This communication reports a new nanocatalytic scheme based on the facts that the redox reaction between a highly outer-spherereaction-philic (OSR-philic) species and a highly inner-spherereaction-philic (ISR-philic) species is slow and that an OSR- and ISRphilic Au-nanocatalyst label can mediate the two different types of redox species. This scheme allows highly sensitive and incubation free detection of creatine kinase-MB. Using outer-sphere to inner-sphere ENc redox cycling that allows high signal amplification. When the ENc redox cycling was applied to a sandwich-type immunosensor for the detection of CK-MB, the calculated detection limit was approximately 20 fg mL1 , indicating that the immunosensor is highly sensitive. The results for clinical serum samples showed that the immunosensor is practically appealing.