Immobilization of hemoglobin on SBA-15 applied to the electrocatalytic reduction of H2O2.

The direct electron transfer between hemoglobin (Hb) and an electrode was realized by first immobilizing the protein onto SBA-15. The results of the immobilization showed that the adsorption was pH-dependent with a maximum adsorption near the isoelectric point of the protein, and SBA-15 with a larger pore diameter showed greater adsorption capacity for Hb. UV-vis spectroscopy and nitrogen adsorption analysis indicated that Hb was adsorbed within the channel of SBA-15 and no significant denaturation occurred to the protein. The Hb/SBA-15 composite obtained was used for the fabrication of a Hb biosensor to detect hydrogen peroxide. A pair of well-defined redox peaks at -0.337 and -0.370 V on the Hb/SBA-15 composite modified glassy carbon electrode was observed, and the electrode reactions showed a surface-controlled process with a single proton transfer at a scan rate range from 20 to 1,000 mV/s. The sensor showed a fast amperometric response, a low detection limit (2.3 x 10(-9) M) and good stability for the detection of H(2)O(2). The electrochemical results indicated that the immobilized Hb still retained its biological activity.