title: A ratiometric fluorescent probe for alkaline phosphatase via regulation of excited-state intramolecular proton transfer.
abstract: A ratiometric fluorescent probe 2-(benzimidazol-2-yl)phenyl phosphoric acid (1) for alkaline phosphatase (ALP) is designed and synthesized. The method employs the modulation of the excited-state intramolecular proton transfer (ESIPT) process of 2-(2'-hydroxyphenyl)benzimidazole (HPBI) through the hydroxyl group protection/deprotection reaction. Upon phosphorylated with POCl3 , HPBI shows only an emission peak at 363 nm due to the blockage of ESIPT. However, once selective enzymatic hydrolysis with alkaline phosphatase (ALP) in Tris-HCl buffer occurs, the probe 1 is returned to HPBI and the ESIPT process is switched on, which results in a decrease in the emission band at 363 nm and an increase in a new fluorescence peak around 430 nm. The fluorescence intensity ratio at 430 and 360 nm (I430/I360) increases linearly with the activity of ALP up to 0.050 U/mL and the detection limit is 0.0013 U/mL. The proposed probe shows excellent specificity toward ALP.
authors.affiliation: Key Study Center of the National Ministry of Education for Tropical Resources Utilization, College of Materials and Chemistry, Hainan University, Haikou, 570228, China.
authors.forename: Chunlei
authors.initials: C
authors.lastname: Fan
authors.affiliation: Key Study Center of the National Ministry of Education for Tropical Resources Utilization, College of Materials and Chemistry, Hainan University, Haikou, 570228, China.
authors.forename: Shengxu
authors.initials: S
authors.lastname: Luo
authors.affiliation: Key Study Center of the National Ministry of Education for Tropical Resources Utilization, College of Materials and Chemistry, Hainan University, Haikou, 570228, China.
authors.forename: Haiping
authors.initials: H
authors.lastname: Qi
mesh_terms: D000469:Alkaline Phosphatase / Q000032:analysis* / Q000378:metabolism; D001562:Benzimidazoles / Q000138:chemical synthesis / Q000737:chemistry*; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000032:analysis* / Q000138:chemical synthesis / Q000737:chemistry*; D011522:Protons; D013379:Substrate Specificity
chemical_list: C000613348:2-(benzimidazol-2-yl)phenyl phosphoric acid; D001562:Benzimidazoles; D005456:Fluorescent Dyes; D011522:Protons; D000469:Alkaline Phosphatase
keywords: alkaline phosphatase; excited-state intramolecular proton transfer; fluorescent probe; ratiometric