Glycyrrhetinic acid modified alginate (GA-ALG) was prepared by covalent attachment of hydrophobic liver targeting ligand glycyrrhetinic acid (GA) onto the nature polysaccharide alginate (ALG).The resulting amphiphilic GA-ALG could form self-assembled nanoparticles (GA-ALG NPs) in an aqueous medium as liver targeting drug delivery carrier.Broad spectrum antitumor drug-doxorubicin (DOX) loaded GA-ALG NPs (DOX/GA-ALG NPs) were obtained by emulsification method for liver targeting drug delivery.Single photon emission computed tomography (SPECT) and some mathematical relationships were used to qualitatively and quantitatively evaluate the targeting efficiency of GA-ALG drug delivery systems in vivo .The SPECT image confirmed that 99mTc labeled GA-ALG nanoparticles mainly accumulated in the liver of Wistar rats after intravenous injection

and the accumulation of 99mTc labeled GA-ALG nanoparticles in the liver was about 40.2% at 3 h after injection.The biodistribution data showed that the concentration of DOX in the liver reached (67.8 4.9) g/g after intravenous administration of DOX/GA-ALG NPs

which was 4.7-fold higher than that of DOXHCl solution at 3 h post-injection.And the data of relative tissue exposure (re)

targeting efficiency (te) and weighted-average targeting efficiency (te*) showed that liver targeting efficiency was enhanced by GA-ALG drug delivery systems.These results revealed the potential of GA-ALG nanoparticles as liver targeting drug delivery carriers.