ROS/RNS and Base Dual Activatable Merocyanine‐Based NIR‐II Fluorescent Molecular Probe for in vivo Biosensing

Inflammation usually results in high‐level reactive oxygen species (ROS) and reactive nitrogen species (RNS) not only in acidic tissue but also in alkaline tissue. However, noninvasively in vivo monitoring reactive species specifically within alkaline tissue remains a huge challenge. Here we introduce a dual activatable fluorescent probe PN910 located in the second near‐infrared window (NIR‐II, 900–1700 nm), which shows high selectivity toward H2O2 and OONO− at pH beyond 7.4. Then we verified that PN910 could be used for the real‐time, specific and accurate monitoring of cystitis and colitis for living animals. This report presents a unique approach to the development of dual activatable probe for in vivo biosensing. Here we developed a ROS/RNS and base dual activatable NIR‐II molecular probe PN910 based on modulating the intramolecular charge transfer (ICT) effect of a merocyanine fluorophore named Chrodol‐3. In vitro and in vivo experiments confirmed that PN910 is a reliable NIR‐II sensor for the non‐invasive specific monitoring of H2O2 and ONOO− in alkaline tissue.