Abstract: Disclosed is a peptide nucleic acid monomer as well as a corresponding peptide nucleic acid molecule. The monomer comprises a terminal amino group and a terminal group A. The terminal amino group and the terminal group A are connected by an aliphatic moiety. The main chain of this aliphatic moiety is free of groups that are charged under physiological conditions. The terminal group A is one of —COOH, —COOR3, —COX, —COSR3, —CN, —CONH2, —CONHR3, —CONR3, R4, with R3 and R4 being H or an aliphatic, alicyclic, aromatic, arylaliphatic or arylalicyclic group, and X being a halogen atom. The terminal amino group is substituted by an aliphatic group with a main chain of at least two carbon atoms and optionally 0 to a bout 2 heteroatoms selected from the group N, O, S, Se and Si. The main chain has a polar head group Z.