Influence of triethylenetetramine on bioceramic synthesis and mechanisms of electrophoretic deposition of hyaluronic acid and composites

This investigation was motivated by the need in the development of electrophoretic deposition (EPD) for the fabrication of hyaluronic acid (HyH) films. EPD of HyH was performed from 5 g L −1 HyH solutions at 20 V during 5 min. The thickness of the film deposited from aqueous solutions was 80 μm, whereas the thickness of the film deposited from mixed water-ethanol solution was 214 μm. EPD offers benefits of fabricating thick, dense, and uniform films. Composite films were deposited by EPD from 5 g L −1 HyH solution in a 3:4 mixture of water: ethanol with 3 g L −1 ceramic nanoparticles. Composite films containing calcium phosphates, such as brushite and hydroxyapatite, TiO 2 , hollow halloysite nanotubes, and SiO 2 in the HyH matrix were obtained. HyH promoted suspension stability acting as a dispersing and charging agent. For the first time hydroxyapatite and TiO 2 were synthesized using triethylenetetramine (TH) as an organic alkali for synthesis. TH acted as an alkalizer-capping agent during synthesis and facilitated the formation of smaller fibrous hydroxyapatite particles, compared to particles prepared using NH 4 OH. The small hydroxyapatite particles were converted to brushite in HyH solutions and co-deposited with HyH, whereas larger hydroxyapatite particles showed improved chemical stability and were incorporated into HyH films by EPD. The strategies used for the synthesis of bioceramic nanoparticles using alkalizer-capping agent, fabrication of HyH and composite films open an avenue for the synthesis of other nanomaterials and deposition of other functional polymers and composites. The deposition mechanism was developed and discussed.