Abstract: Objective: To explore the method to construct the progesterone receptor(PR)-superparamagnetic iron oxide (SPIO)-poly 1actic-co-glycolic acid (PLGA) and perfluorohexane(PFP) molecular probe(PR-s-PFP/PLGA), and to investigate its targeted possibility of binding the breast cancer cells in vitro.Methods: The s-PFP/PLGA nanoparticles were prepared and the diameter and average potential of s-PFP/PLGA nanoparticles were detected. Cytotoxicity experiment was used to compare the relative proliferation rates (RGR) of cells with different concentrations of s-PFP/PLGA. The magnetic resonance imaging (MRI), photoacoustic imaging (PAI) and ultrasound imaging of s-PFP/PLGA nanoparticles were detected,and the echo intensity of s-PFP/PLGA nanoparticles was observed by high intensity focused ultrasound (HIFU) in vitro.The PR-s-PFP/PLGA probe was prepared by carbodiimide method. The breast cancer cell line T-47d with high expression of PR was cultured in vitro. The T-47d cells with DiO green fluorescence were divided into targeted imaging agent group, non-targeted group and blank control group. The binding of the probe to the cells in various groups was observed.Results: The s-PFP/PLGA nanoparticles were spherical under transmission electron microscope (TEM).The SPIO particles were evenly distributed on the shell, the average particle size was (738.5±181.2) nm and the average potential was (-15.8±5.7) mV, and the obvious photoacoustic signals were found. The ultrasound imaging of s-PFP/PLGA nanoparticles in vitro showed a punctate high-level echo, and the echo intensity was enhanced after HIFU irradiation. With the increasing of iron concentrations, the MRI signals showed a increasing trend in T1W1. Under laser scanning confocal microscope, the s-PFP/PLGA nanoparticles, which was phagocytized by T-47d cells, emitted red fluorescence.Conclusion: PR-SPIO-PLGA has excellent physicochemical properties, good stability and strong targeting effect on the cancer cells.

Key words: ultrasonography, contrast media, magnetic resonance imaging, super paramagnetic iron oxide, perfluorohexane