Simple one-step method to produce titanium dioxide–polycaprolactone composite films with increased hydrophilicity, enhanced cellular interaction and improved degradation for skin tissue engineering

Abstract

There is a significant interest in using synthetic polymers, such as polycaprolactone (PCL), in engineering skin to avoid the need for donor sites with autografts, immunological rejection issues with allograft and reproducibility issues with using natural polymers. PCL is promising as it is a US Food and Drug Administration—approved biodegradable polymer with good mechanical properties. However, its hydrophobic nature is not optimal for cellular interaction and biodegradation in skin tissue engineering. In this study, titanium oxide–PCL composite films were prepared using an in situ, one-step synthesis method. Titanium dioxide (TiO2) was introduced to improve the wetting properties of the hydrophobic polymer and so enhance the cell–material interactions and material biodegradation to be more suitable for skin regeneration. Results showed that the simple synthesis method produced nano- and submicron TiO2 particles well dispersed within the PCL matrix. Spin-coated composite films showed increasing hydrophilicity with increasing concentration of TiO2. Degradation of the composite films and pure PCL films were compared using gel permeation chromatography of the films after 14-day-immersion experiments. Molecular weights of PCL after immersion were found to steadily decrease by up to ~65 % with increasing concentration of TiO2. Rates of water penetration into the composite films were found to increase with the concentration of TiO2 and correlate with the molecular weight decreases observed. In vitro experiments with fibroblasts demonstrated enhanced cell adhesion and proliferation on the composite films. This synthesis method therefore provides a simple means of tuning the wetting properties of hydrophobic polymers to enhance their cellular interactions, as well as tuning their biodegradation properties to suit applications such as skin tissue engineering.