Hemoglobin/DNA/layered double hydroxide composites for biosensing applications

摘要

In this paper, hemoglobin/DNA/layered double hydroxide composites were fabricated by co-intercalating hemoglobin (Hb) and DNA in the interlayer galleries of Ni-AI layered double hydroxides (Ni-AI LDH) via a delamination-reassembly procedure. The presence of DNA not only remarkably facilitated the intercalation of Hb into the interlayers of the Ni-AI LDH, but also improved the bioactivity of the entrapped Hb. By depositing the Hb/DNA/LDH composite film onto a glassy carbon electrode, a mediator-free biosensor was obtained. Because of the synergistic effect between the LDH host and the co-intercalated DNA guest, the Hb/DNA/LDH composites modified electrode exhibited a fast direct electron transfer with a rate constant, k_s, of 6.95 ± 3.31 s~(-1) and a sensitive electrocatalytic response to H2O2 and NO_2~- in the linear range of 4.85 x 10~(-7) to 1.94 x 10~(-4) M and 2.5 x 10~(-7) to 3.0 x 10~(-5) M, respectively. Furthermore, with the protective effect provided by the LDH nanosheets, the electrocatalytic response of the intercalated Hb to H2O2 was retained, even at high temperatures (85 °C) or in the presence of an organic solvent (CH3CN).