Figure 9 Detection of a CA mismatch with electrocatalysis at a DNA film. (Adapted from Ref. 25.)

Other methods have been developed that allow the detection of point mutations in nonhybridization based assays. An effective alternative electrochemical method harnesses differences in the kinetics of the reaction of Ru(bpy)32+ with guanine in the context of base mismatches to report base substitutions [47]. In addition, altered patterns of chemical reactivity have been detected in RNA-DNA hybrids containing 2-NH2 modifications in an RNA complement at mispaired positions [48]. Extension of this approach to an immobilized system has not yet been demonstrated, but it may hold promise for any applications where alterations in chemical, rather than electrochemical, reactivity are required.