Abstract:

Electrochemical hybridization biosensor for label-free determination of sequence-specific DNA was described. First, cobalt hexacyanoferrate films and poly (amidoamine)(PAMAM) dendrimer(generation 4.0) were modified on the glassy carbon electrode(GCE) sequentially. Then, DNA probes were successfully immobilized on the modified electrode with G4 PAMAM dendrimer acting as the coupling agent. The hybridization events were monitored by differential pulse voltammetry(DPV) measurement based on the oxidation signals of guanine without any external labels. This biosensor exhibited a superior electrochemical stability, selectivity and sensitivity in detection of the oligonucleotide sequence. Under the optimal conditions, the guanine oxidation signal was directly proportional to the mutant gene sequence concentration from 7.6×10^-11 to 3.05×10^-8 mol/L with a correlation coefficient of 0.9975 and a detection limit of 1.0×10^-11 mol/L(S/N=3).

Key words: Biosensor; Polyamidoamine dendrimer; Label-free; Hybridization; Gene mutation