Irreversible Immobilization of Diisopropylfluorophosphatase in Polyurethane Polymers

Abstract

The synthesis of polyurethane polymers in the presence of diisopropylfluorophosphatase (DFPase) has enabled the irreversible attachment of the enzyme to the polymeric matrix. The resulting bioplastic hydrolyzes diisopropylfluorophosphate (DFP) in buffered media up to 67% of the rate for the same amount of soluble enzyme. Above a DFPase concentration of approximately 0.1 mg/gfoam, the rate of the reaction catalyzed by the enzyme-containing polymer was controlled by internal mass transfer. Increasing foam hydrophilicity, via the use of nonionic surfactants during polymerization, significantly affected the structural properties of matrix, thereby enhancing the intrinsic and apparent efficiency of modified DFPase. The resulting reduction in internal mass transfer limitations was explained morphologically with electron microscopy.

High‐activity enzyme‐polyurethane coatings

“…Protein concentrations were evaluated using the Bradford reagent, as described previously (Drevon et al, 2000).…”

“…As DFPase acts by binding and hydrolyzing DFP (see below), the activity was measured by following¯uoride release with ā uoride ion electrode at room temperature (Drevon et al, 2000). Fluoride bulk solution concentration was measured every 20 sec for 5 min.…”

“…Native DFPase catalyzes the hydrolysis of toxic organophosphorus nerve agents such as soman and DFP (Hartleib et al, 2001a,b;Schar et al, 2001a,b). DFPase was previously copolymerized into monolithic polyurethane foams with a 67% activity retention (Drevon et al, 2000) and an enhanced thermostability (Drevon et al, 2001). Since alterations in enzyme-containing coating (ECC) hydrophilicity could in¯uence activity retention and stability, we performed the immobilization process using polyisocyanates with various hydrophilicities.…”

Engineering materials from proteins

“…39 The challenge is to develop material chemistries that allow preparation of the encapsulating layer without denaturation of the protein due to heat, exposure to organic chemicals, or changes in protein shape due to the formation of chemical bonds. Encapsulation methods enable the formation of solid layers with proteins embedded, and commonly employed methods include incorporation into layer-by-layer assemblies, 71 immobilization in polyurethanes, 72 or the incorporation into self-assembled block copolymer templates. 73 The formation of chemical and physical bonds at the surface of the protein can be used to provide rigid crosslinks that stabilize the protein's tertiary or quaternary structure, 74 and the matrix may additionally contribute hydrogenbonding or osmolytic properties that help to stabilize the protein.…”

“…Not surprisingly, there are active research or commercialization efforts in applications such as enzyme technology for the detection of chemical and biological warfare agents, 72 biomedical applications such as targeted drug delivery, 89 and the preparation of tissue engineering matrices. 90 An increased recent focus on biomass utilization and sustainable materials also poses interesting challenges for researchers and engineers interested in protein materials.…”