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GÜNDÜZ, OĞUZHAN

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GÜNDÜZ

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OĞUZHAN

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2008 - 200912020 - 202421
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Now showing 1 - 10 of 22
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    PublicationOpen Access
    Investigation of the properties of encapsulated hydrophilic and hydrophobic drugs in whey protein microparticles
    (2022-10-01) ULAĞ, SONGÜL; GÜNDÜZ, OĞUZHAN; Irem Deniz K., Ulağ S., Gündüz O.
    © 2022 Elsevier B.V.In this study, the amoxicillin (AMX) and rifampicin (RIF) were loaded into the whey protein (WP) to form the hydrophilic and hydrophobic drugs loaded whey protein microparticles. Scanning electron microscopy (SEM) images demonstrated that AMX addition increased the particle size, but RIF addition decreased the dimensions of the particles. The Fourier-transformed infrared spectroscopy (FTIR) results showed that both drugs were successfully loaded into the protein. AMX and RIF were ultimately released from the WP microparticles after 1440 min, according to the drug release test. Two drugs exhibited the same behaviour, but in the first hour, AMX had more release than the RIF.
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    PublicationOpen Access
    A drug-eluting nanofibrous hyaluronic acid-keratin mat for diabetic wound dressing
    (2022-01-01) EKREN, NAZMİ; GÜNDÜZ, OĞUZHAN; Su S., Bedir T., KALKANDELEN C., Sasmazel H. T. , Basar A. O. , Chen J., EKREN N., GÜNDÜZ O.
    © 2022, Qatar University and Springer Nature Switzerland AG.Diabetes mellitus is a chronic metabolic disease associated with long-term multisystem complications, among which are non-healing diabetic foot ulcers (DFUs). Electrospinning is a sophisticated technique for the preparation of polymeric nanofibers impregnated with drugs for wound healing, burns, and diabetic ulcers. This study describes the fabrication and characterization of a novel drug-eluting dressing made of core–shell structured hyaluronic acid (HA)–keratin (KR)-polyethylene oxide (PEO) and polycaprolactone (PCL) nanofibers to treat diabetic wounds. The core–shell nanofibers produced by the emulsion electrospinning technique provide loading of metformin hydrochloride (MH), HA, and KR in the core of nanofibers, which in return improves the sustained long term release of the drug and prolongs the bioactivity. Morphological and chemical properties of the fibers were examined by SEM, FTIR, and XRD studies. It was observed that the fibers which contain HA and KR showed thin fiber structure, greater swelling capacity, fast degradation and increased cumulative drug release amount than neat emulsion fibers due to the hydrophilic nature of HA and KR. MH showed a sustained release from all fiber samples over 20 days and followed the first-order and Higuchi model kinetics and Fickian diffusion mechanism according to kinetic analysis results. In vitro cell culture studies showed that the developed mats exhibited enhanced biocompatibility performance with HA and KR incorporation. The results show that HA and KR-based emulsion electrospun fiber mats are potentially useful new nanofiber-based biomaterials in their use as drug carriers to treat diabetic wounds.
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    PublicationOpen Access
    Fabrication and optimization of 3D printed gelatin methacryloyl microneedle arrays based on vat photopolymerization
    (2023-01-01) GÜNDÜZ, OĞUZHAN; Baykara D., Bedir T., Ilhan E., Mutlu M. E., GÜNDÜZ O., Narayan R., ÜSTÜNDAĞ C. B.
    Microneedles (MNs) are micrometer-sized arrays that can penetrate the skin in a minimally invasive manner; these devices offer tremendous potential for the transdermal delivery of therapeutic molecules. Although there are many conventional techniques for manufacturing MNs, most of them are complicated and can only fabricate MNs with specific geometries, which restricts the ability to adjust the performance of the MNs. Herein, we present the fabrication of gelatin methacryloyl (GelMA) MN arrays using the vat photopolymerization 3D printing technique. This technique allows for the fabrication of high-resolution and smooth surface MNs with desired geometries. The existence of methacryloyl groups bonded to the GelMA was verified by 1H NMR and FTIR analysis. To examine the effects of varying needle heights (1000, 750, and 500 µm) and exposure times (30, 50, and 70 s) on GelMA MNs, the height, tip radius, and angle of the needles were measured; their morphological and mechanical properties were also characterized. It was observed that as the exposure time increased, the height of the MNs increased; moreover, sharper tips were obtained and tip angles decreased. In addition, GelMA MNs exhibited good mechanical performance with no breakage up to 0.3 mm displacement. These results indicate that 3D printed GelMA MNs have great potential for transdermal delivery of various therapeutics.
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    PublicationOpen Access
    Marine-derived bioceramics for orthopedic, reconstructive and dental surgery applications
    (2022-11-01) OKTAR, FAİK NÜZHET; ÜNAL YILDIRIM, SEMRA; GÜNDÜZ, OĞUZHAN; EKREN, NAZMİ; ALTAN, ERAY; OKTAR F. N. , Unal S., GÜNDÜZ O., Ben Nissan B., Macha I. J. , Akyol S., Duta L., EKREN N., ALTAN E., YETMEZ M.
    Bioceramics are a fast-growing materials group, which are widely used in orthopedics, maxillofacial, dental, and reconstructive surgeries. They are produced using raw materials either from synthetic or natural sources. As naturally originated resources, the bones of sheep and cows are used after converting to calcium phosphates. Human-originated sources in the past were obtained from human cadaver bones, however now-a-days this has been discontinued. On the other hand, the \"golden standard\" in the reconstruction surgery has been using patients own bones, -i.e., autogenous bones, which heal better than other alternatives. Besides natural products, synthetic materials are produced from a range of inorganic raw and natural materials based on marine sources, such as corals, and other marine-derived materials (i.e., seashells, nacre). These are used to produce bioceramics and hence implants, devices, and bone grafts. Although during the last four decades a number of excellent books and book chapters have been published, no comprehensive review has been yet reported to cover the available marine materials and to indicate the related work and corresponding references to allow for both medical and ceramic scientists to access directly and open new avenues for further research on marine structures and their applications in orthopedic, maxillofacial, and reconstructive surgery areas. Hence, this review covers the general marine structures, their locations and availability in different countries and, current research on production methods of these unique structures that are difficult to fabricate synthetically. The authors are confident that this comprehensive review will be an excellent source not only for the ceramists, but also for the medical scientists.
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    PublicationOpen Access
    Microfluidic systems for neural tissue engineering
    (Elsevier Science, Oxford/Amsterdam , 2023-01-01) CESUR, SÜMEYYE; ULAĞ, SONGÜL; GÜNDÜZ, OĞUZHAN; Cesur S., Ulağ S., Gündüz O.
    Damage to the nervous system due to illness or injury can cause serious and lasting loss of function or even fatal consequences. It is necessary to develop new treatment strategies to restore the function of the damaged nervous system.The optimal environment for nerve cell proliferation and differentiation is provided by neural tissue engineering. It aims to improve a new approximation for the therapy of nervous system diseases. Compared to 2D cell culture techniques, 3D cell culture systems ensure a more biomimetic environment and encourage more differentiation of cells. However, certain cell culture parameters have limitations in spatio-temporal control. With the advent of microfluidic systems, it can control the spatio-temporal dispersion of physical and chemical signals at the cellular level. In this section, microfluidic systems are explored as a tool to target both physical and chemical injury and recreate the post-injury environment, to study nerve injury at the cellular grade.
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    PublicationOpen Access
    Casting of Fe-(2–12)Mn-(4–14)Al-(0.09–0.7)C low-density steel via artificial slag practice
    (2022-07-15) GÜNDÜZ, OĞUZHAN; Keler M. K., DAĞLILAR S., KUŞKONMAZ N., Cetin Z., Kart O., Gunduz O., GÜNDÜZ O.
    © 2022In this research theoretical and practical studies have been highlighted about alloy design, casting and steel-slag interaction. The use of a protective slag layer was identified as an advantageous method in the production of low-density steels. For the first time in this study, a unique synthetic steelmaking (CaO/Al2O3:1.57) slag was implemented in an induction furnace with no vacuum chamber to produce high aluminum in steel. This study showed that manganese and aluminum directly influence the solidification structure and carbide formation. Coarser k-carbides have been detected at grain boundaries in austenite as-cast matrix when the Aluminum increases in the low-density steel.
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    PublicationOpen Access
    A Comparison Study of Fiber Diameter's Effect on Characteristic Features of Donepezil/Curcumin-Loaded Polycaprolactone/Polylactic Acid Nanofibers
    (2022-05-01) EKENTOK ATICI, CEYDA; GÜNDÜZ, OĞUZHAN; ÇAM, MUHAMMET EMİN; TATAR, ESRA; YAVUZ, AYŞE NUR; Aydin S., Kabaoglu I., Guler E., Topal F., YAVUZ A. N., EKENTOK ATICI C., TATAR E., Gurbuz F., GÜNDÜZ O., ÇAM M. E.
    Nanofibers (NFs) offer an alternative option for the treatment of Alzheimer\"s disease (AD) by addressing unmet clinical problems. In this study, anti-AD drugs, donepezil (DO) and curcumin (CUR), are loaded in polylactic acid/polycaprolactone NFs. The effect of fiber diameter on drug release behavior is mainly observed, and the successful loading of DO and CUR to NFs is demonstrated. The tensile strength of DO/CUR-loaded NFs (DNFs) with lower fiber diameter is found to be higher. The working temperature is increased by the decrease of glass transition temperature and increase of the melting temperature after loading drugs. Furthermore, the increase in the percentage of swelling and decrease in the degradation rate for NFs are observed due to the increase of fiber diameter. Encapsulation efficiency and burst release percentages for DNFs are augmented by the increase of fiber diameter. Nevertheless, DNFs exhibit a sustained drug release manner over 2 weeks. NFs do not demonstrate a toxic effect on L929 (mouse fibroblast) cells, and additionally, they promote cell proliferation. Considering all these results, it is proven that the fiber diameter affects all characteristic features of NFs, and DNFs lead to a new and promising drug delivery system for the treatment of AD.
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    PublicationOpen Access
    An eco-friendly process to extract hydroxyapatite from sheep bones for regenerative medicine: Structural, morphologic and electrical studies
    (2023-05-01) GÜNDÜZ, OĞUZHAN; OKTAR, FAİK NÜZHET; Gavinho S. R., Bozdag M., KALKANDELEN C., Regadas J. S., Jakka S. K., GÜNDÜZ O., OKTAR F. N., Graça M. P. F.
    Hydroxyapatite (HA) promotes excellent bone regeneration in bone-tissue engineering, due to its similarity to bone mineral and its ability to connect to living tissues. These factors promote the osteointegration process. This process can be enhanced by the presence of electrical charges, stored in the HA. Furthermore, several ions can be added to the HA structure to promote specific biological responses, such as magnesium ions. The main objective of this work was to extract hydroxyapatite from sheep femur bones and to study their structural and electrical properties by adding different amounts of magnesium oxide. The thermal and structural characterizations were performed using DTA, XRD, density, Raman spectroscopy and FTIR analysis. The morphology was studied using SEM, and the electrical measurements were registered as a function of frequency and temperature. Results show that: (i) an increase of MgO amount indicates that the solubility of MgO is below 5%wt for heat treatments at 600 °C; (ii) the rise of MgO content increases the capacity for electrical charge storage; (iii) sheep hydroxyapatite presents itself as a natural source of hydroxyapatite, environmentally sustainable and low cost, and promising for applications in regenerative medicine.
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    PublicationOpen Access
    Biomechanical comparison of a new technique of mandibular angle fractures: Biplanar and bicortical superior proximal 3 holes and bicortical inferior plate fixation
    (2008-01-01) GÜNDÜZ, OĞUZHAN; Turgut G., Kayali M., Soydan A., Gündüz O., Salman S., Oktar F., Baş L.
    Miniplates have been used for mandibular angle fractures during the past 2 decades. The technique of placing single miniplate at the upper border based on the tension lines of the fracture was proposed by Michelet and Champy. The need for a second miniplate to be applied to the lower mandible has been discussed recently. Biomechanical comparison of biplanar and monoplanar dualminiplate fixation techniques was investigated by Haug. Our hypothesis is in dual-miniplate fixation; the proximal 3 holes of superior border miniplate could be fixated by bicortical screws. The first 2 are at the proximal bone segment and are not related to the tooth and also superior to the alveolar nerve. Generally, the third molar tooth is extracted because it is at the fracture site. Hence, the proximal third hole could also be fixated by bicortical screws. We define a biplanar dual-miniplate technique in which the lower plate and the proximal 3 holes of the upper plate are fixated by bicortical screws. We have designed a study for biomechanical comparison of our method and popular types of mandibular fixation methods.
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    PublicationOpen Access
    Gentamicin and fluconazole loaded electrospun polymethylmethacrylate (PMMA) fibers as a novel platform for the treatment of corneal keratitis
    (2022-05-01) GÜNDÜZ, OĞUZHAN; ULAĞ, SONGÜL; GÜNDÜZ O., ULAĞ S.
    In this study, 10 mg fluconazole (10 FCZ) and 10 mg gentamicin (10 GEN) loaded with 40% polymethylmethacrylate (40% PMMA) fibers were fabricated by electrospinning and the performance of the formulations (40% PMMA, 40% PMMA/10 FCZ, 40% PMMA/10 GEN, and 40% PMMA/10 FCZ/10 GEN) was tested. 10 mg Gentamicin-loaded 40% PMMA fiber mat showed a more significant zone of inhibition against the S. aureus compared to the zone of 40% PMMA/10 GEN/10 FCZ fiber. The biocompatibility test using a human adipose-derived mesenchymal stem cell (MSCs) as a cell model proved that the amount of loaded and released GEN has no toxic effects on the MSCs.