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, BNDA@H beta CD, with aggregation-induced emission for detecting the biomarker NO. The molecular probe BNDA and 2-hydroxypropyl-beta-cyclodextrin (H beta CD) form the amphiphilic host-guest complex BNDA-H beta CD, which readily forms nanoaggregates in aqueous media and thereby affords the nanoprobe BNDA@H beta CD. NO reacts with the probe and generates the activated probe, which displays strong NIR-II fluorescence emission and optoacoustic signals. BNDA@H beta CD 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 BNDA@H beta CD is a robust tool for detecting NO in both animals and plants.

Automated summary

Endogenous nitric oxide plays an important role in living beings, making accurate and non-invasive detection of nitric oxide crucial. This study presents an activatable nanoprobe, BNDA@H beta CD, for detecting nitric oxide using aggregation-induced emission. The probe forms nanoaggregates in aqueous media and generates activated probe upon reaction with nitric oxide, resulting in strong NIR-II fluorescence emission and optoacoustic signals. BNDA@H beta CD can detect liver injury and monitor therapeutic outcome in a mouse model, as well as image nitric oxide in soybean sprouts. The results demonstrate that BNDA@H beta CD is a powerful tool for nitric oxide detection in both animals and plants.