Peptide Amphiphiles with Distinct Supramolecular Nanostructures for Controlled Antibacterial Activities

Gemini-type peptide amphiphiles 12-(Lys)_n-12 (n = 2, 4, 6) with different lysine spacer lengths have been established and exhibit excellent antibacterial activities. By varying the lysine number in the spacer, the distinct aggregates with zero- to three-dimensional structures (fibers, short rods, and spherical aggregates) are formed. These different length/diameter ratios of aggregates have great effects on the antibacterial activities and cytotoxicity. 12-(Lys)₂-12 has a relatively higher minimal inhibitory concentration (MIC) value and shows toxicity toward mammalian cells just above its MIC value, while 12-(Lys)₄-12 and 12-(Lys)₆-12 have lower MIC values and no cytotoxicity even at 5 times the MIC values.