Devices for guided tissue regeneration (GTR) include a matrix of chitosan and mutable collagenous tissue (MCT) wherein the chitosan is electrostatically bonded to the MCT to form MCT-chitosan composite material. The MCT can be isolated from invertebrate marine organisms, such as sponges, jellyfish, mollusks and echinoderms. The MCT-chitosan composite material can be formulated as a biofilm, a 3D-sponge, a hydrogel, or as an electrospun nanofiber, or the MCT-chitosan composite material can coat a biomaterial surface. The devices can include wound dressings and tissue sponges, including 3D sponges. Applications include tissue engineering and wound healing, as well as burns and other related guided tissue regeneration applications. MCT and MCT-chitosan composite material, contained in a pharmaceutically acceptable topical carrier, also has cosmeceutical applications, for treating scars, as well as skin discoloration and various pigmentation issues, including melasma/chloasma.