Effect of the secondary structure of poly-L-lysine on the adsorption at the water/dodecane interface

The adsorption of poly-L-lysine of different conformation (a-helix, ß-sheet and random coil) at the water/dodecane interface has been studied by interfacial tension measurements using the drop volume method. The experimental adsorption isotherms provide information about a critical aggregation concentration, the maximum interfacial tension depression??max and the minimum area A occupied by adsorbed molecules at the interface. Differences in??max exist between a-helix and ß-sheet and, moreover, in the area values between random-coil on the one side and a-helix and ß-sheet on the other hand.