This gives a normalised value between -1 and 1, where -1 indicates the intensity contributions in hybrid vesicles are from DiO only, 1 where the intensity contributions in the hybrid vesicles are entirely from PBd22-PEO14-TMR, while an intensity ratio of 0 indicates equal fluorescence intensity contributions in hybrid vesicles from both PBd22-PEO14-TMR and DiO. The resultant histograms are then fitted with a normal distribution curve.