Browsing by Author "Isoglu, Ismail Alper"

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3-Sulfopropyl methacrylate based cryogels as potential tissue engineering scaffolds
(TAYLOR & FRANCIS LTD, 2-4 PARK SQUARE, MILTON PARK, ABINGDON OR14 4RN, OXON, ENGLAND, 2019) Durukan, Adile Yuruk; Isoglu, Ismail Alper; 0000-0001-6428-4207; AGÜ, Yaşam ve Doğa Bilimleri Fakültesi, Biyomühendislik Bölümü
In this study, we developed cryogels containing 3-sulfopropyl methacrylate (SPMA) and 4-vinyl pyridine (4-VP) as a potential scaffold for tissue engineering applications. Cryogels with varying monomer ratios were synthesised by chemical cross-linking under cryogelation conditions. Effect of initiators and cross-linker amount (0.025-0.15 g MBA; 0.012-0.05 g APS; 2.5-12.5 mu l TEMED) and also freezing temperature (-20 and -80oC) were investigated, and the conditions were optimised according to the morphological structures examined by SEM. The functional groups of the materials were characterised by FT-IR. Compression test and swelling were applied to investigate mechanical properties and water absorption ability, respectively. As a preliminary study, selected materials were tested for cell cytotoxicity with MTT. According to our results, the ionic and biocompatible cryogels prepared in this study possessing a highly porous and interconnective structure with good mechanical characteristics and swelling properties can be suitable as tissue scaffolds for many applications.
Advances in Micelle-based Drug Delivery: Cross-linked Systems
(BENTHAM SCIENCE PUBL LTDEXECUTIVE STE Y-2, PO BOX 7917, SAIF ZONE, 1200 BR SHARJAH, U ARAB EMIRATES, 2017) Isoglu, Ismail Alper; Ozsoy, Yildiz; Isoglu, Sevil Dincer; 0000-0002-6887-6549; AGÜ, Yaşam ve Doğa Bilimleri Fakültesi, Biyomühendislik Bölümü
There are several barriers that drug molecules encounter in body beginning from kidney filtration and reticulo-endothelial system (RES) clearance to cellular trafficking. Multifunctional nanocarriers have a great potential for the delivery of drugs by enhancing therapeutic activity of existing methodologies. A variety of nanocarriers are constructed by different material types, which have unique physicochemical properties for drug delivery applications. Micelles formed by amphiphilic polymers are one of the most important drug/nanocarrier formulation products, in which the core part is suitable for encapsulation of hydrophobic agent whereas the outer shell can be utilized for targeting the drug to the disease area. Micelles as self-assembled nanostructures may encounter difficulties in biodistribution of encapsulated drugs because they have a tendency to be dissociated in dilution or high ionic strength. Therefore, therapeutic efficiency is decreased and it requires high amount of drug to be administered to achieve more efficient result. To overcome this problem, covalently stabilized structures produced by cross-linking in core or shell part, which can prevent the micelle dissociation and regulate drug release, have been proposed. These systems can be designed as responsive systems in which cross-links are degradable or hydrolysable under specific conditions such as low pH or reductive environment. These are enhancing characteristics in drug delivery because their cleavage allows the release of bioactive agent encapsulated in the carrier at a certain site or time. This review describes the chemical methodologies for the preparation of cross-linked micelles, and reports an update of latest studies in literature.
Centella AsiaticaExtract Containing Bilayered Electrospun Wound Dressing
(KOREAN FIBER SOC, KOREA SCIENCE TECHNOLOGY CTR #501 635-4 YEOGSAM-DONG, KANGNAM-GU, SEOUL 135-703, SOUTH KOREA, 2020) Isoglu, Ismail Alper; Koc, Nuray; AGÜ, Yaşam ve Doğa Bilimleri Fakültesi, Biyomühendislik Bölümü
Innovative and bioactive wound dressings prepared by electrospinning mimicking the native structure of the extracellular matrix (ECM) have gained significant interest as an alternative to conventional wound care applications. In this study, bilayered wound dressing material was produced by sequential electrospinning of quaternized poly(4-vinyl pyridine) (upper layer) on theCentella Asiatica(CA) extract containing electrospun poly(D, L-lactide-co-glycolide) (PLGA)/poly(3-hydroxybutyrate-co-3-hydroxy valerate) (PHBV) blend membrane (lower layer). Scanning electron microscopy (SEM) was utilized to show a uniform and bead-free fiber structure of electrospun membranes. The average diameter of CA extract containing electrospun PLGA/PHBV blend membrane was calculated 0.471 +/- 0.11 mu m, whereas the average fiber diameter of electrospun poly(Q-VP) membranes was in the range of 0.460 +/- 0.057 mu m. Chemical, thermal, mechanical properties, and adsorption capacity of electrospun membranes, as well as the cumulative release of CA from the electrospun PLGA/PHBV membrane, were investigated. Viability, adhesion, and attachment of human fibroblast cells on the electrospun membranes on pre-set days were evaluated by the colorimetric CellTiter 96 (R) Aqueous One Solution Cell Proliferation Assay (MTS assay) and SEM. Results revealed that CA loaded bilayered electrospun wound dressing showed promoted attachment and proliferation of fibroblasts. Hence, it can be concluded that CA extract containing bilayered electrospun wound dressing prepared in this study has a promising potential for wound healing applications.
Investigation of the Interaction of Adipose-Derived Mesenchymal Stem Cells with ε-Polycaprolactone and Egg White Scaffolds
(GAZİ ÜNİVERSİTESİ, 2023) Oztel, Olga N.; Yilmaz, Hilal; Isoglu, Ismail Alper; Allahverdiyev, Adil; 0000-0001-6428-4207; AGÜ, Yaşam ve Doğa Bilimleri Fakültesi, Biyomühendislik Bölümü; Isoglu, Ismail Alper
The development of three-dimensional (3D) cell culture models is becoming increasingly important due to their numerous advantages over conventional monolayer culture. This study aimed to examine the interaction of adipose tissue-derived mesenchymal stem cells (AD-MSCs) with scaffolds composed of ε-polycaprolactone (ε-PCL) and egg white. In our study, ε-PCL and egg white scaffolds were produced from their monomers by tin octoate catalyzed and heat polymerization, respectively. Characterization of ε-PCL was carried out by Gel Permeation Chromatography (GPC), Fourier Transform Infrared Spectrophotometry (FTIR), Proton Nuclear Magnetic Resonance (H-NMR), Differential Scanning Calorimetry (DSC) and Scanning Electron Microscopy (SEM). AD-MSCs labeled with red fluorescent CellTracker CM-DiI were cultured on egg white and ε-PCL scaffolds for 12 days. Cell viability was determined using 3-(4.5- Dimethylthiazol-2yl)-2.5-diphenyltetrazolium bromide (MTT) and nitric oxide (NO) level was evaluated for toxicity. The results showed that the number of AD-MSCs in the egg white scaffold increased periodically for 12 days compared to the other groups. Although the number of ADMSCs in the ε-PCL scaffold increased until day 6 of the culture, the number of cells started to decrease after day 6. These results were associated with the toxic effect of lactic acid release on cells resulting from the decomposition of ε-PCL scaffolds through catabolic reactions. Therefore, these results indicated that the egg white scaffold enhanced and maintained cell adhesion and cell viability more than the ε-Polycaprolactone scaffold and could be used as a scaffold in tissue engineering studies involving stem cells.
On the detailed mechanical response investigation of PHBV/PCL and PHBV/PLGA electrospun mats
(IOP PUBLISHING LTD, TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND, 2019) Bal, Burak; Tugluca, Ibrahim Burkay; Koc, Nuray; Isoglu, Ismail Alper; 0000-0002-7389-9155; 0000-0001-6428-4207; AGÜ, Yaşam ve Doğa Bilimleri Fakültesi, Biyomühendislik Bölümü
In this study, electrospun mats of pristine poly(epsilon-caprolactone) (PCL), Poly(D, L-lactide-co-glycolide) (PLGA), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), as well as PHBV/PCL blends and PHBV/PLGA blends in different ratios (80:20, 75:25, 50:50, 25:75, 20:80, 10:90, 5:95%, w/w) and Centella Asiatica (CA) loaded (1, 5, 10%, w/v) PHBV/PCL and PHBV/PLGA polyester blends were prepared. Electrospun mats were characterized by scanning electron microscopy (SEM) in order to show uniform and bead and defect-free fiber structure with average diameter. The blend ratio and strain rate dependencies of mechanical behavior of these electrospun membranes were investigated under tensile loading. The tensile tests were conducted at an initial strain rates of 10(-1) s(-1), 10(-2) s(-1), 10(-3) s(-1) and 10(-4) s(-1) at room temperature and the best and worst combinations of PHBV/PLGA, PHBV/PCL blend ratios for both stress and ductility required applications were specified for each strain rate. The effects of blend ratios on the tensile strength and Young's modulus were also investigated. Moreover, the effects of Centella Asiatica on the electrospun membranes' mechanical behavior were demonstrated at different strain rates. Consequently, this study constitutes an important guideline for the selection and usage of the aforementioned electrospun membranes as a wound dressing material in terms of mechanical response at different loading scenarios.
Pericardial fluid and vascular tissue engineering: A preliminary study
(IOS PRESSNIEUWE HEMWEG 6B, 1013 BG AMSTERDAM, NETHERLANDS, 2021) Sonmezer, Dilek; Latifoglu, Fatma; Toprak, Guler; Duzler, Ayhan; Isoglu, Ismail Alper; AGÜ, Mühendislik Fakültesi, Malzeme Bilimi ve Nanoteknoloji Mühendisliği Bölümü; Isoglu, Ismail Alper
BACKGROUND: The heart is surrounded by a membrane called pericardium or pericardial cavity. OBJECTIVE: In this study, we investigated the pericardial fluid (PF) for coating polycaprolactone (PCL) scaffolds. PFS, which is a PF component, was used for the coating material. In addition to using PFS for surface coating, MED and fetal bovine serum (FBS) were also used for comparison. METHODS: Pericardial fluid cells (PFSc) isolated from PF were cultured on coated PCL scaffolds for 1, 3, and 5 days. Cell viability was determined using 3-(4, 5-di-methylthiazol- 2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. RESULTS: The MTT assay results showed that the viability of cells on PCL scaffold coated with PFS increased over time (P < 0.005), and cell viability was significantly different between PCL scaffolds coated with PFS and non-coated PCL scaffolds. However, cell viability was significantly higher in the PCL scaffolds coated with PFS than non-coated and coated with FBS, MED, and PCL scaffolds. Scanning electron microscopy (SEM) microscopy images and MTT assay indicated that PFSc are attached, proliferated, and spread on PCL scaffolds, especially on PCL scaffolds coated with PFS. CONCLUSIONS: These results suggest that PFS is a biocompatible material for surface modification of PCL scaffolds, which can be used as a suitable material for tissue engineering applications.
Preparation and Characterization of Viburnum Opulus Containing Electrospun Membranes as Antibacterial Wound Dressing
(KOREAN FIBER SOC, 2023) Yuruk, Adile; Isoglu, Sevil Dincer; Isoglu, Ismail Alper; 0000-0003-1611-9105; 0000-0002-6887-6549; 0000-0001-6428-4207; AGÜ, Yaşam ve Doğa Bilimleri Fakültesi, Biyomühendislik Bölümü; Yuruk, Adile; Isoglu, Sevil Dincer; Isoglu, Ismail Alper
Herein, we fabricated polycaprolactone/gelatin electrospun membranes possessing different amounts of Viburnum Opulus extract (0, 25, 35, 50%, w/v) as an antibacterial wound dressing. We investigated chemical, morphological, physical, and mechanical properties as well as in vitro degradation behavior of the electrospun membranes. The antibacterial activities of membranes were evaluated against gram-positive Staphylococcus aureus (S. aureus) and gram-negative Escherichia coli (E. coli). The membranes containing Viburnum Opulus exhibited excellent antibacterial activity with the formation of inhibition zones of 25 mm to 36 mm against Escherichia coli and 14 mm to 25 mm against Staphylococcus aureus. The fiber diameters rose from 591 to 1222 nm after adding Viburnum Opulus extract. The extract-containing membranes displayed superior swelling, cell viability, and proliferation properties to neat membranes. Our results showed that the polycaprolactone/gelatin electrospun membranes containing Viburnum Opulus could be a suitable material for wound dressing applications.
Preparation of antibacterial electrospun poly(D, L-lactide-co-glycolide)/gelatin blend membranes containing Hypericum capitatum var. capitatum
(TAYLOR & FRANCIS AS, KARL JOHANS GATE 5, NO-0154 OSLO, NORWAY, 2020) Aksit, Nazende Nur; Gurdap, Seda; Isoglu, Sevil Dincer; Isoglu, Ismail Alper; 0000-0002-6887-6549; 0000-0001-6428-4207; AGÜ, Yaşam ve Doğa Bilimleri Fakültesi, Biyomühendislik Bölümü
In this study, we fabricated poly(D, L-lactide-co-glycolide)/gelatin (PLGA/gelatin) membranes containing different amounts of Hypericum capitatum var. capitatum (HCC) extract (1, 5, 7.5, 10 wt%) by electrospinning technique. We investigated chemical, morphological, physical, and mechanical properties as well as in vitro degradation behavior of the electrospun membranes. We also evaluated the antibacterial activity of the electrospun membranes against Escherichia coli and Staphylococcus aureus. Viability, adhesion, and attachment of human fibroblast cells on the electrospun membranes on pre-set days were evaluated by the colorimetric CellTiter 96(R) AQueous One Solution Cell Proliferation Assay (MTS assay), scanning electron microscopy (SEM), and 4',6-Diamidino-2-Phenylindole (DAPI) staining.
RAFT-synthesized POEGMA-b-P4VP block copolymers: preparation of nanosized micelles for anticancer drug release
(SPRINGERONE NEW YORK PLAZA, SUITE 4600 , NEW YORK, NY 10004, UNITED STATES, 2021) Bayram, Nazende Nur; Topuzogullari, Murat; Isoglu, Ismail Alper; Isoglu, Sevil Dincer; 0000-0002-8697-1654; AGÜ, Yaşam ve Doğa Bilimleri Fakültesi, Biyomühendislik Bölümü; Bayram, Nazende Nur; Isoglu, Ismail Alper; Isoglu, Sevil Dincer
To achieve high stability and biocompatibility in physiological environment, oligoethyleneglycol methacrylate (OEGMA) and 4-vinylpyridine (4VP)-based amphiphilic block copolymers were prepared as micellar carriers to deliver doxorubicin into tumor cells. First, macroinitiator of OEGMA was synthesized by RAFT polymerization at [M](0)/[CTA](0)/[I](0) ratio of 100/1/0.2 in dimethylformamide (DMF) at 70 degrees C, in the presence of 4,4'-azobis(4-cyanovaleric acid) (ACVA) as initiator and 4-cyano-4-(thiobenzoylthio)pentanoic acid (CTA) as chain transfer agent, respectively. It was followed by copolymerization with 4-VP at similar conditions. The formation of RAFT-mediated polymers was approved by FTIR, H-1-NMR and GPC. For the preparation of drug-loaded micelles, a dialysis method was applied and hydrophobic doxorubicin, as a model drug, was entrapped into the micelles. Size distributions and morphologies of drug-loaded micelles were investigated by light scattering and scanning electron microscopy, respectively. Critical micelle concentration was estimated as 0.0019 mg/mL by measuring light scattering intensity in different polymer concentrations. Also, drug loading and entrapment efficiencies were calculated as 4.41% and 17.65% by measuring the DOX amount in the micelles, spectrophotometrically. At last, the drug-loaded micelles were applied to SKBR-3 breast cancer cell lines and revealed up to %40 cell inhibition at 48 and 72 h. As a result, these nanosized and biocompatible micelles can be used for the delivery of hydrophobic drugs, and they can also be modified for further targeting and imaging applications toward specific cancer cells.
Sulfobetaine-Based Homo- and Copolymers by RAFT: Cross-Linked Micelles and Aqueous Solution Properties
(AMER CHEMICAL SOC, 2022) Gurdap, Seda; Bayram, Nazende Nur; Isoglu, Ismail Alper; Isoglu Dincer, Sevil; 0000-0002-6887-6549; 0000-0001-6428-4207; 0000-0001-6582-4981; 0000-0002-8697-1654; AGÜ, Yaşam ve Doğa Bilimleri Fakültesi, Biyomühendislik Bölümü; Gürdap, Seda; Bayram, Nazende Nur; İsoğlu, İsmail Alper; İsoğlu Dinçer, Sevil
In this study, we describe the synthesis and aqueous solution behavior of temperature-sensitive N-(3-sulfopropyl)-N-methacroyloxyethyl-N,N-dimethylammonium betaine (SBMA) homopolymers and core cross-linked micelles (CCMs) with an SBMA shell. Reversible addition–fragmentation chain transfer polymerization has been utilized to synthesize sulfobetaine homopolymers, followed by CCM formation during copolymerization in the presence of an acid-degradable cross-linker. First, SBMA homopolymers of varying chain lengths were synthesized, and it has been demonstrated that an increase in the chain length and concentration of the homopolymer resulted in an increase in the upper critical solution temperature (UCST). Besides, micelles showed concentration-dependent dual temperature-sensitive behavior with UCST and LCST transitions. Also, homopolymers and CCMs were characterized by FTIR, 1H-NMR, GPC, and TEM. Micelle formation and temperature sensitivity were also investigated by DLS. As a result, stabilized micelles were successfully prepared with the motivation of preventing premature drug release and achieving a pH- and temperature-controlled system. Due to their dual-responsive characteristics, the CCMs show promising potential to be used as smart drug carriers for controlled delivery.
Synthesis and characterization of 4-VP/SPMA cryogels
(WILEY, 111 RIVER ST, HOBOKEN 07030-5774, NJ USA, 2019) Isoglu, Ismail Alper; Durukan, A. Yuruk; AGÜ, Yaşam ve Doğa Bilimleri Fakültesi, Moleküler Biyoloji ve Genetik Bölümü;
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