A Fluorophore‐Doped Polymer Nanomaterial for Referenced Imaging of pH and Temperature with Sub‐Micrometer Resolution

Abstract A new kind of pH and temperature sensitive material is reported. It is composed of dye‐doped polymer nanoparticles incorporated into a thin film of a polyurethane hydrogel. The new pH/temperature‐sensitive nanoparticles are obtained by post‐staining oxygen‐impermeable amino‐functionalized polyacrylonitrile nanoparticles with a long‐lifetime reference dye. Staining is followed by covalently linking fluorescein isothiocyanate onto the surface of the nanoparticle. The new sensor material has several distinct features: a) it enables imaging of pH via time domain dual‐lifetime referencing; b) effects of temperature on pH sensing may be compensated for; and c) temperature can simultaneously be visualized via rapid lifetime imaging. The new material enables referenced and temperature‐compensated pH imaging with superior spatial resolution due to the use of nanosized sensor nanoparticles.