Preparation and characterization of biocompatible spongy cryogels of poly(vinyl alcohol)-gelatin and study of water sorption behaviour

Porous biocompatible spongy hydrogels of poly(vinyl alcohol) (PVA)-gelatin were prepared by the freezing-thawing method and characterized by infrared and differential scanning calorimetry. The prepared so-called 'cryogels' were evaluated for their water-uptake potential and the influence of various factors, such as the chemical architecture of the spongy hydrogels, pH and the temperature of the swelling bath, on the degree of water sorption by the cryogels was investigated. It was found that the water sorption capacity constantly decreased with increasing concentration of PVA while initially an increase and thereafter a decrease in swelling was obtained with increasing amounts of gelatin in the cryogel. The water sorption capacity decreased with an increase in the number of freeze-thaw cycles. The hydrogels were also swollen in salt solutions and various simulated biological fluids and a fall in swelling ratio was noticed. The effect of the drying temperature of the cryogel on its water sorption capacity was also investigated, and a decrease in swelling was obtained with increasing temperature of drying. The biocompatibility of the prepared materials was assessed by in vitro methods of blood-clot formation, platelet adhesion, and per cent haemolysis. It was noticed that with increasing concentration of PVA and gelatin the biocompatibility increased, while a reduced biocompatibility was noted with an increasing number of freeze-thaw cycles. (c) 2005 Society of Chemical Industry.