phosphoanhydride bonds. 2 PolyP plays diverse roles in both prokaryotic and eukaryotic cells. For example, it is involved in energy storage, molecular chaperoning, regulating apoptosis, hemostatis and thrombosis, 6 bone mineralization and proinflammatory functions, and oxidative stress response. 8 Moreover, polyP has been linked to cognitive performance as well as neurodegenerative conditions such as Parkinson's disease, Alzheimer's disease, and amyotrophic lateral sclerosis. Short-chain polyPs are found in parasites such as Trypanosoma cruzi, Trypanosoma brucei, and Leishmania major where they are important for parasite metabolism. Besides its biological roles, polyP is also important in biotechnological applications such as e.g. ATP regeneration systems using polyP kinases. Furthermore, the ability of microorganisms to accumulate polyP is used to remove phosphates from wastewater. Given the diverse areas in which polyP plays an important role, there is a significant demand for simple chemical sensors that enable the detection of polyP, ideally with selectivity regarding chain length. For biological applications, such detection would benefit from selectivity over other abundant condensed phosphates, such as e.g. ATP. Currently, there is only a very limited number of colorimetric and fluorescent probes available to visualise polyPs. The use of 4ʹ,6-diamidino-2-phenylindole (DAPI), a yellow fluorescent compound in complex with polyP, is the most popular approach, owing to its significant fluorescence shift when binding to polyP. In addition to DAPI, toluidine blue has also been used for the detection of polyPs. However, literature reports that only polyPs with a chain length longer than 15 units are detected by DAPI and toluidine blue. 1 Also, some interferences with other phosphate containing molecules have been reported.