An ultrasensitive and selective method for visual detection of heparin in 100 % human plasma

Designing sensors for the visual and rapid sensing of the most widely used blood anticoagulant, Heparin, is essential, but yet remains quite a challenging task. Herein, we report an unsymmetrical cyanine-based probe molecule, commercially known as TO-PRO-3, for visually detecting heparin in aqueous samples. The demonstration of visual heparin sensing is based on a huge blue shift (similar to 115 nm) observed in the absorption maximum, which is significantly high as compared to the ones that are reported in literature. The spectroscopic features indicate the formation of H-aggregation of TO-PRO-3 in the presence of heparin. The interaction of TO-PRO-3 with heparin has also been investigated by a variety of other techniques, such as, steady-state emission, circular-dichroism, 1H NMR, dynamic light scattering (DLS), AFM along with molecular docking calculations. The sensing performance of TO-PRO-3 was found to be quite selective for heparin when compared with its structurally similar analogs, chondroitin sulfate and hyaluronic acid and the method offers a LOD of 5.2 nM in aqueous samples. The probe could also be utilized for sensing protamine and heparinase. The performance of the probe in the human serum and human plasma matrix pitches for its potential in real-life applications.

Automated summary

Designing a probe molecule for visually detecting the commonly used blood anticoagulant, Heparin, is challenging. This study introduces TO-PRO-3 as a cyanine-based probe that shows a large blue shift in absorption maximum when heparin is present. The spectroscopic features indicate the formation of H-aggregation of TO-PRO-3 in the presence of heparin. The probe exhibits high selectivity for heparin and has a low LOD in aqueous samples.