The direct comparison between undisturbed DLPC/Chol membranes and membranes with either homodimeric or hairpin structures was carried out via analysis of samples 1-3 (Table 1 ). The homodimer 4 [=H-(Phe(4I)-Tyr-(Phe-Tyr) 4 -Trp-Trp-OH] was embedded at a P/L ratio of 1/10 while the hairpin system 5 [=H-(Phe-Tyr) 3 -Phe(4I)-Tyr-Phe-Tyr-Trp-Trp-Gly-Lys-Pro-Gly-(Phe-Tyr) 2 -Phe(4I)-(Tyr-Phe) 2 -Tyr-Trp-Trp-OH] was embedded at P/L = 1/20, both leading to a peptide-to-helix ratio of 1/20. The equimolar mixture of species 3 and 6 [= H-Lys(TAMRA)-Tyr-(Phe-Tyr) 4 -Trp-Trp-Gly-Lys-([C 2 H 4 O] 2 -CH 2 -CO-gcgtgg-Lys-Lys)-Pro-Gly-(Phe-Tyr) 5 -Trp-Trp-OH] representing the recognition system could at least be incorporated into multilamellar DLPC stacks at P/L = 1/40 avoiding precipitation. A second hairpin sample (sample 4) including compound 5 was prepared at a P/L ratio of 1/40. Therefore, samples 3 and 4 were analyzed to account for the concentration dependency of the observed lipid response. In order to evaluate the applied methodology and due to the fact that the recognition system (3/6) should be most amenable to changes in RH because of its polar PNA moieties facing the water layers, a series of experiments was performed at different RHs ranging from 94% to 25%. All other samples were analyzed at RH = 94%.