Catalase immobilization on electrospun nanoribers: Effects of porphyrin pendants and carbon nanotubes

Carbon nanotube (CNT) has been generally recognized as an electron acceptor, whereas porphyrin can act as an electron donor. In this work, acrylonitrile-based copolymers bearing porphyrin pendants were therefore blended with or without CNTs and then electrospun into nanofibers on which a redox enzyme, catalase, was covalently immobilized. The uniform nanofibers diameters are around 180 nm. Field emission scanning electron microscopy and transmission electron rnicroscopy confirmed the morphologies of the nanofibers and the distribution of CNTs. Rougher surfaces as well as obvious protruded parts induced by the blending of CNTs were observed from the studied nanofibers. Catalase was immobilized onto the nanofiber surface through the activation of carboxyl groups by N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide (EDC/NHS). Results indicate that both the introduction of porphyrin pendants and CNTs obviously improve the activity and stabilities of the immobilized catalases. The facilitation of electron transfer between the immobilized catalases and the ability of both porphyrin pendants and CNTs to retain the active conformation of the catalases might be responsible for the improvements of the activity and stabilities.