A facile four-armed AIE fluorescent sensor for heparin and protamine

In this research a four-armed amino-tailored tetraphenylethene TPE-NH2 was synthesized, and it could detect heparin (Hep) quantitatively, primarily promoted by the electrostatic interactions between its positively charged amino groups and the sulfates, carboxylates of heparin. On account of the aggregation-induced emission (AIE) nature of tetraphenylethene backbone, the aggregation restricted the rotation of CeC single bond through rigidifying the conformation of TPE-NH2, thus making it display intense fluorescence with a broad working range (<= 2.0 mu g/mL) and a low detection limit (down to 35.89 ng/mL) for heparin. Meanwhile, the TPE-NH2/Hep complex can be further disaggregated by protamine due to the stronger affinity between heparin and protamine, consequently leading to the highly sensitive detection of protamine. What's more, the low toxicity of TPE-NH2 makes it a potential functional sensor for detecting heparin in the matrix of human serum.