Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Bilayer Chitosan/Zein Based Nanofibers for Antimicrobial Wound Dressing Application(01. Izmir Institute of Technology, 2021) İskeçman, Nilsu; Tıhmınlıoğlu, Funda; Tıhmınlıoğlu, Funda; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyNowadays, modern functional wound dressings have become prominence due to their biocompatible, biodegradable, and non-toxic nature and ability to mimic ECM of skin. To enhance their mechanical and prolonged cumulative release of drugs in media, environmentally friendly inorganic nanofillers are preferred. Recently, halloysite nanotubes (HNTs) which is a new class of inorganic filler are using to improve mechanical properties and thanks to their tubular structure various agents encapsulated into these tubes to make drug release more controlled. In this thesis, it was aimed to fabricate and characterize bilayer wound dressing by using Zein-Vancomycin loaded HNTs nanofibers as upper layer to mimic ECM of skin and provide antibacterial protection and chitosan sponge as bottom layer to absorb the excess exudates of wound, provide gas transmission and facilitate the migration of inflammatory and fibroblast cells into the healing wounds. The morphology of nanofibers and encapsulation efficiency of HNTs are optimized to achieve similar homogeneous fiber structure with skin tissue and controlled release of Vancomycin drug. Chemical interaction between Vancomycin-HNT and Zein-HNT were characterized by FT-IR. The surface charge differences of HNTs by encapsulating drug into tubes was determined by zeta potential analysis. The weight loss percentage of nanofiber with the addition of HNTs into zein media was characterized by using thermogravimetric analysis (TGA). Bilayer sponges were characterized by SEM, FT-IR, porosity, mechanical properties, contact angle, water vapor transmission rate, swelling, degradation, cumulative drug release and their kinetics and antimicrobial activity analyzes. The diameter of drug loaded HNT-Zein nanofibers were found 202,7±0,05–225,2±0,06 nm which is in the range of native skin collagen fibril (50-500 nm) than can mimic ECM. The water vapor permeability of the wound dressings is between 2833 and 2490 g/m2day which is found in the appropriate range for wound healing. Bilayer dressings reached 78% cumulative release at the end of 14 days and the release medium showed antimicrobial activity against E. coli and for S. epidermidis. In conclusion, the developed drug-loaded bilayer mat has been found as a potential candidate for wound dressings applications to treat the chronic infections.Master Thesis Surface Modified Halloysite Nanotubes Incorporated Polyl-Lactide Nanocomposites for Food Packaging Applications(Izmir Institute of Technology, 2019) Tüzün, Ece Zeynep; Tıhmınlıoğlu, Funda; Tıhmınlıoğlu, Funda; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyBiodegradable Poly (L-lactide) (PLA) can replace petroleum based packaging materials to solve environmental problems. PLA lacks of ductility and have moderate barrier properties. In this study, halloysite nanotubes (HNTs) possessing unique surface chemistry and tubular structure were incorporated into PLA matrix to overcome drawbacks of PLA. Firstly, HNT surface was modified with aminopropyltriethoxysilane (APTES) to enhance interfacial adhesion between HNTs and PLA matrix by decreasing the hydrophilicity of HNTs. Modified HNTs (m-HNTs) were characterized by SEM, FTIR, TGA, N2 adsorption-desorption analysis, XRD and XPS. FTIR, XRD and XPS results revealed that APTES was successfully grafted onto HNTs. The optimum pH and APTES concentration for the silanization of HNTs were determined as 3.50 and 1%, respectively. HNT/PLA and m-HNT/PLA nanocomposite films with different wt% of nanofiller loadings were prepared by solution casting. The films were characterized by FTIR, XRD, tensile test, water vapor permeation, DSC, TGA, contact angle and SEM analysis and color measurements. Better dispersion and consequently better mechanical properties were obtained with m-HNT addition compared to unmodified ones. Tensile strength at break of PLA was increased by 4.7% and 16.6% with 2 wt% HNT and m-HNT addition, respectively. m-HNT/PLA nanocomposites had better water vapor barrier properties than unmodified HNT/PLA nanocomposites while both of them improved the barrier property. Best mechanical and water vapor barrier properties were achieved with 2% modified HNT (1% APTES) containing PLA nanocomposites. Therefore, nanocomposite films produced in this study with high transparency and good barrier property can be a suitable candidate for fresh food packaging.