title: Quantification of proteins using enhanced etching of Ag coated Au nanorods by the Cu(2+)/bicinchoninic acid pair with improved sensitivity.
abstract: Plasmonic nanosensors show great potential in ultrasensitive detection, especially with the plasmon peak position as the detection modality. Herein, a new sensitive but simple total protein quantification method termed the SPR-BCA assay is demonstrated by combining plasmonic nanosensors with protein oxidation by Cu(2+). The easy tuning of localized surface plasmon resonance (LSPR) features of plasmonic nanostructures makes them ideal sensing platforms. We found that the Cu(2+)/bicinchoninic acid (BCA) pair exhibits accelerated etching of Au@Ag nanorods and results in the LSPR peak shift. A linear relationship between Cu(2+) and the LSPR shift is found in a double logarithmic coordinate. Such double logarithm relationship is transferred to the concentration of proteins. Theoretical simulation shows that Au nanorods with large aspect ratios and small core sizes show high detection sensitivity. Via optimized sensor design, we achieved an increased sensitivity (the limit of detection was 3.4 ng ml(-1)) and a wide working range (0.5 to 1000 μg ml(-1)) compared with the traditional BCA assay. The universal applicability of our method to various proteins further proves its potential in practical applications.
authors.affiliation: CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, P. R. China. wuxc@nanoctr.cn and University of the Chinese Academy of Sciences, Beijing 100190, P. R. China.
authors.forename: Wenqi
authors.initials: W
authors.lastname: Liu
authors.affiliation: CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, P. R. China. wuxc@nanoctr.cn and University of the Chinese Academy of Sciences, Beijing 100190, P. R. China.
authors.forename: Shuai
authors.initials: S
authors.lastname: Hou
authors.affiliation: CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, P. R. China. wuxc@nanoctr.cn and University of the Chinese Academy of Sciences, Beijing 100190, P. R. China.
authors.forename: Jiao
authors.initials: J
authors.lastname: Yan
authors.affiliation: CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, P. R. China. wuxc@nanoctr.cn and University of the Chinese Academy of Sciences, Beijing 100190, P. R. China.
authors.forename: Hui
authors.initials: H
authors.lastname: Zhang
authors.affiliation: CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, P. R. China. wuxc@nanoctr.cn.
authors.forename: Yinglu
authors.initials: Y
authors.lastname: Ji
authors.affiliation: CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, P. R. China. wuxc@nanoctr.cn.
authors.forename: Xiaochun
authors.initials: X
authors.lastname: Wu
mesh_terms: D000465:Algorithms; D000818:Animals; D015374:Biosensing Techniques / Q000379:methods; D002417:Cattle; D003300:Copper / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D057230:Limit of Detection; D053768:Metal Nanoparticles / Q000737:chemistry; D046529:Microscopy, Electron, Transmission; D036103:Nanotechnology / Q000379:methods; D043942:Nanotubes / Q000737:chemistry; D011506:Proteins / Q000737:chemistry*; D011804:Quinolines / Q000737:chemistry; D015203:Reproducibility of Results; D012710:Serum Albumin, Bovine / Q000737:chemistry; D012834:Silver / Q000737:chemistry*; D020349:Surface Plasmon Resonance
chemical_list: D011506:Proteins; D011804:Quinolines; D012710:Serum Albumin, Bovine; D012834:Silver; D006046:Gold; D003300:Copper; C047117:bicinchoninic acid