“…[14,16] Similaru ptake properties were found for the enantiomeric TAT [49][50][51][52][53][54][55][56][57] peptidea nd in penetrating peptoidsw ith guanidiniums ide chains anchored at the nitrogen of the amide group. [4,37,48,[50][51][52][53][54][55][56][57][58] However, despite all advances in the field, CPPs still have some limitations, mainly relatedt o their selectivity and toxicity. [17][18][19][20][21][22][23][24][25] Interesting penetrating properties were further discovered in different naturala nd artificial structures, such as polyprolines, [26] guanidinyl glycosides, [27,28] b-peptides, [29] peptiden ucleic acids (PNAs), [30] nonpeptidic guanidinylated dendritic structures, [31] self-assembled nanofibers, [32,33] synthetic polymers, [34][35][36][37] supramolecular structures, [38]…”