title: Ultrasensitive fluorescence detection of heparin based on quantum dots and a functional ruthenium polypyridyl complex.
abstract: A new strategy for the detection of heparin is developed by utilizing quantum dots (QDs) and a functional ruthenium polypyridyl complex [Ru(phen)2(dppz-idzo)](2+) (phen=1,10-phenanthroline, dppz-idzo=dipyrido-[3,2-a:2',3'-c] phenazine-imidazolone). The emission of CdTe QDs is found to be quenched by Ru complex due to electron transfer. Upon addition of the polyanionic heparin, it could remove the quencher (Ru complex) from the surface of QDs owing to the electrostatic and/or hydrogen bonding interactions between heparin and Ru complex, which led to significant fluorescence recovery of CdTe QDs. The fluorescence intensity enhanced with the increase of heparin and a linear relationship was observed in the range of 21-77 nM for heparin detection in buffer solution and the limit of detection (LOD) is 0.38 nM. Moreover, the strategy was successfully applied to detect heparin as low as 0.68 nM with a linear range of 35-98 nM in fetal bovine serum samples. The selectivity results of the fluorescence assay revealed that our system displayed excellent fluorescence selectivity towards heparin over its analogues, such as chondroitin 4-sulfate (Chs) or hyaluronic acid (Hya). This fluorescence "switch on" assay for heparin is label-free, convenient, sensitive and selective, which can be used to detect heparin in biological systems even with the naked eyes.
authors.affiliation: Department of Chemistry, Tongji University, 1239 Siping Road, Shanghai 200092, China.
authors.forename: Yanlin
authors.initials: Y
authors.lastname: Cao
authors.affiliation: Department of Chemistry, Tongji University, 1239 Siping Road, Shanghai 200092, China. Electronic address: shishuo@tongji.edu.cn.
authors.forename: Shuo
authors.initials: S
authors.lastname: Shi
authors.affiliation: Department of Chemistry, Tongji University, 1239 Siping Road, Shanghai 200092, China.
authors.forename: Linlin
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Chemistry, Tongji University, 1239 Siping Road, Shanghai 200092, China.
authors.forename: Junliang
authors.initials: J
authors.lastname: Yao
authors.affiliation: Department of Chemistry, Tongji University, 1239 Siping Road, Shanghai 200092, China. Electronic address: tmyao@tongji.edu.cn.
authors.forename: Tianming
authors.initials: T
authors.lastname: Yao
mesh_terms: D000818:Animals; D000925:Anticoagulants / Q000097:blood; D015374:Biosensing Techniques / Q000379:methods*; D002417:Cattle; D006493:Heparin / Q000097:blood*; D007093:Imidazoles / Q000737:chemistry*; D045663:Quantum Dots; D015203:Reproducibility of Results; D012428:Ruthenium / Q000737:chemistry*; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence / Q000379:methods*
chemical_list: D000925:Anticoagulants; D007093:Imidazoles; C117197:imidazolone; D012428:Ruthenium; D006493:Heparin
keywords: Fetal bovine serum; Fluorescence; Heparin; Quantum dots; Ru complex