A novel CEST-contrast nanoagent for differentiating the malignant degree in breast cancer

Different subtypes of breast cancer (BCC) have variable degrees of malignancy, which is closely related to their extracellular pH (pH(e)). Therefore, it is increasingly significant to monitor the extracellular pH sensitively to further determine the malignancy of different subtypes of BCC. Here, a l-arginine and Eu(3+) assembled nanoparticle Eu(3+)@l-Arg was prepared to detect the pH(e) of two breast cancer models (TUBO is non-invasive and 4T1 is malignant) using a clinical chemical exchange saturation shift imaging technique. The experiments in vivo showed that Eu(3+)@l-Arg nanomaterials could respond sensitively to changes of pH(e). In 4T1 models, the CEST signal enhanced about 5.42 times after Eu(3+)@l-Arg nanomaterials were used to detect the pH(e). In contrast, few enhancements of the CEST signal were seen in the TUBO models. This significant difference had led to new ideas for identifying subtypes of BCC with different degrees of malignancy.