Hemoglobin/DNA/layered double hydroxide composites for biosensing applications

Abstract

In this paper, hemoglobin/DNA/layered double hydroxide composites were fabricated by co-intercalating hemoglobin (Hb) and DNA in the interlayer galleries of Ni–Al layered double hydroxides (Ni–Al LDH) via a delamination-reassembly procedure. The presence of DNA not only remarkably facilitated the intercalation of Hb into the interlayers of the Ni–Al 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 NO₂⁻ in the linear range of 4.85 × 10⁻⁷ to 1.94 × 10⁻⁴ M and 2.5 × 10⁻⁷ to 3.0 × 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).