Fabrication of Novel Film Containing Hydroxyapatite Nanoparticles/Cellulose Derivative and its Evaluation

The novel and flexible film for biomedical application could be fabricated by using hydroxyapatite (Ca10(PO4)6(OH)2; HAp) and cellulose derivatives. Firstly, 0.2 mass% 2,2,6,6-tetramethylpitiperidine-1-oxyl radical (TEMPO) oxidized cellulose (TOC) was agitated at 20,000 rpm for 3 min and then ultrasonically treated for 20 min at the frequency of 45,000 Hz to form the solution containing TOC nanofiber (TOCN). After the nano-sized HAp powder was put into TOCN solution (100 cm3; HAp/TOCN mass ratio of 0.10 or 0.50), the composite film was fabricated by drying it at 50°C for 3 d. The TOCN film with no HAp addition (the thickness: approximately 15 μm) possessed transparency, flexibility and high tensile strength (mean strength: 193 MPa). On the other hand, the tensile strength of HAp-TOCN composite film (thickness: 30 μm) was reduced from 60.1 to 50.2MPa with increasing HAp/TOCN mass ratio from 0.10 to 0.50. When the HAp/TOCN composite films were immersed in SBF at 37.0°C for 2 weeks, the spherical apatite particles were notably found to form on their surfaces.