Effects of nanoporous anodic titanium oxide on human adipose derived stem cells.

The aim of current bone biomaterials research is to design implants that induce controlled, guided, successful, and rapid healing. Titanium implants are widely used in dental, orthopedic, and reconstructive surgery. A series of studies has indicated that cells can respond not only to the chemical properties of the biomaterial, but also, in particular, to the changes in surface topography. Nanoporous materials remain in focus of scientific queries due to their exclusive properties and broad applications. One such material is nanostructured titanium oxide with highly ordered, mutually perpendicular nanopores. Nanoporous anodic titanium dioxide (TiO2) films were fabricated by a three-step anodization process in propan-1,2,3-triol-based electrolyte containing fluoride ions. Adipose-derived stem cells offer many interesting opportunities for regenerative medicine. The important goal of tissue engineering is to direct stem cell differentiation into a desired cell lineage. The influence of nanoporous TiO2 with pore diameters of 80 and 108 nm on cell response, growth, viability, and ability to differentiate into osteoblastic lineage of human adipose-derived progenitors was explored. Cells were harvested from the subcutaneous abdominal fat tissue by a simple, minimally invasive, and inexpensive method. Our results indicate that anodic nanostructured TiO2 is a safe and nontoxic biomaterial. In vitro studies demonstrated that the nanotopography induced and enhanced osteodifferentiation of human adipose-derived stem cells from the abdominal subcutaneous fat tissue.

Nanoporous anodic titanium dioxide layers as potential drug delivery systems: Drug release kinetics and mechanism.

Nanoporous anodic titanium dioxide (ATO) layers on Ti foil were prepared via a three step anodization process in an electrolyte based on an ethylene glycol solution with fluoride ions. Some of the ATO samples were heat-treated in order to achieve two different crystallographic structures - anatase (400°C) and a mixture of anatase and rutile (600°C). The structural and morphological characterizations of ATO layers were performed using a field emission scanning electron microscope (SEM). The hydrophilicity of ATO layers was determined with contact angle measurements using distilled water. Ibuprofen and gentamicin were loaded effectively inside the ATO nanopores. Afterwards, an in vitro drug release was conducted for 24h under a static and dynamic flow conditions in a phosphate buffer solution at 37°C. The drug concentrations were determined using UV-Vis spectrophotometry. The absorbance of ibuprofen was measured directly at 222nm, whether gentamicin was determined as a complex with silver nanoparticles (Ag NPs) at 394nm. Both compounds exhibited long term release profiles, despite the ATO structure. A new release model, based on the desorption of the drug from the ATO top surface followed by the desorption and diffusion of the drug from the nanopores, was derived. The proposed release model was fitted to the experimental drug release profiles, and kinetic parameters were calculated.

Defects analysis in self-organized nanopore arrays formed by anodization of aluminium at various temperatures.

The self-organized anodization of aluminium in sulphuric acid was employed for formation of high-density nanostructures at various cell potentials and temperatures. The well-ordered arrangement of nanopores was obtained by two-step anodization process. The qualitative and quantitative analyses of defects were performed from SEM images of nanostructures. The Fourier transform (FFT) analyses showed that the uniformity of the triangular lattice increases gradually with increasing anodising potential independently of temperature. The order in the nanopore arrangement and size of well-ordered domains increase with increasing anodising potential for all studied temperatures. Quantitative analyses of defects, known as Delanuay triangulations, were performed for various anodising potentials and temperatures. The percentage of generated defects is constant at the cell potential between 15 and 23 V. At the temperature of 1 degree C, the percentage of defects equals to 20% while at temperatures of -8 or 10 degrees C reaches a value of about 30%. At the anodising potential of 25 V the percentage of generated defects in porous alumina is drastically reduced to about 10%, independently of the anodising temperature. The perfect nanopore arrangement on the anodised surface with the smallest number of defects can be obtained at 25 V.