N-gamma-Carboxyalkyl modified peptide nucleic acids (PNAs), containing the four canonical nucleobases, were prepared via solid-phase oligomerization. The inserted peptoid monomers 1 and 2 were constructed through simple synthetic procedures, utilizing appropriate glycidol and iodoalkyl electrophiles. Thermal denaturation studies, performed with complementary antiparallel DNA strands, demonstrated that the length of the Ng-side chain strongly influences the modified PNAs hybridization properties. Moreover, multiple negative charges on the oligoamide backbone, when present on g-nitrogen C6 side chains proved to be beneficial for the oligomers’ water solubility and DNA hybridization specificity.