Browsing by Author "Ozdemir, Suzan"

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    EVALUATING BIODEGRADATION RATES IN NEAT PCL- AND PCL/PLA-BASED BIOCOMPATIBLE TUBULAR SCAFFOLDS
    (Technical University of Liberec, ) Oztemur, Janset; Ozdemir, Suzan; Tezcan-Unlu, Havva; Cecener, Gulsah; Sezgin, Hande; Yalcin-Enis, Ipek; Technická univerzita v Liberci
    Vascular grafts are synthetic tubular structures that play an important role in replacing damaged vessels in the treatment of cardiovascular diseases. Existing grafts, especially in small-diameter vessels, face persistent issues such as thrombosis, immune rejection, and mechanical limitations. Vascular grafts designed with an innovative perspective to overcome these deficiencies are tubular scaffolds with a biodegradable structure and a layered design that mimics the native artery structure. This study focuses on the development of biodegradable and biocompatible tubular scaffolds with randomly distributed and radially oriented fibers in different layers to replicate the native structure of artery, utilizing neat polycaprolactone (PCL) and PCL/polylactic acid (PLA) blend with 4/1 polymer blend ratio. Electrospinning technique is employed to fabricate tubular fibrous structures. The biodegradation profiles of these scaffolds are assessed at 3, 6, and 9 months, with comparative analyses conducted to explore how polymer type and orientation level influence degradation rates and the structural integrity of the materials over time. The findings reveal that scaffolds with randomly distributed fibers exhibit higher biodegradation rates compared to those with oriented fibers, particularly in the PCL/PLA blends. Specifically, the study identifies PCL_R as having the highest degradation rate at 61% weight loss by the 9th month. Importantly, while PCL is known for its slow degradation, the high molecular weight of PLA leads to a slower degradation profile in the PCL/PLA samples. These insights underscore the critical role of scaffold morphology and composition in optimizing the performance and functionality of vascular grafts, highlighting the need for scaffolds that support cellular activities while effectively degrading to facilitate tissue regeneration without toxic effects.
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    SUTURE RETENTION STRENGTH OF BILAYER VASCULAR GRAFTS MADE OF PCL, PLA AND THEIR COPOLYMER
    (Technical University of Liberec, ) Ozdemir, Suzan; Oztemur, Janset; Yolgosteren, Atif; Sezgin, Hande; Enis, Ipek Yalcin; Technická univerzita v Liberci
    The mechanical characteristics of small-diameter vascular grafts, including factors like modulus, elasticity, compliance, burst strength, and suture retention strength, need to be in line with those of native blood vessels. Even a slight mismatch in mechanical properties between the graft and the native vessel can lead to graft failure. Suture retention strength, a critical mechanical aspect, represents the force needed to remove a stitch from the graft or cause the graft wall to rupture. This property is vital for preventing leaks, maintaining proper blood flow, aiding tissue healing, ensuring long-term durability, and reducing complications in vascular grafts. In this study, bilayered vascular grafts are fabricated by electrospinning using polycaprolactone (PCL), poly (lactic acid) (PLA), and poly(l-lactide-co-caprolactone) (PLCL) polymers. The actual suturing conditions of vascular scaffolds are simulated and how the choice of polymer for the inner layer affects suture retention strength is assessed. At the post-mechanical stage, the morphologies of the scaffolds are investigated to gain a clearer understanding of how the material reacts to applied forces. The findings reveal that all the fabricated bilayer vascular scaffolds exhibit excellent suture performance, with strength values exceeding 10 N, and that polymer selection for the inner layer for the grafts significantly influences the results. Blending PCL and PLA in the inner layer is found to reduce suture retention strength, while using neat polymers results in better retention strength. This experiment offers a more precise assessment of suture retention strength for bilayer vascular grafts, facilitating further optimization of tissueengineered grafts to meet specific mechanical requirements.