Rational design of chloride-based ionic iridium(III) complex to construct phosphorescent nanoparticles for cancer cell imaging

Abstract

In the process of cancer cell proliferation and metastasis, folate receptors (FRα, FRβ, and FRγ) play a facilitating role. More importantly, folate receptor, especially FRα, is expressed less in normal tissues but overexpressed in tumor tissues, making it a promising target for anticancer therapy. As a result, various probes targeting FRα have been developed for tumor detection. In this study, a new chloride-based ionic phosphorescent iridium(III) complex is rationally designed and synthesized, and then the phosphorescent nanoparticle (Ir NPs) is prepared by co-precipitation of iridium(III) complex with DSPE-PEG₂₀₀₀ and DSPE-PEG₂₀₀₀-FA, possessing the following advantages: good water solubility, exceptional biocompatibility, favorable surface properties, and excellent phosphorescence properties. Because of these advantages, Ir NPs are exceptionally suitable for biological application. Finally, cellular imaging, as a form of biological application, has been fully investigated. The results show that DSPE-PEG₂₀₀₀-FA can effectively recognize the over-expressed FRα on the surface of various cells, such as KB and MDA-MB-231 cells. We believe that the Ir NPs could be used as a promising phosphorescent probe for selective biological imaging.