Aggregachromic Fluorogenic Asymmetric Cyanine Probes for Sensitive Detection of Heparin and Protamine

The precise and fast detection of heparin, the most widely used anticoagulant, remains a significant challenge for assessing its use in a clinical setting. In this work, we adapt a well-established asymmetric cyanine fluorogenic platform for the purpose of ultrasensitive heparin detection in the presence of common interferant chemical species. Three analogous fluorescence probes are synthesized in order to optimize for the number of binding moieties. Their interaction with heparin is studied using steady-state absorption, fluorescence, and circular dichroism spectroscopy. The obtained probes exhibit a highly sensitive "turn-on" fluorescence response to heparin, with a LOD in the 10-25 nM range, well within practical requirement, as well as a visible colorimetric change. The heparin-probe complex is also employed as a sensitive detection platform for protamine, both in the "turn-off" fluorescence and ratiometric detection schemes.