For fluorescence signal readout, the incubation time after addition of the F-Q probe is also important, because the strand separation of the probe and the hybridization of the FAM-labelled strand with the RCA product is under both thermodynamic and kinetic control. To find out the suitable incubation time, we mixed the RCA products with the F-Q probe for 30 to 120 minutes and measured the fluorescence intensity. As shown in Fig. , after 45 minutes incubation the fluorescence intensity did not increase further. Therefore, in the remaining experiments the incubation time was fixed at 45 min.