title: Enhanced ratiometric pH sensing using SNAFL-2 on silver island films: metal-enhanced fluorescence sensing.
abstract: We have explored the opportunities for enhanced ratiometric pH sensing using the well-known carboxy seminaphthofluorescein (SNAFL-2) and silver island films (SiFs). Our results show that the metallic surfaces can provide up to a 40-fold increase in probe fluorescence intensity as compared to nonmetallic surfaces with the same probe coverage. However, while the S/N is significantly better for pH sensing, the emission wavelength ratiometric values are similar to that obtained in solution, due to the fact that the emission of both the acidic and basic forms of the probe are enhanced to similar extents. To the best of our knowledge this is the first report of enhanced ratiometric fluorescence sensing on metallic surfaces.
authors.affiliation: Institute of Fluorescence, Laboratory for Advanced Medical Plasmonics, Medical Biotechnology Center, University of Maryland Biotechnology Institute, 725 West Lombard St, Baltimore, Maryland 21201, USA.
authors.forename: Kadir
authors.initials: K
authors.lastname: Aslan
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Lakowicz
authors.forename: Henryk
authors.initials: H
authors.lastname: Szmacinski
authors.forename: Chris D
authors.initials: CD
authors.lastname: Geddes
mesh_terms: D005452:Fluoresceins; D005456:Fluorescent Dyes; D006863:Hydrogen-Ion Concentration; D049329:Nanostructures; D011874:Radiometry / Q000379:methods*; D012834:Silver; D013050:Spectrometry, Fluorescence; D013499:Surface Properties
chemical_list: D005452:Fluoresceins; D005456:Fluorescent Dyes; C401959:seminaphthofluorescein; D012834:Silver