A novel mediator-free biosensor based on co-intercalation of DNA and hemoglobin in the interlayer galleries of α-zirconium phosphate

A novel mediator-free biosensor was constructed by the co-intercalation of negatively charged DNA and positively charged hemoglobin (Hb) in the interlayer galleries of layered alpha-zirconium phosphate (alpha-ZrP) with the delamination-assembly procedure at pH 5.5. X-ray diffraction and field-emission scanning electron microscopy results revealed the featured layered structure for the re-assembled DNA/Hb/alpha-ZrP composite. Infrared spectroscopy and circular dichroism results confirmed the coexistence of Hb and DNA in the composite and the considerably retained protein conformation of intercalated Hb. The direct electron transfer of Hb was facilitated by the co-intercalation of DNA and Hb. Because of the synergistic effect of alpha-ZrP host and co-intercalated DNA guest, the DNA/Hb/alpha-ZrP modified electrode exhibited good electrocatalytic response to H2O2 with higher sensitivity of 0.79 A M-1 cm(-2) and lower detection of 4.28 x 10(-7) M in the linear range of 7.28 x 10(-7) to 9.71 x 10(-5) M. Furthermore, the electrocatalytic activity of Hb in the DNA/Hb/alpha-ZrP composite retained at high temperature (85 degrees C) or in the presence of organic solvent (CH3CN), which could be the protection of alpha-ZrP nanosheets. (C) 2010 Elsevier B.V. All rights reserved.