A Dual-Target-Activatable Ruthenium(II) Probe for Naked-Eye Luminescence-Guided Intraoperative Glioma Resection

Abstract Glioma is the most common primary malignant tumor of the central nervous system and represents a devastating disease associated with high mortality and severe neurological morbidity. Currently, surgical resection remains the cornerstone of glioma therapy. However, gliomas are characterized by highly infiltrative growth, which makes tumor boundaries difficult to distinguish under conventional white-light visualization. Therefore, there is an urgent clinical need for imaging approaches that enable high-contrast and high-sensitivity visualization to assist surgeons in delineating glioma margins. In this study, we developed a low-background luminescent Ru(II) complex probe, Ru-GA, which enables luminescence-guided intraoperative glioma resection with naked-eye visibility via dual-target recognition of glutathione S-transferases (GSTs) and azoreductase (AzoR). In this probe, a 2,4-dinitrophenyl ether group and an azobenzene group are introduced into the Ru(II) complex luminophore for the specific recognition of GSTs and AzoR, respectively. Owing to the strong electron-withdrawing effect of the 2,4-dinitrophenyl and azobenzene moieties, strong photoinduced electron transfer and intramolecular charge transfer processes occur within the probe, leading to an efficient quenching of the luminescence of the Ru(II) complex, thus ensuring a low background for imaging. Upon sequential reaction with GSTs and AzoR, the dinitrophenyl group is cleaved off, and the azo group is reduced to amino groups; consequently, the luminescence is restored. Cellular imaging results indicate that both GSTs and AzoR are significantly overexpressed in glioma cells, and the probe successfully distinguishes glioma cells from normal brain cells via luminescence imaging. Meanwhile, the probe is excited by blue light and emits red light, with no spectral overlap between the excitation and emission. Based on these properties, Ru-GA enables luminescence-guided intraoperative glioma resection with naked-eye visibility. For the first time, we validated the feasibility of luminescence-guided resection of human glioma using human glioma tissue sections. To the best of our knowledge, Ru-GA is the first dual-target-activated probe reported for luminescence-guided intraoperative glioma resection with naked-eye visibility.