Malignant tumors constitute a serious disease that threaten human life, and early diagnosis and metastasis prediction are critical to the choice of treatment plan and the timing of treatment. Integrin αvβ3, which has received broad attention as a molecular marker of the tumor neovasculature, is an important target for monitoring tumorigenesis and progression in molecular imaging research. This study reports a magnetic resonance (MR)/fluorescence dual-mode molecular probe, cRGD-Gd-Cy5.5, which targets the integrin αvβ3 receptor and uses liposomes as carrier. The obtained nanoprobe had a size of 60.08 ± 0.45 nm, with good dispersion in water, a uniform distribution of sizes, desirable stability, and high relaxivity. Its r1 relaxation rate was 10.515 mM-1 s-1, much higher than that of other Gd chelates in clinical use. The probe showed no cytotoxicity at the tested concentrations in vitro, and its ability to target A549 cells and SUNE-1-5-8F cells was preliminarily evaluated through in vitro fluorescence imaging and MR imaging. The results demonstrated that the cRGD-Gd-Cy5.5 nanoprobe had good characteristics, showing desirable stability and biosafety, a high T1 relaxation rate, and strong targeting and binding to tumors with high expression of integrin αvβ3. Therefore, cRGD-Gd-Cy5.5 is a promising agent for the visual monitoring of tumor metastasis.
Keywords: Dual-mode molecular probe; Integrin αvβ3; Malignant tumors; Molecular imaging; Tumor metastasis; Visual monitoring.