ABSTRACT
Unlike conventional imaging technologies, fluorescent imaging benefits from its safety, high-spatial resolution and real-time capability, which make it a highly adoptable imaging method for tumor detection and image-guided surgery in clinics. There are two types of fluorescent probes, including always-on type and environment-responsive type, wherein environment-responsive probes are preferred due to higher target-to-background ratios, which can improve sensitivity and specificity. The environment-responsive probes include enzyme-reactive probes, pH-sensitive probes and hypoxia responsive probes. This review summarizes recent progress in environment-responsive probes, and discusses their potentials in tumor detection and image-guided surgery.