Collagen-Templated Bioactive Titanium Dioxide Porous Networks for Drug Delivery

Abstract

A Type I collagen gel was used as a template for fabricating porous titanium dioxide networks. Conducting sol–gel chemistry within the template, followed by a mild solvothermal treatment (selected TiO₂–collagen hybrids only), and then calcination to remove the template, produced anatase TiO₂ porous networks composed of mesoporous fibers. The collagen morphology was retained. TiO₂ fibers had walls up to 300 nm in thickness and hollow cores where the template was removed. Crystallite size, specific surface area (12.3–110 m² g^–1), mesopore diameter (4.2–8.8 nm), and pore volume of the networks varied under different synthesis conditions; solvothermal treatment of the hybrid doubled the surface area and mesopore diameter of the final material. Biomineralization was studied by immersion in a simulated body fluid. All networks displayed in vitro bioactivity, and hence potential bone-bonding capability, with apatite clusters growing on the fibers. Drug delivery was assessed by the adsorption and release of anti-inflammatory ibuprofen. Ibuprofen was stored both at the fiber surface and in mesopores below 15 nm in diameter, while release was a sustained diffusion process. The network solvothermally treated as a hybrid adsorbed ibuprofen up to 58.9 mg g^–1. The TiO₂ networks compared favorably with literature drug delivery vehicles when ibuprofen loading was normalized against surface area. Therefore, porous TiO₂ networks have potential as materials for biomedical applications.