A liposomal formulation study of 2,7-dichlorodihydrofluorescein for detection of reactive oxygen species.

It is known that reactive oxygen species (ROS) are connected with various diseases, and many studies have examined redox conditions in the body. However, there is a problem with stability of ROS and selectivity of detection probe. In this study, we aimed to stabilize the detection probe, and have tried to encapsulate the probe in polyethyleneglycol (PEG)-modified liposomes. Dichlorodihydrofluorescein (DCDHF) is oxidized to dichlorofluorescein (DCF), a highly fluorescent product, by ROS. We tried liposomalization of DCDHF probes by the Bangham method. However, it was found that DCDHF was oxidized during preparation and converted to DCF. In contrast, when we performed to encapsulate DCDHF in the liposome after the preparation of empty liposome, the stabilized DCDHF encapsulated liposome was successfully proposed by the addition of DCDHF solution by freeze-drying and re-hydration. Furthermore, the encapsulated efficacy of PEG-modified liposomes was higher than unmodified liposomes. This DCDHF liposome was examined for reactivity with hydroxyl radical and peroxynitrite as highly ROS. It was confirmed that DCDHF liposome had a protective effect on the hydroxyl radical, though an effect of the liposomalization of DCDHF was not shown on reactivity of the peroxynitrite. Therefore, it is likely that the liposomalization of DCDHF has selectivity for certain radical species. It is hoped that these results can be applied to novel and simple diagnostics for redox detection of conditions in the body.