Hybridization biosensor using 2,9-dimethyl-1,10-phenantroline cobalt as electrochemical indicator for detection of...

A label-free biosensor for the detection of oligonucleotides related to hepatitis B virus sequence via the interactions of DNA with redox-active complex, 2,9-dimethyl-1,10-phenantroline cobalt [Co(dmp)(H2O)(NO3)2] is described. The study was carried out by the hybridization of 21-mer probe DNA modified on glassy carbon electrode (GCE) with target DNA, and [Co(dmp)(H2O)(NO3)2] whose sizes are comparable to those of the small groove of native double-helix DNA was used as an electrochemical indicator. Electrochemical detection was performed by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) over the potential range where the [Co(dmp)(H2O)(NO3)2] was active. Under the optimum conditions, the electrical signal had a linear relationship with the concentration of target DNA ranging from 3.96 x 10(-7) to 1.32 x 10(-6) M, and the detection limit was 1.94 x 10(-8) M (S/N=3). The biosensor has good selectivity by detecting the three-base mismatch sequence ssDNA.