Thermoresponsive low-power light upconverting polymer nanoparticles

We report highly efficient sensitized triplet-triplet annihilation based upconversion in aqueous suspensions of nanoparticles prepared from 9,10-diphenylanthracene- terminated poly(epsilon-caprolactone) and with platinum octaethylporphyrin as the sensitizer. The particles upconversion characteristics are strongly temperature-dependent. This feature gives insights into the mechanisms enabling the process in the nanoparticle environment, and the specific temperature range in which the photophysical parameters change is suitable for live cell and in vivo temperature sensing.