A platinum(II)-acetylide-based conjugated polyelectrolyte for hypoxia imaging via ratiometric and time-resolved luminescence microscopy

Abstract

A platinum(II)-acetylide-based conjugated polyelectrolyte has been designed and synthesized by using polyfluorenes as an O2-insensitive fluorophore and Pt(II) complex as an O2-sensitive phosphor, which can generate conjugated polyelectrolyte nanoparticle (CPE-nanoparticle) in the aqueous solution owing to their amphiphilic structures. The CPE-nanoparticle displays good sensitivity to O2 concentration and can detect oxygen levels reversibly. The intracellular ratiometric O2 sensing performance of the CPE-nanoparticle has been demonstrated by the remarkable variation in the Igreen/Iblue ratio values (0.18–0.85) in HeLa cells under different O2 levels. Furthermore, O2 level detection was carried out through time-resolved luminescence imaging (TRLI) to demonstrate the accuracy of the probe based on the CPE-nanoparticle. The CPE-nanoparticle shows a high phosphorescence quantum yield (19.98%) and oxygen quenching efficiency (0.975), which are superior to the existing O2 probe. The CPE-nanoparticle has been successfully applied in photoluminescence lifetime imaging and time-gated luminescence imaging for monitoring intracellular O2 levels.