The Effect of Surface Nano Topography of TiO2 Nanotube Arrays on Mesenchymal Stem Cell Behavior

The tendency of mesenchymal stem cells to maximize their contact by spreading on the surface they are attached to is known, but detailed studies on the extent of penetration of cells into nanoporous structures or how they can integrate with nanoscaled roughnesses on surfaces are very scarce in the literature. In addition, cell-topography interactions are considered a promising strategy to precisely control stem cell function and differentiation. TiO2 nanotube array, which is a classic example of nanotopography, is a good model to investigate topography-cell interactions due to its good controllability and easy fabrication process. The project offers a holistic and different perspective and research questions in the development of better implant surfaces and the detection of extracellular matrix components that are secreted more, with a better transcriptome profile during differentiation of mesenchymal stem cells cultured in different nanotopographies obtained as a result of varying anodic oxidation parameters.

Synthesis and Characterization of Titanium Dioxide Nanotube-based Membrane Systems for Blood Filtration Applications

Due to high biocompatible properties, titanium dioxide nanotube surface arrays have widely been used in orthopedic and dental implants, biosensor and drug releasing systems. In the presented thesis study, titania nanotube-based membrane structures, which preserving its bulk stability, had been fabricated by three-step electrochemical anodic oxidation and sudden change in application potential at different temperatures. Availability of fabricated titania nanotube-based membrane structures at blood filtration applications were investigated for wearable/portable and implantable artificial kidneys; their chemical and morphological properties had been determined by scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDX), x-ray diffraction analysis (XRD), water contact angle (WCA) and atomic force microscopy (AFM). In this aim, uremic toxin filtration performances of these nanostructures had been tested in  the flow cells which had been manufactured with 3D printing by modernized fused deposition modelling technology of poly(ethlyene tereftalat – gyclycol) (PETG). Two different membrane structures, which having nanotubes with 50 nm radius and 30 µm length on 36% of their surfaces, had been investigated for crossflow pure water flux (PWF), rates of creatinine clearance and bovine serum albumin (BSA) rejection. The nanoceramic ultrafiltration membranes shows 95% in creatinine clearance and 20% in BSA rejection due to negative repulsive electostatic forces in the blood filtration application which being claimed appliable as the results of digital and experimental failure analysis.