(484d) Ionophore-Based Optical Sensors Incorporating Long-Lifetime Phosphorescent Microparticles for Background-Free Ion Detection in Biological Samples

Fluorescent sensors are ideal for biological applications due to their low invasiveness and miniaturizability. However, signal interference from autofluorescence and scattering limits their practical application. Long-lifetime phosphorescent materials have emission lifetimes on the order of hours or even days, and have long been used commercial in street signs and ‘glow-in-the-dark’ materials. More recently these materials have attracted interest as agents for biological imaging and sensing as a method for reducing background noise, since, by programming a delay between excitation and emission collection, the short-lived signals from scattering and autofluorescence can be avoided completely. In this work we demonstrate an ionophore-based optical sensor incorporating long-lifetime phosphorescent microparticles for background-free sodium detection in biological samples. We couple the phosphorescent microparticles to a pH-sensitive quencher dye and sodium-binding ionophore to create a dynamic and reversible optode film selective for sodium. We also characterize the sensor in terms of selectivity and stability and demonstrate its usefulness to detect sodium levels in human serum.