Polyaniline (PANi) powders and films of the emeraldine (EM), nigraniline (N
A) and leucoemeraldine (LM) states, as well as surface-modified EM base fil
ms from graft copolymerization with acrylic acid (AAc) and the subsequent c
ovalent immobilization of collagen were implanted into male Sprague Dawley
rats beneath the dorsal skin, for a period ranging from 19 to 50 weeks to e
valuate the in viva tissue response. It was observed that inflammation asso
ciated with the various forms of PANi was minimal after 50 weeks. Histologi
cal examinations of tissues, 24 weeks after the implantation, revealed that
the pristine EM film was encapsulated by several loosely arranged fibrous
tissue. The collagen-immobilized EM film, on the other hand, showed no feat
ures resulting from tissue incompatibility near the implant.