Room temperature TiO2 atomic layer deposition on collagen membrane from a titanium alkylamide precursor

Low temperature atomic layer deposition (ALD) is an increasingly important technique to functionalize and modify heat-sensitive biomaterials. Collagen is a heat-sensitive biomaterial used in several biomedical applications. In this study, commercially available collagen membrane was selected as a substrate for the ALD of titanium dioxide (TiO2); a thin film of TiO2 on collagen could potentially change the mechanical and chemical properties of collagen. The ALD process was carried out at room temperature using tetrakis(dimethylamido)titanium, a novel titanium precursor for such applications, and ozone as the oxidizer. Four different sample groups were studied: control (native collagen), and collagen-150 cycles, collagen-300 cycles, and collagen-600 cycles, that is, collagen with 150, 300, and 600 TiO2 ALD cycles, respectively. Chemical analysis of the substrate surface showed the presence of titanium oxide on as-deposited samples. Electron microscopy results showed a significant increase in collagen fiber thickness among control and collagen samples with as-deposited TiO2. The collagen fiber diameter was found to increase more than linearly with increasing number of TiO2 ALD cycles. This titanium dioxide-infiltrated dense collagen could be used for the tuning of its properties in several biomedical applications, including bone grafting and wound healing.