OBJECTIVETo prepare a glypican-3 (GPC3)-targeting hepatocellular carcinoma MR molecular probe and to evaluate its targeting specificity using HepG2 cells.

METHODSPoly(lactic-co-glycolic acid) (PLGA) nanoparticles were prepared by a double emulsion solvent evaporation method, and the surfaces were connected with anti-GPC3 mono-antibody and paramagnetic substance Gd3+. The physical properties of the probes were investigated using fluorescence microscopy, electron microscopy, Malvern particle size analysis, inductively coupled plasma atomic emission spectroscopy (ICP-AES) and 1.5T MR imaging. The specificity of the probes to target cultured HepG2 cells was determined by laser confocal microscopy. The signal characteristics, including signal-to-noise ratio (SNR), after co-incubation with HepG2 cells were analyzed by 1.5T MR imaging. Significance of differences between multiple groups (target group, non-target group, and control group) was assessed by one-way analysis of variance, and between two groups was assessed by the LSD-t test. A difference was considered to be statistically significant at P less than 0.05.

RESULTSThe GPC3-targeting hepatocellular carcinoma MR molecular probes were successfully prepared. The nanoparticles had a spherical shape, size of 495 +/- 17.5 nm, uniform size distribution, good dispersibility, no obvious aggregation, and could significantly increase the T1 signal. Using the ICP-AES measurement, 1 mol PLGA carried about 12 mol Gd3+, and as the Gd3+ concentration increased, the T1 signal increased. The prepared MR molecular probes could specifically target HepG2 cells, and could increase the T1 signal. The SNR value of the target group was 3.45 +/- 0.21, of the non-target group was 1.43 +/- 0.07, and of the control group was 1.12 +/- 0.03. The SNR value of the target group was significantly higher than that of the non-target group and the control group (P less than 0.05); there was no significant difference between the non-target group and the control group (P more than 0.05).

CONCLUSIONPLGA nanoparticles, anti-GPC3 mono-antibody and paramagnetic Gd3+ can be used to successfully prepare GPC3-targeting hepatocellular carcinoma MR molecular probes which are capable of specifically targeting HepG2 cells in vitro and being detected by 1.5T MR imaging. These MR molecular probes may represent a useful noninvasive imaging method for detecting early hepatocellular carcinoma in vivo.