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Endoglucanase, one part of the multicomponent enzyme cellulase, is an extremely important enzyme in the textile industry (biopolishing), the pulp and paper industry (de-inking operations and recycling of used paper), and the detergent industry. One major problem in such applications is the inactivation of the enzyme at elevated temperatures and pH conditions. We present herein details of the encapsulation of this enzyme in thermally evaporated fatty amine films and studies of the enzymatic activity of the biocomposite film under different pH and temperature conditions. Substrate protection of the enzyme by carboxymethyl cellulose was essential to stabilize the enzyme against inactivation in the lipid matrix. The optimum operation temperature shifted to higher values relative to that of the free enzyme in solution. The enhanced stability at high temperatures coupled with significant catalytic activity of the enzyme−lipid biocomposite films at elevated pH conditions indicate immediate application of the biocomposite film in high temperature−high pH industrial applications.

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The synthesis of polyurethane microsphere-gold nanoparticle "core-shell" structures and their use in the immobilization of the enzyme endoglucanase are described. Assembly of gold nanoparticles on the surface of polymer microspheres occurs through interaction of the nitrogens in the polymer with the nanoparticles, thereby precluding the need for modifying the polymer microspheres to enable such nanoparticle binding. Endoglucanse could thereafter be bound to the gold nanoparticles decorating the polyurethane microspheres, leading to a highly stable biocatalyst with excellent reuse characteristics. The immobilized enzyme retains its biocatalytic activity and exhibits improved thermal stability relative to free enzyme in solution. The high surface area of the host gold nanoparticles renders the immobilized enzyme "quasi free", while at the same time retaining advantages of immobilization such as ease of reuse, enhanced temporal and thermal stability, etc.