DISPOSABLE ELECTRODE SYSTEM FOR DETECTION OF SELECTED NUCLEIC ACID SEQUENCES

摘要

A single stranded DNA probe is synthesized to be complementary to the desired target strand, and is functionalized on one terminus with a thiol group and on the other with a reversibly electrooxidizable group such as ferrocene or thionine. The thiol modification allows the probes to be immobilized in a mixed monolayer on the gold surface of an electrode. Self complementary regions near the ends of the DNA probe cause it to self-hybridize into a hairpin loop structure in the absence of target DNA, which effectively constrains the redox active label near the surface of the electrode such that it can be cyclically oxidized and reduced by application of a cycled potential at the electrode. Hybridization to a complementary strand of DNA or RNA causes the probe to undergo a conformational change in which the redox active label is displaced from the surface, impeding the efficiency of electron tranfer from the electrode and resulting in diminished cyclic redox current. Probes to the users specifications may be synthesized using commercially available solid phase techniques amenable to the automated phosphoramidite method.