Hemin-confined thin films composed of poly(ethyleneimine) (PEI) and carboxymethylcellulose (CMC) were fabricated by layer-by-layer (LbL) deposition on the surface of a glassy carbon (GC) electrode for the detection of hydrogen peroxide (H 2 O 2 ). Hemin could be easily immobilized in LbL films by immersing an LbL-filmmodified electrode in hemin solution, irrespective of the electric charge on the surface layer of the film. The results showed that a small amount of hemin located near the surface

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... of the electrode is involved in the electrochemical reaction, while most of the hemin molecules in the film are not involved. The hemin-modified electrode showed an excellent amperometric response to H 2 O 2 on the basis of electrocatalytic reduction under electrode potentials of -0.6 and -0.4 V. The hemin-modified electrode exhibited a linear calibration graph for 0.005-0.8 mM H 2 O 2 when operated at -0.6 V. The hemin-modified electrode was found to be stable for about 2 weeks. Thus, the usefulness of LbL films composed of PEI and CMC as a scaffold for immobilizing hemin was demonstrated.