OBJECTIVETo investigate the feasibility of in vivo tumor detection using magnetic resonance (MR) molecular imaging with targeted magnetic nanoparticles as imaging probe.

METHODSTargeted probe was synthesized by covalently linking the recombinant human gonadotropin releasing hormone analog (the targeting portion) with the ultrasmall superparamagnetic iron oxide nanoparticles (the imaging portion). The imaging portion served as the control material. The in vitro tumor cell experiment and the in vivo experiment using nude mice bearing tumors were carried out to test the targeting ability of the probe. In the in vitro experiment, the targeting probe and control materials were incubated separately with A549 cells which had high affinity to gonadotropin releasing hormone. Then the cells were taken out and lysed. The resultant solution was then subjected to MR imaging. The T2 value of the solutions was measured and compared. In the in vivo experiment, the targeting probe was administered into nude mice bearing A549 tumors. Dynamic MR imaging was carried out to measure the signal and T2 value of the tumor. The control material was also administered into control group of nude mice, and dynamic magnetic resonance imaging was performed. The T2 value of the tumor in both groups were recorded and compared.

RESULTSBoth the in vitro and in vivo experiments proved the targeting ability of targeted probe. Compared with control material, the targeting probe had higher combining ability with tumor cells.

CONCLUSIONMR molecular imaging of tumor can be realized by using targeting magnetic nanoparticles.