Steric hindrance engineering to construct NIR-II probe for high-sensitivity G4 imaging in vivo

G-Quadruplexes play key roles in tumorigenesis, but detecting them in vivo remains challenging. We developed NIRGQ-3, a NIR-II fluorescent probe, with 25-fold fluorescence enhancement and improved sensitivity (limit of detection: 35 nM). It enables high-contrast tumor imaging (SBR = 25), providing a powerful tool to decipher G-quadruplex dynamics and advancing cancer diagnostics.