A label-free fluorescent-hydrogel sensor for heparin detection in diluted whole blood

Heparin is a widely used blood anticoagulant and its monitoring in blood is essential during surgery. Unavoidable interference factors such as blood color and luminescence can interfere with the fluorescence visualization of heparin. Herein, we found a ratiometric fluorescence probe consisting of SYBR green and cresyl violet responsive to heparin mainly based on electrostatic interactions. A simple sensor was further embedded in an agarose hydrogel, exhibiting an obvious color change from orange to green without complex pretreatment of blood, which overcomes the susceptibility of fluorescence sensors toward biological samples.