Hwang K J, Mauk M R
Proc Natl Acad Sci U S A. 1977 Nov;74(11):4991-5. doi: 10.1073/pnas.74.11.4991.
The structural integrity of unilamellar vesicles has been studied in vitro and in vivo by use of gamma-ray perturbed angular correlation techniques. These studies utilize 111In3+ weakly bound to the chelator nitrilotriacetic acid as a probe to monitor the percentage of intact vesicles. When complexes of 111In3+ and nitrilotriacetic acid is encapsulated in vesicles, 111In3+ exhibits a fast tumbling rate. Upon alteration of the membrane, 111In3+ is released from the liposomes and becomes bound to macromolecules, consequently exhibiting a decrease in 111In3+ tumbling rate. The in vitro experiments show that the present technique is capable of determining quantitatively the percentage of material released from the vesicles upon the addition of serum or Triton X-100 to vesicles. The percentage of vesicles remaining intact in vivo can also be monitored continuously by the present technique. In mice, the half-life of dipalmitoyl phosphatidylcholine-cholesterol vesicles after intraperitoneal injection was estimated to be 10-13 hr. The present study suggest that the vesicles remain intact in various tissues for extended periods, thereby allowing a slow release of the encapsulated material at those sites.
已通过使用γ射线扰动角关联技术在体外和体内研究了单层囊泡的结构完整性。这些研究利用与螯合剂次氮基三乙酸弱结合的111In3+作为探针来监测完整囊泡的百分比。当111In3+与次氮基三乙酸的复合物被包裹在囊泡中时，111In3+表现出快速的翻滚速率。当膜发生改变时，111In3+从脂质体中释放出来并与大分子结合，结果111In3+的翻滚速率降低。体外实验表明，本技术能够定量测定在向囊泡中加入血清或 Triton X-100后从囊泡中释放的物质的百分比。通过本技术也可以连续监测体内保持完整的囊泡的百分比。在小鼠中，腹腔注射后二棕榈酰磷脂酰胆碱-胆固醇囊泡的半衰期估计为10 - 13小时。本研究表明，囊泡在各种组织中长时间保持完整，从而允许在这些部位缓慢释放包裹的物质。
