title: Ratiometric fluorescent response of electrospun fibrous strips for real-time sensing of alkaline phosphatase in serum.
abstract: The development of rapid, convenient and reliable assays for monitoring alkaline phosphatase (ALP) levels is valuable for clinical diagnoses and biomedical research. In the current study, a ratiometric assay of ALP activity has been realized by covalent immobilization of fluorescein onto polyethylene terephthalate (PET) fibers, followed by electrostatic adsorption of bisquaternary ammonium salt of tetraphenylethene (TPE-2N+). In the absence of ALP, the complex formation between phosphorylated fluorescein and TPE-2N+results in the aggregation-induced emission (AIE) of TPE at 471nm. While in the presence of ALP, the hydrolysis of phosphoesters leads to a gradual removal of TPE-2N+and the restoration of fluorescein emission at 514nm. Fibers with surface amine densities of 30 nmol/mg show the most significant and almost linear increases in I514/I471ratios from 0.73 to 3.05 with increasing ALP concentrations from 0 to 100 mU/mL. The ratiometric fluorescence responses result in color changes of fibrous strips from blue (TPE-2N+) to green (fluorescein) under an ultraviolet lamp in a matter of minutes. The color changes are more suitable for an eyeball detection of ALP levels ranging from 0 to 80 mU/mL, which is included in the concentration range of ALP in human serum considering the dilution factor if necessary. The ALP detection indicates no apparent interference by serum components and good agreement with enzyme-linked immunosorbent assay (ELISA). Thus, this is the first study on ratiometric fluorescent assay of serum ALP levels by fibrous strips, which offers a capacity to exploit electrospun fibrous mats and ratiometric responses for real-time assays of bioactive substances as self-test devices.
authors.affiliation: Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, PR China.
authors.forename: Long
authors.initials: L
authors.lastname: Zhao
authors.affiliation: Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, PR China.
authors.forename: Songzhi
authors.initials: S
authors.lastname: Xie
authors.affiliation: Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, PR China.
authors.forename: Xiaojie
authors.initials: X
authors.lastname: Song
authors.affiliation: Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, PR China.
authors.forename: Jiaojun
authors.initials: J
authors.lastname: Wei
authors.affiliation: Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, PR China.
authors.forename: Zhao
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, PR China. Electronic address: xhli@swjtu.edu.cn.
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Li
mesh_terms: D000469:Alkaline Phosphatase / Q000032:analysis / Q000097:blood*; D000586:Amination; D064751:Ammonium Compounds / Q000737:chemistry; D015374:Biosensing Techniques / Q000379:methods*; D019793:Fluorescein / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry*; D006801:Humans; D057230:Limit of Detection; D057139:Nanofibers / Q000737:chemistry* / Q000648:ultrastructure; D011093:Polyethylene Terephthalates / Q000737:chemistry*; D011934:Reagent Strips / Q000032:analysis; D013050:Spectrometry, Fluorescence / Q000379:methods
chemical_list: D064751:Ammonium Compounds; D005456:Fluorescent Dyes; D011093:Polyethylene Terephthalates; D011934:Reagent Strips; D000469:Alkaline Phosphatase; D019793:Fluorescein
keywords: Aggregation-induced emission; Electrospun fibrous mats; Fluorescent color strip; Ratiometric detection; Real-time assay