Objective: To prove the long-circulating and distribution of liposome which is modified with choesterol-poly (ethylene glycol)2000-glycyrrhetinic acid (Chol-PEG-GA)(CPGL) in vivo and provide theoretical basis for targeting therapy of tumor. Method: The biodistribution of NIRD-15 labeled liposome was studied in mice by fluorescence animal imaging. The mice were randomly separated in conventional liposomes (LP) group and CPGL group. The fluorescence intensities in vivo and in isolated organs were measured 5

10

15

30

60

120

180

360

600 min after injection. Result: LP faded away quickly through metabolism in organs of body

transferred by circulation system

while few phenomenon of NIRD-15's enrichment in liver occurred. After injected CPGL into body

the content ratio of NIRD-15 in the body was increased slowly. The phenomenon of NIRD-15 enrichment occurred in the liver 15 min after administration

and the concentration was still higher than LP after 600 min

which suggested liposomes modified with Chol-PEG-GA can target to the liver and extend its residence time in liver. Conclusion: CPGL can control the release of the drug in vivo

prolong the biological half life

and improve the liver targeting effect.