Biocatalytic Generation of Ppy-Enzyme-CNT Nanocomposite: From Network Assembly to Film Growth

Nanocomposites have attracted great research and development interests. Lactate oxidase (LOD) in the presence of lactate was used to initiate the polymerization of pyrrole monomer with and without carbon nanotube (CNT) presence to produce a 2- or 3-component nanocomposite. We found that the formation mechanisms for the 2- and 3-component nanocomposites were different from network assembly to film growth. Enzyme molecules served as the seeds for polymerization without CNT presence and preferentially resulted in the formation of nanoparticles. In this case, an interesting self-assembly of the nanoparticles was observed. However, when CNTs were introduced into the reaction system, they functioned as the seeds for the polymerization and a CNT-networked nanocomposite film was formed. The morphology, components, and the thickness of the composite film could be easily tailored by the reaction time, the ratio of pyrrole to CNTs, and the amount of enzyme. The application of the nanocomposite for the lactase biosensor and the effects of components of the nanocomposite on both sensing and electronic properties were also studied, demonstrating their novelty and superior properties. This work is the first one to report the biocatalytic production of polypyrrole (Ppy)-enzyme-CNT, a 3-component nanocomposite, its formation mechanism, and its applications.