Refashioning benzothiadiazole dye as an activatable nanoprobe for biomarker detection with NIR-II fluorescence/optoacoustic imaging

Endogenous nitric oxide is important for living beings; hence, accurate and non-invasive detection of nitric oxide (NO) in situ is of significance. Benzothiadiazole-core chromophores are important near-infrared II (NIR-II) dyes, but such limitations as fluorescence quenching in aqueous media and non-activatable response constitute major barriers for biological applications. To address these issues, here we report an activatable nanoprobe, [email protected]βCD, with aggregation-induced emission for detecting the biomarker NO. The molecular probe BNDA and 2-hydroxypropyl-β-cyclodextrin (HβCD) form the amphiphilic host-guest complex BNDA-HβCD, which readily forms nanoaggregates in aqueous media and thereby affords the nanoprobe [email protected]βCD. NO reacts with the probe and generates the activated probe, which displays strong NIR-II fluorescence emission and optoacoustic signals. [email protected]βCD can detect liver injury and monitor therapeutic outcome in a mouse model by detecting hepatic NO; it can also image NO in soybean sprouts. The results indicate that [email protected]βCD is a robust tool for detecting NO in both animals and plants.