Enzyme immobilization into polymers and coatings

In this study, we have developed strategies to immobilize enzymes into various polymer and coatings. Three categories of bioplastic matrices were investigated. The first type of bioplastics was prepared by irreversibly incorporating di-isopropylfluorophosphatase (DFPase) into polyurethane (PU) foams. The resulting bioplastic retained up to 67% of the activity for native enzyme. The thermostability of DFPase was highly affected by the immobilization process. Unlike native enzyme, immobilized DFPase had biphasic deactivation kinetics. Our data demonstrated that the initial rapid deactivation of immobilized DFPase lead to the formation of a hyper-stable and still active form of enzyme. Spectroscopic studies enabled a structural analysis of the hyper-stable intermediate.;Enzyme-containing PU- and Michael adduct (MA)-based coatings correspond to the last category of bioplastics that was investigated. DFPase was irreversibly incorporated into PU coatings. The distribution of immobilized DFPase as well as activity retention were homogeneous within the coating. The resulting enzyme-containing coating (ECC) film hydrolyzed DFP in buffered media at high rates retaining approximately 39% intrinsic activity. DFPase-ECC had a biphasic deactivation profile similar to that of bioplastic foams. The synthesis of enzyme-containing MA coatings was performed in a two-step process using carbonic anhydrase (CA, E.C. 4.2.1.1). CA was first covalently immobilized into NVF-based water-soluble polymer (EP). The resulting EP was further entrapped into the matrix of MA coating. The so-formed ECC's exhibited approximately 7% apparent activity. CA-ECC showed good stability under ambient conditions and retained 55% activity after 90 days of storage.;Biopolymers were also prepared via atom transfer radical polymerization (ATRP) using acrylic and sulfonate-derived monomers. ATRP ensured the covalent and multi-point immobilization of enzyme within polymer matrices. However, this approach was only partially successful, as no activity retention was obtained after polymerization.