Two-Photon Oxygen Sensing with Quantum Dot-Porphyrin Conjugates

Supramolecular assemblies of a quantum dot (QD) associated to palladium­(II) porphyrins have been developed to detect oxygen (pO2) in organic solvents. Palladium porphyrins are sensitive in the 0–160 Torr range, making them ideal phosphors for in vivo biological oxygen quantification. Porphyrins with meso pyridyl substituents bind to the surface of the QD to produce self-assembled nanosensors. Appreciable overlap between QD emission and porphyrin absorption features results in efficient Förster resonance energy transfer (FRET) for signal transduction in these sensors. The QD serves as a photon antenna, enhancing porphyrin emission under both one- and two-photon excitation, demonstrating that QD-palladium porphyrin conjugates may be used for oxygen sensing over physiological oxygen ranges.