Carboxyethyl-functionalized 3D porous polypyrrole synthesized using a porogen-free method for covalent immobilization of urease

The immobilization of enzymes onto porous supports is a common strategy for obtaining improved stability, fast product separation, enzyme reusability, and, ultimately, lower operating costs. Therefore, the development of new supports with specific surface functionalities that enable the covalent attachment of enzymes is of significant interest. Herein, stable three-dimensional (3D) porous materials were synthesized from polypyrrole by a simple template approach and used as an immobilization support for urease. The template method entails the use of polypyrrole nanoparticle building blocks, onto which a carboxylic acid-functionalized pyrrole monomer was polymerized, forming a 3D porous structure with tunable pore size distribution. Scanning electron microscopy (SEM) images, together with static light scattering (SLS), revealed the 3D porous nature of the materials. The properties of both the supports and the immobilized enzyme were characterized using a combination of techniques. The ability of the bioconjugated urease to catalyze the hydrolysis of urea into carbon dioxide and ammonia was then tested. The immobilized enzyme exhibited good catalytic activity, stability and reusability. Overall, these results suggest that such 3D porous materials with chemically accessible surfaces have considerable potential for use as biocatalyst supports.