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3D Biyobaskı Parametrelerinin PCL İskelesinin Basılabilirliği ve Mekanik Davranışı Üzerindeki Etkisi
(Abdullah Gül Üniversitesi / Fen Bilimleri Enstitüsü, 2023) Ceylan, Saniye Aylin; İşoğlu, İsmail Alper
Polycaprolactone (PCL) is a synthetic polymer that exhibits desirable properties such as biodegradability, tolerable mechanical properties, and biocompatibility for a diverse range of tissue engineering applications. In this study, we analyzed the effects of polymer concentration (10%, 25%, 50% and 75% w/v), solvent effect (dichloromethane, chloroform and acetic acid), and device parameters (pressure, speed, nozzle-surface distance, nozzle gauge, infill density) on printed scaffolds fabricated through 3D Bioprinting. Scanning electron microscopy (SEM) and optical microscopy were used to assess printability, and uniaxial tensile testing was performed to evaluate mechanical behavior. The aim of this study was to investigate the effects of different printing speeds (5 mm/s, 10 mm/s, and 15 mm/s) on the mechanical properties of PCL_DCM and PCL_CF scaffolds. The scaffolds printed at the lowest speed exhibited the highest ultimate tensile strength (UTS) values. Scaffolds printed at 5 mm/s with the highest printing pressure (480 kPa) demonstrated a remarkably high Young's modulus of 39.69 MPa and a UTS value of 6.4 for PCL_DCM, as well as Young's modulus of 26.80 MPa and a UTS value of 6.3 MPa for PCL_CF. Additionally, we investigated the influence of polymer concentrations (50% and 75%) and infill densities (50%, 70%, and 90%). The results showed that increasing the infill density and using a lower concentration (50%) led to improvements in Young's modulus and UTS values for both PCL_DCM and PCL_CF scaffolds. These results highlight the importance of carefully controlling printing parameters to optimize the mechanical properties of the printed scaffolds.
Işık ile Çapraz Bağlanabilen Aljinat Bazlı Tannik Asit ile Güçlendirilmiş Biyomürekkep Hidrojellerin Hazırlanması ve Karakterizasyonu
(Abdullah Gül Üniversitesi / Fen Bilimleri Enstitüsü, 2023) Demirci, Enes Hamdi; İşoğlu, Sevil Dinçer; Demirtaş, Tuğrul Tolga
Alginate is a commonly used biopolymer in bioprinting applications. However, alginate-based bioinks have some mechanical limitations for printing purposes. Also, existing methacrylation methods are time consuming and have low methacrylation efficiencies. Based on these facts, we focused on enhancing mechanical strength of alginate within the scope of this thesis. To do this, we applied microwave irradiation during methacrylation process of alginate and compared the efficiencies between conventional and microwave irradiation. Here, we report a significantly faster and more effective method for the controlled synthesis of methacrylated alginate (Alg-MA) by microwave energy (250 W) with approximately 80% degree of methacrylation (DM) even with a very low amount of metyhacrylation agent (aminoethyl methacrylate (AEMA)). Rheological and mechanical analyses showed that Alg-MAs synthesized by microwave irradiation allowed the formation of more elastic and stronger hydrogels with very high stability than the ones synthesized by the conventional method. Additionally, we combined these hydrogels with tannic acid by a second cross-linking in order to improve their mechanical strength and tissue integration ability. Addition of TA provided hydrogels very good mechanical strength and also antibacterial characteristics towards gram-positive and gram-negative bacteria. As a conclusion, hydrogels with mechanically superior properties and antibacterial characteristics were obtained by MW-assisted methacrylation and physical cross-linking by TA.

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