pH/Viscosity dual-response fluorescent probes as highly selective tumor visualization tools

Due to the complexity of physiological environment and the small changes of related parameters, it is difficult for a single-mode fluorescent probe to achieve excellent and accurate detection. In this paper, two dual-mode fluorescent probes responding to both pH and viscosity were designed and synthesized based on inhibited intramolecular charge transfer (ICT) and twisted intramolecular charge transfer (TICT) processes. At low pH and high viscosity, the fluorescence intensity of probes would be doubly amplified, providing excellent contrast for biological imaging. The wavelength of CL-2 was redshifted by 45 nm for better penetration by extending the conjugated system of CL-1. Fluorescence imaging in living cells, tissue and organs further illustrated that the probes synthesized in this paper could selectively realize the visualization of cancer.