Sensitive electrochemical DNA sensor for the detection of HIV based on a polyaniline/graphene nanocomposite

A nanocomposite of polyaniline/graphene (PAN/GN) was prepared using reverse-phase polymerization. The nanocomposite material was dropcast onto a glassy carbon electrode (GCE). Then, a single-stranded DNA (ssDNA) probe for HIV-1 gene detection was immobilized on the modified electrode, and the negative charged phosphate backbone of the HIV-1 was bound to the modified electrode surface via π-π∗ stacking interactions. The hybridization between the ssDNA probe and the target HIV-1 formed double-stranded DNA (dsDNA), and the electron transfer resistance of the electrode was measured using impedimetric studies with a [Fe(CN)6]3-/4- redox couple. Under the optimized experimental conditions, the change of the impedance value was linearly related to the logarithm of the concentration of HIV genes in the range from 5.0 × 10−16 M to 1.0 × 10−10 M (R = 0.9930), and the HIV sensor exhibited a lower detection limit of 1.0 × 10−16 M (S/N = 3). The results show that this biosensor presented wonderful selectivity, sensitivity and specificity for HIV-1 gene detection. Thus, this biosensor provides a new method for the detection of HIV gene fragments.