Person: TOKSOY ÖNER, EBRU
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TOKSOY ÖNER
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Publication Metadata only Lecithin-acrylamido-2-methylpropane sulfonate based crosslinked phospholipid nanoparticles as drug carrier(WILEY, 2016) TOKSOY ÖNER, EBRU; Mutlu, Esra Cansever; Bostan, Muge Sennaroglu; Bahadori, Fatemeh; Kocyigit, Abdurrahim; Oner, Ebru Toksoy; Eroglu, Mehmet S.In this study, a novel paclitaxel (PTX) loaded and a crosslinked solid phospholipid nanoparticles (SLN-PTX) with negative surface charge was prepared by UV polymerization for drug delivery. Capping of positive charge of zwitterionic lecithin with negative charge of sodium 2-acrylamido-2-methyl-1-propanesulfonate (AMPS-Na) through cation exchange interaction produced a lecithin-AMPS (L-AMPS) complex. The amphiphilic and negative charged lipid complex was emulsified in the presence of emulsifier, paclitaxel, initiator, and methacrylated poly epsilon-caprolacton-diol (PCL-MAC) as a spacer. The colloidal system was subjected to UV-irradiation to obtain crosslinked nanoparticles. Completion of the UV-polymerization was monitored with differential scanning calorimetry (DSC), which indicated the disappearance of exothermic peaks of vinyl groups. The nanoparticle system, having an average size of 200 nm, exhibited high drug encapsulation (96%) with negatively charged surface (zeta potential had an average of -70 mV). PTX release profiles of the crosslinked and uncrosslinked SLN-PTXs were studied and their pharmacological properties were compared. The crosslinked nanoparticles exhibited more controlled release behavior with longer release time compared to the uncrosslinked ones. In vitro cytotoxicity test was conducted on MCF-7 human breast adenocarcinoma cell line, which indicated that the crosslinked SLN-PTXs have a potential therapeutic effect for breast cancer treatments. (c) 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44105.Publication Metadata only Synthesis and characterization of levan hydrogels and their use for resveratrol release(SAGE PUBLICATIONS LTD, 2021) TOKSOY ÖNER, EBRU; Selvi, Sinem Selvin; Haskoylu, Merve Erginer; Genc, Seval; Toksoy Oner, EbruConsidering the need for systematic studies on levan based hydrogels to widen their use in drug delivery systems and biomedical applications, this study is mainly focused on the synthesis and comprehensive characterization as well as drug release properties of hydrogels based on Halomonas levan (HL) and its chemical derivatives. For this, hydrolyzed and phosphonated HL derivatives were chemically synthesized and then cross-linked with 1,4-Butanediol diglycidyl ether (BDDE) and the obtained hydrogels were characterized in terms of their swelling, adhesivity, and rheological properties. Both native and phosphonated HL hydrogels retained their rigid gel like structure with increasing shear stress levels and tack test analysis showed superior adhesive properties of the phosphonated HL hydrogels. Moreover, hydrogels were loaded with resveratrol and entrapment and release studies as well as cell culture studies with human keratinocytes were performed. Biocompatible and adhesive features of the hydrogels confirmed their suitability for tissue engineering and drug delivery applications.Publication Metadata only Novel levan and pNIPA temperature sensitive hydrogels for 5-ASA controlled release(ELSEVIER SCI LTD, 2017) TOKSOY ÖNER, EBRU; Osman, Asila; Oner, Ebru Toksoy; Eroglu, Mehmet S.Levan based cross-linker was successfully synthesized and used to prepare a series of more biocompatible and temperature responsive levan/N-isopropyl acrylamide (levan/pNIPA) hydrogels by redox polymerization at room temperature. Volume phase transition temperature (VPTT) of the hydrogels were precisely determined by derivative differential scanning calorimetry (DDSC). Incorporation of levan into the pNIPA hydrogel increased the VPTT from 32.8 degrees C to 35.09 degrees C, approaching to body temperature. Swelling behavior and 5-aminosalicylic acid (5-ASA) release of the hydrogels were found to vary significantly with temperature and composition. Moreover, a remarkable increase in thermal stability of levan within hydrogel with increase of pNIPA content was recorded. The biocompatibility of the hydrogels were tested against mouse fibroblast L929 cell line in phosphate buffer saline (PBS, pH 7.4). The hydrogels showed increasing biocompatibility with increasing Levan ratio, indicating levan enhanced the hydrogel surface during swelling. (C) 2017 Elsevier Ltd. All rights reserved.Publication Metadata only Encapsulated melatonin in polycaprolactone (PCL) microparticles as a promising graft material(ELSEVIER SCIENCE BV, 2019) ÖZBEYLİ, DİLEK; Gurler, Esra Bihter; Ergul, Necdet Mekki; Ozbek, Burak; Ekren, Nazmi; Oktar, Faik Nuzhet; Haskoylu, Merve Erginer; Oner, Ebru Toksoy; Eroglu, Mehmet Sayip; Ozbeyli, Dilek; Korkut, Veysel; Temiz, Ahmet Furkan; Kocanali, Nil; Gungordu, Rosa Juvan; Kilickan, Duhan Berkan; Gunduz, OguzhanElectrospraying assures many advantages with taking less time and costing less relatively to the other conventional particle production methods. In this research, we investigated the encapsulation of melatonin (MEL) hormone in polycaprolactone (PCL) microparticles by using electrospraying method. Morphology analysis of the produced particles completed with Scanning Electron Microscopy (SEM). SEM images demonstrated that microparticles of 3 wt% PCL solution has the most suitable particle diameter size (2.3 +/- 0.64 mu m) for melatonin encapsulation. According to the characterization of the particles, electrospraying parameters like optimal collecting distance, the flow rate of the solution and voltage of the system detected as 8 cm, 0.5 ml/h, and 10 kV respectively. For determining the chemical bonds of scaffold Fourier-Transform Infrared Spectroscopy (FTIR) were used and FTIR results showed that melatonin successfully loaded into PCL micro-particles. Drug release kinetics of the melatonin loaded particles indicated that melatonin released with a burst at the beginning and release behavior became sustainable over a period of 8 h with the encapsulation efficiency of about 73%. In addition, both in-vitro and in-vivo studies of the graft materials also completed. Primary human osteoblasts (HOB) cells and female Sprague Dawley rats were used in in-vitro and in-vivo studies. Test results demonstrate cell population, and bone volume of the rats grafted with composites has remarkably increased, this caused remodelling in bone structure. Overall, these findings indicate that encapsulation of melatonin in the PCL particles with electrospray method is optimum for new synthetic graft material.Publication Metadata only Adhesive nanostructured multilayer films using a bacterial exopolysaccharide for biomedical applications(ROYAL SOC CHEMISTRY, 2013) TOKSOY ÖNER, EBRU; Costa, Rui R.; Neto, Ana I.; Calgeris, Ilker; Correia, Clara R.; Pinho, Antonio C. M.; Fonseca, Jaime; Oner, Ebru T.; Mano, Joao F.Medical adhesives and sealants often require that long-term adhesiveness is achieved. In this work, nanostructured coatings consisting of chitosan and the adhesive bacterial exopolysaccharide levan are fabricated using layer-by-layer (LbL) assembly. Taking advantage of the electrostatic self-assembly mechanism of LbL, the charges of both chitosan and a phosphonate-derivatized levan (Ph-levan) are measured and the feasibility of constructing hybrid films is monitored and confirmed using a quartz crystal microbalance with dissipation monitoring (QCM-D). The adhesive properties between two identical bonded films with a total of 100 layers are compared to control films in which Ph-levan is replaced by alginate, revealing that the detachment force of the former is about 3 times higher than the control. Scanning electron microscopy of the films surface shows that the surface of Ph-levan films is smooth and homogeneous. Cell adhesion tests were conducted using a L929 cell line. Early cell adhesion is significantly higher in chitosan/Ph-levan films when compared to chitosan/alginate controls. These findings establish levan derivatives as bioinspired ingredients for conceiving medical adhesive devices that allow achieving enhanced mechanical and biological performance.Publication Metadata only Gradient multifunctional biopolymer thin film assemblies synthesized by combinatorial MAPLE(ELSEVIER SCIENCE BV, 2019) TOKSOY ÖNER, EBRU; Mihailescu, Natalia; Haskoylu, Merve Erginer; Ristoscu, Carmen; Bostan, Muge Sennaroglu; Sopronyi, Mihai; Eroglu, Mehmet S.; Chifiriuc, Mariana Carmen; Mustaciosu, Cosmin Catalin; Axente, Emanuel; Oner, Ebru Toksoy; Mihailescu, Ion N.Combinatorial Matrix-Assisted Pulsed Laser Evaporation (C-MAPLE) was recently introduced to the fast generation of compositional libraries of two biopolymers in a single-step process, for tissue engineering and regenerative medicine applications. Synchronized laser irradiation of two distinct cryogenic targets, one consisting of Sulfated Halomonas Levan and the other of quaternized low molecular weight Chitosan was used to fabricate compositional gradient coatings for surface functionalization. Synthesized coatings preserved the base material composition as confirmed by Fourier Transform Infrared Spectroscopy. Morphological study by Scanning Electron Microscopy, Atomic Force Microscopy and profilometry correlated with water contact angles measurements demonstrated that the obtained thin coatings have improved surface properties with respect to pure material coatings. Fluorescence microscopy validated the compositional gradient, while in vitro assays evidenced characteristic responses of mouse fibroblasts (L929 cell line) by distinct deposition surface regions. The coagulation test pointed out good properties for Sulfated Halomonas Levan coatings as compared to the case of an increased amount of quaternized low molecular weight Chitosan biopolymer or the control. The antimicrobial effect of the coatings was demonstrated against Escherichia coli and Staphylococcus aureus strains, representative for both Gram negative and Gram positive bacterial species, respectively, mainly involved in implant and nosocomial infections. The assembled nanostructures possess variable anti-biofilm activity along the compositional gradient, with a stronger inhibitory effect on the initial adherence phase of both tested microbial strains, but also against mature Escherichia coli biofilms. It was shown that C-MAPLE can generate discrete areas of blended polymeric composition exhibiting improved surface properties for a broad range of biomedicine applications, e.g. the fabrication of thin bioactive and cell-instructive coatings with anti-adherence properties.