Triplet–Triplet Annihilation Upconversion-Based Oxygen Sensors to Overcome the Limitation of Autofluorescence
Adrian A. Mendonsa, Cassandra C. Soeldner, Natalie E. Mudd, Samuel C. Saccomano, Kevin J. Cash
Abstract
Autofluorescence is one of the many challenges in bioimaging as it can mask the emission from fluorescent probes or markers, a limitation that can be overcome via upconversion. Herein, we have developed a nanosensor that uses triplet–triplet annihilation upconversion to optically report changes in the dissolved oxygen concentration. Using a sensitizer–annihilator dye pairing of platinum(II) octaethylporphyrin and 9,10-diphenylanthracene, we monitored the oxygen consumption (as a proxy for metabolic activity) over time in a biological system─ Saccharomyces cerevisiae (brewing yeast). The nanosensor demonstrated good reversibility over multiple cycles and showed good signal and colloidal stability when tested over the course of 7 days, and it was sensitive to dissolved oxygen from 0.00 to 3.17 mg/L O 2 . Additionally, there was no signal overlap between the nanosensor emission and S. cerevisiae autofluorescence, thus underscoring the utility of upconversion as a facile and economical means of overcoming autofluorescence.