title: A fluorescence ratiometric nano-pH sensor based on dual-fluorophore-doped silica nanoparticles.
abstract: We have synthesized dual-fluorophore-doped core-shell silica nanoparticles used as ratiometric pH sensor. The nanoparticles were prepared with a reverse microemulsion technique by simultaneously encapsulating two different fluorophores, the pH-sensitive dye fluorescein as a pH indicator and the pH-insensitive dye phenosafranine as an internal reference for fluorescence ratiometric measurement, into silica shell. The nanoparticles prevent the fluorescence dyes leaching from the silica matrix when immersed inside water. The hydrophilic silica shells were made by hydrolysing and polymerizing tetraethoxysilane (TEOS) in water-in-oil microemulsion. The fluorescence intensity ratio of the two dyes varied linearly as a function of pH in the range from 4.0 to 8.0. The sensor was also applied to measure pH of real water samples. The results are in good agreements with that using the conventional glass electrode method. The as-prepared fluorescent nanoparticles showed rapid response, excellent stability and high reproducibility as pH sensors.
authors.affiliation: College of Chemistry and Materials Science, Anhui Key Laboratory of Functional Molecular Solids, Anhui Normal University, Wuhu 241000, PR China.
authors.forename: Feng
authors.initials: F
authors.lastname: Gao
authors.forename: Lijuan
authors.initials: L
authors.lastname: Tang
authors.forename: Lu
authors.initials: L
authors.lastname: Dai
authors.forename: Lun
authors.initials: L
authors.lastname: Wang
mesh_terms: D019793:Fluorescein / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D053758:Nanoparticles / Q000737:chemistry*; D012821:Silanes / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry*; D013050:Spectrometry, Fluorescence / Q000379:methods*
chemical_list: D005456:Fluorescent Dyes; D012821:Silanes; C040733:tetraethoxysilane; D012822:Silicon Dioxide; D019793:Fluorescein