEMATrp] microbeads were prepared for solid phase extraction (SPE) of melatonin (MLT) from edible plants prior to high performance liquid chromatography (HPLC) analysis. The microbeads were prepared via molecular imprinting technique by using MLT as a template. The MLT-PEMATrp microbeads were characterized by using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermal gravimetic analysis (TGA), N2 adsorption/desorption isotherms and swelling test. The parameters such as adsorption time, temperature, adsorbent amount, pH and ionic strength were detailedly optimized to increase the effciency of MLT adsorption procedure. The adsorption properties of MLT onto the MLT-PEMATrp microbeads (MIP) and non-imprinted PEMATrp microbeads (NIP) were investigated to show the effectiveness of imprinting. MIP showed higher adsorption capacity for MLT (QMIP = 207.71 mg g-1) than NIP (QNIP = 12.15 mg g-1). The relative selectivity coefficients calculated for serotonin (3.41) and L-tryptophan (5.94) indicated that MLT-PEMATrp microbeads exhibit significantly high selectivity for MLT. The microbeads were used for SPE of MLT from Linden (Tilia tomentosa), fennel (Foeniculum Vulgare), sage (Salvia officinalis) and chamomilla (Matricaria chamomilla) samples prior to HPLC analysis. The recoveries of MLT in the samples were in the range of 90-103.4%. The SPE method had a limit of detection (LOD) in the range of 0.026-0.094 mu g mL-1. The MLTPEMATrp microbeads was very effective for SPE of MLT.Publication Superhydrophobic surface based on cross-linked polymer(Iop Publishing Ltd, 2019-05-01) Osman, Bilgen; OSMAN, BİLGEN; Aydemir, Tuğba Gün; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi; 0000-0001-8406-149X; ABF-4791-2020The aim of this study was to prepare a superhydrophobic surface by coating poly(divinylbenzene-N-methacryloyl-amido-L-phenylalanine ethyl ester) [poly(DVB-MAPA)] cross-linked polymer onto a glass surface. N-methacryloyl-amido-L-phenylalanine ethyl ester (MAPA) and 1, 4-divinylbenzene (DVB) were used as a monomer and a cross-linker, respectively. The polymerization mixture was dispersed in 1, 4 butanediol (BDO) for phase separation and polymerized on the glass surface. The superhydrophobic surface was characterized with Fourier transform infrared spectroscopy (FTIR), x-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and contact angle measurements. The effect of the composition of a polymerization mixture on hydrophobicity was investigated by varying the cross-linker to monomer mol ratio. Additionally, the influence of the composition of monomer/BDO mixtures was determined. The prepared poly(DVB-MAPA) surface showed a superhydrophobicity with a high water contact angle (WCA) of 162 degrees and a low sliding angle (SA) of 7 degrees . Moreover, the poly(DVB-MAPA) surface has a good chemical, thermal and daylight stability.Publication Adsorptive removal of 4-hydroxybenzoic acid via cross-linked polymeric microbeads: Analysis of isothermal, kinetic and thermodynamic parameters(Taylor & Francis Inc, 2023-05-26) Özer, Elif Tumay; Osman, Bilgen; KÜÇÜK, MELİKE; OSMAN, BİLGEN; TÜMAY ÖZER, ELİF; Bursa Uludağ Üniversitesi/Fen Edebiyat Fakültesi/Kimya Bölümü.; 0000-0001-8406-149X; JCP-4547-2023In this study, the performance of cross-linked microbeads prepared through suspension polymerization was investigated for removal of 4-hydroxybenzoic acid (4-HBA) from aqueous solution. Adsorption studies were conducted at different pHs (2.0-8.0), temperatures (282-308 K) and initial 4-HBA concentrations (1-500 mg/L). The maximum 4-HBA adsorption was 49.05 +/- 2.89 mg/g at pH 2.0 (282 K). The adsorption data obeyed to the Langmuir isotherm model. The modified Ritchie second-order and the pseudo second-order kinetic model fitted the adsorption data. The 4-HBA adsorption capacity did not significantly change after 10 consecutive usages. Gibbs free energy changes of the adsorption were calculated as -24.372, -28.431 and -29.093 kJ/mol for 282, 298 and 308 K, respectively. The microbeads were also used for the removal of 4-HBA from spiked river water samples. The removal efficiencies of 43.2% to 68.8% and RSDs of 0.49% to 4.78% demonstrated the usability of the microbeads in application.Publication P(hema)-so 3 h catalyst: Preparation, characterization and its catalytic activity in ritter reaction(Springer, 2022-10-15) ARIKAN ÖLMEZ, NEVİN; Ölmez, Nevin Arıkan; OSMAN, BİLGEN; Osman, Bilgen; Bursa Uludağ Üniversitesi/Fen Edebiyat Fakültesi/ Kimya Bölümü.; 0000-0001-8406-149X; AAH-6337-2021In this study, poly(hydroxyethyl methacrylate) [P(HEMA)] microsphere-supported sulfuric acid [P(HEMA)-SO3H] was prepared as a novel heterogenous solid acid catalyst and its catalytic activity was investigated in the synthesis of amides via Ritter reaction. The P(HEMA) microspheres were synthesized via suspension polymerization and characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Brunauer, Emmett and Teller surface area and energy dispersive X-ray (EDX) analyses. The specific surface area and the pore volume of the microspheres were determined as 33.80 m(2)/g and 1.490 cm(3)/g, respectively. The pore size was in the range of 9.18-122.59 A degrees. The specific surface area of P(HEMA)-SO3H catalyst was 26.24 m(2)/g decreasing after modification with sulfo groups. FTIR, SEM and EDX analyses demonstrated that P(HEMA) microspheres were successfully modified with sulfo groups. The acidity of P(HEMA)-SO3H catalyst was determined as to 7.48 +/- 0.16 mmol H+/g P(HEMA)-SO3H catalyst by titration with standardized NaOH solution. The catalyst was then successfully applied in the Ritter reaction to prepare a series of different amides in high to excellent yields. The P(HEMA)-SO3H catalyst was recovered and reused four times without a significant decrease in the catalytic activity. The other advantages of this novel catalyst include excellent yield, short reaction time and solvent-free conditions.[GRAPHICS]