A novel fluorescence turn-on assay for heparin has been developed based on DNA-templated gold nanoclusters (AuNCs) and Cytochrome c (Cyt c). In the design, poly A (A15) ssDNA was selected as a template for fabricating AuNCs. AuNCs possess strong fluorescence emission at 471 nm. Upon addition of Cyt c, the fluorescence of AuNCs was quenched effectively by electron transfer (ET) between AuNCs and the heme cofactor of Cyt c. In the presence of heparin, the much higher electrostatic binding of heparin to Cyt c caused Cyt c to be away from AuNCs, leading to a recovery of fluorescence intensity of AuNCs. The proposed method was found to be simple, fast, and sensitive for heparin detection, with a linear range from 0.5 μg/mL to 12 μg/mL, and a detection limit of 0.15 μg/mL. Furthermore, this work was successfully applied to detection of heparin in fetal bovine serum samples, with good recoveries from 93.53% to 103.6%.

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