Abstract: The invention concerns a method for analyzing biological targets of DNA or RNA type, which comprises the following steps: a) contacting the targets to be analyzed (ICAM-20) with oligonucleotide probes (ISIS) labeled with a cofactor A of an enzyme E; b) adding, to the reaction medium, enzyme E corresponding to cofactor A and a substrate S of enzyme E, substrate S being converted by enzyme E into a compound C; c) measuring a signal representative of the activity of enzyme E on substrate S, for example the fluorescence intensity (I) of substrate S; and d) comparing this signal with the signal obtained when the oligonucleotide probes labeled with cofactor A (ISIS) are contacted with enzyme E and substrate S, under the same conditions, but in the absence of the targets, the difference between the two signals indicating the presence of complementary targets (ICAM-20) of the oligonucleotide probes.