title: Facile and Sensitive Fluorescence Sensing of Alkaline Phosphatase Activity with Photoluminescent Carbon Dots Based on Inner Filter Effect.
abstract: A simple and sensitive fluorescent assay for detecting alkaline phosphatase (ALP) based on the inner filter effect (IFE) has been proven, which is conceptually different from the previously reported ALP fluorescent assays. In this sensing platform, N-doped carbon dots (CDs) with a high quantum yield of 49% were prepared by one-pot synthesis and were directly used as a fluorophore in IFE. p-Nitrophenylphosphate (PNPP) was employed to act as an ALP substrate, and its enzyme catalytic product (p-nitrophenol (PNP)) was capable of functioning as a powerful absorber in IFE to influence the excitation of fluorophore (CDs). When in the presence of ALP, PNPP was transformed into PNP and induced the absorption band transition from 310 to 405 nm, which resulted in the complementary overlap between the absorption of PNP and the excitation of CDs. Because of the competitive absorption, the excitation of CDs was significantly weakened, resulting in the quenching of CDs. The present IFE-based sensing strategy showed a good linear relationship from 0.01 to 25 U/L (R(2) = 0.996) and provided an exciting detection limit of 0.001 U/L (signal-to-noise ratio of 3). The proposed sensing approach was successfully applied to ALP sensing in serum samples, ALP inhibitor investigation and phosphatase cell imaging. The presented IFE-based CDs fluorescence sensing strategy gives new insight on the development of the facile and sensitive optical probe for enzyme activity assay because the surface modification or the linking between the receptor and the fluorophore is no longer required.
authors.affiliation: Key Laboratory of Life-Organic Analysis of Shandong Province, Qufu Normal University , Qufu 273165, People's Republic of China.|Key Laboratories of Chemical Safety and Health, China National Center for Food Safety Risk Assessment , Beijing 100050, People's Republic of China.
authors.forename: Guoliang
authors.initials: G
authors.lastname: Li
authors.affiliation: Key Laboratory of Life-Organic Analysis of Shandong Province, Qufu Normal University , Qufu 273165, People's Republic of China.
authors.forename: Huili
authors.initials: H
authors.lastname: Fu
authors.affiliation: Key Laboratory of Life-Organic Analysis of Shandong Province, Qufu Normal University , Qufu 273165, People's Republic of China.
authors.forename: Xuejie
authors.initials: X
authors.lastname: Chen
authors.affiliation: Key Laboratory of Life-Organic Analysis of Shandong Province, Qufu Normal University , Qufu 273165, People's Republic of China.
authors.forename: Peiwei
authors.initials: P
authors.lastname: Gong
authors.affiliation: Key Laboratory of Life-Organic Analysis of Shandong Province, Qufu Normal University , Qufu 273165, People's Republic of China.
authors.forename: Guang
authors.initials: G
authors.lastname: Chen
authors.affiliation: Key Laboratory of Life-Organic Analysis of Shandong Province, Qufu Normal University , Qufu 273165, People's Republic of China.
authors.forename: Lian
authors.initials: L
authors.lastname: Xia
authors.affiliation: Key Laboratory of Life-Organic Analysis of Shandong Province, Qufu Normal University , Qufu 273165, People's Republic of China.
authors.forename: Hua
authors.initials: H
authors.lastname: Wang
authors.affiliation: Key Laboratory of Life-Organic Analysis of Shandong Province, Qufu Normal University , Qufu 273165, People's Republic of China.|Key Laboratory of Tibetan Medicine Research, Northwest Institute of Plateau Biology, Chinese Academy of Sciences , Xining 810001, People's Republic of China.
authors.forename: Jinmao
authors.initials: J
authors.lastname: You
authors.affiliation: Key Laboratories of Chemical Safety and Health, China National Center for Food Safety Risk Assessment , Beijing 100050, People's Republic of China.
authors.forename: Yongning
authors.initials: Y
authors.lastname: Wu
mesh_terms: D000469:Alkaline Phosphatase / Q000032:analysis*; D000818:Animals; D015374:Biosensing Techniques / Q000379:methods*; D002244:Carbon; D002460:Cell Line; D057075:Enzyme Assays; D005453:Fluorescence; D008027:Light; D051379:Mice; D009596:Nitrophenols / Q000378:metabolism; D009943:Organophosphorus Compounds / Q000378:metabolism; D045663:Quantum Dots
chemical_list: D009596:Nitrophenols; D009943:Organophosphorus Compounds; C008644:nitrophenylphosphate; D002244:Carbon; D000469:Alkaline Phosphatase; C024836:4-nitrophenol