Objective To synthesize a molecular probe targeted to human hepatoma HepG2 cells with high expression of integrin αvβ3 (RGD-PEG-VSOP) and evaluate its MRI efficacy in vitro.Methods RGD-PEG-VSOP was characterized and analyzed by 1H NMR and TEM.MTT test was used to evaluate its biological safety.In vitro experiments at the cellular level,the targeting effect of RGD-PEG-VSOP to integrin was assessed,meanwhile the nontargeted nanoparticles were used as controls.Results TEM showed that the nanoparticles were spherical and uniform in size,with a relatively high r1 relaxivity of 1.37 mM-1S-1.MRI showed the signal intensity of the HepG2 cells treated with RGD-PEG--VSOP was significantly higher than that of the HepG2 cells treated with PEG-VSOP (P＜0.05).Conclusion RGD-PEG-VSOP has positive T1 contrast effect.At the cellular level,the RGD-PEG-VSOP nanoparticles have the characteristics targeted to integrin αvβ3.