title: A peptide with a cysteine terminus: probe for label-free fluorescent detection of thrombin activity.
abstract: Thrombin has been implicated in atherosclerotic disease development. However, thrombin activity detection is currently limited because of the lack of convenient fluorescent probes. We developed a label-free fluorescent method to assay thrombin activity on the basis of a designed peptide probe with a thrombin-cleavable peptide sequence and a cysteine terminus. The peptide probe can be conjugated to DNA-templated silver nanoclusters (DNA-AgNCs) through Ag-S bonding; as a result, the fluorescence of DNA-AgNCs was enhanced. As the DNA-AgNCs-peptide conjugate was adsorbed to graphene oxide (GO), the enhanced fluorescence of DNA-AgNCs was quenched. Once the peptide probe was cleaved by thrombin, the resulting release of the DNA-AgNCs from the surface of GO restored the enhanced fluorescence. Thrombin can be determined with a linear range of 0.0-50.0 nM with a detection limit of 1 nM. The thrombin-sensitive probe with a cysteine terminus may be developed into probes to detect other proteases.
authors.affiliation: Key Laboratory of Analytical Chemistry for Life Science of Shaanxi Province, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an 710062, PR China. ydzhang@snnu.edu.cn.
authors.forename: Jingjing
authors.initials: J
authors.lastname: Feng
authors.forename: Caixia
authors.initials: C
authors.lastname: Zhuo
authors.forename: Xuejuan
authors.initials: X
authors.lastname: Ma
authors.forename: Shuangqin
authors.initials: S
authors.lastname: Li
authors.forename: Yaodong
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D015374:Biosensing Techniques; D003545:Cysteine / Q000737:chemistry*; D004247:DNA / Q000737:chemistry; D006108:Graphite; D006801:Humans; D053768:Metal Nanoparticles; D010455:Peptides / Q000737:chemistry*; D012834:Silver; D013917:Thrombin / Q000032:analysis*
chemical_list: D010455:Peptides; D012834:Silver; D006108:Graphite; D004247:DNA; D013917:Thrombin; D003545:Cysteine