To fabricate tAu@glutathione(GSH)@Gd nanoprobe for tumor angiogenesis bimodal (MR/CT) imaging, and evaluate its characteristics and potential for MR/CT imaging in vivo.

The tAu@GSH@Gd nanoprobes were constructed by encapsulating Au and Gd atoms into the GSH shell with cyclic asparagine-glycine-arginine (cNGR) peptide conjugation. EMT-6 BALB/c mice subcutaneous transplantation tumor models were established (n=30) and divided into blank control group (saline), control group (Au@GSH@Gd nanoparticles) and experimental group (tAu@GSH@Gd nanoprobes) (n=10 in each group). In vivo MR/CT imaging and distribution study were performed at different time points after tail intravenously injection. Relative MR signal value and relative CT value of tumor site and main organs in mice were used to evaluate MR/CT imaging property and biological distribution. After that, tumor tissues were collected for silver staining to study the accumulation of Au@GSH@Gd nanoparticles and tAu@GSH@Gd nanoprobes. Independent-sample t test was used for data analysis.

The tAu@GSH@Gd nanoprobes were (6.40±0.22) nm with high T₁ relaxation efficiency ((36.91±0.07) mmol·L^-1·s^-1). MR/CT imaging of tAu@GSH@Gd nanoprobes showed good performance in vitro. In vivo MR/CT imaging demonstrated MR/CT imaging of tumor was significantly enhanced by tAu@GSH@Gd nanoprobes after 2 h post injection. The strongest enhancement was observed at 24 h, with an increased relative MR signal value from 1.04±0.12 (before injection) to 1.84±0.26 (t=12.61, P=0.006), and increased relative CT value from 1.01±0.04 (before injection) to 1.95±0.05 (t=15.34, P=0.004). The highest MR/CT effect in control group appeared at 16 h, with the relative MR signal value of 1.50±0.06 and the relative CT value of 1.53±0.10, which were significantly lower than those in experimental group (1.84±0.26 and 1.95±0.05; t values: 5.35 and 16.46, both P<0.05). Distribution in normal tissues showed that most of tAu@GSH@Gd nanoprobes were metabolized through the kidneys. Tissue silver staining experiment verified the tumor angiogenesis targeting effect.

The tAu@GSH@Gd nanoprobes exhibit favorable tumor angiogenesis target MR/CT imaging ability, providing a new design concept and basis for assessing tumor angiogenesis.

Breast neoplasms; Neovascularization, pathologic; Magnetic resonance imaging; Tomography, X-ray computed; Nanotechnology; Gold; Gadolinium; Mice