Photomodification of biological membranes with emphasis on singlet oxygen mechanisms.

This review discusses photomodification of biological membranes and model membrane systems. Current concepts of membrane structure are first reviewed briefly. The role of preillumination association of sensitizer with membranes as it relates to photomodification rate is discussed, as well as the role of singlet oxygen in membrane photomodification. Finally the characteristics of singlet oxygen generation in membranes are considered. The evidence clearly indicates that membrane photomodification cannot be understood based only on the properties of sensitizers and singlet oxygen in aqueous solution. Rather the properties of sensitizers in association with membranes are the determinants of membrane photomodifcation. These properties differ significantly in aqueous solution and in membranes.