The invention relates to novel electropolymerisable monomers which are to be polymerised in an aqueous solution and comprise: an electropolymerisable pattern selected from acetylene, pyrrols, thiophenes, indols, anilines, azines, p-phenylene vinylenes, p-phenylenes, pyrenes, furanes, selenophenes, pyrridazines, carbazoles, acrylates, methacrylates and the derivatives thereof, and a metalloporphyrine which is substituted by at least two ionised or ionisable entities in an aqueous solution. The invention also relates to a method for the polymerisation of such monomers, to the electroactive probe that can be obtained by the polymerisation of such monomers, and to a method for detecting a target ligand in a biological sample using one such electroactive probe.