The present study investigated the effect of the 6-monodeoxy-6-monoamine-beta-cyclodextrin(Am-beta-CD)/DNA (Am-beta-CD/DNA) complex, as well as of culture medium components and proteins, at pH 7.4 and 5.0, on membranes of anionic and pH-sensitive liposomes comprised of DOPE-CHEMS, using energy dispersive X-ray diffraction (EDXD). At pH 7.4, the Am-beta-CD/DNA complex induced the appearance of lamellar and hexagonal phases of DOPE. However, at pH 5.0, only non-lamellar phases could be observed. The presence of biological components led to a disruption of lipid order, but the pH-sensitivity of liposomes was maintained. (c) 2011 Elsevier B.V. All rights reserved.