Fluorescent pH Sensors for Broad-Range pH Measurement Based on a Single Fluorophore

• Published in: Analytical chemistry (Washington) 2015-06, Vol.87 (12), p.5897-5904
• Main Authors: Qi, Jing, Liu, Daying, Liu, Xiaoyan, Guan, Shiquan, Shi, Fengli, Chang, Hexi, He, Huarui, Yang, Guangming
• Format: Article
• Language: English
• Subjects: 1-Naphthylamine - analogs & derivatives; 1-Naphthylamine - chemistry; Acidity; Analytical chemistry; Chemical compounds; Electrodes; Electron transfer; Fluorescence; Fluorescent Dyes - chemical synthesis; Fluorescent Dyes - chemistry; Hydrogen-Ion Concentration; Ionophores - chemistry; Molecular Structure; Naphthalimides - chemistry; Optical properties; Optical sensors; Quinolones - chemistry; Receptors; Sensors; Signal transduction
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/acs.analchem.5b00053

We constructed a series of novel optical sensors for determination of broad-range pH based on a single fluorophore and multi-ionophores with different pK a values. These optical sensors use photoinduced electron transfer (PET) as the signal transduction and follow the design concept of “fluorophore-spacer-receptor (ionophore)” which employs 4-amino-1,8-naphthalimide as the single fluorophore, ethyl moiety as the spacer, and a series of phenols and anilines as the receptors. Key to the successful development of this sensor system is that coupling the receptors with six different pK a values with a single fluorophore produces the correct optical properties. This rational design affords a series of optical pH sensors with unique fluorescence property and accurately tunable pH measurement ranging from 1 to 14 pH units. Because of covalent immobilization of the indicators, these sensors demonstrate excellent stability, adequate reversibility, and satisfactory dynamic range up to full pH ranges (pH 1–14).