Objective      To prepare Fe

3

O

4

-loaded thrombus-targeting poly lactic-co-glycolic acid (PLGA) microparticles

and to investigate its related characteristics and targeting ability to thrombus in vitro by MRI.       Methods       PLGA was employed as the core of microparticles of drug carriers. Fe

3

O

4

-loaded PLGA microparticles were first prepared through double emul

sion solvent evaporation technique and the ligands Arg-Gly-Asp-Ser (RGDS) were further covalently bound to the surface of microparticles via carbodiimide-mediated amide bond formation. The physical and chemical properties of RGDS-Fe

3

O

4

-PLGA microparticles were measured

and their feasibility and efficacy of targeting thrombus were estimated by in vitro experiment. MR images of the microparticles were observed with a 3.0 T clinical MR scanner.       Results      The RGDS-Fe

3

O

4

-PLGA microparticles were spherical in shape with a mean diameter of 1 105±83 nm

and had neither aggregation nor adhesion tendencies. The carrier rate of Fe

3

O

4

was 43.6% through atomic absorption spectrometer

and the conjugate rate of RGDS was detected as 23.57% by flow cytometry. Pathological section confirmed that the microparticles specifically accumulated in the edge of thrombus. MR scanning demonstrated the microparticles effectively targeted thrombus and significantly decreased T

2

signal on the edge of the thrombus.       Conclusion       Our prepared RGDS-Fe

3

O

4

-PLGA microparticles have good affinity to thrombus and exhibit contrast-enhanced effect in in vitro MI images.