Figure 5: (A) Optical microscope image of a PLGA-based micro-system encapsulated with alginate-catalase. Immobilization of catalase onto an alginate chain was carried out using EDC/NHS chemistry. The alginate layer coating on the PLGA micro-system was produced by the dripping method, in which the gelation of alginate was achieved using divalent calcium(II) ions. (B) Theoretical decomposition route for H2O2 in a micro-system in releasing oxygen.