Effect of deposition parameters and post-deposition annealing on the morphology and cellular response of electrosprayed TiO2 films

Titania films (TiO2) were deposited on Ti alloy substrates by electrohydrodynamic atomization (EHDA), also called electrospraying, and the morphology and phase composition of the coatings were evaluated. A range of TiO2 sols (2-8 wt%) were prepared via the hydrolysis of polymeric precursors using isopropanol (prOH) as a solvent carrier. Stable cone-jet formation during the EHDA process was greatly influenced by varying the liquid physical properties. Deposition parameters such as sol concentration, needle-to-substrate distance and spray time were found to affect film morphology. Dense and continuous films were obtained under optimized conditions whereby a 2 wt% TiO2 sol was atomized at a flow rate of 5 μl min-1 by a needle of 300 μm inner diameter, kept at a distance of 20 mm from the grounded substrate and operating at an applied voltage of 3.5-4.2 kV. The films were then crystallized by heating to 300-600 deg. C. Annealing increased the hydrophilicity of the films but did not significantly affect the surface roughness of the films. In vitro cellular response was determined by studying the interaction between MG63 cells and the films annealed at the various temperatures. MG63 cells were able to grow and proliferate on all the TiO2 films, while the highest proliferation rate was found on the TiO2 films annealed at 600 0C. Our results indicate that electrosprayed TiO2 films possess great potential for biomedical applications.