Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Ayşegül Ülkü Metin is active.

Publication


Featured researches published by Ayşegül Ülkü Metin.


Bioresource Technology | 2010

Reversible immobilization of glucose oxidase on polyaniline grafted polyacrylonitrile conductive composite membrane.

Gulay Bayramoglu; Ayşegül Ülkü Metin; Begum Altintas; M. Yakup Arica

Polyacrylonitrile membrane surfaces were modified with chemical polymerization of conductive polyaniline. The effect of aniline concentration on the grafting efficiency was investigated. As the amount of grafted PANI increased on the PAN membrane, the electrical resistance of composite membrane decreased. Composite (PAN/PANI)-1-5 membrane were used for reversible immobilization of GOD. The immobilization efficiency and the activity of the immobilized GOD were increased with increasing PANI contents of the composite membrane. The maximum amount of immobilized enzyme into composite PAN/PANI-5 membrane containing 2.1% PANI was about 251 microg/cm(2). Immobilized GOD exhibited 66% of its original activity even after two months of storage at 4 degrees C while the free enzyme lost its initial activity after three weeks.


Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy | 2017

One step effective removal of Congo Red in chitosan nanoparticles by encapsulation

Erol Alver; Mehmet Bulut; Ayşegül Ülkü Metin; Hakan Çiftçi

Chitosan nanoparticles (CNPs) were prepared with ionotropic gelation between chitosan and tripolyphosphate for the removal of Congo Red. The production of chitosan nanoparticles and the dye removal process was carried out in one-step. The removal efficiency of Congo Red by encapsulation within chitosan from the aqueous solution and its storage stability are examined at different pH values. The influence of some parameters such as the initial dye concentration, pH value of the dye solution, electrolyte concentration, tripolyphosphate concentration, mixing time and speed on the encapsulation is examined. Congo Red removal efficiency and encapsulation capacity of chitosan nanoparticles were determined as above 98% and 5107mg Congo Red/g chitosan, respectively.


European Journal of Pharmaceutics and Biopharmaceutics | 2017

Poly (methyl vinyl ether-co-maleic acid) – Pectin based hydrogel-forming systems: Gel, film, and microneedles

Yusuf K. Demir; Ayşegül Ülkü Metin; Betül Şatıroğlu; Mehmet E. Solmaz; Veysel Kayser; Karsten Mäder

Graphical abstract Figure. No caption available. ABSTRACT Cross‐linking of natural and synthetic polymers is widely explored to achieve the desired material properties (mechanical strength, drug loading capacity, swelling and erosion rates). However, the potential of polymers produced by crosslinking poly (methyl vinyl ether‐co‐maleic acid) (PMVE/MA) and pectin (PE) in pharmaceutics is mainly unexplored so far. We have investigated the effect of various esterification conditions and pectin content on the physicochemical properties. Materials have been characterized by fourier transform infrared, differential scanning calorimetry and scanning electron microscopy. In addition, swelling and bioadhesive features of PMVE/MA‐PE hydrogel systems were investigated. A band shift for the carbonyl group from 1706 to 1776 cm−1, and glass transition (Tg) increased from 55.4 ± 0.9 °C to 119.5 ± 0.3 °C confirmed the formation of esterification reaction within the cross‐linked films. Cross‐linked PMVE/MA:PE films with a ratio of 5 demonstrated a superior mass increase when compared to 2.5, 3.125, 3.75, 6.25, and 7.5 ratios of the same hydrogel film. Formulations containing PMVE/MA and pectin with a ratio of 3.75 showed superior bioadhesive features. For the first time, we engineered three‐dimensional printing based swell‐able microneedle arrays made out of cross‐linked PMVE/MA‐PE. Microneedle arrays height and aspect ratio were ranged from 702.5 ± 11.9 &mgr;m to 726 ± 23.3 &mgr;m and 3.12 ± 0.20 to 3.29 ± 0.21, respectively. Cross‐linked PMVE/MA‐PE Microneedle arrays (10‐2, 24 h) indicated the least height loss, 22.33 ± 4.15%, during axial compression test; whilst, transverse failure of cross‐linked PMVE/MA‐PE Microneedle arrays was varied from 0.15 ± 0.05 to 0.25 ± 0.04 N/needle. In conclusion, we obtained a novel cross‐linked polymer system with promising features of drug delivery and bio‐analytical applications.


Artificial Cells Nanomedicine and Biotechnology | 2013

Fabrication and characterization of gold-nanoparticles/chitosan film: a scaffold for L929-fibroblasts

Mustafa Türk; Ugur Tamer; Erol Alver; Hakan Çiftçi; Ayşegül Ülkü Metin; Siyami Karahan

Abstract The objective of the present study was to fabricate a gold nanoparticle crosslinked chitosan (Ch/AuNPs) composite film simple and to evaluate its use as a carrier matrix for L929- fibroblasts. L929- fibroblasts were seeded either onto Ch or Ch/AuNPs scaffolds. The Ch/AuNPs scaffold exhibited a higher cell proliferation and growth rate. The cytotoxicity test determined trypan blue staining indicated that Ch scaffolds devoid of AuNPs expressed almost no toxicity while the Ch/AuNPs composite scaffolds expressed a very limited toxicity only at higher doses. The Ch/AuNPs scaffold promotes cell attachment, growth and proliferation with almost no cytotoxicity.


Journal of Dispersion Science and Technology | 2018

Bioremoval of mercury (II) from aqueous solutions by Phragmites australis: Kinetic and equilibrium studies

Gökben Başaran Kankılıç; Ayşegül Ülkü Metin; Yaşar Aluç; Ogün Bozkaya

Abstract In this study, the removal of mercury (II) ions from aqueous solutions by dried biomass of Phragmites australis was investigated in the batch system. The biomass was characterized by Fourier transform infrared spectroscopy (FT-IR), energy dispersive X-ray fluorescence (ED-XRF), Brunauer–Emmett–Teller (BET) surface area techniques (BET). Inductively Coupled Plasma Atomic Emission Spectrophotometer (ICP-OES, Spectro Blue) was used to analyze Hg(II) concentration and obtained data in batch experiments indicated that Hg (II) was rapidly adsorbed and such adsorption reached equilibrium within 60 min. The initial pH of the solution was effective parameter for Hg (II) biosorption. The biosorption kinetics was in better good fit with pseudo-second order kinetics and the results obtained from the batch experiments were conformed better with the Langmuir isotherm model than Freundlich and D-R isotherm models. The maximum Hg (II) biosorption capacity of P.australis was 20.0 ± 0.4 mg/g. The availability of other metal ions affected mercury biosorption. Adsorption/desorption studies demonstrated that the adsorbed Hg (II) could be desorbed effectively with a 0.1 M ethylenediamine tetra-acetic acid (EDTA) solution. The biosorption capacity of the regenerated biosorbent could still be maintained at 72% at the fifth adsorption–desorption cycle. Consequently, it can be said that P. australis can be used as an applicable, cost-efficient, nature friendly biosorbent for treating wastewater. Graphical Abstract


Environmental Technology | 2018

Investigation on phenol degradation capability of Scenedesmus regularis: influence of process parameters

Gökben Başaran Kankılıç; Ayşegül Ülkü Metin; Yaşar Aluç

ABSTRACT Phenol removal from environmental solutions has attracted much attention due to phenol’s high toxicity, even at low concentrations. This study aims to reveal the phenol biodegradation capacity of Scenedesmus regularis. Batch system parameters (pH, amount of algal cell, phenol concentration) on biodegradation were examined. After 24 h of treatment, 92.16, 94.50, 96.20, 80.53, 65.32, 52 and 40% of phenol were removed by Scenedesmus regularis in aqueous solutions containing 5, 10, 15, 20, 30, 40 and 50 mg/L of phenol, respectively. To describe the correlation between degradation rate and phenol concentration, the Michaelis–Menten kinetic equation was used where Vmax and Km are 0.82 mg phenol g algea−1 h−1 and 24.97 ppm, respectively. Phenol remediation ability of S.regularis can enable the usage of the spent biomass as biofuel feedstock and animal feed makes it a ‘green’ environmental sustainable process. GRAPHICAL ABSTRACT


Chemical Engineering Journal | 2012

Anionic dye removal from aqueous solutions using modified zeolite: Adsorption kinetics and isotherm studies

Erol Alver; Ayşegül Ülkü Metin


Process Biochemistry | 2009

Polyaniline grafted polyacylonitrile conductive composite fibers for reversible immobilization of enzymes: Stability and catalytic properties of invertase

Gulay Bayramoglu; Meral Karakışla; Begum Altintas; Ayşegül Ülkü Metin; Mehmet Saçak; M. Yakup Arica


Mikrochimica Acta | 2016

Non-enzymatic sensing of glucose using a glassy carbon electrode modified with gold nanoparticles coated with polyethyleneimine and 3-aminophenylboronic acid

Hakan Çiftçi; Erol Alver; Filiz Çelik; Ayşegül Ülkü Metin; Ugur Tamer


Industrial & Engineering Chemistry Research | 2013

Efficient Removal of Acidic Dye Using Low-Cost Biocomposite Beads

Ayşegül Ülkü Metin; Hakan Çiftçi; Erol Alver

Collaboration


Dive into the Ayşegül Ülkü Metin's collaboration.

Top Co-Authors

Avatar

Erol Alver

Kırıkkale University

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Researchain Logo
Decentralizing Knowledge