Structure and properties of polyacrylamide gels for medical applications

The effect of conditions of preparing hydrogels based on acrylamide and N,N'-methylenebisacrylamide on the properties of gels in the condensed state and the structure of polymer networks was studied by IR and NMR spectroscopy, thermornechanical analysis, and computer simulation. It was shown that, depending on the synthesis conditions, gels exert different physiological impacts on body tissues. After additional heat treatment of a gel in an autoclave and additional gamma-irradiation, the crosslink density of the network somewhat increases and alkene moieties arise in its chains. Basic potentialities for using the title gels in medicine were estimated by histology and morphology. It was demonstrated that the hydrogel formed upon additional gamma-irradiation and heat treatment holds its shape for a long time after having been implanted into a living organism. The tissue responsiveness for implantation of this gel is minimum: after 3-90 days, the inflammatory reaction is weak, the fibroblastic response is weakly pronounced, and a capsule remains thin after prolonged occurrence of the gel in the organism (6-9 months). The resorption of the gel by macrophages and its intergrowth by the connective tissue take place very slowly and only in the near-capsule layer.