Swelling properties of nano-hydroxyapatite reinforced poly(vinyl alcohol) gel biocomposites

Nano-hydroxyapatite reinforced poly(vinyl alcohol) (nano-HA/PVA) gel composites is proposed as a promising biomaterial to replace diseased or damaged articular cartilage. Nano-HA/PVA gel composites were prepared by in situ synthesis of nano-HA particles in PVA solution and accompanied by freeze/thaw method. The influences of freeze/thaw cycle times, nano-HA content, PVA concentration and swelling media on the swelling characteristics of the gel composites were investigated. The results showed that the swelling ratio of the gel composites increased, but its swelling rate decreased with the rise of swelling time. Both the swelling ratio and equilibrium swelling ratio of the gel composites in the different swelling media presented an increasing trend with the rise of freeze/thaw cycle times. Contrarily, the equilibrium swelling ratio of the gel composites decreased with the rise of nano-HA and PVA concentration. Swelling media have significant influence on the swelling behaviour of the gel composites. The equilibrium swelling ratio of the gel composites in distilled water was the largest and it reached the lowest in bovine serum. Simultaneously, the equilibrium swelling ratio in bovine serum was far lower than that in inorganic swelling media, such as distilled water and physiological saline.