Patent ID: 6864055

Claim:
A method of detecting a ratio of content of complementary nucleic acid fragments contained in plural samples which comprises the steps of: attaching an electroconductive label to nucleic acid fragments in one sample and attaching another electroconductive label to nucleic acid fragments in another sample, the former electroconductive label and the latter electroconductive label having oxidation-reduction potentials differing from each other; preparing a mixture of the samples containing nucleic acid fragments to which electroconductive labels are attached; bringing the mixture into contact with an electroconductive microarray having plural electrodes onto which probe molecules complementary to the nucleic acid fragments are fixed, so that hybridization between the nucleic acid fragments having electroconductive labels and the probe molecules on the electroconductive microarray can proceed to form hybrid structures on the electrodes; applying to the electrode an electric potential corresponding to the oxidation-reduction potential of the former electroconductive label and detecting on the electrode an electric current flowing along the hybrid structure; applying to the electrode an electric potential corresponding to the oxidation-reduction potential of the latter electroconductive label and detecting on the electrode an electric current flowing along the hybrid structure; and comparing the electric current detected in the former detecting procedure and the electric current detected in the latter detecting procedure, whereby detecting the ratio of content of the complementary nucleic acid fragments between plural samples.