Related Experiment Video
Updated: Dec 17, 2025

Ratiometric Imaging of Extracellular pH in Dental Biofilms
Published on: March 9, 2016
Characterization of a Bio-sourced, Fluorescent, Ratiometric pH Indicator with Alkaline pKa
Samar Alheety1, Domenic Valenti1, Nirvani Mujumdar1
1University of Central Florida, Orlando, FL.
Abstract:
Utilizing organisms as sources of fluorophores relieves the demand for petroleum feedstock in organic synthesis of fluorescent products, and endophytic fungi provide a promising vein for natural fluorescent products. We report the characterization of a pH-responsive fluorophore from an endophytic fungus isolated from sand pine. The endogenous fluorescence of the live organism was measured using fluorescence microscopy. Computational interpretation of the spectra was accomplished with time-dependent density functional theory methods. The combined use of experimental and theoretically predicted spectra revealed the pH equilibria and photoexcited tautomerization of the natural product, 5-methylmellein. This product shows promise both as a stand-alone pH-indicating fluorophore, with alkaline pKa , and as "green" feedstock for synthesis of custom fluorophores.
Related Concept Videos
Indicators
Photoluminescence: Applications
Variables Affecting Phosphorescence and Fluorescence
Titration of a Weak Acid with a Weak Base
As a result, there is no simple...
Fluorescence and Phosphorescence: Instrumentation
Titration of Polyprotic Base with a Strong Acid

