This work describes a general method for the encapsulation of enzymes with albumin as wall material and the enzyme catalase as prime example. Care was taken for the preparation of biochemically active sub-micrometer particles in order to prevent oxygen toxicity induced by artificial oxygen carriers of any type. In cell culture experiments, capsules containing catalase did not exhibit any harmful activities in the absence of peroxides. In the presence of hydrogen peroxide application of low and medium dosed capsules below 0.05 vol% (final concentration 0.001 vol%) even increased the cell damaging process. However, a higher dosage of capsules (>0.05 vol%) prevented completely cellular disruption induced by 5 mM hydrogen peroxide and decreased up to 90% of cellular damage at higher peroxide concentrations. These results demonstrated that encapsulated catalase was enzymatically active and the overall activity of prepared catalase capsules was determined to be >1900 U mL À1 vol% À1 .

In this work we present a method for the encapsulation of intracellular enzymes into a shell of albumin, using the example of catalase. We take advantage of organic, inorganic and physical chemistry for the preparation of biochemically active micrometer particles to prevent oxygen toxicity induced by artificial oxygen carriers of any type. In cell culture experiments, catalase capsules presented to be non-noxious in absence of peroxides. However, application of low and medium dosed capsules below 0.05 vol% (final concentration 0.001 vol%) increased the process of cell damaging induced by hydrogen peroxide and its decomposition products, while high dosed capsules > 0.05 vol% nullified all cell damage up to 5 mM hydrogen peroxide and reduced up to 90% of cellular damage for higher peroxide concentrations. The over-all activity of prepared catalase capsules was determined to be > 1000 U ∙ mL-1 ∙ vol%-1.