Abstract

Polyethylene glycol (PEG) is one of the most widely used polymers in cosmetic and biomedical products. The supported lipid multi-bilayer (SLMB) is an important model membrane, which is highly advantageous to surface diffraction techniques . In this study, in-situ grazing-incidence X-ray diffraction, X-ray reflectivity , and X-ray rocking scans are combined to systematically study the effects of PEG on SLMBs. A structure restoring effect of PEG is revealed, which is indicated by the reduced bilayer periodicity, improved molecular packing, and enhanced membrane orientation of the SLMBs. Moreover, this effect is found to be irreversible; i.e ., removing PEG does not eliminate this effect. This finding may contribute to a better understanding of PEG-membrane interaction and the further biomedical applications of PEG.