The present invention is directed to a new class of lipids, more specifically ether-lipids having a polar headgroup, as well as vesicles comprising these lipids, methods of their preparation as well as their uses in medical applications, wherein the ether-lipids are represented by general formula I wherein Y represents O, N, S or a covalent bond； P1 represents H, an Y-protecting group or an Y-activating group or a spacer group； P2, P3 represent independently of each other H, an amino-protecting group or a spacer group, or P2 and P3 form together with the N to which they are bound a ring structure； L is a group of formula (a) wherein the dashed line represents the linkage to N； R1 represents H or a group of formula -(CH2)2-ORb1； R1' represents H or a group of formula -(CH2)2-ORb2, R2 represents H or a group of formula -CH2-ORc； R2'represents H or a group of formula -ORd or -CH2-ORd； R3 represents H or a group of formula -(CH2)2-ORe or -(CH2)3-ORe； Ra, Rb1, Rb2, Rc, Rd, Re represent independently of each other a saturated or unsaturated, straight or branched hydrocarbon chain, and m is 1, 2 or 3； with the proviso that at least one of R1, R1', R2, R2', R3 is not H.本發明係關於一類新穎脂質，更特定言之為具有極性頭基之醚脂，以及包含此等脂質之囊泡、其製備方法以及其在醫學應用中之用途，其中該等醚脂由通式I表示其中Y表示O、N、S或共價鍵；P1表示H、Y保護基或Y活化基團或者間隔基團；P2、P3彼此獨立地表示H、胺基保護基或間隔基團，或P2及P3與其所結合之N一起形成環結構；L為式(a)之基團其中虛線表示鍵聯至N；R1表示H或式-(CH2)2-ORb1之基團；R1'表示H或式-(CH2)2-ORb2之基團；R2表示H或式-CH2-ORc之基團；R2'表示H或式-ORd或-CH2-ORd之基團；R3表示H或式-(CH2)2-ORe或-(CH2)3-ORe之基團；Ra、Rb1、Rb2、Rc、Rd、Re彼此獨立地表示飽和或不飽和直鏈或分支鏈烴鏈，且m為1、2或3；其限制條件為R1、R1'、R2、R2'、R3中之至少一者不為H。
