title: A novel label-free upconversion fluorescence resonance energy transfer-nanosensor for ultrasensitive detection of protamine and heparin.
abstract: A novel label-free fluorescence nanosensor was developed for ultrasensitive detection of protamine and heparin based on fluorescence resonance energy transfer (FRET) between NaYF4:Yb,Er upconversion nanoparticles (UCNPs) and gold nanoparticles (AuNPs). The FRET system was formed by the electrostatic adsorption of AuNPs on UCNPs, and the fluorescence of UCNPs was significantly quenched. When protamine was added to the mixture of UCNPs-AuNPs, the AuNPs interacted with protamine and then desorbed from the surface of UCNPs and aggregated, resulting in the recovery of the fluorescence of UCNPs. On the addition of both protamine and heparin, the FRET system formed owing to the stronger interaction between heparin and protamine than that with AuNPs, leading to a marked fluorescence quenching of UCNPs. The concentrations of protamine and heparin were proportional to the changes of the fluorescence of UCNPs. The linear response range was obtained over the concentration ranges of 0.02 to 1.2μg/ml and 0.002 to 2.0μg/ml with low detection limits of 6.7 and 0.7ng/ml for protamine and heparin, respectively. Simultaneous measurement of protamine and heparin in human serum can be achieved, suggesting that the nanosensor can be used in a complex biological sample matrix.
authors.affiliation: Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education), College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081, People's Republic of China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Long
authors.affiliation: Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education), College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081, People's Republic of China.
authors.forename: Jiangna
authors.initials: J
authors.lastname: Zhao
authors.affiliation: Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education), College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081, People's Republic of China.
authors.forename: Bangda
authors.initials: B
authors.lastname: Yin
authors.affiliation: Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education), College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081, People's Republic of China.
authors.forename: Haitao
authors.initials: H
authors.lastname: Li
authors.affiliation: Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education), College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081, People's Republic of China. Electronic address: zhangyy@hunnu.edu.cn.
authors.forename: Youyu
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education), College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081, People's Republic of China.
authors.forename: Shouzhuo
authors.initials: S
authors.lastname: Yao
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D031541:Fluorescence Resonance Energy Transfer; D006046:Gold / Q000737:chemistry; D006493:Heparin / Q000032:analysis*; D006801:Humans; D057230:Limit of Detection; D053768:Metal Nanoparticles / Q000737:chemistry; D008958:Models, Molecular; D008968:Molecular Conformation; D036103:Nanotechnology / Q000379:methods*; D011479:Protamines / Q000032:analysis*
chemical_list: D011479:Protamines; D006046:Gold; D006493:Heparin
keywords: Fluorescence resonance energy transfer; Gold nanoparticle; Heparin; Protamine; Upconversion nanoparticles