Bimodal Visualization of Endogenous Nitric Oxide inLysosomes with a Two-Photon Iridium(III) Phosphorescent Probe

Nitric oxide (NO) is a fundamental signaling molecule that shows complex effects on the catabolic autophagy process, which is closely linked with lysosomal function. However, owing to the dynamic transformation of the components of the highly heterogeneous lysosomes and the complicated microenvironment in lysosomes , it is hard to explore the interaction between NO and lysosomes. In this study, a new lysosome-targeted, pH-independent and two-photon phos-phorescent iridium(III) complex, Ir-BPDA, has been investigated for endogenous NO detection and imaging. The rational design of the probe, as the addition of the morpholine moieties and the substitution of a benzyl group in the amino group in Ir-BPDA, facilitates its accumulation in lysosomes and makes the reaction product with NO, Ir-BPDA-NO, insuscepti-ble in its phosphorescence intensity and lifetime against pH changes (pH 4~10), well suited for lysosomal NO detection (pH 4~6). Furthermore, Ir-BPDA exhibits a fast and 50-fold response to NO in phosphore...