GCRIS

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Synthesis and Characterization of Novel Organometallic-Semicondutor Nanocomposit Photoelectrodes
(Izmir Institute of Technology, 2022) Göl, Yusuf Emre; Karabudak, Engin; Karabudak, Engin
Studies on novel electrochemical catalyst synthesis for efficient oxygen evolution reaction (OER) attract the attention of researchers. In general, changing of synthesis method and the doping metal affect the electrochemical activities of BSCF. In this work, silver doped Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF-Ag) perovskite structure is shown to be a better electrocatalyst for oxygen evolution reaction (OER) due to its lower overpotential and extended durability. BSCF structure was synthesized by the EDTA-citric acid method. Appropriate amount of Ba(NO3)2 and EDTA were dissolved 0.1 M NH4OH solution. Nitrate salts of other metals were dissolved in distilled water, then mixed with prepared Ba(NO3)2 solution. The mixture was stirred at 70 °C until gelation occurred. The gelled samples obtained were baked in a drying oven at 250 °C for 24 h before being calcined at 1000 °C for 12 h. To achieve a current density of 10 mA cm−2, BSCF-Ag has required an overpotential of 0.36 V, which is very low compared to BSCF. To determine the stability of BSCF-Ag, continuous chronopotentiometry tests were carried out for 5 h and at a constant current density of 10 mA cm−2. BSCF-Ag was characterized by XRD, SEM, and XPS. Recent advances in inkjet printing technology for applications relating to heterogeneous catalysis are presented. Catalysts lie at the heart of most chemical reactions where raw materials are converted to value-added products. Therefore, synthesis and immobilization of active catalysts in the reactor are of great importance. Inkjet printing is an additive manufacturing technology introduced recently as a useful method for the fabrication and application of catalysts as a class of functional materials. Inkjet printing provides special features which can be tailored to the design of high-efficient catalytic processes. This thesis presents an overview of the technology along with developments and challenges associated with the combination of inkjet printing and heterogeneous catalysis, such as ink preparation, thin-film properties and real-life applications.
Xylan Based Composite Nanoparticles and Biofoams for Drug Delivery and Tissue Engineering
(01. Izmir Institute of Technology, 2022) Zeybek, Nüket; Büyükkileci, Ali Oğuz
Xylan is a hemicellulosic polysaccharide, which can be obtained from forest and agricultural wastes. Similar to some other polysaccharides, xylan can find application in drug delivery and tissue engineering due to its availability, structural diversity, biocompatibility, biodegradability, and low cost. In the first part of the study, xylan-based nanoparticles were developed for colontargeted oral drug delivery. Xylan is resistant to digestion and absorption in the upper GIT and is degraded by hydrolysis of glycosidic bonds by the colon microbiota; this makes it prominent in targeted drug delivery to the colon. The drug carrier was combined with a polymeric micelles system to increase the bioavailability of hydrophobic bioactive molecules in the colon targeting. The model hydrophobic molecule, curcumin, was loaded in the core of the triblock copolymer P-123 micelles by the thin-film hydration method. Curcumin-loaded micelles were coated with xylan supported by chitosan and tripolyphosphate using the ionic gelation method. In another approach, xylan was also used to coat curcumin-loaded mesoporous silica nanoparticles to prevent premature drug release in the upper GIT in colon-targeted delivery. In both approaches, the drugcontaining structures were maintained up to the colon and the drug was released upon bacterial hydrolysis of xylan. In the second part, xylan-based biofoams were synthesized by the oil in water emulsion templated method. Several physicochemical and mechanical tests have shown that at the optimal conditions foams with promising properties could be synthesized. Besides, to develop a more effective tissue therapy by utilizing the synergistic effect of the drug delivery and scaffold system, a model drug was successfully loaded into biofoams. This study showed that xylan is a promising feedstock for the synthesis of stable and biocompatible materials in biomedical applications, which reveals its potential capability in drug carriers and scaffolds.

Phd Degree / Doktora

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