Bacteria growing resistant to common antibiotics is a growing problem and research in new types of medicines which do not induce resistance is therefore very important. Novel hyperbranched drugs based on antimicrobial peptides have been synthesized and they have shown great potency towards various bacteria. Working in a non-specific manner via electrostatic and hydrophobic interactions they decrease the risk of resistance inducement. QCM-D, AFM and preliminary NR data have already given insight into the uptake mechanism of these types of drugs, but complementary NR experiments are needed in order to fully understand the mechanism of action. In this proposal we intend to investigate in detail the effect of fluidity of cell membranes for dendrimer drug interaction by the use of a binary model system which displays varying degrees of fluidity depending on the ratio between the two lipids.