A facile chemiluminescence sensing for ultrasensitive detection of heparin using charge effect of positively-charged AuNPs.

Heparin is a glycosaminoglycan with the highest negative charge density of any known biological molecule. Herein, this highly negative charge structure of heparin and the charge effect from positively-charged AuNPs for luminol chemiluminescence (CL) reaction were combined to build a facile and sensitive CL strategy for detection of heparin. The highly negative charge structure of heparin molecules (four negatively-charged side groups per repeat unit) and the effective signal amplification of charge effect from positively-charged AuNPs make this analysis to display high sensitivity for heparin detection, and the detection limit is as low as 0.06 ng/mL. It is about two orders of magnitude lower than the previously reported colorimetric assay and far lower than the current analysis methods. The established CL strategy is to use the electrostatic interaction between heparin and signal probe (positively-charged AuNPs). Since polyanionic heparin has the highest negative charge in biological system, this CL sensing shows high selectivity for the detection of heparin, and hyaluronic acid (HA), an analogue of heparin, cannot cause interference. This CL sensing succeeded in detecting heparin in human serum samples. Besides, polycationic protamine, heparin antidote, can respond to the system's CL signals through its strong interactions with heparin, thus indirectly detecting protamine. For protamine in serum samples, the detection result was basically consistent with Coomassie brilliant blue assay.