Laurdan-labelled GUVs were used to obtain GP values from 15-20 individual vesicles for each GUV composition studied using a confocal microscope. Interestingly, all compositions studied (pure lipid and pure polymer vesicles and 50 mol% hybrid GUVs) were found to have GP values < 0, indicating a hydrated disordered membrane (Figure ). There is only a small apparent increase in the average GP value between the pure lipid GUVs and the GUVs made purely of each polymer (Figure ), where the measured difference in GP is not statistically significant (p > 0.05, Tukey and Bonferroni ANOVA). Therefore all hybrid GUV membranes studied here have a comparable hydration state and membrane ordering, which likely contributes to the formation of well-mixed hybrid GUVs. No lateral heterogeneities were observed in the hydration state of these membranes, providing further evidence for a lack of distinct microscale membrane domains forming in these GUV compositions (Figure ).