The present application relates to methods of detecting a mutation in a target nucleic acid molecule. Two phosphorodiamidate morpholino oligomer probes that differ by at least one base are each covalently coupled to a nanoparticle and hybridised to a target sequence. The melting temperature of the complexes between each of the two probes and the target nucleic acid are measured and compared to determine whether the sample contains a nucleic acid with the mutation. Further, the present invention relates to kits comprising a first and second conjugate as described herein and to the use of such kits for the detection of mutations in a target nucleic acid molecule or for assigning a genotype to a target nucleic acid molecule.