Electrochemical DNA biosensor for the detection of specific gene related to Microcystis species

A new electrochemical biosensor is described for voltammetric detection of gene sequence related to bloom-forming genera of cyanobacteria, Microcystis spp. The sensor involves the immobilization of a 17-mer DNA probe, which is complementary to a specific gene sequence related to Microcystis spp. on a gold electrode through specific adsorption. The DNA probe was used to determine the amount of target gene in solution using methylene blue (MB) and ruthenium bipyridine as the electrochemical indicators. The anodic peak currents (i(pa)) of Ru(bpy)(3)(2+) were linearly related to the concentration of the target oligonucleotide sequence in the range 1.8 x 10(-10) -9.0 x 10(-8) M. The detection limit of this approach was 9.0 x 10(-11) M. In addition, these indicators were capable of selectively discriminating against mismatches: a very desirable condition for the detection of disease-related point-mutation in guanine bases of the cyanobacteria. (C) 2001 Published by Elsevier Science B.V.