Hybridization biosensor using di(1,10-phenanthroline) (imidazo[f]1,10-phenanthroline)cobalt(II) as electrochemical indicator for detection of human immunodeficiency virus DNA

The complex [Co(phen)2IP] · 2ClO4 · 3H2O, where phen = 1,10-phenanthroline and IP = imidazo[f] [J. Wang, Anal. Chem. 71 (1999) 328; I.V. Yang, P.A. Ropp, H.H. Thorp, Anal. Chem. 74 (2002) 347] phenanthroline, was synthesized and characterized by infrared spectrometry (IR). Cyclic voltammetry (CV) was used to investigate the interaction between [Co(phen)2IP]2+ and salmon sperm DNA. [Co(phen)2IP]2+ had excellent electrochemical activity on the glassy carbon electrode (GCE) with a couple quasi-reversible redox peaks. In 0.2 M pH 4.0 Britton–Robinson (B–R) buffer solution, the binding ratio between [Co(phen)2IP]2+ and salmon sperm DNA was calculated to be 1:1 and the binding constant was 3.74 × 105 L mol−1. A human immunodeficiency virus (HIV) DNA biosensor was developed by immobilizing covalently single-stranded HIV DNA fragments to a modified glassy carbon electrode (GCE). The surface hybridization of the immobilized single-stranded HIV DNA fragment with its complementary DNA fragment was evidenced by electrochemical methods using [Co(phen)2IP]2+ as a novel electrochemical indicator, with a detection limit of 27 pmol and a linear range from 1.6 × 10−10 to 6.2 × 10−9 mol. Selective determination of complementary ssDNA was achieved using differential pulse voltammetry (DPV).