Layer-by-layer assembled multilayers using catalase-encapsulated gold nanoparticles.

We introduce a novel and versatile approach for the preparation of multilayers, based on catalase-encapsulated gold nanoparticles (CAT-Au(NP)), allowing electrostatic charge reversal and structural transformation through pH adjustment. CAT-Au(NP), which are synthesized directly from CAT stabilizer, can be electrostatically assembled with anionic and cationic PEs as a result of the charge reversal of the catalase stabilizers through pH control. In particular, at pH 5.2, near the pI of catalase, dispersed CAT-Au(NP) are structurally transformed into colloidal or network CAT-Au(NP) nanocomposites. Furthermore, we demonstrate that the layer-by-layer assembled multilayers composed of PEs and CAT-Au(NP) induce an effective electron transfer between CAT and the electrode as well as a high loading of CAT and Au(NP), and resultantly exhibit a highly catalytic activity toward H(2)O(2).