Processes of functionalization and reagents used in such processes using an aza-isatoic anhydride or its derivatives, organic molecules thus treated and kits

The present invention relates to a process of functionalising at least one ribonucleic acid (RNA) molecule which comprises the following steps: a) having at least: a binding molecule constituted by an isatoic anhydride or a derivative thereof, a group of interest, and a binding arm linking the binding molecule with the group of interest, b) reacting the anhydride function of the binding molecule with at least one hydroxyl group in: position 2' of the ribose of one of the RNA nucleotides, and/or position(s) 2' and/or 3' of the ribose of the nucleotide at the 3' terminal end of the RNA, and c) obtaining an anthranilate linking, via the binding arm, the RNA to the group of interest. The invention also relates to a functionalising reagent able to be used in such processes, a functionalised biological RNA molecule capable of being obtained by these processes and a kit for detecting a target RNA molecule comprising such a reagent. Said invention finds a preferential application in the field of in vitro diagnosis.